Journal of Signal Transduction http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Signaling Pathways Involved in Renal Oxidative Injury: Role of the Vasoactive Peptides and the Renal Dopaminergic System Tue, 11 Nov 2014 07:40:22 +0000 http://www.hindawi.com/journals/jst/2014/731350/ The physiological hydroelectrolytic balance and the redox steady state in the kidney are accomplished by an intricate interaction between signals from extrarenal and intrarenal sources and between antinatriuretic and natriuretic factors. Angiotensin II, atrial natriuretic peptide and intrarenal dopamine play a pivotal role in this interactive network. The balance between endogenous antioxidant agents like the renal dopaminergic system and atrial natriuretic peptide, by one side, and the prooxidant effect of the renin angiotensin system, by the other side, contributes to ensuring the normal function of the kidney. Different pathological scenarios, as nephrotic syndrome and hypertension, where renal sodium excretion is altered, are associated with an impaired interaction between two natriuretic systems as the renal dopaminergic system and atrial natriuretic peptide that may be involved in the pathogenesis of renal diseases. The aim of this review is to update and comment the most recent evidences about the intracellular pathways involved in the relationship between endogenous antioxidant agents like the renal dopaminergic system and atrial natriuretic peptide and the prooxidant effect of the renin angiotensin system in the pathogenesis of renal inflammation. N. L. Rukavina Mikusic, M. C. Kravetz, N. M. Kouyoumdzian, S. L. Della Penna, M. I. Rosón, B. E. Fernández, and M. R. Choi Copyright © 2014 N. L. Rukavina Mikusic et al. All rights reserved. Signaling Network Map of Endothelial TEK Tyrosine Kinase Mon, 13 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/jst/2014/173026/ TEK tyrosine kinase is primarily expressed on endothelial cells and is most commonly referred to as TIE2. TIE2 is a receptor tyrosine kinase modulated by its ligands, angiopoietins, to regulate the development and remodeling of vascular system. It is also one of the critical pathways associated with tumor angiogenesis and familial venous malformations. Apart from the vascular system, TIE2 signaling is also associated with postnatal hematopoiesis. Despite the involvement of TIE2-angiopoietin system in several diseases, the downstream molecular events of TIE2-angiopoietin signaling are not reported in any pathway repository. Therefore, carrying out a detailed review of published literature, we have documented molecular signaling events mediated by TIE2 in response to angiopoietins and developed a network map of TIE2 signaling. The pathway information is freely available to the scientific community through NetPath, a manually curated resource of signaling pathways. We hope that this pathway resource will provide an in-depth view of TIE2-angiopoietin signaling and will lead to identification of potential therapeutic targets for TIE2-angiopoietin associated disorders. Aafaque Ahmad Khan, Varot K. Sandhya, Priyata Singh, Deepak Parthasarathy, Awinav Kumar, Jayshree Advani, Rudrappa Gattu, Dhanya V. Ranjit, Rama Vaidyanathan, Premendu Prakash Mathur, T. S. Keshava Prasad, F. Mac Gabhann, Akhilesh Pandey, Rajesh Raju, and Harsha Gowda Copyright © 2014 Aafaque Ahmad Khan et al. All rights reserved. TGF-β Signaling Cooperates with AT Motif-Binding Factor-1 for Repression of the α-Fetoprotein Promoter Thu, 03 Jul 2014 06:25:44 +0000 http://www.hindawi.com/journals/jst/2014/970346/ α-Fetoprotein (AFP) is known to be highly produced in fetal liver despite its barely detectable level in normal adult liver. On the other hand, hepatocellular carcinoma often shows high expression of AFP. Thus, AFP seems to be an oncogenic marker. In our present study, we investigated how TGF-β signaling cooperates with AT motif-binding factor-1 (ATBF1) to inhibit AFP transcription. Indeed, the expression of AFP mRNA in HuH-7 cells was negatively regulated by TGF-β signaling. To further understand how TGF-β suppresses the transcription of the AFP gene, we analyzed the activity of the AFP promoter in the presence of TGF-β. We found that the TGF-β signaling and ATBF1 suppressed AFP transcription through two ATBF1 binding elements (AT-motifs). Using a heterologous reporter system, both AT-motifs were required for transcriptional repression upon TGF-β stimulation. Furthermore, Smads were found to interact with ATBF1 at both its N-terminal and C-terminal regions. Since the N-terminal (ATBF1N) and C-terminal regions of ATBF1 (ATBF1C) lack the ability of DNA binding, both truncated mutants rescued the cooperative inhibitory action by the TGF-β signaling and ATBF1 in a dose-dependent manner. Taken together, these findings indicate that TGF-β signaling can act in concert with ATBF1 to suppress the activity of the AFP promoter through direct interaction of ATBF1 with Smads. Nobuo Sakata, Satoshi Kaneko, Souichi Ikeno, Yutaka Miura, Hidekazu Nakabayashi, Xue-Yuan Dong, Jin-Tang Dong, Taiki Tamaoki, Naoko Nakano, and Susumu Itoh Copyright © 2014 Nobuo Sakata et al. All rights reserved. A Network Map of FGF-1/FGFR Signaling System Wed, 16 Apr 2014 10:15:12 +0000 http://www.hindawi.com/journals/jst/2014/962962/ Fibroblast growth factor-1 (FGF-1) is a well characterized growth factor among the 22 members of the FGF superfamily in humans. It binds to all the four known FGF receptors and regulates a plethora of functions including cell growth, proliferation, migration, differentiation, and survival in different cell types. FGF-1 is involved in the regulation of diverse physiological processes such as development, angiogenesis, wound healing, adipogenesis, and neurogenesis. Deregulation of FGF-1 signaling is not only implicated in tumorigenesis but also is associated with tumor invasion and metastasis. Given the biomedical significance of FGFs and the fact that individual FGFs have different roles in diverse physiological processes, the analysis of signaling pathways induced by the binding of specific FGFs to their cognate receptors demands more focused efforts. Currently, there are no resources in the public domain that facilitate the analysis of signaling pathways induced by individual FGFs in the FGF/FGFR signaling system. Towards this, we have developed a resource of signaling reactions triggered by FGF-1/FGFR system in various cell types/tissues. The pathway data and the reaction map are made available for download in different community standard data exchange formats through NetPath and NetSlim signaling pathway resources. Rajesh Raju, Shyam Mohan Palapetta, Varot K. Sandhya, Apeksha Sahu, Abbas Alipoor, Lavanya Balakrishnan, Jayshree Advani, Bijesh George, K. Ramachandra Kini, N. P. Geetha, H. S. Prakash, T. S. Keshava Prasad, Yu-Jung Chang, Linyi Chen, Akhilesh Pandey, and Harsha Gowda Copyright © 2014 Rajesh Raju et al. All rights reserved. Signal Transduction in Astrocytes during Chronic or Acute Treatment with Drugs (SSRIs, Antibipolar Drugs, GABA-ergic Drugs, and Benzodiazepines) Ameliorating Mood Disorders Mon, 24 Feb 2014 11:05:01 +0000 http://www.hindawi.com/journals/jst/2014/593934/ Chronic treatment with fluoxetine or other so-called serotonin-specific reuptake inhibitor antidepressants (SSRIs) or with a lithium salt “lithium”, carbamazepine, or valproic acid, the three classical antibipolar drugs, exerts a multitude of effects on astrocytes, which in turn modulate astrocyte-neuronal interactions and brain function. In the case of the SSRIs, they are to a large extent due to -mediated upregulation and editing of genes. These alterations induce alteration in effects of cPLA2, GluK2, and the receptor, probably including increases in both glucose metabolism and glycogen turnover, which in combination have therapeutic effect on major depression. The ability of increased levels of extracellular K+ to increase is increased as a sign of increased K+-induced excitability in astrocytes. Acute anxiolytic drug treatment with benzodiazepines or receptor stimulation has similar glycogenolysis-enhancing effects. The antibipolar drugs induce intracellular alkalinization in astrocytes with lithium acting on one acid extruder and carbamazepine and valproic acid on a different acid extruder. They inhibit K+-induced and transmitter-induced increase of astrocytic and thereby probably excitability. In several cases, they exert different changes in gene expression than SSRIs, determined both in cultured astrocytes and in freshly isolated astrocytes from drug-treated animals. Leif Hertz, Dan Song, Baoman Li, Ting Du, Junnan Xu, Li Gu, Ye Chen, and Liang Peng Copyright © 2014 Leif Hertz et al. All rights reserved. Upregulation of Voltage-Gated Calcium Channel Cav1.3 in Bovine Somatotropes Treated with Ghrelin Wed, 18 Dec 2013 15:51:49 +0000 http://www.hindawi.com/journals/jst/2013/527253/ Activation of the growth hormone (GH) secretagogue receptor (GHS-R) by synthetic GH releasing peptides (GHRP) or its endogenous ligand (Ghrelin) stimulates GH release. Though much is known about the signal transduction underlying short-term regulation, there is far less information on the mechanisms that produce long-term effects. In the current report, using an enzyme-linked immunosorbent assay for GH detection and whole-cell patch-clamp recordings, we assessed the long-term actions of such regulatory factors on voltage-activated Ca2+ currents in bovine somatotropes (BS) separated on a Percoll gradient and detected by immunohistochemistry. After 24 h of treatment with Ghrelin (10 nM) or GHRP-6 (100 nM) enhanced BS secretory activity; GH secretion stimulated by GHS through the activation of GHS-R because treatment with the antagonist of GHS-R (D-Lys3-GHRP-6, 10 M) blocked the GH secretion, and the effect was dose and time dependent (24, 48, and 72 h). GH secretion stimulated by GHRP-6 was abolished by nifedipine (0.5 M), a blocker of L-type HVA Ca2+ channels, and KN-62 (10 M), an inhibitor of Ca2+/CaM-KII. After 72 h in culture, all recorded BS exhibited two main Ca2+ currents: a low voltage-activated (LVA; T-type) and a high voltage-activated (HVA; mostly dihydropyridine-sensitive L-type) current. Interestingly, HVA and LVA channels were differentially upregulated by Ghrelin. Chronic treatment with the GHS induced a significant selective increase on the Ba2+ current through HVA Ca2+ channels, and caused only a small increase of currents through LVA channels. The stimulatory effect on HVA current density was accompanied by an augment in maximal conductance with no apparent changes in the kinetics and the voltage dependence of the Ca2+ currents, suggesting an increase in the number of functional channels in the cell membrane. Lastly, in consistency with the functional data, quantitative real-time RT-PCR revealed transcripts encoding for the Cav1.2 and Cav1.3 pore-forming subunits of L-type channels. The treatment with Ghrelin significantly increased the Cav1.3 subunit expression, suggeting that the chronic stimulation of the GHS receptor with Ghrelin or GHRP-6 increases the number of voltage-gated Ca2+ channels at the cell surface of BS. V. M. Salinas Zarate, A. Magdaleno Méndez, B. Domínguez Mancera, A. Rodríguez Andrade, M. Barrientos Morales, P. Cervantes Acosta, A. Hernández Beltrán, D. Romero Salas, J. L. V. Flores Hernández, E. Monjaraz Guzmán, and D. R. Félix Grijalva Copyright © 2013 V. M. Salinas Zarate et al. All rights reserved. AP-1 Gene Expression Levels May Be Correlated with Changes in Gene Expression of Some Stemness Factors in Colon Carcinomas Wed, 11 Dec 2013 14:25:04 +0000 http://www.hindawi.com/journals/jst/2013/497383/ The AP-1 transcription factor is a heterodimer protein that regulates gene expression in response to a variety of extrinsic stimuli through signal transduction. It is involved in processes including differentiation, proliferation, and apoptosis. Among the genes it regulates are transcription factors that contribute to the stemness phenotype. Cancer stem cells have the ability to self-renew and initiate differentiation into heterogenic cancer cells, which may cause metastasis and relapses. In the present study, we evaluated the effect of AP-1 complexes, as well as the C-FOS and C-JUN genes, in relation to NANOG, OCT3/4, and SOX2 transcription factors. All assays were undertaken with colon cancer stem cells. Knockdown experiments with siRNA were performed for each individual gene as well as their combination. Changes in gene expression were calculated with quantitative polymerase chain reaction experiments, while the effect on cell cycle distribution and apoptosis was studied by flow cytometry. The results differed depending on the percentage of repression, as well as the gene that was suppressed. In all cases, the number of apoptotic cells was increased. These findings indicate that AP-1 may have a crucial role in the maintenance of cancer stem cells. Panagiotis Apostolou, Maria Toloudi, Eleni Ioannou, Marina Chatziioannou, Eleni Kourtidou, Ioanna Vlachou, and Ioannis Papasotiriou Copyright © 2013 Panagiotis Apostolou et al. All rights reserved. The Functional State of Hormone-Sensitive Adenylyl Cyclase Signaling System in Diabetes Mellitus Sat, 28 Sep 2013 11:37:48 +0000 http://www.hindawi.com/journals/jst/2013/594213/ Diabetes mellitus (DM) induces a large number of diseases of the nervous, cardiovascular, and some other systems of the organism. One of the main causes of the diseases is the changes in the functional activity of hormonal signaling systems which lead to the alterations and abnormalities of the cellular processes and contribute to triggering and developing many DM complications. The key role in the control of physiological and biochemical processes belongs to the adenylyl cyclase (AC) signaling system, sensitive to biogenic amines and polypeptide hormones. The review is devoted to the changes in the GPCR-G protein-AC system in the brain, heart, skeletal muscles, liver, and the adipose tissue in experimental and human DM of the types 1 and 2 and also to the role of the changes in AC signaling in the pathogenesis and etiology of DM and its complications. It is shown that the changes of the functional state of hormone-sensitive AC system are dependent to a large extent on the type and duration of DM and in experimental DM on the model of the disease. The degree of alterations and abnormalities of AC signaling pathways correlates very well with the severity of DM and its complications. Alexander O. Shpakov and Kira V. Derkach Copyright © 2013 Alexander O. Shpakov and Kira V. Derkach. All rights reserved. A Novel Interaction between Pyk2 and MAP4K4 Is Integrated with Glioma Cell Migration Sun, 15 Sep 2013 13:34:56 +0000 http://www.hindawi.com/journals/jst/2013/956580/ Glioma cell migration correlates with Pyk2 activity, but the intrinsic mechanism that regulates the activity of Pyk2 is not fully understood. Previous studies have supported a role for the N-terminal FERM domain in the regulation of Pyk2 activity as mutations in the FERM domain inhibit Pyk2 phosphorylation. To search for novel protein-protein interactions mediated by the Pyk2 FERM domain, we utilized a yeast two-hybrid genetic selection to identify the mammalian Ste20 homolog MAP4K4 as a binding partner for the Pyk2 FERM domain. MAP4K4 coimmunoprecipitated with Pyk2 and was a substrate for Pyk2 but did not coimmunoprecipitate with the closely related focal adhesion kinase FAK. Knockdown of MAP4K4 expression inhibited glioma cell migration and effectively blocked Pyk2 stimulation of glioma cell. Increased expression of MAP4K4 stimulated glioma cell migration; however, this stimulation was blocked by knockdown of Pyk2 expression. These data support that the interaction of MAP4K4 and Pyk2 is integrated with glioma cell migration and suggest that inhibition of this interaction may represent a potential therapeutic strategy to limit glioblastoma tumor dispersion. Joseph C. Loftus, Zhongbo Yang, Jean Kloss, Harshil Dhruv, Nhan L. Tran, and Daniel L. Riggs Copyright © 2013 Joseph C. Loftus et al. All rights reserved. An Fc Gamma Receptor-Mediated Upregulation of the Production of Interleukin 10 by Intravenous Immunoglobulin in Bone-Marrow-Derived Mouse Dendritic Cells Stimulated with Lipopolysaccharide In Vitro Tue, 18 Jun 2013 16:20:49 +0000 http://www.hindawi.com/journals/jst/2013/239320/ Intravenous immunoglobulin (IVIG), a highly purified immunoglobulin fraction prepared from pooled plasma of several thousand donors, increased anti-inflammatory cytokine IL-10 production, while decreased proinflammatory cytokine IL-12p70 production in bone-marrow-derived mouse dendritic cells (BMDCs) stimulated with lipopolysaccharide (LPS). The changes of cytokine production were confirmed with the transcription levels of these cytokines. To study the mechanisms of this bidirectional effect, we investigated changes of intracellular molecules in the LPS-induced signaling pathway and observed that IVIG upregulated ERK1/2 phosphorylation while downregulated p38 MAPK phosphorylation. Using chemical inhibitors specific to protein kinases involved in activation of Fc gamma receptors (FcRs), which mediate IgG signals, we found that hyperphosphorylation of ERK1/2 and Syk phosphorylation occurred after stimulation of BMDC with LPS and IVIG, and the increasing effect on IL-10 production was abolished by these inhibitors. Furthermore, an antibody specific to FcRI, one of FcRs involved in immune activation, inhibited IVIG-induced increases in IL-10 production, but not IL-12p70 decreases, whereas the anti-IL-10 antibody restored the decrease in IL-12p70 induced by IVIG. These findings suggest that IVIG induced the upregulation of IL-10 production through FcRI activation, and IL-10 was indispensable to the suppressing effect of IVIG on the production of IL-12p70 in LPS-stimulated BMDC. Akihiro Fujii, Yuko Kase, Chiaki Suzuki, Akihito Kamizono, and Teruaki Imada Copyright © 2013 Akihiro Fujii et al. All rights reserved. Signals Regulating Adhesion Dynamics Mon, 31 Dec 2012 15:53:17 +0000 http://www.hindawi.com/journals/jst/2012/785196/ Donna J. Webb, Claire M. Brown, and Kris A. DeMali Copyright © 2012 Donna J. Webb et al. All rights reserved. Signal Transduction Alterations in Glioma: Implications for Diagnosis and Therapy Sun, 09 Dec 2012 12:26:18 +0000 http://www.hindawi.com/journals/jst/2012/704247/ Laura Cerchia, Juan-Carlos Martinez Montero, and Parisa Monfared Copyright © 2012 Laura Cerchia et al. All rights reserved. Commitment of Satellite Cells Expressing the Calcium Channel α2δ1 Subunit to the Muscle Lineage Thu, 29 Nov 2012 09:09:35 +0000 http://www.hindawi.com/journals/jst/2012/460842/ Satellite cells can maintain or repair muscle because they possess stem cell properties, making them a valuable option for cell therapy. However, cell transplants into skeletal muscle of patients with muscular dystrophy are limited by donor cell attachment, migration, and survival in the host tissue. Cells used for therapy are selected based on specific markers present in the plasma membrane. Although many markers have been identified, there is a need to find a marker that is expressed at different states in satellite cells, activated, quiescent, or differentiated cell. Furthermore, the marker has to be present in human tissue. Recently we reported that the plasma membrane α2δ1 protein is involved in cell attachment and migration in myoblasts. The α2δ1 subunit forms a part of the L-type voltage-dependent calcium channel in adult skeletal muscle. We found that the α2δ1 subunit is expressed in the majority of newly isolated satellite cells and that it appears earlier than the α1 subunits and at higher levels than the β or γ subunits. We also found that those cells that expressed α2δ1 would differentiate into muscle cells. This evidence indicates that the α2δ1 may be used as a marker of satellite cells that will differentiate into muscle. Tammy Tamayo, Liliana Grajales, and Jesús García Copyright © 2012 Tammy Tamayo et al. All rights reserved. Protein-Tyrosine Kinase Signaling in the Biological Functions Associated with Sperm Sun, 11 Nov 2012 15:13:44 +0000 http://www.hindawi.com/journals/jst/2012/181560/ In sexual reproduction, two gamete cells (i.e., egg and sperm) fuse (fertilization) to create a newborn with a genetic identity distinct from those of the parents. In the course of these developmental processes, a variety of signal transduction events occur simultaneously in each of the two gametes, as well as in the fertilized egg/zygote/early embryo. In particular, a growing body of knowledge suggests that the tyrosine kinase Src and/or other protein-tyrosine kinases are important elements that facilitate successful implementation of the aforementioned processes in many animal species. In this paper, we summarize recent findings on the roles of protein-tyrosine phosphorylation in many sperm-related processes (from spermatogenesis to epididymal maturation, capacitation, acrosomal exocytosis, and fertilization). Takashi W. Ijiri, A. K. M. Mahbub Hasan, and Ken-ichi Sato Copyright © 2012 Takashi W. Ijiri et al. All rights reserved. Levels of CaV1.2 L-Type Ca2+ Channels Peak in the First Two Weeks in Rat Hippocampus Whereas CaV1.3 Channels Steadily Increase through Development Sun, 14 Oct 2012 12:18:22 +0000 http://www.hindawi.com/journals/jst/2012/597214/ Influx of calcium through voltage-dependent channels regulates processes throughout the nervous system. Specifically, influx through L-type channels plays a variety of roles in early neuronal development and is commonly modulated by G-protein-coupled receptors such as GABAB receptors. Of the four isoforms of L-type channels, only CaV1.2 and CaV1.3 are predominately expressed in the nervous system. Both isoforms are inhibited by the same pharmacological agents, so it has been difficult to determine the role of specific isoforms in physiological processes. In the present study, Western blot analysis and confocal microscopy were utilized to study developmental expression levels and patterns of CaV1.2 and CaV1.3 in the CA1 region of rat hippocampus. Steady-state expression of CaV1.2 predominated during the early neonatal period decreasing by day 12. Steady-state expression of CaV1.3 was low at birth and gradually rose to adult levels by postnatal day 15. In immunohistochemical studies, antibodies against CaV1.2 and CaV1.3 demonstrated the highest intensity of labeling in the proximal dendrites at all ages studied (P1–72). Immunohistochemical studies on one-week-old hippocampi demonstrated significantly more colocalization of GABAB receptors with CaV1.2 than with CaV1.3, suggesting that modulation of L-type calcium current in early development is mediated through CaV1.2 channels. Audra A. Kramer, Nicholas E. Ingraham, Emily J. Sharpe, and Michelle Mynlieff Copyright © 2012 Audra A. Kramer et al. All rights reserved. Estrogen Regulates MAPK-Related Genes through Genomic and Nongenomic Interactions between IGF-I Receptor Tyrosine Kinase and Estrogen Receptor-Alpha Signaling Pathways in Human Uterine Leiomyoma Cells Tue, 09 Oct 2012 15:55:52 +0000 http://www.hindawi.com/journals/jst/2012/204236/ Estrogen and growth factors play a major role in uterine leiomyoma (UtLM) growth possibly through interactions of receptor tyrosine kinases (RTKs) and estrogen receptor-alpha (ER) signaling. We determined the genomic and nongenomic effects of 17-estradiol (E2) on IGF-IR/MAPKp44/42 signaling and gene expression in human UtLM cells with intact or silenced IGF-IR. Analysis by RT2 Profiler PCR-array showed genes involved in IGF-IR/MAPK signaling were upregulated in UtLM cells by E2 including cyclin D kinases, MAPKs, and MAPK kinases; RTK signaling mediator, GRB2; transcriptional factors ELK1 and E2F1; CCNB2 involved in cell cycle progression, proliferation, and survival; and COL1A1 associated with collagen synthesis. Silencing (si)IGF-IR attenuated the above effects and resulted in upregulation of different genes, such as transcriptional factor ETS2; the tyrosine kinase receptor, EGFR; and DLK1 involved in fibrosis. E2 rapidly activated IGF-IR/MAPKp44/42 signaling nongenomically and induced phosphorylation of ER at ser118 in cells with a functional IGF-IR versus those without. E2 also upregulated IGF-I gene and protein expression through a prolonged genomic event. These results suggest a pivotal role of IGF-IR and possibly other RTKs in mediating genomic and nongenomic hormone receptor interactions and signaling in fibroids and provide novel genes and targets for future intervention and prevention strategies. Linda Yu, Alicia B. Moore, Lysandra Castro, Xiaohua Gao, Hoang-Long C. Huynh, Michelle Klippel, Norris D. Flagler, Yi Lu, Grace E. Kissling, and Darlene Dixon Copyright © 2012 Linda Yu et al. All rights reserved. Pathogenic Role of Store-Operated and Receptor-Operated Channels in Pulmonary Arterial Hypertension Thu, 27 Sep 2012 18:53:44 +0000 http://www.hindawi.com/journals/jst/2012/951497/ Pulmonary circulation is an important circulatory system in which the body brings in oxygen. Pulmonary arterial hypertension (PAH) is a progressive and fatal disease that predominantly affects women. Sustained pulmonary vasoconstriction, excessive pulmonary vascular remodeling, in situ thrombosis, and increased pulmonary vascular stiffness are the major causes for the elevated pulmonary vascular resistance (PVR) in patients with PAH. The elevated PVR causes an increase in afterload in the right ventricle, leading to right ventricular hypertrophy, right heart failure, and eventually death. Understanding the pathogenic mechanisms of PAH is important for developing more effective therapeutic approach for the disease. An increase in cytosolic free concentration () in pulmonary arterial smooth muscle cells (PASMC) is a major trigger for pulmonary vasoconstriction and an important stimulus for PASMC migration and proliferation which lead to pulmonary vascular wall thickening and remodeling. It is thus pertinent to define the pathogenic role of signaling in pulmonary vasoconstriction and PASMC proliferation to develop new therapies for PAH. in PASMC is increased by influx through channels in the plasma membrane and by release or mobilization from the intracellular stores, such as sarcoplasmic reticulum (SR) or endoplasmic reticulum (ER). There are two entry pathways, voltage-dependent influx through voltage-dependent channels (VDCC) and voltage-independent influx through store-operated Ca2+ channels (SOC) and receptor-operated channels (ROC). This paper will focus on the potential role of VDCC, SOC, and ROC in the development and progression of sustained pulmonary vasoconstriction and excessive pulmonary vascular remodeling in PAH. Ruby A. Fernandez, Premanand Sundivakkam, Kimberly A. Smith, Amy S. Zeifman, Abigail R. Drennan, and Jason X.-J. Yuan Copyright © 2012 Ruby A. Fernandez et al. All rights reserved. The Role of Semaphorins and Their Receptors in Gliomas Sun, 23 Sep 2012 15:12:48 +0000 http://www.hindawi.com/journals/jst/2012/902854/ Gliomas are the most common tumor in the central nervous system. High-grade glioblastomas are characterized by their high invasiveness and resistance to radiotherapy, leading to high recurrence rate and short median survival despite radical surgical resection. Characterizations of gliomas at molecular level have revealed aberrations of various growth factor receptors, receptor tyrosine kinases, and tumor suppressor genes that lead to deregulation of multiple signaling pathways, thereby contributing to abnormal proliferation, invasion, and resistance to apoptosis in cancer cells. Recently, accumulating evidence points to the emerging role of axon guidance molecules in glioma progression. Notably, many signaling events harnessed by guidance molecules to regulate cell migration and axon navigation during development are also found to be involved in the modulation of deregulated pathways in gliomas. This paper focused on the signalings triggered by the guidance molecule semaphorins and their receptors plexins and neuropilins, and how their crosstalk with oncogenic pathways in gliomas might modulate cancer progression. The emerging role of semaphorins and plexins as tumor suppressors or oncogenes is also discussed. Janice Wai Sze Law and Alan Yiu Wah Lee Copyright © 2012 Janice Wai Sze Law and Alan Yiu Wah Lee. All rights reserved. RGD-Dependent Epithelial Cell-Matrix Interactions in the Human Intestinal Crypt Wed, 05 Sep 2012 11:43:35 +0000 http://www.hindawi.com/journals/jst/2012/248759/ Interactions between the extracellular matrix (ECM) and integrin receptors trigger structural and functional bonds between the cell microenvironment and the cytoskeleton. Such connections are essential for adhesion structure integrity and are key players in regulating transduction of specific intracellular signals, which in turn regulate the organization of the cell microenvironment and, consequently, cell function. The RGD peptide-dependent integrins represent a key subgroup of ECM receptors involved in the maintenance of epithelial homeostasis. Here we review recent findings on RGD-dependent ECM-integrin interactions and their roles in human intestinal epithelial crypt cells. Yannick D. Benoit, Jean-François Groulx, David Gagné, and Jean-François Beaulieu Copyright © 2012 Yannick D. Benoit et al. All rights reserved. Involvement of Src in the Adaptation of Cancer Cells under Microenvironmental Stresses Mon, 03 Sep 2012 14:31:51 +0000 http://www.hindawi.com/journals/jst/2012/483796/ Protein-tyrosine phosphorylation, which is catalyzed by protein-tyrosine kinase (PTK), plays a pivotal role in a variety of cellular functions related to health and disease. The discovery of the viral oncogene Src (v-Src) and its cellular nontransforming counterpart (c-Src), as the first example of PTK, has opened a window to study the relationship between protein-tyrosine phosphorylation and the biology and medicine of cancer. In this paper, we focus on the roles played by Src and other PTKs in cancer cell-specific behavior, that is, evasion of apoptosis or cell death under stressful extracellular and/or intracellular microenvironments (i.e., hypoxia, anoikis, hypoglycemia, and serum deprivation). A. K. M. Mahbub Hasan, Takashi Ijiri, and Ken-ichi Sato Copyright © 2012 A. K. M. Mahbub Hasan et al. All rights reserved. Prolonged Action Potential and After depolarizations Are Not due to Changes in Potassium Currents in NOS3 Knockout Ventricular Myocytes Tue, 28 Aug 2012 13:49:02 +0000 http://www.hindawi.com/journals/jst/2012/645721/ Ventricular myocytes deficient in endothelial nitric oxide synthase (NOS3−/−) exhibit prolonged action potential (AP) duration and enhanced spontaneous activity (early and delayed afterdepolarizations) during β-adrenergic (β-AR) stimulation. Studies have shown that nitric oxide is able to regulate various K+ channels. Our objective was to examine if NOS3-/- myocytes had altered K+ currents. APs, transient outward (𝐼to), sustained (𝐼Ksus), and inward rectifier (𝐼K1) K+ currents were measured in NOS3-/- and wild-type (WT) myocytes. During β-AR stimulation, AP duration (measured as 90% repolarization-APD90) was prolonged in NOS3−/− compared to WT myocytes. Nevertheless, we did not observe differences in 𝐼to, 𝐼Ksus, or 𝐼K1 between WT and NOS3−/− myocytes. Our previous work showed that NOS3−/− myocytes had a greater Ca2+ influx via L-type Ca2+ channels with β-AR stimulation. Thus, we measured β-AR-stimulated SR Ca2+ load and found a greater increase in NOS3−/− versus WT myocytes. Hence, our data suggest that the prolonged AP in NOS3−/− myocytes is not due to changes in 𝐼to, 𝐼Ksus, or 𝐼K1. Furthermore, the increase in spontaneous activity in NOS3−/− myocytes may be due to a greater increase in SR Ca2+ load. This may have important implications for heart failure patients, where arrhythmias are increased and NOS3 expression is decreased. Honglan Wang, Ingrid M. Bonilla, Xin Huang, Quanhua He, Mark J. Kohr, Cynthia A. Carnes, and Mark T. Ziolo Copyright © 2012 Honglan Wang et al. All rights reserved. The Role of HCN Channels on Membrane Excitability in the Nervous System Mon, 13 Aug 2012 07:59:40 +0000 http://www.hindawi.com/journals/jst/2012/619747/ Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels were first reported in heart cells and are recently known to be involved in a variety of neural functions in healthy and diseased brains. HCN channels generate inward currents when the membrane potential is hyperpolarized. Voltage dependence of HCN channels is regulated by intracellular signaling cascades, which contain cyclic AMP, PIP2, and TRIP8b. In addition, voltage-gated potassium channels have a strong influence on HCN channel activity. Because of these funny features, HCN channel currents, previously called funny currents, can have a wide range of functions that are determined by a delicate balance of modulatory factors. These multifaceted features also make it difficult to predict and elucidate the functional role of HCN channels in actual neurons. In this paper, we focus on the impacts of HCN channels on neural activity. The functions of HCN channels reported previously will be summarized, and their mechanisms will be explained by using numerical simulation of simplified model neurons. Daisuke Kase and Keiji Imoto Copyright © 2012 Daisuke Kase and Keiji Imoto. All rights reserved. Contractile Activity Regulates Inducible Nitric Oxide Synthase Expression and NOi Production in Cardiomyocytes via a FAK-Dependent Signaling Pathway Thu, 26 Jul 2012 13:08:22 +0000 http://www.hindawi.com/journals/jst/2012/473410/ Intracellular nitric oxide (NOi) is a physiological regulator of excitation-contraction coupling, but is also involved in the development of cardiac dysfunction during hypertrophy and heart failure. To determine whether contractile activity regulates nitric oxide synthase (NOS) expression, spontaneously contracting, neonatal rat ventricular myocytes (NRVM) were treat with L-type calcium channel blockers (nifedipine and verapamil) or myosin II ATPase inhibitors (butanedione monoxime (BDM) and blebbistatin) to produce contractile arrest. Both types of inhibitors significantly reduced iNOS but not eNOS expression, and also reduced NOi production. Inhibiting contractile activity also reduced focal adhesion kinase (FAK) and AKT phosphorylation. Contraction-induced iNOS expression required FAK and phosphatidylinositol 3-kinase (PI(3)K), as both PF573228 and LY294002 (10 μM, 24 h) eliminated contraction-induced iNOS expression. Similarly, shRNAs specific for FAK (shFAK) caused FAK knockdown, reduced AKT phosphorylation at T308 and S473, and reduced iNOS expression. In contrast, shRNA-mediated knockdown of PYK2, the other member of the FAK-family of protein tyrosine kinases, had much less of an effect. Conversely, overexpression of a constitutively active form of FAK (CD2-FAK) or AKT (Myr-AKT) reversed the inhibitory effect of BDM on iNOS expression and NOi production. Thus, contraction-induced iNOS expression and NOi production in NRVM are mediated via a FAK-PI(3)K-AKT signaling pathway. Miensheng Chu, Yevgeniya Koshman, Rekha Iyengar, Taehoon Kim, Brenda Russell, and Allen M. Samarel Copyright © 2012 Miensheng Chu et al. All rights reserved. Prolactin and Dexamethasone Regulate Second Messenger-Stimulated Cl− Secretion in Mammary Epithelia Wed, 25 Jul 2012 08:26:37 +0000 http://www.hindawi.com/journals/jst/2012/192142/ Mammary gland ion transport is essential for lactation and is regulated by prolactin and glucocorticoids. This study delineates the roles of prolactin receptors (PRLR) and long-term prolactin and dexamethasone (P-D)-mediation of [Ca2+]i and Cl− transport in HC-11 cells. P-D (24 h) suppressed ATP-induced [Ca2+]i. This may be due to decreased Ca2+ entry since P-D decreased transient receptor potential channel 3 (TRPC3) but not secretory pathway Ca2+-ATPase 2 (SPCA2) mRNA. ATP increased Cl− transport, measured by iodide (I−) efflux, in control and P-D-treated cells. P-D enhanced I− efflux response to cAMP secretagogues without altering Cl− channels or NKCC cotransporter expression. HC-11 cells contain only the long form of PRLR (PRLR-L). Since the short isoform, PRLR-S, is mammopoietic, we determined if transfecting PRLR-S (rs) altered PRLR-L-mediated Ca2+ and Cl− transport. Untreated rs cells showed an attenuated [Ca2+]i response to ATP with no further response to P-D, in contrast to vector-transfected (vtc) controls. P-D inhibited TRPC3 in rs and vtc cells but increased SPCA2 only in rs cells. As in wild-type, cAMP-stimulated Cl− transport, in P-D-treated vtc and rs cells. In summary, 24 h P-D acts via PRLR-L to attenuate ATP-induced [Ca2+]i and increase cAMP-activated Cl− transport. PRLR-S fine-tunes these responses underscoring its mammopoietic action. Utchariya Anantamongkol, Mei Ao, Jayashree Sarathy nee Venkatasubramanian, Y. Sangeeta Devi, Nateetip Krishnamra, and Mrinalini C. Rao Copyright © 2012 Utchariya Anantamongkol et al. All rights reserved. Focal Adhesion Kinases in Adhesion Structures and Disease Thu, 19 Jul 2012 13:48:26 +0000 http://www.hindawi.com/journals/jst/2012/296450/ Cell adhesion to the extracellular matrix (ECM) is essential for cell migration, proliferation, and embryonic development. Cells can contact the ECM through a wide range of matrix contact structures such as focal adhesions, podosomes, and invadopodia. Although they are different in structural design and basic function, they share common remodeling proteins such as integrins, talin, paxillin, and the tyrosine kinases FAK, Pyk2, and Src. In this paper, we compare and contrast the basic organization and role of focal adhesions, podosomes, and invadopodia in different cells. In addition, we discuss the role of the tyrosine kinases, FAK, Pyk2, and Src, which are critical for the function of the different adhesion structures. Finally, we discuss the essential role of these tyrosine kinases from the perspective of human diseases. Pierre P. Eleniste and Angela Bruzzaniti Copyright © 2012 Pierre P. Eleniste and Angela Bruzzaniti. All rights reserved. NPM-ALK: The Prototypic Member of a Family of Oncogenic Fusion Tyrosine Kinases Wed, 18 Jul 2012 08:37:51 +0000 http://www.hindawi.com/journals/jst/2012/123253/ Anaplastic lymphoma kinase (ALK) was first identified in 1994 with the discovery that the gene encoding for this kinase was involved in the t(2;5)(p23;q35) chromosomal translocation observed in a subset of anaplastic large cell lymphoma (ALCL). The NPM-ALK fusion protein generated by this translocation is a constitutively active tyrosine kinase, and much research has focused on characterizing the signalling pathways and cellular activities this oncoprotein regulates in ALCL. We now know about the existence of nearly 20 distinct ALK translocation partners, and the fusion proteins resulting from these translocations play a critical role in the pathogenesis of a variety of cancers including subsets of large B-cell lymphomas, nonsmall cell lung carcinomas, and inflammatory myofibroblastic tumours. Moreover, the inhibition of ALK has been shown to be an effective treatment strategy in some of these malignancies. In this paper we will highlight malignancies where ALK translocations have been identified and discuss why ALK fusion proteins are constitutively active tyrosine kinases. Finally, using ALCL as an example, we will examine three key signalling pathways activated by NPM-ALK that contribute to proliferation and survival in ALCL. Joel D. Pearson, Jason K. H. Lee, Julinor T. C. Bacani, Raymond Lai, and Robert J. Ingham Copyright © 2012 Joel D. Pearson et al. All rights reserved. DNA Methylation, Histone Modifications, and Signal Transduction Pathways: A Close Relationship in Malignant Gliomas Pathophysiology Tue, 17 Jul 2012 18:50:41 +0000 http://www.hindawi.com/journals/jst/2012/956958/ Gliomas are the most common type of primary brain tumor. Although tremendous progress has been achieved in the recent years in the diagnosis and treatment, its molecular etiology remains unknown. In this regard, epigenetics represents a new approach to study the mechanisms that control gene expression and function without changing the sequence of the genome. In the present paper we describe the main findings about the alterations of cell signaling pathways in the most aggressive glioma in the adult population, namely, glioblastoma, in which epigenetic mechanisms and the emerging role of cancer stem cell play a crucial function in the development of new biomarkers for its detection and prognosis and the corresponding development of new pharmacological strategies. Raúl Alelú-Paz, Nadia Ashour, Ana González-Corpas, and Santiago Ropero Copyright © 2012 Raúl Alelú-Paz et al. All rights reserved. Angiogenic Signalling Pathways Altered in Gliomas: Selection Mechanisms for More Aggressive Neoplastic Subpopulations with Invasive Phenotype Tue, 17 Jul 2012 09:22:58 +0000 http://www.hindawi.com/journals/jst/2012/597915/ The angiogenesis process is a key event for glioma survival, malignancy and growth. The start of angiogenesis is mediated by a cascade of intratumoural events: alteration of the microvasculature network; a hypoxic microenvironment; adaptation of neoplastic cells and synthesis of pro-angiogenic factors. Due to a chaotic blood flow, a consequence of an aberrant microvasculature, tissue hypoxia phenomena are induced. Hypoxia inducible factor 1 is a major regulator in glioma invasiveness and angiogenesis. Clones of neoplastic cells with stem cell characteristics are selected by HIF-1. These cells, called “glioma stem cells” induce the synthesis of vascular endothelial growth factor. This factor is a pivotal mediator of angiogenesis. To elucidate the role of these angiogenic mediators during glioma growth, we have used a rat endogenous glioma model. Gliomas induced by prenatal ENU administration allowed us to study angiogenic events from early to advanced tumour stages. Events such as microvascular aberrations, hypoxia, GSC selection and VEGF synthesis may be studied in depth. Our data showed that for the treatment of gliomas, developing anti-angiogenic therapies could be aimed at GSCs, HIF-1 or VEGF. The ENU-glioma model can be considered to be a useful option to check novel designs of these treatment strategies. Susana Bulnes, Harkaitz Bengoetxea, Naiara Ortuzar, Enrike G. Argandoña, Álvaro Garcia-Blanco, Irantzu Rico-Barrio, and José V. Lafuente Copyright © 2012 Susana Bulnes et al. All rights reserved. Receptor Tyrosine Kinases: Molecular Switches Regulating CNS Axon Regeneration Mon, 16 Jul 2012 15:42:38 +0000 http://www.hindawi.com/journals/jst/2012/361721/ The poor or lack of injured adult central nervous system (CNS) axon regeneration results in devastating consequences and poor functional recovery. The interplay between the intrinsic and extrinsic factors contributes to robust inhibition of axon regeneration of injured CNS neurons. The insufficient or lack of trophic support for injured neurons is considered as one of the major obstacles contributing to their failure to survive and regrow their axons after injury. In the CNS, many of the signalling pathways associated with neuronal survival and axon regeneration are regulated by several classes of receptor tyrosine kinases (RTK) that respond to a variety of ligands. This paper highlights and summarises the most relevant recent findings pertinent to different classes of the RTK family of molecules, with a particular focus on elucidating their role in CNS axon regeneration. Vasanthy Vigneswara, Sarina Kundi, and Zubair Ahmed Copyright © 2012 Vasanthy Vigneswara et al. All rights reserved. The Phosphorylation-Dependent Regulation of Mitochondrial Proteins in Stress Responses Sun, 15 Jul 2012 15:18:52 +0000 http://www.hindawi.com/journals/jst/2012/931215/ To maintain cellular homeostasis, cells are equipped with precise systems that trigger the appropriate stress responses. Mitochondria not only provide cellular energy but also integrate stress response signaling pathways, including those regulating cell death. Several lines of evidence suggest that the mitochondrial proteins that function in this process, such as Bcl-2 family proteins in apoptosis and phosphoglycerate mutase family member 5 (PGAM5) in necroptosis, are regulated by several kinases. It has also been suggested that the phosphorylation-dependent regulation of mitochondrial fission machinery, dynamin-related protein 1 (Drp1), facilitates appropriate cellular stress responses. However, mitochondria themselves are also damaged by various stresses. To avoid the deleterious effects exerted by damaged mitochondria, cells remove these mitochondria in a selective autophagic degradation process called mitophagy. Interestingly, several kinases, such as PTEN-induced putative kinase 1 (PINK1) in mammals and stress-responsive mitogen-activated protein (MAP) kinases in yeast, have recently been shown to be involved in mitophagy. In this paper, we focus on the phosphorylation-dependent regulation of mitochondrial proteins and discuss the roles of this regulation in the mitochondrial and cellular stress responses. Yusuke Kanamaru, Shiori Sekine, Hidenori Ichijo, and Kohsuke Takeda Copyright © 2012 Yusuke Kanamaru et al. All rights reserved.