The transient receptor potential melastatin member 7 (TRPM7) and member 6 (TRPM6) are divalent cation channel kinases essential for magnesium (Mg(2+)) homeostasis in vertebrates. It remains unclear how TRPM6 affects divalent cation transport and whether this involves functional homomeric TRPM6 plasma membrane channels or heteromeric channel assemblies with TRPM7. We show that homomeric TRPM6 is highly sensitive to intracellular free Mg(2+) and therefore unlikely to be active at physiological levels of [Mg(2+)]i. Co-expression of TRPM7 and TRPM6 produces heteromeric TRPM7/M6 channels with altered pharmacology and sensitivity to intracellular Mg·ATP compared with homomeric TRPM7. Strikingly, the activity of heteromeric TRPM7/M6 channels is independent of intracellular Mg·ATP concentrations, essentially uncoupling channel activity from cellular energy status. Disruption of TRPM6 kinase phosphorylation activity re-introduces Mg·ATP sensitivity to the heteromeric channel similar to that of TRPM7. Thus, TRPM6 modulates the functionality of TRPM7, and the TRPM6 kinase plays a critical role in tuning the phenotype of the TRPM7·M6 channel complex.

Intracellular Ca²⁺ ([Ca²⁺]_i) regulation in endothelial cells depends on transient receptor potential channels (TRPs), and the role of canonical TRPs (TRPCs) during hypoxia–reoxygenation (H–R) is unclear. We hypothesized that TRPC3 contributes to endothelial nitric oxide (NO) release and that H–R may reduce TRPC3 activity and the associated endothelial function, including NO release. Measurements of [Ca²⁺]_i and patch-clamp study in primary cultured porcine coronary endothelial cells, measurements of NO and endothelium-dependent relaxation in porcine coronary arteries, and RT-PCR and western blot were conducted. Pre-treatment with SKF96365 (an inhibitor of TRPCs) or the selective TRPC3 inhibitor Pyr3 significantly decreased bradykinin-induced vasorelaxation. One hour of hypoxia followed by reoxygenation significantly reduced the vasorelaxation (70.3 ± 6.4 vs. 88.9 ± 3.5%) and NO concentration (24.0 ± 1.3 vs. 45.2 ± 2.8 nmol/L), and they were restored by pre-incubation with the TRPC3/6/7 activator 1-oleoyl-2-acetyl-sn-glycerol (96.4 ± 1.8% and 41.1 ± 4.7 nmol/L, respectively). In porcine coronary endothelial cells, H–R inhibited bradykinin-activated membrane current (8.6 ± 0.4 vs. 14.0 ± 1.5 pA/pF) and Pyr3-sensitive TRPC3 current (3.8 ± 0.3 vs. 6.3 ± 0.6 pA/pF; P< 0.01). H–R also inhibited bradykinin-induced Ca²⁺ influx and the Ca²⁺ influx via TRPC3. Cell surface expression of TRPC3 was decreased after H–R. We have, for the first time, demonstrated that Ca²⁺ entry via endothelial TRPC3 contributes to NO release and have revealed that H–R is associated with inhibition of TRPC3 activity. Inhibition of channel trafficking to the cell surface is involved in the underlying mechanism of the decrease of TRPC3 current and the reduction in Ca²⁺ entry through TRPC3 during H–R. This study suggests that TRPC3 may have the potential to be a new target for endothelial protection during H–R.

Purpose: Obesity in children and in adolescents can lead to adult cardiovascular diseases, and the gut microbiota plays a crucial role in obesity pathophysiology. Exercise and diet interventions are typical approaches to improve physical condition and to alter the gut microbiota in individuals with obesity. However, whether central hemodynamic parameters including subendocardial viability ratio, the augmentation index standardized to a heart rate of 75/min (AIx75), resting heart rate, and blood pressure, correlate with gut microbiota changes associated with exercise and diet is unclear.Methods: Adolescents (n = 24, 12.88 ± 0.41 years) with obesity completed our 6-week program of endurance and strength exercises along with dietary restriction. Blood and fecal samples were collected, and physical parameters were measured before and 24 h after the last session of the intervention program. Pulse wave analysis using applanation tonometry provided the subendocardial viability ratio, a surrogate measure of microvascular myocardial perfusion, and AIx75, a measure of arterial stiffness and peripheral arteriolar resistance. Correlation analysis detected any associations of anthropometric or central hemodynamic parameters with gut microbiome composition.Results: Exercise and diet interventions significantly reduced body weight, body mass index, body fat, and waist-to-hip ratio, and lowered levels of fasting blood glucose, serum triglycerides, and high-density lipoprotein cholesterol. AIx75 and resting heart rate were also significantly reduced after the intervention without changes to systolic or diastolic blood pressure. The ratio of intestinal microbiota Firmicutes to Bacteroidetes displayed a marked increase after intervention. Interventional changes in gut microbiota members were significantly associated with anthropometric and metabolic parameters. Microbial changes were also significantly correlated with central hemodynamic parameters, including subendocardial viability ratio, AIx75, and resting heart rate.Conclusion: Exercise and diet interventions significantly improved measures of central hemodynamics, including subendocardial viability ratio, AIx75, and resting heart rate, which were correlated with altered gut microbiota in adolescents with obesity. Our findings shed light on the effects and mechanisms underlying exercise and diet interventions on obesity and suggest this approach for treating patients with both cardiovascular disease and obesity.

Magnesium (Mg2+) is an essential cation implicated in carcinogenesis, solid tumor progression and metastatic potential. The Transient Receptor Potential Melastatin Member 7 (TRPM7) is a divalent ion channel involved in cellular and systemic Mg2+ homeostasis. Abnormal expression of TRPM7 is found in numerous cancers, including colon, implicating TRPM7 in this process. To establish a possible link between systemic magnesium (Mg2+) status, the Mg2+ conducting channel TRPM7 in colon epithelial cells, and colon carcinogenesis, in vitro whole-cell patch clamp electrophysiology, qPCR, and pharmacological tools were used probing human colorectal adenocarcinoma HT-29 as well as normal primary mouse colon epithelial cells. This was extended to and combined with aberrant crypt foci development in an azoxymethane-induced colorectal cancer mouse model under hypomagnesemia induced by diet or pharmacologic intervention. We find that TRPM7 drives colon cancer cell proliferation in human HT-29 and expresses in normal primary mouse colon epithelia. This is linked to TRPM7’s dominant role as Mg2+ transporter, since high extracellular Mg2+ supplementation cannot rescue inhibition of cell proliferation caused by suppressing TRPM7 either genetically or pharmacologically. In vivo experiments in mice provide evidence that the specific TRPM7 inhibitor waixenicin A, given as a single bolus injection, induces transient hypomagnesemia and increases intestinal absorption of calcium. Repeated injections of waixenicin A over 3 weeks cause hypomagnesemia via insufficient Mg2+ absorption by the colon. However, neither waixenicin A, nor a diet low in Mg2+, affect aberrant crypt foci development in an azoxymethane-induced colorectal cancer mouse model. Early stage colon cancer proceeds independent of systemic Mg2+ status and TRPM7, and waixenicin A is a useful pharmacological tool to study of TRPM7 in vitro and in vivo.