Review Article

Structure and Function of Mitochondria-Associated Endoplasmic Reticulum Membranes (MAMs) and Their Role in Cardiovascular Diseases

Table 1

Components of MAMs involved in cardiovascular disease.

ProteinsRelevant function(s) in MAMsFunctions in CVDExpression in cardiovascular system

Protethering proteins
GRP75Increased MAM formation and mitochondria Ca2+ uptakeMitochondrial calcium overload and hypoxia/reoxygenation injury in cardiomyocytesHigh
IP3RsInteracts with GRP75 and VDACs, modulates calcium in MAMsUpregulation in cardiac hypertrophy. Modulates excitation-contraction coupling in ventricular and atrial cardiomyocytesLow
VDACsInteracts with GRP75 and IP3Rs, regulates intracellular Ca2+ levelMarked elevation of VDAC1 in myocardial infarction. VDAC1 inhibition alleviates excessive fibrosis in the atrial myocardiumMedium
MFN2Modulator of ER-mitochondria tethering and mitochondrial fusionDownregulation in cardiac hypertrophy. MFN2 upregulation ameliorated the cardiac hypertrophy.Medium
MFN1Tethering mitochondria to MAMs via interaction with ER-resident MFN2Represses cardiac hypertrophy and ischemia/reperfusion injuryNot detected
Fis1Modulates ER-mitochondria tethering and induces apoptosis. Induces mitophagyInhibition of the CREB/Fis1 pathway leads to heart diseaseHigh
BECN1Enhances MAM formation and autophagosomesDeregulation leads to heart diseases, through altered myocardial autophagy and apoptosisLow
FUNDC1Promotes mitochondrial fission and mitophagy. Increases Ca2+Required for cardiac ischemia/reperfusion injury-activated mitophagyMedium
ParkinMediates mitophagy. Increases the ER-mitochondria contacts and induces Ca2+ transfer and ATP synthesisUpregulated during I/R injuryLow
IP3Rs/GRP75/VDAC complex-modulated proteins
Sig-1RProlongs Ca2+ signaling; Sig-1R increase represses ER stress response, whereas Sig-1R decrease induces apoptosisSig-1R activation represses hypertrophy and cardiomyocyte injury. Sig-1R KO displays cardiac remodelingHigh
CypDRegulates Ca2+ transfer from the ER to mitochondria through IP3R1The CypD/GRP75/IP3R/VDAC complex inhibition improved hypoxia/reoxygenation injury in cardiomyocytesNA
GSK3βInhibition of GSK3β results in decreased ER Ca2+ release as well as sensitivity to apoptosisGSK3β inhibition reduced infarct size in reperfused heartsNot detected
Antitethering proteins
CAV1Negatively regulates the formation of MAMs and impairs Ca2+ transferCAV1 ablation aggravates cardiac dysfunction and decreases survival in myocardial ischemiaMedium
Upstream regulators of the formation of MAMs
p38 MAPKPhosphorylation of Gp78 at S538 by p38 MAPK inhibits MAM formation and mitochondrial fusion by promoting degradation of MFN1/2p38 MAPK has been implicated in cardiomyocyte dysfunction and apoptosisMedium
FOXO1Augments MAM formation by inducing PDK4 and promotes mitochondrial Ca2+ accumulation, mitochondrial dysfunction, and ER stressFOXO1 protein is associated with ischemic heart disease (IHD)Not detected