Lianmei Qiwu Decoction relieves diabetic cardiac autonomic neuropathy by regulating AMPK/TrkA/TRPM7 signaling pathway / 中国中药杂志

This study investigated the effect of Lianmei Qiwu Decoction(LMQWD) on the improvement of cardiac autonomic nerve remodeling in the diabetic rat model induced by the high-fat diet and explored the underlying mechanism of LMQWD through the AMP-activated protein kinase(AMPK)/tropomyosin receptor kinase A(TrkA)/transient receptor potential melastatin 7(TRPM7) signaling pathway. The diabetic rats were randomly divided into a model group, an LMQWD group, an AMPK agonist group, an unloaded TRPM7 adenovirus group(TRPM7-N), an overexpressed TRPM7 adenovirus group(TRPM7), an LMQWD + unloaded TRPM7 adenovirus group(LMQWD+TRPM7-N), an LMQWD + overexpressed TRPM7 adenovirus group(LMQWD+TRPM7), and a TRPM7 channel inhibitor group(TRPM7 inhibitor). After four weeks of treatment, programmed electrical stimulation(PES) was employed to detect the arrhythmia susceptibility of rats. The myocardial cell structure and myocardial tissue fibrosis of myocardial and ganglion samples in diabetic rats were observed by hematoxylin-eosin(HE) staining and Masson staining. The immunohistochemistry, immunofluorescence, real-time quantitative polymerase chain reaction(RT-PCR), and Western blot were adopted to detect the distribution and expression of TRPM7, tyrosine hydroxylase(TH), choline acetyltransferase(ChAT), growth associated protein-43(GAP-43), nerve growth factor(NGF), p-AMPK/AMPK, and other genes and related neural markers. The results showed that LMQWD could significantly reduce the arrhythmia susceptibility and the degree of fibrosis in myocardial tissues, decrease the levels of TH, ChAT, and GAP-43 in the myocardium and ganglion, increase NGF, inhibit the expression of TRPM7, and up-regulate p-AMPK/AMPK and p-TrkA/TrkA levels. This study indicated that LMQWD could attenuate cardiac autonomic nerve remodeling in the diabetic state, and its mechanism was associated with the activation of AMPK, further phosphorylation of TrkA, and inhibition of TRPM7 expression.

Disseminated intravascular coagulation phenotype is regulated by the TRPM7 channel during sepsis

BACKGROUND: Sepsis is an uncontrolled inflammatory response against a systemic infection that results in elevated mortality, mainly induced by bacterial products known as endotoxins, producing endotoxemia. Disseminated intravascular coagulation (DIC) is frequently observed in septic patients and is associated with organ failure and death. Sepsis activates endothelial cells (ECs), promoting a prothrombotic phenotype contributing to DIC. Ion channel mediated calcium permeability participates in coagulation. The transient reception potential melastatin 7 (TRPM7) non-selective divalent cation channel that also contains an α-kinase domain, which is permeable to divalent cations including Ca2+, regulates endotoxin-stimulated calcium permeability in ECs and is associated with increased mortality in septic patients. However, whether endothelial TRPM7 mediates endotoxemia-induced coagulation is not known. Therefore, our aim was to examine if TRPM7 mediates coagulation during endotoxemia. RESULTS: The results showed that TRPM7 regulated endotoxin-induced platelet and neutrophil adhesion to ECs, dependent on the TRPM7 ion channel activity and by the α-kinase function. Endotoxic animals showed that TRPM7 mediated neutrophil rolling on blood vessels and intravascular coagulation. TRPM7 mediated the increased expression of the adhesion proteins, von Willebrand factor (vWF), intercellular adhesion molecule 1 (ICAM-1), and P-selectin, which were also mediated by the TRPM7 α-kinase function. Notably, endotoxin-induced expression of vWF, ICAM-1 and P-selectin were required for endotoxin-induced platelet and neutrophil adhesion to ECs. Endotoxemic rats showed increased endothelial TRPM7 expression associated with a procoagulant phenotype, liver and kidney dysfunction, increased death events and an increased relative risk of death. Interestingly, circulating ECs (CECs) from septic shock patients (SSPs) showed increased TRPM7 expression associated with increased DIC scores and decreased survival times. Additionally, SSPs with a high expression of TRPM7 in CECs showed increased mortality and relative risk of death. Notably, CECs from SSPs showed significant results from the AUROC analyses for predicting mortality in SSPs that were better than the Acute Physiology and Chronic Health Evaluation II (APACHE II) and the Sequential Organ Failure Assessment (SOFA) scores. CONCLUSIONS: Our study demonstrates that sepsis-induced DIC is mediated by TRPM7 in ECs. TRPM7 ion channel activity and α-kinase function are required by DIC-mediated sepsis-induced organ dysfunction and its expression are associated with increased mortality during sepsis. TRPM7 appears as a new prognostic biomarker to predict mortality associated to DIC in SSPs, and as a novel target for drug development against DIC during infectious inflammatory diseases.

Research progress of trpm7 channel and tumor development / 中国药理学通报

Transient receptor potential melastatin-subfamily member 7(TRPM7) is a non-selective cation channel fused with a functional kinase domain. Studies have shown that TRPM7 is aberrantly expressed in tumor cells. TRPM7 plays a variety of functional roles in cancer cells including survival t cell cycle progression, proliferation, invasion, epithelial-mesenchymal transition (EMT) and angiogenesis. The high correlation between TR-PM7 and tumorigcnesis makes TRPM7 a prognostic indicator and a potential therapeutic target for malignant tumors. In this arti cle , we review the research progress of TRPM7 and tumor progression, explore the mechanism of TRPM7-mediated tumor development and the clinical treatment of tumor strategy targeting TRPM7, and provide some reference for follow-up research and clinical treatment.

Restrição dietética de magnésio associada à dieta hiperlipídica: implicações sobre a homeostase do mineral e sensibilidade à insulina / Dietary magnesium restriction associated with a high-fat diet: implications on mineral homeostasis and insulin sensitivity

A resistência dos tecidos à ação da insulina é uma das principais complicações do excesso de peso. O aumento da gordura corporal, decorrente do consumo excessivo de nutrientes, é acompanhado por um quadro de inflamação crônica de baixa intensidade que está relacionado com a fisiopatologia da resistência à insulina. O magnésio (Mg) é um mineral envolvido com diversos processos fisiológicos e bioquímicos, especialmente aqueles relacionados ao metabolismo energético e ao controle glicêmico. Apesar de a deficiência deste mineral estar relacionada com condições pré-diabéticas, não está claro se a inadequação dietética promove alterações na sensibilidade à insulina e/ou se condições de resistência à insulina causam distúrbios na homeostase de Mg. O objetivo deste trabalho foi investigar os efeitos da restrição dietética de Mg e sua associação com o excesso de lipídios sobre a homeostase do mineral e a sensibilidade à insulina. Ratos Wistar, machos, com peso entre 97-123 g, permaneceram em gaiolas individuais por 24 semanas. Os animais receberam rações normolipídicas (CON, 7% de lipídios) ou hiperlipídicas (HL, 32% de lipídios), adequadas (CON e HL Mg; 500 mg de Mg/kg de ração; n = 6 para cada grupo) ou com restrição de Mg (Mg[50] e HL Mg[50]; 50 mg de Mg/kg de ração; n = 6 para cada grupo). O consumo da dieta HL promoveu maior acúmulo de tecido adiposo e maior ganho de peso corporal (p < 0,05). Os animais que consumiram rações com restrição de Mg apresentaram hipomagnesemia (p<0,01), menor excreção urinária (p < 0,01) e fecal (p < 0,001) de Mg e menor concentração óssea desse mineral (p < 0,001). No entanto, não foram observadas alterações no Mg muscular (p > 0,05). O grupo HL Mg[50] apresentou maior concentração de Mg no eritrócito quando comparado aos outros grupos. A restrição dietética de Mg, isoladamente, não promoveu alterações na sensibilidade à insulina (avaliada pelo teste de tolerância à insulina). Quando associada à dieta hiperlipídica, resultou em aumento da glicemia de jejum e em redução da sensibilidade à insulina, após 16 semanas (p < 0,01). Em nível molecular, a fosforilação da proteína quinase B (Akt) no músculo e no fígado foi significantemente menor no grupo HL Mg[50] (p < 0,05). A restrição dietética de Mg induziu ao aumento do conteúdo proteico dos canais TRPM6 e TRPM7 no rim, independentemente da sensibilidade à insulina. Os resultados deste estudo apontam que a deficiência de Mg tende a agravar as repercussões metabólicas do consumo de dietas hiperlipídicas na sensibilidade à insulina e que a resistência à insulina altera a compartimentalização do Mg

Insulin resistance is one of the main complications of overweight. Increase body fat, due to excessive consumption of nutrients is accompanied by a chronic low-grade inflammation related to insulin resistance pathophysiology. Magnesium (Mg) is a mineral involved in many physiological and biochemical processes, especially those related to energy metabolism and glycemic control. Although Mg deficiency is related to pre-diabetic conditions, it is unclear whether dietary inadequacy promotes changes in insulin sensitivity and/or if conditions of insulin resistance cause disturbances in Mg homeostasis. This work aimed to investigate the effects of dietary Mg restriction and its association with high-fat diet on mineral homeostasis and insulin sensitivity. Male Wistar rat (97-123 g) remained in individual cages for 24 weeks. Animals received normolipid diet (CON, 7% lipid) or high-fat diet (HF, 32% lipid), adequate (CON and HF, 500 mg Mg / kg diet, n = 6 for each group) or Mg restricted (Mg[50] and HF Mg[50], 50 mg of Mg / kg of diet, n = 6 for each group). High-fat diet promoted a greater adipose tissue excess and body weight gain (p<0.05). Animals with Mg restricted diet had hypomagnesemia (p<0.01), lower Mg urinary (p<0.01) and faecal loss (p<0.001) and lower bone Mg concentration (p<0.001). However, no changes were observed in muscle Mg (p>0.05). HF Mg[50] group presented higher concentration of erythrocyte Mg when compared to the other groups. Singly, dietary Mg restriction did not induce changes in insulin sensitivity (as assessed by the insulin tolerance test). When associated with high-fat diet, dietary Mg restriction resulted in higher fasting glycemia and lower insulin sensitivity after 16 weeks (p<0.01). At the molecular level, protein kinase B (Akt) phosphorylation in muscle and liver was significantly lower in HFMg [50] group (p<0.05). Dietary Mg restriction induced increased protein content of renal TRPM6 and TRPM7 channels, regardless of insulin sensitivity. The results of this study indicate that Mg deficiency worsens metabolic effects of high-fat diet on insulin sensitivity. In addition, insulin resistance changes Mg compartmentalization

The role of TRPM7 ion channel in the proliferation and migration of oral squamous cancer cells / 实用口腔医学杂志

Objective:To investigate the role of the transient receptor potential melastatin subfamily member 7 (TRPM7) ion channel in the proliferation and migration of oral squamous cancer cells OC2.Methods:The expression of TRPM7 in OC2 cells was examined by western blotting,RT-PCR and indirect immunofluorescence assay.The influence of TRPM7 on cell proliferation and migration under the inhibition of TRPM7 ion channel with 2-APB or siRNA TRPM7 in OC2 cells was examined by MTT and Transwell respectively.The influence of PI3K/AKT signal pathway on the expression of TRPM7 in OC2 cells was tested by Western blotting.The change of positive ion current when the OC2 cells were treated with TRPM7 inhibitor and activator was explored with patch clamp technique.Results:TRPM7 overexpression in OC2 cells mainly in the cytoplasm was observed,siRNA TRPM7 downregulated the expression of TRPM7.Inhibition of TRPM7 (2-APB or siRNA TRPM7) inhibited the growth and proliferation of OC2 cells in a time-and dose-dependent manner.Blockage of TRPM7 ion channel inhibited the migration capacity of OC2 cells.Inhibition of TRPM7 downregulated the expression of phosphorylated AKT and phosphorylated ERK.Patch clamp assay showed the activation of TRPM7-like current in OC2 cells.2-APB could weaken this current while Bradykinin could enhance the current.Conclusion:TRPM7 may regulate the proliferation and migration of oral cancer cells by the regulation of PI3K/AKT and MAPK/ERK signal pathways and cell positive current.

The Pathophysiologic Roles of TRPM7 Channel

Transient receptor potential melastatin 7 (TRPM7) is a member of the melastatin-related subfamily and contains a channel and a kinase domain. TRPM7 is known to be associated with cell proliferation, survival, and development. It is ubiquitously expressed, highly permeable to Mg2+ and Ca2+, and its channel activity is negatively regulated by free Mg2+ and Mg-complexed nucleotides. Recent studies have investigated the relationships between TRPM7 and a number of diseases. TRPM7 regulates cell proliferation in several cancers, and is associated with ischemic cell death and vascular smooth muscle cell (VSMC) function. This review discusses the physiologic and pathophysiologic functions and significance of TRPM7 in several diseases.

TRPM7 Is Essential for RANKL-Induced Osteoclastogenesis

The transient receptor potential melastatin type 7 (TRPM7) channel is a widely expressed non-selective cation channel with fusion to the C-terminal alpha kinase domain and regarded as a key regulator of whole body Mg2+ homeostasis in mammals. However, the roles of TRPM7 during osteoclastogenesis in RAW264.7 cells and bone marrow-derived monocyte/macrophage precursor cells (BMMs) are not clear. In the present study, we investigate the roles of TRPM7 in osteoclastogenesis using methods of small interfering RNA (siRNA), RT-PCR, patch-clamp, and calcium imaging. RANKL (receptor activator of NF-kappaB ligand) stimulation did not affect the TRPM7 expression and TRPM7-mediated current was activated in HEK293, RAW264.7, and BMM cells by the regulation of Mg2+. Knock-down of TRPM7 by siTRPM7 reduced intracellular Ca2+ concentration ([Ca2+]i) increases by 0 mM [Mg2+]e in HEK293 cells and inhibited the generation of RANKL-induced Ca2+ oscillations in RAW264.7 cells. Finally, knock-down of TRPM7 suppressed RANKL-mediated osteoclastogenesis such as activation and translocation of NFATc1, formation of multinucleated cells, and the bone resorptive activity, sequentially. These results suggest that TRPM7 plays an essential role in the RANKL-induced [Ca2+]i oscillations that triggers the late stages of osteoclastogenesis.

pH-mediated Regulation of Pacemaker Activity in Cultured Interstitial Cells of Cajal

Interstitial cells of Cajal (ICCs) are pacemakers in gastrointestinal tracts, regulating rhythmicity by activating nonselective cation channels (NSCCs). In the present study, we investigated the general characteristics and pH-mediated regulation of pacemaker activity in cultured interstitial cells of Cajal. Under voltage clamp mode and at the holding potential of -60 mV, the I-V relationships and difference current showed that there was no reversal potential and voltage-independent inward current. Also, when the holding potentials were changed from +20 mV to -80 mV with intervals of 20 mV, there was little difference in inward current. In pacemaker activity, the resting membrane potential (RMP) was depolarized (In pH 5.5, 23+/-1.5 mV depolarized) and the amplitude was decreased by a decrease of the extracellular pH. However, in case of increase of extracellular pH, the RMP was slightly hyperpolarized and the amplitude was decreased a little. The melastatin type transient receptor potential (TRPM) channel 7 has been suggested to be required for intestinal pacemaking activity. TRPM7 produced large outward currents and small inward currents by voltage ramps, ranging from +100 to -100 mV from a holding potential of -60 mV. The inward current of TRPM7 was dramatically increased by a decrease in the extracellular pH. At pH 4.0, the average inward current amplitude measured at -100 mV was increased by about 7 fold, compared with the current amplitude at pH 7.4. Changes in the outward current (measured at +100 mV) were much smaller than those of the inward current. These results indicate that the resting membrane potential of pacemaking activity might be depolarized by external acidic pH through TRPM7 that is required for intestinal pacemaking activity.

Higher Expression of TRPM7 Channels in Murine Mature B Lymphocytes than Immature Cells

TRPM7, a cation channel protein permeable to various metal ions such as Mg2+, is ubiquitously expressed in variety of cells including lymphocytes. The activity of TRPM7 is tightly regulated by intracellular Mg2+, thus named Mg2+-inhibited cation (MIC) current, and its expression is known to be critical for the viability and proliferation of B lymphocytes. In this study, the level of MIC current was compared between immature (WEHI-231) and mature (Bal-17) B lymphocytes. In both cell types, an intracellular dialysis with Mg2+-free solution (140 mM CsCl) induced an outwardly-rectifying MIC current. The peak amplitude of MIC current and the permeability to divalent cation (Mn2+) were several fold higher in Bal-17 than WEHI-231. Also, the level of mRNAs for TRPM7, a molecular correspondence of the MIC channel, was significantly higher in Bal-17 cells. The amplitude of MIC was further increased, and the relation between current and voltage became linear under divalent cation-free conditions, demonstrating typical properties of the TRPM7. The stimulation of B cell receptors (BCR) by ligation with antibodies did not change the amplitude of MIC current. Also, increase of extracellular [Mg2+]c to enhance the Mg2+ influx did not affect the BCR ligation-induced death of WEHI-231 cells. Although the level of TRPM7 was not directly related with the cell death of immature B cells, the remarkable difference of TRPM7 might indicate a fundamental change in the permeability to divalent cations during the development of B cells.

Effect of Electroacupuncture on TRPM7 mRNA Expression after Cerebral Ischemia/reperfusion in Rats via TrkA Pathway / 华中科技大学学报（医学）（英德文版）

Summary: The effect of electroacupuncture (EA) on TRPM7 mRNA expression of focal cerebral ischemia in rats and further the role of EA in the relationship between TRPM7 and trkA pathway was investigated. Thirty SD rats were randomly divided into 5 groups : normal group, ischemia/reperfusion group, EA treated group (ischemic rats with EA treatment), TE infusion group (ischemic rats with EA treatment and TE buffer infusion),AS-ODN group (ischemic rats with EA treatment and antisense trkA oligonucleotide infusion). The stroke animal model was established by the modified method of middle cerebral artery occlusion. Antisense trkA oligonucleotide that blocked NGF's effects was injected into cerebroventricle before EA. The TRPM7 mRNA was detected by RT-PCR method. The results showed that there were low TRPM7 mRNA levels in cortex and hippocampus in normal group. Compared with normal group, TRPM7 mRNA expression was increased significantly in ischemia/reperfusion group (P<0.05). A significant reduction in the expression of TRPM7 mRNA was found in EA treated group in contrast to ischemia/reperfusion group (P<0.05). The expression of TRPM7 mRNA in AS-ODN group was remarkably increased compared with EA treated group and TE infusion group (P<0.05). The results indicated that TRPM7 channels in the ischemic cortex and hippocampus in rats might play a key role in ischemic brain injury. EA could reverse the overexpression of TRPM7 in cerebral ischemia/reperfusion rats. And the inhibitory effect of EA on TRPM7 channels might be through trkA pathway.