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 Ca<sup  >2+</sup> currents in bovine somatotropes (BS) separated on a Percoll gradient and detected by immunohistochemistry. After 24&#x2009;h of treatment with Ghrelin (10&#x2009;nM) or GHRP-6 (100&#x2009;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&#x2009;<svg     style="vertical-align:-3.56265pt;width:9.5625px;" id="M1" height="12.175" version="1.1" viewBox="0 0 9.5625 12.175" width="9.5625"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><path id="x1D707" d="M538 96q-38 -45 -84 -76.5t-71 -31.5q-44 0 -15 117q12 49 18 89h-2q-99 -128 -163 -178q-36 -28 -70 -28q-26 0 -44 38h-2q-16 -69 -16 -129q0 -43 11 -75.5t24 -42.5l1 -6q-7 -12 -24.5 -23t-37.5 -11q-40 0 -40 76q0 52 35 202l94 407l78 24l5 -5q-32 -122 -72 -310&#xA;q-7 -33 0 -55t25 -22q36 0 105.5 75t107.5 145l32 146l75 26h10q-50 -197 -78 -347q-7 -38 6 -38q7 0 31 17t47 39z" /></g>

		
	
</svg>M) blocked the GH secretion, and the effect was dose and time dependent (24, 48, and 72&#x2009;h). GH secretion stimulated by GHRP-6 was abolished by nifedipine (0.5&#x2009;<svg     style="vertical-align:-3.56265pt;width:9.5625px;" id="M2" height="12.175" version="1.1" viewBox="0 0 9.5625 12.175" width="9.5625"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><use xlink:href="#x1D707"/></g>

		
	
</svg>M), a blocker of L-type HVA Ca<sup  >2+</sup> channels, and KN-62 (10&#x2009;<svg     style="vertical-align:-3.56265pt;width:9.5625px;" id="M3" height="12.175" version="1.1" viewBox="0 0 9.5625 12.175" width="9.5625"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><use xlink:href="#x1D707"/></g>

		
	
</svg>M), an inhibitor of Ca<sup  >2+</sup>/CaM-KII. After 72&#x2009;h in culture, all recorded BS exhibited two main Ca<sup  >2+</sup> 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 Ba<sup  >2+</sup> current through HVA Ca<sup  >2+</sup> 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 Ca<sup  >2+</sup> 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 Ca<sub  >v</sub>1.2 and Ca<sub  >v</sub>1.3 pore-forming subunits of L-type channels. The treatment with Ghrelin significantly increased the Ca<sub  >v</sub>1.3 subunit expression, suggeting that the chronic stimulation of the GHS receptor with Ghrelin or GHRP-6 increases the number of voltage-gated Ca<sup  >2+</sup> channels at the cell surface of BS.

V. M. Salinas Zarate

A. Magdaleno M&#xe9;ndez

B. Dom&#xed;nguez Mancera

A. Rodr&#xed;guez Andrade

M. Barrientos Morales

P. Cervantes Acosta

A. Hern&#xe1;ndez Beltr&#xe1;n

D. Romero Salas

J. L. V. Flores Hern&#xe1;ndez

E. Monjaraz Guzm&#xe1;n

D. R. F&#xe9;lix Grijalva

Upregulation of Voltage-Gated Calcium Channel Ca<sub>v</sub>1.3 in Bovine Somatotropes Treated with Ghrelin

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 <i>C-FOS</i> and <i>C-JUN</i> 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

Ioannis Papasotiriou

AP-1 Gene Expression Levels May Be Correlated with Changes in Gene Expression of Some Stemness Factors in Colon Carcinomas

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

Kira V. Derkach

The Functional State of Hormone-Sensitive Adenylyl Cyclase Signaling System in Diabetes Mellitus

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

Daniel L. Riggs

A Novel Interaction between Pyk2 and MAP4K4 Is Integrated with Glioma Cell Migration

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 (Fc<svg     style="vertical-align:-3.56265pt;width:8.6374998px;" id="M1" height="12.175" version="1.1" viewBox="0 0 8.6374998 12.175" width="8.6374998"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><path id="x1D6FE" d="M478 372q0 -39 -31 -97t-61 -98t-78 -98q-45 -55 -73 -102q-13 -79 -13 -197q-11 -11 -43.5 -25.5t-53.5 -15.5l-15 17q5 35 26 101.5t47 123.5q8 72 -1.5 174.5t-37.5 178.5q-14 37 -29 37q-20 0 -67 -65l-25 21q37 60 73 90.5t63 30.5q47 0 72 -112q13 -56 17.5 -141.5&#xA;t0.5 -143.5h2q155 193 155 297q0 26 -12 47q-5 8 -5 15q0 16 12.5 27t29.5 11q21 0 34 -21t13 -55z" /></g>

		
	
</svg>Rs), 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 Fc<svg     style="vertical-align:-3.56265pt;width:8.6374998px;" id="M2" height="12.175" version="1.1" viewBox="0 0 8.6374998 12.175" width="8.6374998"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><use xlink:href="#x1D6FE"/></g>

		
	
</svg>RI, one of Fc<svg     style="vertical-align:-3.56265pt;width:8.6374998px;" id="M3" height="12.175" version="1.1" viewBox="0 0 8.6374998 12.175" width="8.6374998"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><use xlink:href="#x1D6FE"/></g>

		
	
</svg>Rs 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 Fc<svg     style="vertical-align:-3.56265pt;width:8.6374998px;" id="M4" height="12.175" version="1.1" viewBox="0 0 8.6374998 12.175" width="8.6374998"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><use xlink:href="#x1D6FE"/></g>

		
	
</svg>RI 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

Teruaki Imada

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 <i>In Vitro</i>

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Journal of Signal Transduction