The dual role of transient receptor potential melastatin cation channels in sepsis.

The transient receptor potential melastatin (TRPM) channel family has been previously implicated in various diseases, including those related to temperature sensing, cardiovascular health, and neurodegeneration. Nowadays, increasing evidence indicates that TRPM family members also play significant roles in various types of cancers, exhibiting both pro- and anti-tumorigenic functions. They are involved in tumor cell proliferation, survival, invasion, and metastasis, serving as potential diagnostic and prognostic biomarkers for cancer. This paper begins by describing the structure and physiological functions of the TRPM family members. It then outlines their roles in several common malignancies, including pancreatic, prostate, colorectal, breast, brain cancer, and melanoma. Subsequently, we focused on investigating the specific mechanisms by which TRPM family members are involved in tumorigenesis and development from both the tumor microenvironment (TME) and intracellular signaling. TRPM channels not only transmit signals from the TME to regulate tumor cell functions, but also mediate extracellular matrix remodeling, which is conducive to the malignant transformation of tumor cells. Importantly, TRPM channels depend on the regulation of the inflow of various ions in cells, and participate in key signaling pathways involved in tumor progression, such as Wnt/β-catenin, MAPK, PI3K/AKT, p53, and autophagy. Finally, we summarize the current strategies and challenges of targeting TRPM channels in tumor treatment, and discuss the feasibility of combining targeted TRPM channel drugs with cancer immunotherapy.

The cation channel transient receptor potential melastatin 4 (TRPM4) is a calcium-activated non-selective cation channel and acts in cardiomyocytes as a negative modulator of the L-type Ca2+ influx. Global deletion of TRPM4 in the mouse led to increased cardiac contractility under β-adrenergic stimulation. Consequently, cardiomyocyte-specific inactivation of the TRPM4 function appears to be a promising strategy to improve cardiac contractility in heart failure patients. The aim of this study was to develop a gene therapy approach in mice that specifically silences the expression of TRPM4 in cardiomyocytes. First, short hairpin RNAmiR30 (shRNAmiR30) sequences against the TRPM4 mRNA were screened in vitro using lentiviral transduction for a stable expression of the shRNA cassettes. Western blot analysis identified three efficient shRNAmiR30 sequences out of six, which reduced the endogenous TRPM4 protein level by up to 90 ± 6%. Subsequently, the most efficient shRNAmiR30 sequences were delivered into cardiomyocytes of adult mice using adeno-associated virus serotype 9 (AAV9)-mediated gene transfer. Initially, the AAV9 vector particles were administered via the lateral tail vein, which resulted in a downregulation of TRPM4 by 46 ± 2%. Next, various optimization steps were carried out to improve knockdown efficiency in vivo. First, the design of the expression cassette was streamlined for integration in a self-complementary AAV vector backbone for a faster expression. Compared to the application via the lateral tail vein, intravenous application via the retro-orbital sinus has the advantage that the vector solution reaches the heart directly and in a high concentration, and eventually a TRPM4 knockdown efficiency of 90 ± 7% in the heart was accomplished by this approach. By optimization of the shRNAmiR30 constructs and expression cassette as well as the route of AAV9 vector application, a 90% reduction of TRPM4 expression was achieved in the adult mouse heart. In the future, AAV9-RNAi-mediated inactivation of TRPM4 could be a promising strategy to increase cardiac contractility in preclinical animal models of acute and chronic forms of cardiac contractile failure.

The Ca(2+)-permeable cation channel transient receptor potential melastatin 2 (TRPM2) plays a key role in pathogen-evoked phagocyte activation, postischemic neuronal apoptosis, and glucose-evoked insulin secretion, by linking these cellular responses to oxidative stress. TRPM2 channels are coactivated by binding of intracellular ADP ribose and Ca(2+) to distinct cytosolically accessible sites on the channels. These ligands likely regulate the activation gate, conserved in the voltage-gated cation channel superfamily, that comprises a helix bundle formed by the intracellular ends of transmembrane helix six of each subunit. For several K(+) and TRPM family channels, activation gate opening requires the presence of phosphatidylinositol-bisphosphate (PIP(2)) in the inner membrane leaflet. Most TRPM family channels inactivate upon prolonged stimulation in inside-out patches; this "rundown" is due to PIP(2) depletion. TRPM2 currents also run down within minutes, but the molecular mechanism of this process is unknown. Here we report that high-affinity PIP(2) binding regulates Ca(2+) sensitivity of TRPM2 activation. Nevertheless, TRPM2 inactivation is not due to PIP(2) depletion; rather, it is state dependent, sensitive to permeating ions, and can be completely prevented by mutations in the extracellular selectivity filter. Introduction of two negative charges plus a single-residue insertion, to mimic the filter sequence of TRPM5, results in TRPM2 channels that maintain unabated maximal activity for over 1 h, and display altered permeation properties but intact ADP ribose/Ca(2+)-dependent gating. Thus, upon prolonged stimulation, the TRPM2 selectivity filter undergoes a conformational change reminiscent of that accompanying C-type inactivation of voltage-gated K(+) channels. The noninactivating TRPM2 variant will be invaluable for gating studies.

Transient receptor potential melastatin (TRPM) channels, a subfamily of the TRP superfamily, constitute a diverse group of ion channels involved in mediating crucial cellular processes like calcium homeostasis. These channels exhibit complex regulation, and one of the key regulatory mechanisms involves their interaction with calmodulin (CaM), a cytosol ubiquitous calcium-binding protein. The association between TRPM channels and CaM relies on the presence of specific CaM-binding domains in the channel structure. Upon CaM binding, the channel undergoes direct and/or allosteric structural changes and triggers down- or up-stream signaling pathways. According to current knowledge, ion channel members TRPM2, TRPM3, TRPM4, and TRPM6 are directly modulated by CaM, resulting in their activation or inhibition. This review specifically focuses on the interplay between TRPM channels and CaM and summarizes the current known effects of CaM interactions and modulations on TRPM channels in cellular physiology.

Aldosterone plays a major role in atrial structural and electrical remodeling, in particular through Ca2+-transient perturbations and shortening of the action potential. The Ca2+-activated non-selective cation channel Transient Receptor Potential Melastatin 4 (TRPM4) participates in atrial action potential. The aim of our study was to elucidate the interactions between aldosterone and TRPM4 in atrial remodeling and arrhythmias susceptibility. Hyperaldosteronemia, combined with a high salt diet, was induced in mice by subcutaneously implanted osmotic pumps during 4 weeks, delivering aldosterone or physiological serum for control animals. The experiments were conducted in wild type animals (Trpm4+/+) as well as Trpm4 knock-out animals (Trpm4-/-). The atrial diameter measured by echocardiography was higher in Trpm4-/- compared to Trpm4+/+ animals, and hyperaldosteronemia-salt produced a dilatation in both groups. Action potentials duration and triggered arrhythmias were measured using intracellular microelectrodes on the isolated left atrium. Hyperaldosteronemia-salt prolong action potential in Trpm4-/- mice but had no effect on Trpm4+/+ mice. In the control group (no aldosterone-salt treatment), no triggered arrythmias were recorded in Trpm4+/+ mice, but a high level was detected in Trpm4-/- mice. Hyperaldosteronemia-salt enhanced the occurrence of arrhythmias (early as well as delayed-afterdepolarization) in Trpm4+/+ mice but decreased it in Trpm4-/- animals. Atrial connexin43 immunolabelling indicated their disorganization at the intercalated disks and a redistribution at the lateral side induced by hyperaldosteronemia-salt but also by Trpm4 disruption. In addition, hyperaldosteronemia-salt produced pronounced atrial endothelial thickening in both groups. Altogether, our results indicated that hyperaldosteronemia-salt and TRPM4 participate in atrial electrical and structural remodeling. It appears that TRPM4 is involved in aldosterone-induced atrial action potential shortening. In addition, TRPM4 may promote aldosterone-induced atrial arrhythmias, however, the underlying mechanisms remain to be explored.

Objective To evaluate the role of glial cell line-derived neurotrophic factor family receptor alpha3(GFRα3)in the expression and membrane trafficking of transient receptor potential melastatin 8(TRPM8)in the dorsal root ganglion(DRG)during cold hyperalgesia in rats with neuropathic pain(NP). Methods Thirty-two healthy adult male Sprague-Dawley rats, aged 10-12 weeks, weighing 250-280 g, in which intrathecal catheters were successfully implanted, were divided into 4 groups(n=8 each)using a random number table: sham operation plus GFRα3 dsRNA group(Sham+ dsRNA group), sham operation plus GFRα3 siRNA group(group Sham+ siRNA), NP plus GFRα3 dsRNA group(group NP+ dsRNA)and NP plus GFRα3 siRNA group(group NP+ siRNA). NP was produced by chronic constriction injury to the sciatic nerve.At 10-30 days after operation, GFRα3 dsRNA 10 μg/20 μl was intrathecally injected once a day for 4 consecutive days in Sham+ dsRNA and NP+ dsRNA groups, and 10 μg/20 μl GFRα3 siRNA, of which the sense strand was modified with 2′-O-methyl and 5′-cholesterol, was intrathecally injected once a day for 4 consecutive days in Sham+ siRNA and NP+ siRNA groups.The number of paw lifts on the cold plate, mechanical paw withdrawal threshold(MWT)and thermal paw withdrawal latency(TWL)were measured on 1 day before operation and 10, 11, 12, 13(before intrathecal injection)and 14 days after operation.The rats were sacrificed after the last behavioral testing, and ipsilateral DRGs of the lumbar segment(L4-6)were dissected for detection of the expression of GFRα3 and TRPM8 in total and membrane proteins by Western blot, and the ratio of TRPM8 expression in the membrane protein to that in the total protein(m/t ratio)was calculated. Results Compared with group Sham+ dsRNA, the number of paw lifts on the cold plate was significantly increased, the MWT was decreased, and TWL was shortened after operation in NP+ dsRNA and NP+ siRNA groups, the expression of GFRα3 and TRPM8 in total and membrane proteins was significantly up-regulated, and m/t ratio was increased in group NP+ dsRNA, and the expression of GFRα3 in DRGs was significantly down-regulated(P 0.05). Compared with group NP+ dsRNA, the number of paw lifts on the cold plate was significantly decreased, the expression of GFRα3 and TRPM8 in total and membrane proteins was down-regulated, m/t ratio was decreased(P 0.05). Conclusion GFRα3 in DRGs can up-regulate the expression of TRPM8 and enhance the membrane trafficking of TRPM8, which may be involved in the maintenance mechanism of cold hyperalgesia in rats with NP. Key words: Glial cell line-derived neurotrophic factor receptors; TRPM cation channels; Neuralgia; Hyperalgesia, cold; Ganglia, spinal

Ischemia/reperfusion injury (IRI) is a complex pathophysiological condition resulting from temporary loss of blood flow followed by reoxygenation. A systematic literature search was conducted in PubMed, Web of Science, and Scopus up to October 2025 to identify studies on TRPM channels in ischemia/reperfusion injury (IRI). This review delves into the mechanistic roles of transient receptor potential melastatin (TRPM) channels in IRI, highlighting their involvement in key processes such as oxidative stress, calcium overload, inflammation, endothelial dysfunction, and mitochondrial damage. The aberrant activation of TRPM channels contributes to tissue damage and cell death during IRI. We provide a comprehensive overview of the impact of specific TRPM channels on IRI across different organs, including the brain, heart, liver, and kidney. Additionally, the review examines the therapeutic potential of pharmacological inhibitors or activators targeting TRPM channels, underscoring their promise as viable strategies for mitigating IRI. Our findings advocate for continued research into TRPM channels as potential therapeutic targets, offering insights into novel treatment approaches for IRI.

Ischemia is a leading cause of acute kidney injury. Kidney ischemia is associated with loss of cellular ion homeostasis; however, the pathways that underlie ion homeostasis dysfunction are poorly understood. Here, we evaluated the nonselective cation channel transient receptor potential melastatin 2 (TRPM2) in a murine model of kidney ischemia/reperfusion (I/R) injury. TRPM2-deficient mice were resistant to ischemic injury, as reflected by improved kidney function, reduced histologic damage, suppression of proapoptotic pathways, and reduced inflammation. Moreover, pharmacologic TRPM2 inhibition was also protective against I/R injury. TRPM2 was localized mainly in kidney proximal tubule epithelial cells, and studies in chimeric mice indicated that the effects of TRPM2 are due to expression in parenchymal cells rather than hematopoietic cells. TRPM2-deficient mice had less oxidative stress and lower levels of NADPH oxidase activity after ischemia. While RAC1 is a component of the NADPH oxidase complex, its relation to TRPM2 and kidney ischemic injury is unknown. Following kidney ischemia, TRPM2 promoted RAC1 activation, with active RAC1 physically interacting with TRPM2 and increasing TRPM2 expression at the cell membrane. Finally, inhibition of RAC1 reduced oxidant stress and ischemic injury in vivo. These results demonstrate that TRPM2-dependent RAC1 activation increases oxidant stress and suggest that therapeutic approaches targeting TRPM2 and/or RAC1 may be effective in reducing ischemic kidney injury.

Neurobiology of TRPM channels in pain processing: Current advances and future directions.

Camphor is known to potentiate both heat and cold sensations. Although the sensitization to heat could be explained by the activation of heat-sensitive transient receptor potential (TRP) channels TRPV1 and TRPV3, the camphor-induced sensitization to cooling remains unexplained. In this study, we present evidence for the activation of the cold- and menthol-sensitive channel transient receptor potential melastatin 8 (TRPM8) by camphor. Calcium transients evoked by camphor in HEK293 cells expressing human and rat TRPM8 are inhibited by the TRPM8 antagonists 4-(3-chloro-2-pyridinyl)-N-[4-(1,1-dimethylethyl)phenyl]-1-piperazinecarboxamide and 2-aminoethyl diphenylborinate. Camphor also sensitized the cold-induced calcium transients and evoked desensitizing outward-rectifying currents in TRPM8-expressing HEK293 cells. In the presence of ruthenium red (a blocker of TRPV1, TRPV3, and TRPA1), the camphor sensitivity of cultured rat dorsal root ganglion neurons was highest in a subpopulation of cold- and icilin-sensitive neurons, strongly suggesting that camphor activates native TRPM8. Camphor has a dual action on TRPM8: it not only activates the channel but also inhibits its response to menthol. The icilin-insensitive chicken TRPM8 was also camphor insensitive. However, camphor was able to activate an icilin-insensitive human TRPM8 mutant channel. The activation and sensitization to cold of mammalian TRPM8 are likely to be responsible for the psychophysical enhancement of innocuous cold and "stinging/burning" cold sensations by camphor.

Transient receptor potential melastatin 7 (TRPM7) cation channel is a unique protein that has the dual ability to act as a channel to regulate transmembrane Mg 2+ transport and also as a kinase to promote cellular signaling. Despite increasing awareness of the importance of Mg 2+ in cardiovascular biology nothing is known about TRPM7 and its kinase domain in the pathophysiology of hypertension. We previously demonstrated that Ang II regulates TRPM7 in vitro . Here we studied TRPM7 kinase-deficient mice to explore the role of the TRPM7 kinase domain in Ang II-induced hypertension. TRPM7 kinase deficient mice (TRPM7 +/- ) and wild type (WT) counterparts were infused with Ang II (400 ng/kg/min; minipumps) for 4 weeks. Blood pressure (BP) was measured by tail cuff. Vascular reactivity and structure studies were performed by myography in mesenteric arteries. Although baseline BP tended to be higher in TRPM7 +/- versus WT mice (127 ± 6.0 vs 119 ± 2.2 mmHg), significance was not achieved. TRPM7 +/- mice displayed earlier onset of BP increase by Ang II (2 weeks; WT-Ang II: 145 ± 5 vs TRPM7 +/- Ang II: 178 ± 9; mmHg). After 4 weeks, BP was significantly higher in TRPM7 +/- (174 ± 10 mmHg) than in WT mice (147 ± 8 mmHg). Ang II-induced hypertension was associated with cardiac hypertrophy, an effect that was exaggerated in TRPM7 +/- mice (WT: 4.4 ± 0.1; WT-Ang II: 5.0 ± 0.2; TRPM7 +/- : 4.5 ± 0.1; TRPM7 +/- Ang II: 5.7 ± 0.1 g/body weight). Mesenteric arteries from Ang II-infused TRPM7 +/- mice exhibited decreased sensitivity to acetylcholine (pD2; WT-Ang II: 7.6 ± 0.3 vs. TRPM7 +/- Ang II: 6.7 ± 0.4), and reduced maximal relaxation compared to WT mice (WT-Ang II: 88 ± 8% vs TRPM7 +/- Ang II: 59 ± 10%). Ang II induced a leftward shift in the stress-strain relationship for both WT and TRPM7 +/- mice in a similar fashion. Plasma analysis revealed that TRPM7 +/- mice were hypomagnesemic, and that Ang II increased Mg 2+ levels to a greater extent in WT than in TRPM7 +/- mice (WT: 0.65 ± 0.02; WT-Ang II: 0.74 ± 0.04; TRPM7 +/- : 0.60 ± 0.01; TRPM7 +/- Ang II: 0.64 ± 0.02; mmol/L). In conclusion, our findings demonstrate that hypertension, cardiac hypertrophy and endothelial dysfunction are exaggerated by Ang II in TRPM7 +/- hypomagnesemic mice, suggesting a novel role for TRPM7 kinase domain in cardiovascular pathophysiology.

The divalent cation-selective channel transient receptor potential melastatin 7 (TRPM7) channel was shown to affect the proliferation of some types of cancer cell. However, the function of TRPM7 in the viability of breast cancer cells remains unclear. Here we show that TRPM inhibitors suppressed the viability of TRPM7-expressing breast cancer cells. We first demonstrated that the TRPM7 inhibitors 2-aminoethyl diphenylborinate (2-APB), ginsenoside Rd (Gin Rd), and waixenicin A preferentially suppressed the viability of human embryonic kidney HEK293 overexpressing TRPM7 (HEK-M7) cells over wildtype HEK293 (WT-HEK). Next, we confirmed the effects of 2-APB on the TRPM7 channel functions by whole-cell currents and divalent cation influx. The inhibition of the viability of HEK-M7 cells by 2-APB was not mediated by the increase in cell death but by the interruption of the cell cycle. Similar to HEK-M7 cells, the viability of TRPM7-expressing human breast cancer MDA-MB-231, AU565, and T47D cells were also suppressed by 2-APB by arresting the cell cycle in the S phase. Furthermore, in a novel TRPM7 knock-out MDA-MB-231 (KO-231) cell line, decreased divalent influx and reduced proliferation were observed compared to the wildtype MDA-MB-231 cells. 2-APB and Gin Rd preferentially suppressed the viability of wildtype MDA-MB-231 cells over KO-231 by affecting the cell cycle in wildtype but not KO-231 cells. Our results suggest that TRPM7 regulates the cell cycle of breast cancers and is a potential therapeutic target.

The Mg(2+) and Ca(2+) conducting transient receptor potential melastatin 7 (TRPM7) channel-enzyme (chanzyme) has been implicated in immune cell function. Mice heterozygous for a TRPM7 kinase deletion are hyperallergic, while mice with a single point mutation at amino acid 1648, silencing kinase activity, are not. As mast cell mediators trigger allergic reactions, we here determine the function of TRPM7 in mast cell degranulation and histamine release. Our data establish that TRPM7 kinase activity regulates mast cell degranulation and release of histamine independently of TRPM7 channel function. Our findings suggest a regulatory role of TRPM7 kinase activity on intracellular Ca(2+) and extracellular Mg(2+) sensitivity of mast cell degranulation. Transient receptor potential melastatin 7 (TRPM7) is a divalent ion channel with a C-terminally located α-kinase. Mice heterozygous for a TRPM7 kinase deletion (TRPM7(+/∆K) ) are hypomagnesaemic and hyperallergic. In contrast, mice carrying a single point mutation at amino acid 1648, which silences TRPM7 kinase activity (TRPM7(KR) ), are not hyperallergic and are resistant to systemic magnesium (Mg(2+) ) deprivation. Since allergic reactions are triggered by mast cell-mediated histamine release, we investigated the function of TRPM7 on mast cell degranulation and histamine release using wild-type (TRPM7(+/+) ), TRPM7(+/∆K) and TRPM7(KR) mice. We found that degranulation and histamine release proceeded independently of TRPM7 channel function. Furthermore, extracellular Mg(2+) assured unperturbed IgE-DNP-dependent exocytosis, independently of TRPM7. However, impairment of TRPM7 kinase function suppressed IgE-DNP-dependent exocytosis, slowed the cellular degranulation rate, and diminished the sensitivity to intracellular calcium (Ca(2+) ) in G protein-induced exocytosis. In addition, G protein-coupled receptor (GPCR) stimulation revealed strong suppression of histamine release, whereas removal of extracellular Mg(2+) caused the phenotype to revert. We conclude that the TRPM7 kinase activity regulates murine mast cell degranulation by changing its sensitivity to intracellular Ca(2+) and affecting granular mobility and/or histamine contents.

Cell death modulation by transient receptor potential melastatin channels TRPM2 and TRPM7 and their underlying molecular mechanisms

The Plasma Membrane TRPM8 Plays a Protective Role against Prostate Cancer Progression; Trpm8 Gene as a Downstream Target of P53 Tumor-Suppressor