Negatively Charged Amino Acids Near and in Transient Receptor Potential (TRP) Domain of TRPM4 Channel Are One Determinant of Its Ca2+Sensitivity

Transient receptor potential melastatin 4 (TRPM4) channels are Ca2+-activated nonselective cation channels that have been recently identified as regulators of detrusor smooth muscle (DSM) function in rodents. However, their expression and function in human DSM remain unexplored. We provide insights into the functional role of TRPM4 channels in human DSM under physiological conditions. We used a multidisciplinary experimental approach, including RT-PCR, Western blotting, immunohistochemistry and immunocytochemistry, patch-clamp electrophysiology, and functional studies of DSM contractility. DSM samples were obtained from patients without preoperative overactive bladder symptoms. RT-PCR detected mRNA transcripts for TRPM4 channels in human DSM whole tissue and freshly isolated single cells. Western blotting and immunohistochemistry with confocal microscopy revealed TRPM4 protein expression in human DSM. Immunocytochemistry further detected TRPM4 protein expression in DSM single cells. Patch-clamp experiments showed that 9-phenanthrol, a selective TRPM4 channel inhibitor, significantly decreased the transient inward cation currents and voltage step-induced whole cell currents in freshly isolated human DSM cells. In current-clamp mode, 9-phenanthrol hyperpolarized the human DSM cell membrane potential. Furthermore, 9-phenanthrol attenuated the spontaneous phasic, carbachol-induced and nerve-evoked contractions in human DSM isolated strips. Significant species-related differences in TRPM4 channel activity between human, rat, and guinea pig DSM were revealed, suggesting a more prominent physiological role for the TRPM4 channel in the regulation of DSM function in humans than in rodents. In conclusion, TRPM4 channels regulate human DSM excitability and contractility and are critical determinants of human urinary bladder function. Thus, TRPM4 channels could represent promising novel targets for the pharmacological or genetic control of overactive bladder.

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Pharmacological Modulation and (Patho)Physiological Roles of TRPM4 Channel—Part 2: TRPM4 in Health and Disease

Pharmaceuticals ◽

10.3390/ph15010040 ◽

2021 ◽

Vol 15 (1) ◽

pp. 40

Author(s):

Csaba Dienes ◽

Zsigmond Máté Kovács ◽

Tamás Hézső ◽

János Almássy ◽

János Magyar ◽

...

Keyword(s):

Transient Receptor Potential ◽

Divalent Cations ◽

Ischemia Reperfusion ◽

Receptor Potential ◽

Immune Functions ◽

Excitable Cells ◽

Transient Receptor Potential Melastatin ◽

Health And Disease ◽

Transient Receptor ◽

Trpm4 Channel

Transient receptor potential melastatin 4 (TRPM4) is a unique member of the TRPM protein family and, similarly to TRPM5, is Ca2+ sensitive and permeable for monovalent but not divalent cations. It is widely expressed in many organs and is involved in several functions; it regulates membrane potential and Ca2+ homeostasis in both excitable and non-excitable cells. This part of the review discusses the currently available knowledge about the physiological and pathophysiological roles of TRPM4 in various tissues. These include the physiological functions of TRPM4 in the cells of the Langerhans islets of the pancreas, in various immune functions, in the regulation of vascular tone, in respiratory and other neuronal activities, in chemosensation, and in renal and cardiac physiology. TRPM4 contributes to pathological conditions such as overactive bladder, endothelial dysfunction, various types of malignant diseases and central nervous system conditions including stroke and injuries as well as in cardiac conditions such as arrhythmias, hypertrophy, and ischemia-reperfusion injuries. TRPM4 claims more and more attention and is likely to be the topic of research in the future.

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The Ca2+-activated cation channel TRPM4 is a positive regulator of pressure overload-induced cardiac hypertrophy

eLife ◽

10.7554/elife.66582 ◽

2021 ◽

Vol 10 ◽

Author(s):

Yang Guo ◽

Ze-Yan Yu ◽

Jianxin Wu ◽

Hutao Gong ◽

Scott Kesteven ◽

...

Keyword(s):

Ventricular Hypertrophy ◽

Transient Receptor Potential ◽

Pressure Overload ◽

Receptor Potential ◽

Mechanical Stretch ◽

Initial Step ◽

Left Ventricular ◽

Transient Receptor Potential Melastatin ◽

Transient Receptor ◽

Trpm4 Channel

Pathological left ventricular hypertrophy (LVH) occurs in response to pressure overload and remains the single most important clinical predictor of cardiac mortality. The molecular pathways in the induction of pressure overload LVH are potential targets for therapeutic intervention. Current treatments aim to remove the pressure overload stimulus for LVH, but do not completely reverse adverse cardiac remodelling. Although numerous molecular signalling steps in the induction of LVH have been identified, the initial step by which mechanical stretch associated with cardiac pressure overload is converted into a chemical signal that initiates hypertrophic signalling remains unresolved. In this study, we show that selective deletion of transient receptor potential melastatin 4 (TRPM4) channels in mouse cardiomyocytes results in an approximately 50% reduction in the LVH induced by transverse aortic constriction. Our results suggest that TRPM4 channel is an important component of the mechanosensory signalling pathway that induces LVH in response to pressure overload and represents a potential novel therapeutic target for the prevention of pathological LVH.

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Ablation of PM20D1 reveals N-acyl amino acid control of metabolism and nociception

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1803389115 ◽

2018 ◽

Vol 115 (29) ◽

pp. E6937-E6945 ◽

Cited By ~ 15

Author(s):

Jonathan Z. Long ◽

Alexander M. Roche ◽

Charles A. Berdan ◽

Sharon M. Louie ◽

Amanda J. Roberts ◽

...

Keyword(s):

Insulin Resistance ◽

Amino Acids ◽

Body Temperature ◽

Transient Receptor Potential ◽

Receptor Potential ◽

Mitochondrial Uncoupling ◽

Acid Control ◽

Direct Administration ◽

Transient Receptor

N-acyl amino acids (NAAs) are a structurally diverse class of bioactive signaling lipids whose endogenous functions have largely remained uncharacterized. To clarify the physiologic roles of NAAs, we generated mice deficient in the circulating enzyme peptidase M20 domain-containing 1 (PM20D1). Global PM20D1-KO mice have dramatically reduced NAA hydrolase/synthase activities in tissues and blood with concomitant bidirectional dysregulation of endogenous NAAs. Compared with control animals, PM20D1-KO mice exhibit a variety of metabolic and pain phenotypes, including insulin resistance, altered body temperature in cold, and antinociceptive behaviors. Guided by these phenotypes, we identify N-oleoyl-glutamine (C18:1-Gln) as a key PM20D1-regulated NAA. In addition to its mitochondrial uncoupling bioactivity, C18:1-Gln also antagonizes certain members of the transient receptor potential (TRP) calcium channels including TRPV1. Direct administration of C18:1-Gln to mice is sufficient to recapitulate a subset of phenotypes observed in PM20D1-KO animals. These data demonstrate that PM20D1 is a dominant enzymatic regulator of NAA levels in vivo and elucidate physiologic functions for NAA signaling in metabolism and nociception.

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Cholesterol Stimulates the Transient Receptor Potential Melastatin 4 Channel in mpkCCDc14 Cells

Frontiers in Pharmacology ◽

10.3389/fphar.2021.627875 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yong-Xu Cai ◽

Bao-Long Zhang ◽

Miao Yu ◽

Yan-Chao Yang ◽

Xue Ao ◽

...

Keyword(s):

Patch Clamp ◽

Transient Receptor Potential ◽

Cholesterol Biosynthesis ◽

Receptor Potential ◽

Water Soluble ◽

Exogenous Cholesterol ◽

Transient Receptor Potential Melastatin ◽

Transient Receptor ◽

Trpm4 Channel ◽

Inside Out

We have shown that cholesterol regulates the activity of ion channels in mouse cortical collecting duct (CCD) mpkCCDc14 cells and that the transient receptor potential melastatin 4 (TRPM4) channel is expressed in these cells. However, whether TRPM4 channel is regulated by cholesterol remains unclear. Here, we performed inside-out patch-clamp experiments and found that inhibition of cholesterol biosynthesis by lovastatin significantly decreased, whereas enrichment of cholesterol with exogenous cholesterol significantly increased, TRPM4 channel open probability (Po) by regulating its sensitivity to Ca2+ in mpkCCDc14 cells. In addition, inside-out patch-clamp data show that acute depletion of cholesterol in the membrane inner leaflet by methyl-β-cyclodextrin (MβCD) significantly reduced TRPM4 Po, which was reversed by exogenous cholesterol. Moreover, immunofluorescence microscopy, Western blot, cell-surface biotinylation, and patch clamp analysis show that neither inhibition of intracellular cholesterol biosynthesis with lovastatin nor application of exogenous cholesterol had effect on TRPM4 channel protein abundance in the plasma membrane of mpkCCDc14 cells. Sucrose density gradient centrifugation studies demonstrate that TRPM4 was mainly located in cholesterol-rich lipid rafts. Lipid-protein overlay experiments show that TRPM4 directly interacted with several anionic phospholipids, including PI(4,5)P2. Depletion of PI(4,5)P2 with either wortmannin or PGE2 abrogated the stimulatory effects of exogenous cholesterol on TRPM4 activity, whereas exogenous PI(4,5)P2 (diC8-PI(4,5)P2, a water-soluble analog) increased the effects. These results suggest that cholesterol stimulates TRPM4 via a PI(4,5)P2-dependent mechanism.

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The Sulfonylurea Receptor 1 (Sur1)-Transient Receptor Potential Melastatin 4 (Trpm4) Channel

Journal of Biological Chemistry ◽

10.1074/jbc.m112.428219 ◽

2012 ◽

Vol 288 (5) ◽

pp. 3655-3667 ◽

Cited By ~ 101

Author(s):

Seung Kyoon Woo ◽

Min Seong Kwon ◽

Alexander Ivanov ◽

Volodymyr Gerzanich ◽

J. Marc Simard

Keyword(s):

Transient Receptor Potential ◽

Receptor Potential ◽

Sulfonylurea Receptor ◽

Transient Receptor Potential Melastatin ◽

Sulfonylurea Receptor 1 ◽

Transient Receptor ◽

Trpm4 Channel

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Pharmacological Modulation and (Patho)Physiological Roles of TRPM4 Channel—Part 1: Modulation of TRPM4

Pharmaceuticals ◽

10.3390/ph15010081 ◽

2022 ◽

Vol 15 (1) ◽

pp. 81

Author(s):

Zsigmond Máté Kovács ◽

Csaba Dienes ◽

Tamás Hézső ◽

János Almássy ◽

János Magyar ◽

...

Keyword(s):

Membrane Potential ◽

Transient Receptor Potential ◽

Divalent Cations ◽

Receptor Potential ◽

Dominant Negative ◽

Excitable Cells ◽

Pharmacological Modulation ◽

Transient Receptor Potential Melastatin ◽

Transient Receptor ◽

Trpm4 Channel

Transient receptor potential melastatin 4 is a unique member of the TRPM protein family and, similarly to TRPM5, is Ca2+-sensitive and permeable to monovalent but not divalent cations. It is widely expressed in many organs and is involved in several functions by regulating the membrane potential and Ca2+ homeostasis in both excitable and non-excitable cells. This part of the review discusses the pharmacological modulation of TRPM4 by listing, comparing, and describing both endogenous and exogenous activators and inhibitors of the ion channel. Moreover, other strategies used to study TRPM4 functions are listed and described. These strategies include siRNA-mediated silencing of TRPM4, dominant-negative TRPM4 variants, and anti-TRPM4 antibodies. TRPM4 is receiving more and more attention and is likely to be the topic of research in the future.

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