Temperature adaptation patterns in Chinese cattle revealed by TRPM2 gene mutation analysis

Cattle are sensitive to temperature fluctuations but adapt well to inclement weather conditions. When environmental temperatures exceed specific thresholds, heat stress becomes a critical concern for cattle. The TRPM2 gene, which resides on cattle chromosome 1 encodes a TRP channel protein, holding a unique capacity to sense temperature changes and facilitate rapid response to avoid heat stress. Here, we utilized the Bovine Genome Variation Database (BGVD) (http://animal.omics.pro/code/index.php/BosVar), and identified a missense mutation site, c.805A > G: p. Met269Val (rs527146862), within the TRPM2 gene. To elucidate the functional assessment of this mutation in temperature adaptation attributes of Chinese cattle, we genotyped 407 samples from 20 distinct breeds representing diverse climatic zones across China. The association analysis incorporates three temperature parameters and revealed compelling insights in terms of allele frequency. Interestingly, the prevalence of the wild-type allele A was notably higher among northern cattle breeds and this trend diminished gradually as observed in southern cattle populations. Conversely, the mutant-type allele G demonstrated a contrasting trend. Moreover, southern cattle exhibited markedly higher frequencies of GG and GA genotypes (P < 0.01). The presence of heterozygous and homozygous mutations appears to confer an enhanced capacity for adaptation to elevated temperatures. These results provide unequivocal correlation evidence between TRPM2 genotypes (AA, GA, GG) and environmental temperature parameters and comprehend the genetic mechanisms governing temperature adaptation in cattle. This provides valuable insights for strategic breed selection across diverse climatic regions, thereby aiding livestock production amid evolving climate challenges.

Reviewing critical TRPM2 variants through a structure-function lens

The transient receptor potential melastatin 2 (TRPM2) channel plays a central role in connecting redox state with calcium signaling in living cells. This coupling makes TRPM2 essential for physiological functions such as pancreatic insulin secretion or cytokine production, but also allows it to contribute to pathological processes, including neuronal cell death or ischemia-reperfusion injury. Genetic deletion of the channel, albeit not lethal, alters physiological functions in mice. In humans, population genetic studies and whole-exome sequencing have identified several common and rare genetic variants associated with mental disorders and neurodegenerative diseases, including single nucleotide variants (SNVs) in exonic regions. In this review, we summarize available information on the four best-documented SNVs: one common (rs1556314) and three rare genetic variants (rs139554968, rs35288229, and rs145947009), manifested in amino acid substitutions D543E, R707C, R755C, and P1018L respectively. We discuss existing evidence supporting or refuting the associations between SNVs and disease. Furthermore, we aim to interpret the molecular impacts of these amino acid substitutions based on recently published structures of human TRPM2. Finally, we formulate testable hypotheses and suggest means to investigate them. Studying the function of proteins with rare mutations might provide insight into disease etiology and delineate new drug targets.

miR-217 Regulates Normal and Tumor Cell Fate Following Induction of Endoplasmic Reticulum Stress

Rapidly proliferating cancer cells require a microenvironment where essential metabolic nutrients like glucose, oxygen, and growth factors become scarce as the tumor volume surpasses the established vascular capacity of the tissue. Limits in nutrient availability typically trigger growth arrest and/or apoptosis to prevent cellular expansion. However, tumor cells frequently co-opt cellular survival pathways thereby favoring cell survival under this environmental stress. The unfolded protein response (UPR) pathway is typically engaged by tumor cells to favor adaptation to stress. PERK, an endoplasmic reticulum (ER) protein kinase and UPR effector is activated in tumor cells and contributes tumor cell adaptation by limiting protein translation and balancing redox stress. PERK also induces miRNAs that contribute to tumor adaptation. miR-211 and miR-216b were previously identified as PERK-ATF4-regulated miRNAs that regulate cell survival. We have identified another PERK-responsive miRNA, miR-217, with increased expression under prolonged ER stress. Key targets of miR-217 are identified as TRPM1, the host gene for miR-211 and EZH2. Evidence is provided that miR-217 expression is essential for the rapid loss of miR-211 in prolonged ER stress and provides a functional link for determining whether cells adapt to stress or commit to apoptosis.

IMPLICATIONS

PERK-dependent induction of miR-217 limits accumulation and function of the prosurvival miRNA, miR-211, to establish cell fate and promote cell commitment to apoptosis.

Exploring the role of TRPM4 in calcium-dependent triggered activity and cardiac arrhythmias

Cardiac arrhythmias pose a major threat to a patient's health, yet prove to be often difficult to predict, prevent and treat. A key mechanism in the occurrence of arrhythmias is disturbed Ca2+ homeostasis in cardiac muscle cells. As a Ca2+-activated non-selective cation channel, TRPM4 has been linked to Ca2+-induced arrhythmias, potentially contributing to translating an increase in intracellular Ca2+ concentration into membrane depolarisation and an increase in cellular excitability. Indeed, evidence from genetically modified mice, analysis of mutations in human patients and the identification of a TRPM4 blocking compound that can be applied in vivo further underscore this hypothesis. Here, we provide an overview of these data in the context of our current understanding of Ca2+-dependent arrhythmias.

TRPM2-dependent autophagy inhibition exacerbates oxidative stress-induced CXCL16 secretion by keratinocytes in vitiligo

Vitiligo is a depigmented skin disease due to the destruction of melanocytes. Under oxidative stress, keratinocyte-derived chemokine C-X-C motif ligand 16 (CXCL16) plays a critical role in recruiting CD8+ T cells, which kill melanocytes. Autophagy serves as a protective cell survival mechanism and impairment of autophagy has been linked to increased secretion of the proinflammatory cytokines. However, the role of autophagy in the secretion of CXCL16 under oxidative stress has not been investigated. Herein, we initially found that autophagy was suppressed in both keratinocytes of vitiligo lesions and keratinocytes exposed to oxidative stress in vitro. Autophagy inhibition also promoted CXCL16 secretion. Furthermore, upregulated transient receptor potential cation channel subfamily M member 2 (TRPM2) functioned as an upstream oxidative stress sensor to inhibit autophagy. Moreover, TRPM2-mediated Ca2+ influx activated calpain to shear autophagy related 5 (Atg5) and Atg12-Atg5 conjugate formation was blocked to inhibit autophagy under oxidative stress. More importantly, Atg5 downregulation enhanced the binding of interferon regulatory factor 3 (IRF3) to the CXCL16 promoter region by activating Tank-binding kinase 1 (TBK1), thus promoting CXCL16 secretion. These findings suggested that TRPM2-restrained autophagy promotes CXCL16 secretion via the Atg5-TBK1-IRF3 signaling pathway under oxidative stress. Inhibition of TRPM2 may serve as a potential target for the treatment of vitiligo. © 2024 The Pathological Society of Great Britain and Ireland.

Synergic actions of botulinum neurotoxin A and oxaliplatin on colorectal tumour cell death through the upregulation of TRPM2 channel-mediated oxidative stress

Botulinum neurotoxin A (BoNT) is being shown to have anticancer action as a potential adjuvant treatment. The transient receptor potential (TRP) melastatin 2 (TRPM2) stimulator action of BoNT was reported in glioblastoma cells, but not in colorectal cancer (HT29) cells. By activating TRPM2, we evaluated the impacts of BoNT and oxaliplatin (OXA) incubations on oxidant and apoptotic values within the HT29 cells. Control, BoNT (5 IU for 24 h), OXA (50 μM for 24 h) and their combinations were induced. We found that TRPM2 protein is upregulated and mediates enhanced BoNT and OXA-induced Ca2+ entry in cells as compared to control cells. The increase of free reactive oxygen species (ROS), but the decrease of glutathione is the main ROS responsible for TRPM2 activation on H29 exposure to oxidative stress. BoNT and OXA-mediated Ca2+ entry through TRPM2 stimulation in response to H2 O2 results in mitochondrial Ca2+ overload, followed by mitochondrial membrane depolarization, apoptosis and caspase-3/-8/-9, although they were diminished in the TRPM2 antagonist groups (N-(p-amylcinnamoyl)anthranilic acid and carvacrol). In conclusion, by increasing the susceptibility of HT29 tumour cells to oxidative stress and apoptosis, the combined administration of BoNT and OXA via the targeting of TRPM2 may offer a different approach to kill the tumour cells.

A Rare Case of Neonatal Hypomagnesemia with Secondary Hypocalcemia Caused by a Novel Homozygous TRPM6 Gene Variant

BACKGROUND Familial hypomagnesemia with secondary hypocalcemia (HSH) is a rare autosomal recessive disorder (OMIM# 602014) caused by mutations in the gene encoding transient receptor potential melastatin 6 (TRPM6)) on chromosome 9q22, a channel involved in epithelial magnesium resorption. While a plethora of studies have delineated various clinical manifestations pertinent to this mutation, the literature is devoid of connections between TRPM6 mutations and bleeding diathesis, or sudden infant death syndrome (SIDS). This report presents a case of familial HSH associated with the novel homozygous TRPM6 gene variant c.5281C>G p. (Arg1761Gly) chr9: 77354845. CASE REPORT This report details a 26-day-old neonate, born full term with optimal Apgar scores, who experienced an abrupt emergence of apnea, cyanosis, bilateral nasal bleeding, and diminished alertness. Despite the neonate's initially unremarkable clinical birth indicators, a meticulous assessment unveiled a pronounced family history of SIDS, including a sibling previously diagnosed with hypomagnesemia. Laboratory examination of the infant demonstrated severe hypomagnesemia and hypocalcemia, conditions which were promptly ameliorated following intravenous administration of magnesium and calcium. Whole-exome sequencing identified a homozygous TRPM6 gene mutation c.5281C>G p. (Arg1761Gly) at chr9: 77354845. This gene is crucial for magnesium regulation. The mutation involves a cytosine-to-guanine shift, resulting in an arginine to glycine amino acid substitution at position 1761 of the TRPM6 protein. CONCLUSIONS This report has highlighted that infantile hypomagnesemia may be associated with symptoms and signs that can mimic infection, or it can present with seizures. Although familial HSH is a rare genetic disorder that can be identified by genetic testing, correction of hypomagnesemia is the most important and immediate clinical management strategy.

Borneol exerts its antipruritic effects by inhibiting TRPA1 and activating TRPM8

ETHNOPHARMACOLOGICAL RELEVANCE

Borneol is a long-established traditional Chinese medicine that has been found to be effective in treating pain and itchy skin. However, whether borneol has a therapeutic effect on chronic itch and its related mechanisms remain unclear.

AIM OF THE STUDY

To investigate the antipruritic effect of borneol and its molecular mechanism.

MATERIALS AND METHODS

DrugBAN framework and molecular docking were applied to predict the targets of borneol, and the calcium imaging or patch-clamp recording analysis were used to detect the effects of borneol on TRPA1, TRPM8 or TRPV3 channels in HEK293T cells. In addition, various mouse models of acute itch and chronic itch were established to evaluate the antipruritic effects of borneol on C57BL/6J mice. Then, the borneol-induced pruritic relief was further investigated in Trpa1-/-, Trpm8-/-, or Trpa1-/-/Trpm8-/- mice. The effects of borneol on the activation of TRPM8 and the inhibition of TRPA1 were also measured in dorsal root ganglia neurons of wild-type (WT), Trpm8-/- and Trpv1-/- mice. Lastly, a randomized, double-blind study of adult patients was conducted to evaluate the clinical antipruritic effect of borneol.

RESULTS

TRPA1, TRPV3 and TRPM8 are the potential targets of borneol according to the results of DrugBAN algorithm and molecular docking. Calcium imaging and patch-clamp recording analysis demonstrated that borneol activates TRPM8 channel-induced cell excitability and inhibits TRPA1 channel-mediated cell excitability in transfected HEK293T cells. Animal behavior analysis showed that borneol can significantly reduce acute and chronic itch behavior in C57BL/6J mice, but this effect was eliminated in Trpa1-/-, Trpm8-/- mice, or at least in Trpa1-/-/Trpm8-/- mice. Borneol elicits TRPM8 channel induced [Ca2+]i responses but inhibits AITC or SADBE-induced activation of TRPA1 channels in dorsal root ganglia neurons of WT and Trpv1-/- mice, respectively. Furthermore, the clinical results indicated that borneol could reduce itching symptoms in patients and its efficacy is similar to that of menthol.

CONCLUSION

Borneol has therapeutic effects on multiple pruritus models in mice and patients with chronic itch, and the mechanism may be through inhibiting TRPA1 and activating TRPM8.

Separation of Oral Cooling and Warming Requires TRPM8

Cooling sensations arise inside the mouth during ingestive and homeostasis behaviors. Oral presence of cooling temperature engages the cold and menthol receptor TRPM8 (transient receptor potential melastatin 8) on trigeminal afferents. Yet, how TRPM8 influences brain and behavioral responses to oral temperature is undefined. Here we used in vivo neurophysiology to record action potentials stimulated by cooling and warming of oral tissues from trigeminal nucleus caudalis neurons in female and male wild-type and TRPM8 gene deficient mice. Using these lines, we also measured orobehavioral licking responses to cool and warm water in a novel, temperature-controlled fluid choice test. Capture of antidromic electrophysiological responses to thalamic stimulation identified that wild-type central trigeminal neurons showed diverse responses to oral cooling. Some neurons displayed relatively strong excitation to cold <10°C (COLD neurons) while others responded to only a segment of mild cool temperatures below 30°C (COOL neurons). Notably, TRPM8 deficient mice retained COLD-type but lacked COOL cells. This deficit impaired population responses to mild cooling temperatures below 30°C and allowed warmth-like (≥35°C) neural activity to pervade the normally innocuous cool temperature range, predicting TRPM8 deficient mice would show anomalously similar orobehavioral responses to warm and cool temperatures. Accordingly, TRPM8 deficient mice avoided both warm (35°C) and mild cool (≤30°C) water and sought colder temperatures in fluid licking tests, whereas control mice avoided warm but were indifferent to mild cool and colder water. Results imply TRPM8 input separates cool from warm temperature sensing and suggest other thermoreceptors also participate in oral cooling sensation.

Sodium-Permeable Ion Channels TRPM4 and TRPM5 are Functional in Human Gastric Parietal Cells in Culture and Modulate the Cellular Response to Bitter-Tasting Food Constituents

Gastric parietal cells secrete chloride ions and protons to form hydrochloric acid. Besides endogenous stimulants, e.g., acetylcholine, bitter-tasting food constituents, e.g., caffeine, induce proton secretion via interaction with bitter taste receptors (TAS2Rs), leading to increased cytosolic Ca2+ and cAMP concentrations. We hypothesized TAS2R activation by bitter tastants to result in proton secretion via cellular Na+ influx mediated by transient receptor potential channels (TRP) M4 and M5 in immortalized human parietal HGT-1 cells. Using the food-derived TAS2R agonists caffeine and l-arginine, we demonstrate both bitter compounds to induce a TRPM4/M5-mediated Na+ influx, with EC50 values of 0.65 and 10.38 mM, respectively, that stimulates cellular proton secretion. Functional involvement of TAS2Rs in the caffeine-evoked effect was demonstrated by means of the TAS2R antagonist homoeriodictyol, and stably CRISPR-Cas9-edited TAS2R43ko cells. Building on previous results, these data further support the suitability of HGT-1 cells as a surrogate cell model for taste cells. In addition, TRPM4/M5 mediated a Na+ influx after stimulating HGT-1 cells with the acetylcholine analogue carbachol, indicating an interaction of the digestion-associated cholinergic pathway with a taste-signaling pathway in parietal cells.

Clinical and genetic studies for a cohort of patients with congenital stationary night blindness

BACKGROUND

Congenital stationary night blindness (CSNB) is an inherited retinal disorder. Most of patients have myopia. This study aims to describe the clinical and genetic characteristics of fifty-nine patients with CSNB and investigate myopic progression under genetic cause.

RESULTS

Sixty-five variants were detected in the 59 CSNB patients, including 32 novel and 33 reported variants. The most frequently involved genes were NYX, CACNA1F, and TRPM1. Myopia (96.61%, 57/59) was the most common clinical finding, followed by nystagmus (62.71%, 37/59), strabismus (52.54%, 31/59), and nyctalopia (49.15%, 29/59). An average SE of -7.73 ± 3.37 D progressed to -9.14 ± 2.09 D in NYX patients with myopia, from - 2.24 ± 1.53 D to -4.42 ± 1.43 D in those with CACNA1F, and from - 5.21 ± 2.89 D to -9.24 ± 3.16 D in those with TRPM1 during the 3-year follow-up; the TRPM1 group showed the most rapid progression.

CONCLUSIONS

High myopia and strabismus are distinct clinical features of CSNB that are helpful for diagnosis. The novel variants identified in this study will further expand the knowledge of variants in CSNB and help explore the molecular mechanisms of CSNB.

Cold temperature induces a TRPM8-independent calcium release from the endoplasmic reticulum in human platelets

The detection of temperature by the human sensory system is life-preserving and highly evolutionarily conserved. Platelets are sensitive to temperature changes and are activated by a decrease in temperature, akin to sensory neurons. However, the molecular mechanism of this temperature-sensing ability is unknown. Yet, platelet activation by temperature could contribute to numerous clinical sequelae, most importantly to reduced quality of ex vivo-stored platelets for transfusion. In this multidisciplinary study, we present evidence for the expression of the temperature-sensitive ion channel transient receptor potential cation channel subfamily member 8 (TRPM8) in human platelets and precursor cells. We found the TRPM8 mRNA and protein in MEG-01 cells and platelets. Inhibition of TRPM8 prevented temperature-induced platelet activation and shape change. However, chemical agonists of TRPM8 did not seem to have an acute effect on platelets. When exposing platelets to below-normal body temperature, we detected a cytosolic calcium increase which was independent of TRPM8 but was completely dependent on the calcium release from the endoplasmic reticulum. Because of the high interindividual variability of TRPM8 expression, a population-based approach should be the focus of future studies. Our study suggests that the cold response of platelets is complex and TRPM8 appears to play a role in early temperature-induced activation of platelets, while other mechanisms likely contribute to later stages of temperature-mediated platelet response.

miR135a administration ameliorates brain ischemic damage by preventing TRPM7 activation during brain ischemia

BACKGROUND

miRNA-based strategies have recently emerged as a promising therapeutic approach in several neurodegenerative diseases. Unregulated cation influx is implicated in several cellular mechanisms underlying neural cell death during ischemia. The brain constitutively active isoform of transient receptor potential melastatin 7 (TRPM7) represents a glutamate excitotoxicity-independent pathway that significantly contributes to the pathological Ca2+ overload during ischemia.

AIMS

In the light of these premises, inhibition of TRPM7 may be a reasonable strategy to reduce ischemic injury. Since TRPM7 is a putative target of miRNA135a, the aim of the present paper was to evaluate the role played by miRNA135a in cerebral ischemia. Therefore, the specific objectives of the present paper were: (1) to evaluate miR135a expression in temporoparietal cortex of ischemic rats; (2) to investigate the effect of the intracerebroventricular (icv) infusion of miR135a on ischemic damage and neurological functions; and (3) to verify whether miR135a effects may be mediated by an alteration of TRPM7 expression.

METHODS

miR135a expression was evaluated by RT- PCR and FISH assay in temporoparietal cortex of ischemic rats. Ischemic volume and neurological functions were determined in rats subjected to transient middle cerebral artery occlusion (tMCAo) after miR135a intracerebroventricular perfusion. Target analysis was performed by Western blot.

RESULTS

Our results demonstrated that, in brain cortex, 72 h after ischemia, miR135a expression increased, while TRPM7 expression was parallelly downregulated. Interestingly, miR135a icv perfusion strongly ameliorated the ischemic damage and improved neurological functions, and downregulated TRPM7 protein levels.

CONCLUSIONS

The early prevention of TRPM7 activation is protective during brain ischemia.

TRPM channels in health and disease

Different cell channels and transporters tightly regulate cytoplasmic levels and the intraorganelle distribution of cations. Perturbations in these processes lead to human diseases that are frequently associated with kidney impairment. The family of melastatin-related transient receptor potential (TRPM) channels, which has eight members in mammals (TRPM1-TRPM8), includes ion channels that are highly permeable to divalent cations, such as Ca2+, Mg2+ and Zn2+ (TRPM1, TRPM3, TRPM6 and TRPM7), non-selective cation channels (TRPM2 and TRPM8) and monovalent cation-selective channels (TRPM4 and TRPM5). Three family members contain an enzymatic protein moiety: TRPM6 and TRPM7 are fused to α-kinase domains, whereas TRPM2 is linked to an ADP-ribose-binding NUDT9 homology domain. TRPM channels also function as crucial cellular sensors involved in many physiological processes, including mineral homeostasis, blood pressure, cardiac rhythm and immunity, as well as photoreception, taste reception and thermoreception. TRPM channels are abundantly expressed in the kidney. Mutations in TRPM genes cause several inherited human diseases, and preclinical studies in animal models of human disease have highlighted TRPM channels as promising new therapeutic targets. Here, we provide an overview of this rapidly evolving research area and delineate the emerging role of TRPM channels in kidney pathophysiology.

Mouse transient receptor potential melastatin 2 (TRPM2) isoform 7 attenuates full-length mouse TRPM2 activity through reductions in its expression by targeting it to ER-associated degradation

Transient receptor potential melastatin 2 (TRPM2) assembles into tetramers to function as an oxidative stress-sensitive Ca2+ channel at the surface membrane. Limited information is currently available on the 10 protein isoforms of mouse TRPM2 (mTRPM2) identified. This study investigated whether these isoforms function as Ca2+ channels and examined their effects on full-length mTRPM2 activity using the HEK 293 cell exogenous expression system. Only full-length mTRPM2, isoform 1 localized to the surface membrane and was activated by oxidative stress. Isoform 7 was clearly recognized by protein quality control systems and degraded by endoplasmic reticulum-associated degradation after transmembrane proteolysis. In the co-expression system, the activation and expression of full-length mTRPM2 were attenuated by its co-expression with isoform 7, but not with the other isoforms. This decrease in the expression of full-length mTRPM2 was recovered by the proteasomal inhibitor. The present results suggest that isoforms other than isoform 1 did not function as oxidative stress-sensitive channels and also that only isoform 7 attenuated the activation of full-length mTRPM2 by targeting it to endoplasmic reticulum-associated degradation. The present study will provide important information on the functional nature of mTRPM2 isoforms for the elucidation of their roles in physiological and patho-physiological responses in vivo using mouse models.

Sterile inflammation via TRPM8 RNA-dependent TLR3-NF-kB/IRF3 activation promotes antitumor immunity in prostate cancer

Inflammation is a common condition of prostate tissue, whose impact on carcinogenesis is highly debated. Microbial colonization is a well-documented cause of a small percentage of prostatitis cases, but it remains unclear what underlies the majority of sterile inflammation reported. Here, androgen- independent fluctuations of PSA expression in prostate cells have lead us to identify a prominent function of the Transient Receptor Potential Cation Channel Subfamily M Member 8 (TRPM8) gene in sterile inflammation. Prostate cells secret TRPM8 RNA into extracellular vesicles (EVs), which primes TLR3/NF-kB-mediated inflammatory signaling after EV endocytosis by epithelial cancer cells. Furthermore, prostate cancer xenografts expressing a translation-defective form of TRPM8 RNA contain less collagen type I in the extracellular matrix, significantly more infiltrating NK cells, and larger necrotic areas as compared to control xenografts. These findings imply sustained, androgen-independent expression of TRPM8 constitutes as a promoter of anticancer innate immunity, which may constitute a clinically relevant condition affecting prostate cancer prognosis.

Pulmonary Hypertension Induces Serotonin Hyperreactivity and Metabolic Reprogramming in Coronary Arteries via NOX1/4-TRPM2 Signaling Pathway

BACKGROUND

Clinical evidence revealed abnormal prevalence of coronary artery (CA) disease in patients with pulmonary hypertension (PH). The mechanistic connection between PH and CA disease is unclear. Serotonin (5-hydroxytryptamine), reactive oxygen species, and Ca2+ signaling have been implicated in both PH and CA disease. Our recent study indicates that NOXs (NADPH [nicotinamide adenine dinucleotide phosphate] oxidases) and TRPM2 (transient receptor potential cation channel subfamily M member 2) are key components of their interplay. We hypothesize that activation of the NOX-TRPM2 pathway facilitates the remodeling of CA in PH.

METHODS

Left and right CAs from chronic hypoxia and monocrotaline-induced PH rats were collected to study vascular reactivity, gene expression, metabolism, and mitochondrial function. Inhibitors or specific siRNA were used to examine the pathological functions of NOX1/4-TRPM2 in CA smooth muscle cells.

RESULTS

Significant CA remodeling and 5-hydroxytryptamine hyperreactivity in the right CA were observed in PH rats. NOX1/4-mediated reactive oxygen species production coupled with TRPM2-mediated Ca2+ influx contributed to 5-hydroxytryptamine hyperresponsiveness. CA smooth muscle cells from chronic hypoxia-PH rats exhibited increased proliferation, migration, apoptosis, and metabolic reprogramming in an NOX1/4-TRPM2-dependent manner. Furthermore, the NOX1/4-TRPM2 pathway participated in mitochondrial dysfunction, involving mitochondrial DNA damage, reactive oxygen species production, elevated mitochondrial membrane potential, mitochondrial Ca2+ accumulation, and mitochondrial fission. In vivo knockdown of NOX1/4 alleviated PH and suppressed CA remodeling in chronic hypoxia rats.

CONCLUSIONS

PH triggers an increase in 5-hydroxytryptamine reactivity in the right CA and provokes metabolic reprogramming and mitochondrial disruption in CA smooth muscle cells via NOX1/4-TRPM2 activation. This signaling pathway may play an important role in CA remodeling and CA disease in PH.

Hereditary hypomagnesemia with secondary hypocalcemia caused by a novel mutation in TRPM6 gene

OBJECTIVES

Hereditary hypomagnesemia with secondary hypocalcemia (HSH), which results from variations in the transient receptor potential melastatin 6 (TRPM6) genes, is a rare hereditary cause of extremely low serum magnesium levels. We describe an infant with triggered seizures due to hypomagnesemia and a novel mutation in TRPM6 gene was identified.

CASE PRESENTATION

A 10-month-old boy presented with multidrug resistant seizures, and axial hypotonia due to severe hypomagnesemia. Electroencephalography and neuroimaging of the patient was normal. He had a favorable outcome with magnesium supplement. In this study, the patient underwent clinical exome sequencing (CES) which detected a novel homozygous variant in the TRPM6 gene: NM_017662.5: c.5571-3C>G. After replacing his magnesium orally, he was free from seizures and had an encouraging outcome at the twelfth-month follow-up.

CONCLUSIONS

HSH often presents with developmental issues, treatment-resistant seizures, and increased neuromuscular excitability. Untreated hypomagnesemia can potentially be fatal and severely impair cognitive function. Clinical suspicion is essential for early diagnosis and treatment.

Rare cause of recurrent hypocalcaemia and functional hypoparathyroidism due to hypomagnesaemia caused by TRPM6 gene mutation

Magnesium is essential for the functioning and release of parathyroid hormone. Therefore, its deficiency can present as functional hypoparathyroidism. This case report describes a rare inherited disorder called congenital hypomagnesaemia with secondary hypocalcaemia due to TRPM6 gene mutation. This disease clinically and biochemically mimics hypoparathyroidism. However, unlike hypoparathyroidism, it can be treated only by long-term oral magnesium supplements. The patient presented to us with recurrent hypocalcaemic convulsions. The laboratory picture in each admission was similar to that of hypoparathyroidism. However, the hypocalcaemia persisted, and it was noticed to be associated with persistent hypomagnesaemia. A defect in the tubular magnesium reabsorption was postulated and a genetic analysis of the patient was done, which revealed a TRPM6 mutation causing hypomagnesaemia by excessive renal excretion of magnesium. The child responded well to oral magnesium supplements and is currently developmentally appropriate for her age and thriving well.

The TRPM2 ion channel regulates metabolic and thermogenic adaptations in adipose tissue of cold-exposed mice

Introduction

During thermogenesis, adipose tissue (AT) becomes more active and enhances oxidative metabolism. The promotion of this process in white AT (WAT) is called "browning" and, together with the brown AT (BAT) activation, is considered as a promising approach to counteract obesity and metabolic diseases. Transient receptor potential cation channel, subfamily M, member 2 (TRPM2), is an ion channel that allows extracellular Ca2+ influx into the cytosol, and is gated by adenosine diphosphate ribose (ADPR), produced from NAD+ degradation. The aim of this study was to investigate the relevance of TRPM2 in the regulation of energy metabolism in BAT, WAT, and liver during thermogenesis.

Methods

Wild type (WT) and Trpm2-/- mice were exposed to 6°C and BAT, WAT and liver were collected to evaluate mRNA, protein levels and ADPR content. Furthermore, O2 consumption, CO2 production and energy expenditure were measured in these mice upon thermogenic stimulation. Finally, the effect of the pharmacological inhibition of TRPM2 was assessed in primary adipocytes, evaluating the response upon stimulation with the β-adrenergic receptor agonist CL316,243.

Results

Trpm2-/- mice displayed lower expression of browning markers in AT and lower energy expenditure in response to thermogenic stimulus, compared to WT animals. Trpm2 gene overexpression was observed in WAT, BAT and liver upon cold exposure. In addition, ADPR levels and mono/poly-ADPR hydrolases expression were higher in mice exposed to cold, compared to control mice, likely mediating ADPR generation.

Discussion

Our data indicate TRPM2 as a fundamental player in BAT activation and WAT browning. TRPM2 agonists may represent new pharmacological strategies to fight obesity.

Expression and function of transient receptor potential melastatin 3 in the spinal afferent innervation of the mouse colon

Abdominal pain is a cardinal symptom of inflammatory bowel disease (IBD). Transient receptor potential (TRP) channels contribute to abdominal pain in preclinical models of IBD, and TRP melastatin 3 (TRPM3) has recently been implicated in inflammatory bladder and joint pain in rodents. We hypothesized that TRPM3 is involved in colonic sensation and is sensitized during colitis. We used immunohistochemistry, ratiometric Ca2+ imaging, and colonic afferent nerve recordings in mice to evaluate TRPM3 protein expression in colon-projecting dorsal root ganglion (DRG) neurons, as well as functional activity in DRG neurons and colonic afferent nerves. Colitis was induced using dextran sulfate sodium (DSS) in drinking water. TRPM3 protein expression was observed in 76% of colon-projecting DRG neurons and was often colocalized with calcitonin gene-related peptide. The magnitudes of intracellular Ca2+ transients in DRG neurons in response to the TRPM3 agonists CIM-0216 and pregnenolone sulfate sodium were significantly greater in neurons from mice with colitis compared with controls. In addition, the percentage of DRG neurons from mice with colitis that responded to CIM-0216 was significantly increased. CIM-0216 also increased the firing rate of colonic afferent nerves from control and mice with colitis. The TRPM3 inhibitor isosakuranetin inhibited the mechanosensitive response to distension of wide dynamic range afferent nerve units from mice with colitis but had no effect in control mice. Thus, TRPM3 contributes to colonic sensory transduction and may be a potential target for treating pain in IBD.NEW & NOTEWORTHY This is the first study to characterize TRPM3 protein expression and function in colon-projecting DRG neurons. A TRPM3 agonist excited DRG neurons and colonic afferent nerves from healthy mice. TRPM3 agonist responses in DRG neurons were elevated during colitis. Inhibiting TRPM3 reduced the firing of wide dynamic range afferent nerves from mice with colitis but had no effect in control mice.

Screening Mutations of the Monogenic Syndromic High Myopia by Whole Exome Sequencing From MAGIC Project

Purpose

This observational study aimed to identify mutations in monogenic syndromic high myopia (msHM) using data from reported samples (n = 9370) of the Myopia Associated Genetics and Intervention Consortium (MAGIC) project.

Methods

The targeted panel containing 298 msHM-related genes was constructed and screening of clinically actionable variants was performed based on whole exome sequencing. Capillary sequencing was used to verify the identified gene mutations in the probands and perform segregation analysis with their relatives.

Results

A total of 381 candidate variants in 84 genes and 85 eye diseases were found to contribute to msHM in 3.6% (335/9370) of patients with HM. Among them, the 22 genes with the most variations accounted for 62.7% of the diagnostic cases. In the genotype-phenotype association analysis, 60% (201/335) of suspected msHM cases were recalled and 25 patients (12.4%) received a definitive genetic diagnosis. Pathogenic variants were distributed in 18 msHM-related diseases, mainly involving retinal dystrophy genes (e.g. TRPM1, CACNA1F, and FZD4), connective tissue disease genes (e.g. FBN1 and COL2A1), corneal or lens development genes (HSF4, GJA8, and MIP), and other genes (TEK). The msHM gene mutation types were allocated to four categories: nonsense mutations (36%), missense mutations (36%), frameshift mutations (20%), and splice site mutations (8%).

Conclusions

This study highlights the importance of thorough molecular subtyping of msHM to provide appropriate genetic counselling and multispecialty care for children and adolescents with HM.

Dimerization of the CNNM extracellular domain

Cystathionine-β $$ \beta $$ -synthase (CBS)-pair domain divalent metal cation transport mediators (CNNMs) are an evolutionarily conserved family of magnesium transporters. They mediate magnesium homeostasis directly by transport of Mg2+ ions and indirectly by regulation of the transient receptor potential ion channel subfamily M member 7 (TRPM7). Here, we report the crystal structure of the extracellular domain of tapeworm CNNM4. The domain forms a dimer of immunoglobulin-like (Ig-like) folds with electron density observed for three glycosylation sites. Analytical ultracentrifugation confirms that mutations in the extracellular domain of human CNNM4 prevent its dimerization. An analogous mutation in mouse CNNM2 impairs its activity in a cellular assay of Mg2+ transport.

Transient receptor potential channel TRPM4 favors oxidized low-density lipoprotein-induced coronary endothelial cell dysfunction via a mechanism involving ferroptosis

Accelerating the repair of damaged endothelium can effectively inhibit the progression of atherosclerosis (AS). Transient receptor potential channel TRPM4 is a non-selective cation channel activated by internal Ca2+, which is expressed in endothelial cells. This study aimed to reveal the potential role of TRPM4 in AS along with the mechanism. Human coronary artery endothelial cells (HCAECs) induced by ox-LDL was regarded as an in vitro model. The impacts of TRPM4 knockdown on cellular inflammation response, oxidative stress, normal endothelial function and lipid peroxidation were evaluated. Given that ferroptosis promotes AS progression, the effects of TRPM4 on intracellular iron ions and ferroptosis-related proteins was determined. Afterwards, HCAECs were treated with ferroptosis inducer erastin, and the influence of ferroptosis in the cellular model was revealed. TRPM4 was elevated in response to ox-LDL treatment in HCAECs. TRPM4 knockdown reduced the inflammation response, oxidative stress and lipid peroxidation caused by ox-LDL, and maintained the normal function of HCAECs. Erastin treatment destroyed the impacts of TRPM4 knockdown that are beneficial for cells to resist ox-LDL, showing the enhancement of the above adverse factors. Together, this study found that TRPM4 knockdown reduced ox-LDL-induced inflammation, oxidative stress, and dysfunction in HCAECs, possibly via a mechanism involving Fe2+ and ferroptosis-related proteins.

Joint CB1 and NGF Receptor Activation Suppresses TRPM8 Activation in Etoposide-Resistant Retinoblastoma Cells

In childhood, retinoblastoma (RB) is the most common primary tumor in the eye. Long term therapeutic management with etoposide of this life-threatening condition may have diminishing effectiveness since RB cells can develop cytostatic resistance to this drug. To determine whether changes in receptor-mediated control of Ca2+ signaling are associated with resistance development, fluorescence calcium imaging, semi-quantitative RT-qPCR analyses, and trypan blue dye exclusion staining patterns are compared in WERI-ETOR (etoposide-insensitive) and WERI-Rb1 (etoposide-sensitive) cells. The cannabinoid receptor agonist 1 (CNR1) WIN55,212-2 (40 µM), or the transient receptor potential melastatin 8 (TRPM8) agonist icilin (40 µM) elicit similar large Ca2+ transients in both cell line types. On the other hand, NGF (100 ng/mL) induces larger rises in WERI-ETOR cells than in WERI-Rb1 cells, and its lethality is larger in WERI-Rb1 cells than in WERI-ETOR cells. NGF and WIN55,212-2 induced additive Ca2+ transients in both cell types. However, following pretreatment with both NGF and WIN55,212-2, TRPM8 gene expression declines and icilin-induced Ca2+ transients are completely blocked only in WERI-ETOR cells. Furthermore, CNR1 gene expression levels are larger in WERI-ETOR cells than those in WERI-Rb1 cells. Therefore, the development of etoposide insensitivity may be associated with rises in CNR1 gene expression, which in turn suppress TRPM8 gene expression through crosstalk.

[Effect of TRPM8 on pain symptom and neuronal proliferation in mice with interstitial cystitis/bladder pain syndrome]

Objective: To explore the effects between transient receptor potential melastatin 8 (TRPM8) on pain symptom and neuronal proliferation in mice with interstitial cystitis/bladder pain syndrome (IC/BPS). Methods: Female wild-type C57BL/6 mice (8-10 weeks old) were divided into control group, IC/BPS model group, and IC/BPS model+menthol group (6 mice each) by random number table method; TRPM8 knockout mice were randomly divided into TRPM8 knockout group and TRPM8 knockout model group (6 mice each). The IC/BPS model group, the IC/BPS model+menthol group, and the TRPM8 knockout model group were injected subcutaneously with residues 65-84 of murine uroplakin 3A (UPK3A65-84). The IC/BPS model+menthol group continued to be injected with menthol. After successful modeling, the differences in pain thresholds between the groups were assessed by mechanosensitivity. The bladder wall was injected with a cell membrane red fluorescent probe (Dil), and the dorsal root ganglion (DRG) tissues were collected 10 days later. The differences in the protein and mRNA levels of TRPM8 and GAP43 in the groups were detected by Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR), respectively. Immunofluorescence was used to detect the distribution of TRPM8 expression with GAP43 or Dil in DRG tissues. The relationship between TRPM8 and pain symptom and its role in neuronal proliferation in IC/BPS mice were analyzed. Results: The models were all constructed successfully. Compared with the control group, the pain thresholds of mice in the IC/BPS model group and IC/BPS model+menthol group were reduced [(8.50±1.22), (5.50±1.05) vs (11.67±2.16), respectively, all P<0.001]. Compared with the control group, the expression of TRPM8 mRNA was elevated in the IC/BPS model group and IC/BPS model+menthol group, while TRPM8 was not expressed in the TRPM8 knockout group [(3.16±0.05), (6.46±0.21), and 0 vs (1.00±0.06), respectively, all P<0.001]. The expression of TRPM8 protein and mRNA in each group had the same trend (P<0.001). Compared with the control group, the expression of GAP43 mRNA in the DRG of the IC/BPS model group and the IC/BPS model+menthol group was increased, whereas the expression of GAP43 mRNA in the TRPM8 knockout model group was decreased (all P<0.001). The trend of GAP43 protein expression was the same as that of mRNA expression (P<0.001). Immunofluorescence results showed an increase in the number of GAP43-positive neurons in the DRG of the IC/BPS model group and the IC/BPS model+menthol group, and a decrease in the TRPM8 knockout group compared with the control group (all P<0.001). Compared with the control group, the number of Dil-positive neurons in the DRG of the IC/BPS model group and the IC/BPS model+menthol group was increased, while the TRPM8 knockout group was decreased (all P<0.001). Conclusion: TRPM8 can exacerbate pain symptom in IC/BPS mice, and the mechanism may be related to the induction of sensory nerve proliferation at the DRG level.

A Cataract-Causing Mutation in the TRPM3 Cation Channel Disrupts Calcium Dynamics in the Lens

TRPM3 belongs to the melastatin sub-family of transient receptor potential (TRPM) cation channels and has been shown to function as a steroid-activated, heat-sensitive calcium ion (Ca2+) channel. A missense substitution (p.I65M) in the TRPM3 gene of humans (TRPM3) and mice (Trpm3) has been shown to underlie an inherited form of early-onset, progressive cataract. Here, we model the pathogenetic effects of this cataract-causing mutation using 'knock-in' mutant mice and human cell lines. Trpm3 and its intron-hosted micro-RNA gene (Mir204) were strongly co-expressed in the lens epithelium and other non-pigmented and pigmented ocular epithelia. Homozygous Trpm3-mutant lenses displayed elevated cytosolic Ca2+ levels and an imbalance of sodium (Na+) and potassium (K+) ions coupled with increased water content. Homozygous TRPM3-mutant human lens epithelial (HLE-B3) cell lines and Trpm3-mutant lenses exhibited increased levels of phosphorylated mitogen-activated protein kinase 1/extracellular signal-regulated kinase 2 (MAPK1/ERK2/p42) and MAPK3/ERK1/p44. Mutant TRPM3-M65 channels displayed an increased sensitivity to external Ca2+ concentration and an altered dose response to pregnenolone sulfate (PS) activation. Trpm3-mutant lenses shared the downregulation of genes involved in insulin/peptide secretion and the upregulation of genes involved in Ca2+ dynamics. By contrast, Trpm3-deficient lenses did not replicate the pathophysiological changes observed in Trpm3-mutant lenses. Collectively, our data suggest that a cataract-causing substitution in the TRPM3 cation channel elicits a deleterious gain-of-function rather than a loss-of-function mechanism in the lens.

TRPM8 inhibits substance P release from primary sensory neurons via PKA/GSK-3beta to protect colonic epithelium in colitis

Transient receptor potential melastatin 8 (TRPM8) is a cold sensory receptor in primary sensory neurons that regulates various neuronal functions. Substance P (SP) is a pro-inflammatory neuropeptide secreted by the neurons, and it aggravates colitis. However, the regulatory role of TRPM8 in SP release is still unclear. Our study aimed to investigate TRPM8's role in SP release from primary sensory neurons during colitis and clarify the effect of SP on colonic epithelium. We analyzed inflammatory bowel disease patients' data from the Gene Expression Omnibus dataset. Dextran sulfate sodium (DSS, 2.5%)-induced colitis in mice, mouse dorsal root ganglion (DRG) neurons, ND7/23 cell line, and mouse or human colonic organoids were used for this experiment. Our study found that TRPM8, TAC1 and WNT3A expression were significantly correlated with the severity of ulcerative colitis in patients and DSS-induced colitis in mice. The TRPM8 agonist (menthol) and the SP receptor antagonist (Aprepitant) can attenuate colitis in mice, but the effects were not additive. Menthol promoted calcium ion influx in mouse DRG neurons and inhibited the combination and phosphorylation of PKAca from the cAMP signaling pathway and GSK-3β from the Wnt/β-catenin signaling pathway, thereby inhibiting the effect of Wnt3a-driven β-catenin on promoting SP release in ND7/23 cells. Long-term stimulation with SP inhibited proliferation and enhanced apoptosis in both mouse and human colonic organoids. Conclusively, TRPM8 inhibits SP release from primary sensory neurons by inhibiting the interaction between PKAca and GSK-3β, thereby inhibiting the role of SP in promoting colonic epithelial apoptosis and relieving colitis.

2'-deoxy-ADPR activates human TRPM2 faster than ADPR and thereby induces higher currents at physiological Ca2+ concentrations

TRPM2 is a Ca2+ permeable, non-selective cation channel in the plasma membrane that is involved in the innate immune response regulating, for example, chemotaxis in neutrophils and cytokine secretion in monocytes and macrophages. The intracellular adenine nucleotides ADP-ribose (ADPR) and 2'-deoxy-ADPR (2dADPR) activate the channel, in combination with their co-agonist Ca2+. Interestingly, activation of human TRPM2 (hsTRPM2) by 2dADPR is much more effective than activation by ADPR. However, the underlying mechanism of the nucleotides' differential effect on the channel is not yet fully understood. In this study, we performed whole-cell patch clamp experiments with HEK293 cells heterologously expressing hsTRPM2. We show that 2dADPR has an approx. 4-fold higher Ca2+ sensitivity than ADPR (EC50 = 190 and 690 nM). This allows 2dADPR to activate the channel at lower and thus physiological intracellular Ca2+ concentrations. Kinetic analysis of our data reveals that activation by 2dADPR is faster than activation by ADPR. Mutation in a calmodulin binding N-terminal IQ-like motif in hsTRPM2 completely abrogated channel activation by both agonists. However, mutation of a single amino acid residue (W1355A) in the C-terminus of hsTRPM2, at a site of extensive inter-domain interaction, resulted in slower activation by 2dADPR and neutralized the difference in rate of activation between the two agonists. Taken together, we propose a mechanism by which 2dADPR induces higher hsTRPM2 currents than ADPR by means of faster channel activation. The finding that 2dADPR has a higher Ca2+ sensitivity than ADPR may indicate that 2dADPR rather than ADPR activates hsTRPM2 in physiological contexts such as the innate immune response.

The Combination of 5-FU and Resveratrol Can Suppress the Growth of Glioblastoma Cells Through Downregulation of TRPM2 and β-Catenin

Glioblastoma multiforme (GBM) is the most common as well as the most fatal primary malignant tumor of the central nervous system (CNS), which still lacks a definitive cure. 5-FU is an anti-metabolite anti-cancer agent which has shown promising results for GBM treatment. Resveratrol (Res) is a phytochemical anti-oxidant that has also been effective in suppressing the progression of GBM. The combination of 5-FU and Res has been studied in a variety of cancers, but no study has assessed this combination in GBM. In this study, we investigated how 5-FU and Res, in combination and alone, may affect the growth and apoptosis of GBM cells and also the potential of TRPM2 and β-catenin as the mediator of their effects. U87 cells were cultured as the in vitro model. MTT assay was used for measuring cellular growth, and RT-qPCR was used to measure the level of caspase-3, TRPM2, and β-catenin; caspase-3 level served as the indicator of apoptotic rate. 5-FU and Res, in combination and alone, suppressed the growth while promoting the apoptosis of U87 cells; these effects were significantly greater when they were used in combination. RT-qPCR showed downregulation of TRPM-2 and β-catenin in response to this combination, which suggested that these two molecules may mediate the cited anti-oncogenic effects. In conclusion, our study confirmed the synergism between 5-FU and Res in suppressing the progression of GBM and suggested the putative axis of TRPM2/ β-catenin as the downstream mediator of this therapeutic regime. Future studies may be able to approve the eligibility of this therapeutic regime for GBM treatment and also the underlying mechanism.

The Role of TRPM7 in Oncogenesis

This review summarizes the current understanding of the role of transient receptor potential melastatin-subfamily member 7 (TRPM7) channels in the pathophysiology of neoplastic diseases. The TRPM family represents the largest and most diverse group in the TRP superfamily. Its subtypes are expressed in virtually all human organs playing a central role in (patho)physiological events. The TRPM7 protein (along with TRPM2 and TRPM6) is unique in that it has kinase activity in addition to the channel function. Numerous studies demonstrate the role of TRPM7 chanzyme in tumorigenesis and in other tumor hallmarks such as proliferation, migration, invasion and metastasis. Here we provide an up-to-date overview about the possible role of TRMP7 in a broad range of malignancies such as tumors of the nervous system, head and neck cancers, malignant neoplasms of the upper gastrointestinal tract, colorectal carcinoma, lung cancer, neoplasms of the urinary system, breast cancer, malignant tumors of the female reproductive organs, prostate cancer and other neoplastic pathologies. Experimental data show that the increased expression and/or function of TRPM7 are observed in most malignant tumor types. Thus, TRPM7 chanzyme may be a promising target in tumor therapy.

Transient receptor potential melastatin 2 is involved in trinitrobenzene sulfonic acid-induced acute and chronic colitis-associated fibrosis progression in mice

Crohn's disease, a chronic and recurrent gastrointestinal disease, frequently causes intestinal fibrosis. Transient receptor potential melastatin 2 (TRPM2), a non-selective cation channel, is activated by reactive oxygen species. This study investigated the role of TRPM2 in acute colitis and chronic colitis-associated fibrosis progression. Acute colitis and chronic colitis-associated fibrosis were induced in TRPM2-deficient (TRPM2KO) and wild-type (WT) mice through single and repeated intrarectal injections of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Bone marrow-derived macrophages (BMDMs) from WT and TRPM2KO mice were stimulated using H2O2. In WT mice, a single TNBS injection induced acute colitis with upregulated inflammatory cytokines/chemokines and Th1/Th17-related cytokines, while repeated TNBS injections induced chronic colitis-associated fibrosis with upregulation of fibrogenic factors and Th2-related cytokines. Acute colitis and chronic colitis-associated fibrosis with cytokines/chemokine upregulation and fibrogenic factors were considerably suppressed in TRPM2KO mice. Treating BMDMs with H2O2 increased cytokine/chemokine expression and JNK, ERK, and p38 phosphorylation; however, these responses were significantly less in TRPM2KO than in WT mice. These findings suggest that TRPM2 contributes to acute colitis progression via Th1/Th17-mediated immune responses. Furthermore, TRPM2 may be directly involved in colitis-associated fibrosis induction, likely due to the regulation of Th2/TGF-β1-mediated fibrogenesis in addition to a consequence of acute colitis progression.

Renal diseases that course with hypomagnesemia. Comments on a new hereditary hypomagnesemic tubulopathy

Renal diseases associated with hypomagnesemia are a complex and diverse group of tubulopathies caused by mutations in genes encoding proteins that are expressed in the thick ascending limb of the loop of Henle and in the distal convoluted tubule. In this paper, we review the initial description, the clinical expressiveness and etiology of four of the first hypomagnesemic tubulopathies described: type 3 Bartter and Gitelman diseases, Autosomal recessive hypomagnesemia with secondary hypocalcemia and Familial hypomagnesemia with hypercalciuria and nephrocalcinosis. The basic biochemical patterns observed in renal tubular hypomagnesemias and the modalities of transport and interaction that occur between the transporters involved in the reabsorption of magnesium in the distal convoluted tubule are described below. Finally, the recent report of a new renal disease with hypomagnesemia, type 2 hypomagnesemia with secondary hypocalcemia caused by reduced TRPM7 channel activity is described.

TRPM4 and PLCβ3 contribute to normal behavioral responses to an array of sweeteners and carbohydrates but PLCβ3 is not needed for taste-driven licking for glucose

The peripheral taste system is more complex than previously thought. The novel taste-signaling proteins TRPM4 and PLCβ3 appear to function in normal taste responding as part of Type II taste cell signaling or as part of a broadly responsive (BR) taste cell that can respond to some or all classes of tastants. This work begins to disentangle the roles of intracellular components found in Type II taste cells (TRPM5, TRPM4, and IP3R3) or the BR taste cells (PLCβ3 and TRPM4) in driving behavioral responses to various saccharides and other sweeteners in brief-access taste tests. We found that TRPM4, TRPM5, TRPM4/5, and IP3R3 knockout (KO) mice show blunted or abolished responding to all stimuli compared with wild-type. IP3R3 KO mice did, however, lick more for glucose than fructose following extensive experience with the 2 sugars. PLCβ3 KO mice were largely unresponsive to all stimuli except they showed normal concentration-dependent responding to glucose. The results show that key intracellular signaling proteins associated with Type II and BR taste cells are mutually required for taste-driven responses to a wide range of sweet and carbohydrate stimuli, except glucose. This confirms and extends a previous finding demonstrating that Type II and BR cells are both necessary for taste-driven licking to sucrose. Glucose appears to engage unique intracellular taste-signaling mechanisms, which remain to be fully elucidated.

TRPM8 knockdown relieved inflammatory response and cell apoptosis in pneumonia model induced by Streptococcus pneumoniae in vitro

Streptococcus pneumoniae infection remains a leading cause of pneumonia-related deaths. Transient receptor potential melastatin 8 (TRPM8) exerts crucial roles in lung diseases. We first dissected the role of TRPM8 in pneumococcal pneumonia and the mechanism related to TRPM8 effects. TRPM8 expression and inflammation cytokines level were determined in 15 paired patients and controls. A549 cells were pretreated with si-TRPM8, followed by infection with S. pneumoniae D39 strain (D39). TRPM8 expressions in D39-treated cells were detected and the effect of TRPM8 inhibition on the viability, apoptosis, and inflammation induced by D39 was evaluated. To explore the mechanism underlying TRPM8 effects, cells in D39+si-TRPM8 group were further treated with MAPK activator (Anisomycin, ANIS). TRPM8 was highly expressed in patients and cell models at mRNA or/and protein levels. Cytokines of TNF-α, IL-1β and IL-6 were intensely upregulated in the serum samples of patients and cells infected with D39 (p<0.05). TRPM8 knockdown attenuated the reduced cell viability and increased cell apoptosis (reflected by the upregulation of Bax and downregulation of Bcl-2) in D39 group (p<0.05). The expression level of inflammation cytokines was lower in D39+si-TRPM8 group than D39 group (p<0.05). The protein levels of NF-κB p-p65 and p-p38 MAPK were intensely accumulated in D39 treated cells, while reduced by TRPM8 inhibition (p<0.05). ANIS addition significantly attenuated the altered cell viability, cell apoptosis and inflammation response in D39+si-TRPM8 group (p<0.05). TRPM8 knockdown relieved D39 infection-caused inflammation and cell apoptosis via NF-κB/MAPK signaling.

LncRNA SNHG8 regulates the migration and angiogenesis of pHUVECs induced by high glucose via the TRPM7/ERK1/2 signaling axis

This study aimed to evaluate the regulatory effect and molecular mechanism of long noncoding RNA small nucleolus RNA host gene 8 (LncRNA SNHG8) in the migration and angiogenesis of primary human umbilical vein endothelial cells (pHUVECs) under high-glucose (HG) conditions. The HG-induced endothelial injury model was established in vitro.The cell model of silencing SNHG8, overexpressing SNHG8, and silencing TRPM7 was established by transfecting SNHG8-siRNA, SNHG8 plasmid and TRPM7-siRNA into cells with liposomes.The SNHG8 level was determined through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The expression levels of transient receptor potential melastatin 7 (TRPM7), endothelial nitric oxide synthase (eNOS), p-eNOS, extracellular signal-regulated kinase 1/2(ERK1/2), and p-ERK1/2 were assessed through western blot. Nitric oxide (NO) levels were measured with DAF-FM. pHUVEC migration was examined through wound healing and Transwell assay, and pHUVEC angiogenesis was observed through a tube formation assay. Results showed that HG promoted the expression of lncRNA SNHG8 and TRPM7 and decreased the ratio of p-eNOS/eNOS and p-ERK1/2/ERK1/2 in pHUVECs . NO production, migration , and angiogenesis were inhibited in pHUVECs under HG conditions. Silencing lncRNA SNHG8 and TRPM7 could significantly reverse the HG-induced decrease in eNOS activation, NO production , migration, and angiogenesis . SNHG8 and U0126 (ERK pathway inhibitor) overexpression enhanced the HG effects, whereas using U0126 did not affect the TRPM7 expression. In conclusion, lncRNA SNHG8 participates in HG-induced endothelial cell injury and likely regulates NO production, migration, and angiogenesis of pHUVECs via the TRPM7/ERK1/2 signaling axis.

In silico analysis of TRPM4 variants of unknown clinical significance

BACKGROUND

TRPM4 is a calcium-activated channel that selectively permeates monovalent cations. Genetic variants of the channel in cardiomyocytes are associated with various heart disorders, such as progressive familial heart block and Brugada syndrome. About97% of all known TRPM4 missense variants are classified as variants of unknown clinical significance (VUSs). The very large number of VUSs is a serious problem in diagnostics and treatment of inherited heart diseases.

METHODS AND RESULTS

We collected 233 benign or pathogenic missense variants in the superfamily of TRP channels from databases ClinVar, Humsavar and Ensembl Variation to compare performance of 22 algorithms that predict damaging variants. We found that ClinPred is the best-performing tool for TRP channels. We also used the paralogue annotation method to identify disease variants across the TRP family. In the set of 565 VUSs of hTRPM4, ClinPred predicted pathogenicity of 299 variants. Among these, 12 variants are also categorized as LP/P variants in at least one paralogue of hTRPM4. We further used the cryo-EM structure of hTRPM4 to find scores of contact pairs between parental (wild type) residues of VUSs for which ClinPred predicts a high probability of pathogenicity of variants for both contact partners. We propose that 68 respective missense VUSs are also likely pathogenic variants.

CONCLUSIONS

ClinPred outperformed other in-silico tools in predicting damaging variants of TRP channels. ClinPred, the paralogue annotation method, and analysis of residue contacts the hTRPM4 cryo-EM structure collectively suggest pathogenicity of 80 TRPM4 VUSs.

PDIA6, which is regulated by TRPM2-AS/miR-424-5p axis, promotes endometrial cancer progression via TGF-beta pathway

PDIA6 have been reported to be involved in a variety of cancers, however, the underlying role in endometrial cancer is still unclear. In this study, we aimed to study the function of PDIA6 in endometrial cancer. Firstly, we verified that PDIA6 was significantly upregulated in endometrial cancer, which was correlated with the progression of endometrial cancer patients. Furthermore, we identified PDIA6 significantly altered the ability of endometrial cancer cells to proliferate and metastasize. In addition, our result illustrated the oncogene effects of PDIA6 in promoting malignant biological behavior of endometrial cancer cells by regulating TGF-β pathway and being modulated by TRPM2-AS/miR-424-5p axis for the first time. Taken together, this study suggested that PDIA6 may be a new candidate target for endometrial cancer therapy.

DNA Sensor-Based Strategy to Visualize the TRPM7 mRNA-Mg2+ Signaling Pathway in Cancer Cells

Technological advances and methodological innovations in cell signaling pathway analysis will facilitate progress in understanding biological processes, intervening in diseases, and screening drugs. In this work, an elaborate strategy for visualizing and monitoring the transient receptor potential melastatin 7 (TRPM7)-Mg2+ signaling pathway in living cells was constructed through the logical analysis of upstream mRNA and downstream molecules by two individual DNA sensors. The DNA sensors are constructed by modifying the dye-labeled DNA sequences on the surface of gold nanoparticles. By hybridizing with upstream mRNA, Cy5-modified DNA sensor 1 can detect and silence it simultaneously, outputting a red fluorescence signal. When the upstream mRNA is silenced, the concentration of downstream molecules of Mg2+ will be affected and down-regulated. The FAM-modified DNA sensor 2 detects this change and emits a green fluorescence as a signal. Therefore, the dynamic information on TRPM7 mRNA and the Mg2+-mediated signaling pathway can be successfully obtained by fluorescence imaging methods. Furthermore, the TRPM7 mRNA-Mg2+ signaling pathway also affects cell activity and migratory function through cell scratching and other experiments. More importantly, the proposed sensor also shows potential for screening signaling pathway inhibitors. Our work provides a simple and general strategy for the visualization of signaling pathways, which helps to understand the changes in the physiological activities of cancer cells and the causes of carcinogenesis and is crucial for cancer diagnosis and prognosis.

De novo TRPM3 missense variant associated with neurodevelopmental delay and manifestations of cerebral palsy

We identified a de novo heterozygous transient receptor potential cation channel subfamily M (melastatin) member 3 (TRPM3) missense variant, p.(Asn1126Asp), in a patient with developmental delay and manifestations of cerebral palsy (CP) using phenotype-driven prioritization analysis of whole-genome sequencing data with Exomiser. The variant is localized in the functionally important ion transport domain of the TRPM3 protein and predicted to impact the protein structure. Our report adds TRPM3 to the list of Mendelian disease-associated genes that can be associated with CP and provides further evidence for the pathogenicity of the variant p.(Asn1126Asp).

Transcriptomic profile of the mechanosensitive ion channelome in human cardiac fibroblasts

Human cardiac fibroblasts (HCFs) have mRNA transcripts that encode different mechanosensitive ion channels and channel regulatory proteins whose functions are not known yet. The primary goal of this work was to define the mechanosensitive ion channelome of HCFs. The most common type of cationic channel is the transient receptor potential (TRP) family, which is followed by the TWIK-related K+ channel (TREK), transmembrane protein 63 (TMEM63), and PIEZO channel (PIEZO) families. In the sodium-dependent NON-voltage-gated channel (SCNN) subfamily, only SCNN1D was shown to be highly expressed. Particular members of the acid-sensing ion channel (ASIC) (ASIC1 and ASIC3) subfamilies were also significantly expressed. The transcripts per kilobase million (TPMs) for Piezo 2 were almost 100 times less abundant than those for Piezo 1. The tandem of P domains in a weak inward rectifying K+ channel (TWIK)-2 channel, TWIK-related acid-sensitive K+ channel (TASK)-5, TASK-1, and the TWIK-related K1 (TREK-1) channel were the four most prevalent types in the K2P subfamily. The highest expression in the TRPP subfamily was found for PKD2 and PKD1, while in the TRPM subfamily, it was found for TRPM4, TRPM7, and TRPM3. TRPV2, TRPV4, TRPV3, and TRPV6 (all members of the TRPV subfamily) were also substantially expressed. A strong expression of the TRPC1, TRPC4, TRPC6, and TRPC2 channels and all members of the TRPML subfamily (MCOLN1, MCOLN2, and MCOLN3) was also shown. In terms of the transmembrane protein 16 (TMEM16) family, the HCFs demonstrated significant expression of the TMEM16H, TMEM16F, TMEM16J, TMEM16A, and TMEM16G channels. TMC3 is the most expressed channel in HCFs of all known members of the transmembrane channel-like protein (TMC) family. This analysis of the mechanosensitive ionic channel transcriptome in HCFs: (1) agrees with previously documented findings that all currently identified mechanosensitive channels play a significant and well recognized physiological function in elucidating the mechanosensitive characteristics of HCFs; (2) supports earlier preliminary reports that point to the most common expression of the TRP mechanosensitive family in HCFs; and (3) points to other new mechanosensitive channels (TRPC1, TRPC2, TWIK-2, TMEM16A, ASIC1, and ASIC3).

Loss of TRPM8 Exacerbate Herpes Simplex Keratitis Infection in Mice by Promoting the Infiltration of CD11b+ Ly6G+ Cells and Increasing the Viral Load in the Cornea

Purpose

To reveal the role of transient receptor potential cation subfamily M member 8 (TRPM8) channels in herpes simplex keratitis (HSK).

Methods

HSK models were established using TRPM8 knockout (TRPM8-/-) mice and their wild-type (WT) littermates. The infected corneas were graded and harvested to evaluate the mRNA levels of inflammatory factors through quantitative real-time polymerase chain reaction (RT-PCR), as well as the infiltration of inflammatory cells through immunofluorescence staining and flow cytometry. Viral titers were determined by plaque assay and absolute quantitative method. RNA-sequencing was conducted to elucidate the transcriptome of corneal epithelium in response to TRPM8 knockout after infection. The anti-inflammatory effect of TRPM8 agonist menthol was documented via subconjunctival administration.

Results

Compared to their wild-type counterparts, TRPM8-deficient mice exhibited exacerbated infection symptoms and thicker corneas in HSK models. Infection in TRPM8-deficient mice resulted in significant lymphocyte infiltration, primarily consisting of Ly6G+ CD11b+ cells. Additionally, TRPM8-deficient mice displayed increased levels of corneal viral titers after infection, along with decreased expression of interferon-stimulated genes (ISGs). Subconjunctival administration of menthol effectively alleviated infection-induced symptoms and Ly6G+ CD11b+ cell infiltration in herpes simplex virus type 1 (HSV-1)-treated mice.

Conclusions

TRPM8 promoted host resistance to HSV-1 infection by suppressing the accumulation of Ly6G+ CD11b+ cells and virus replication. These findings suggest that targeting TRPM8 could be valuable for therapeutic interventions against HSV-1 infections.

Ischemia-Reperfusion Increases TRPM7 Expression in Mouse Retinas

Ischemia is the main cause of cell death in retinal diseases such as vascular occlusions, diabetic retinopathy, glaucoma, or retinopathy of prematurity. Although excitotoxicity is considered the primary mechanism of cell death during an ischemic event, antagonists of glutamatergic receptors have been unsuccessful in clinical trials with patients suffering ischemia or stroke. Our main purpose was to analyze if the transient receptor potential channel 7 (TRPM7) could contribute to retinal dysfunction in retinal pathologies associated with ischemia. By using an experimental model of acute retinal ischemia, we analyzed the changes in retinal function by electroretinography and the changes in retinal morphology by optical coherence tomography (OCT) and OCT-angiography (OCTA). Immunohistochemistry was performed to assess the pattern of TRPM7 and its expression level in the retina. Our results show that ischemia elicited a decrease in retinal responsiveness to light stimuli along with reactive gliosis and a significant increase in the expression of TRPM7 in Müller cells. TRPM7 could emerge as a new drug target to be explored in retinal pathologies associated with ischemia.

Circ_0040994 depletion alleviates lipopolysaccharide-induced HK2 cell injury through miR-17-5p/TRPM7 axis

BACKGROUND

Sepsis is a fatal systemic inflammatory disease that causes septic acute kidney injury (AKI). In this work, we explored the roles of circ_0040994 in lipopolysaccharide (LPS)-induced human kidney-2 (HK2) cell injury.

METHODS

Circ_0040994, miR-17-5p and transient receptor potential melastatin 7 (TRPM7) expression were detected by qRT-PCR. Cell functions were examined by MTT assay, flow cytometry assay, western blot, ELISA assay, and oxidative stress assay. The molecular association was detected by dual-luciferase reporter assay.

RESULTS

Circ_0040994 was upregulated in the serum of septic AKI patients in comparison with the serum of healthy controls. Silencing circ_0040994 enhanced cell viability but inhibited cell apoptosis, cell inflammation and oxidative stress in LPS-triggered HK2 cells. Circ_0040994 acted as a miR-17-5p sponge to regulate the level of TRPM7. Moreover, miR-17-5p could alleviate LPS-induced HK2 cell injury by suppressing TRPM7.

CONCLUSION

Circ_0040994 downregulation alleviated LPS-induced HK2 cell injury through the miR-17-5p/TRPM7 axis.

Contribution and underlying mechanisms of lncRNA TRPM2-AS in the development and progression of human cancers

Long-stranded non-coding RNAs (lncRNAs) are RNA molecules that are longer than 200 nucleotides and do not code for proteins. They play a significant role in various biological processes, including epigenetics, cell cycle, and cell differentiation. Many studies have shown that the occurrence of human cancer is closely related to the abnormal expression of lncRNA. In recent years, lncRNAs have been a hot topic in cancer research. TRPM2-AS, a novel lncRNA, is aberrantly expressed in many human cancers, and its overexpression is strongly linked to poor clinical outcomes in patients. It has been demonstrated that TRPM2-AS acts as a ceRNA, participates in signaling pathways, and interacts with biological proteins and other molecular mechanisms to regulate gene expression. In addition, it can regulate the proliferation, migration, invasion, apoptosis, and treatment resistance of cancer cells. As a result, TRPM2-AS may be a potential target for cancer treatment and a possible biomarker for cancer prognosis. This review outlined the expression, biological processes, and molecular mechanisms of TRPM2-AS in various malignancies, and discussed potential therapeutic uses.

Magnesium Status, Genetic Variants of Magnesium-Related Ion Channel Transient Receptor Potential Membrane Melastatin 6 (TRPM6) and the Risk of Gestational Diabetes Mellitus in Chinese Pregnant Women: A Nested Case-Control Study

SCOPE

Magnesium plays an important role in regulating glucose metabolism. The study attempts to explore association between magnesium status and single nucleotide polymorphisms (SNPs) of gene involved in magnesium absorption-transient receptor potential membrane melastatin 6 (TRPM6) and gestational diabetes mellitus (GDM) risk METHODS AND RESULTS: A nested case-control study including 170 GDM cases and matched 340 controls is conducted based on Tongji Birth Cohort. Dietary, serum, and urine magnesium are evaluated before the diagnosis of GDM. Compared to the lowest tertile, women in the highest tertile of serum magnesium are at a lower risk of GDM (adjusted odds ratio [aOR] 0.42, 95% confidence intervals [CI] 0.21-0.84). Serum magnesium is inversely associated with insulin and homeostatic model assessment of insulin resistance (β = -0.05, p = 0.002; β = -0.04, p = 0.001, respectively). The aOR for GDM in carriers of the CT or CC genotypes of TRPM6 rs2274924 compared with carriers of the TT genotype is 2.76 (95% CI 1.78-4.26). Dietary magnesium is positively associated with serum magnesium (β = 0.02, p = 0.004), but not with GDM risk.

CONCLUSION

Serum magnesium and the TRPM6 rs2274924 polymorphism are associated with the risk of GDM.

Intestinal hypomagnesemia in an Iranian patient with a novel TRPM6 variant: a case report and review of the literature

TRPM6 is predominantly expressed in the kidney and colon and encodes a protein containing an ion channel domain and a protein kinase domain. It is crucial for magnesium homeostasis and plays important roles in epithelial magnesium transport and the active magnesium absorption. In this study, we present a 70-day-old Iranian female patient from consanguineous parents with hypomagnesemia and secondary hypocalcemia. She presented with seizures 19 days after birth and refractory watery non-bloody diarrhea. She consequently had failure to thrive. Other features included hypotonia, wide anterior fontanel, ventriculomegaly, and pseudotumor cerebri following administration of nalidixic acid. She had severe hypomagnesemia and hypocalcemia which were treated with magnesium and calcium supplementation. Despite initial unstable response to supplemental magnesium, she eventually improved and the diarrhea discontinued. The patient was discharged by magnesium and calcium therapy. At the last follow-up at age 2.5 years, the patient remained well without any recurrence or complication. Genetic testing by whole-exome sequencing revealed a novel homozygous frameshift insertion-deletion (indel) variant in exon 26 of the TRPM6 gene, c.3693-3699del GCAAGAG ins CTGCTGTTGACATCTGCT, p.L1231Ffs*36. Segregation analysis revealed the TRPM6 heterozygous variant in both parents. Patients with biallelic TRPM6 pathogenic variants typically exhibit hypomagnesemia with secondary hypocalcemia and present with neurologic manifestations including seizures. In some patients, this is also complicated by chronic diarrhea and failure to thrive. Long-term complications are rare and most of the patients show a good prognosis with supplemental magnesium therapy.

SIRT1 slows the progression of lupus nephritis by regulating the NLRP3 inflammasome through ROS/TRPM2/Ca2+ channel

Systemic lupus erythematosus (SLE) is a chronic multisystem inflammatory disease associated with autoantibody formation. Lupus nephritis (LN) is one of the most severe organ manifestations of SLE. The inflammatory response is a key factor in kidney injury, and the NLRP3 inflammasome is frequently associated with the pathogenesis of LN. Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD +)-dependent histone deacetylase, is a promising therapeutic target for preventing renal injury. However, the mechanism of SIRT1 in LN remains unclear. Here, we aimed to investigate the mechanism by which SIRT inhibits the NLRP3 inflammasome to slow the progression of LN. We detected the expression of SIRT1 and the infiltration of macrophages in MRL/lpr mice; the results showed that the expression of SIRT1 was decreased, and the symptoms of lupus nephritis were relieved after the use of resveratrol, which upregulated SIRT1. In vitro studies showed that after lipopolysaccharide (LPS) stimulation, SIRT1 expression decreased, and the NLRP3 inflammasome was activated. Upregulation of SIRT1 inhibits NLRP3 inflammasome activation and assembly by interfering with two signalling pathways. First, SIRT1 affects NF-κB expression, transcription, and inflammatory cytokine expression. Second, SIRT1 modulates calcium influx induced by transient receptor potential channel M2 (TRPM2), which could be partly due to the inhibition of reactive oxygen species (ROS) production. Our findings suggest that upregulated SIRT1 inhibits the NLRP3 inflammasome to slow the progression of lupus nephritis by regulating NF-κB and ROS/TRPM2/Ca2+ channels. This study reveals a new anti-inflammatory mechanism of SIRT1, suggesting that SIRT1 may be a potential therapeutic target for the prevention of LN.

TRPM2-L Participates in the Interleukin-6 Pathway to Enhance Tumor Growth in Prostate Cancer by Hypoxia-Inducible Factor-1α

Interleukin-6 (IL-6) can promote cell proliferation in prostate cancer (PCa). Full-length transient receptor potential melastatin 2 (TRPM2-L) is highly expressed in PCa. However, the association between IL-6 and TRPM2-L in PCa is unclear. Here, human PCa cell lines, PC-3 and DU-145, were treated with 10 μg/mL tocilizumab, an IL-6 receptor (IL-6R) inhibitor, and the TRPM2-L protein expression in cells was significantly decreased. Cells were stably transfected with TRPM2 short-interfering RNA (siRNA) and cell survival clearly declined. Recombinant IL-6 treatment weakened the effects of TRPM2-siRNA on cell survival. TRPM2-L binds directly to IL-6R in PC-3 and DU-145 cells. The protein expression of hypoxia-inducible factor-1α was suppressed by reduction with TRPM2-L in PC-3 and DU-145 cells. Human umbilical vein endothelial cells (HUVECs) were indirectly cocultured with PCa cells, and the invasion and angiogenic activity of HUVECs were enhanced after coculture with PCa cells. However, TRPM2-L reduction in PCa cells significantly decreased the invasion and angiogenic activity of HUVECs compared to the control coculture. In vivo, xenograft tumors were induced using PC-3 cells. Tocilizumab treatment or TRPM2-L reduction clearly suppressed tumor growth. Meanwhile, the injection of mouse recombinant IL-6 weakened the antitumor effects of TRPM2-L reduction. These data demonstrate that the IL-6/TRPM2-L axis in PCa tumor growth is important, and interference of the IL-6/TRPM2-L axis may be a novel approach for PCa therapy.