5′-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is an evolutionarily conserved serine/threonine kinase that was originally identified as the key player in maintaining cellular energy homeostasis. Intensive research over the last decade has identified diverse molecular mechanisms and physiological conditions that regulate the AMPK activity. AMPK regulates diverse metabolic and physiological processes and is dysregulated in major chronic diseases, such as obesity, inflammation, diabetes and cancer. On the basis of its critical roles in physiology and pathology, AMPK is emerging as one of the most promising targets for both the prevention and treatment of these diseases. In this review, we discuss the current understanding of the molecular and physiological regulation of AMPK and its metabolic and physiological functions. In addition, we discuss the mechanisms underlying the versatile roles of AMPK in diabetes and cancer.
AMP-Activated Protein Kinases* ; Chronic Disease ; Homeostasis ; Inflammation ; Obesity ; Pathology ; Phosphotransferases ; Physiological Processes ; Physiology* ; Protein Kinases

Necroptosis is one of the regulated cell death, which involves receptor interacting protein kinase (RIPK) 1/RIPK3/mixed lineage kinase domain like protein (MLKL) signaling pathway. Among them, MLKL is the final execution of necroptosis. The formation of RIPK1/RIPK3/MLKL necrosome induces the phosphorylated MLKL, and the activated MLKL penetrates into the membrane bilayer to form membrane pores, which damages the integrity of the membrane and leads to cell death. In addition to participating in necroptosis, MLKL is also closely related to other cell death, such as NETosis, pyroptosis, and autophagy. Therefore, MLKL is involved in the pathological processes of various diseases related to abnormal cell death pathways (such as cardiovascular diseases, neurodegenerative diseases and cancer), and may be a therapeutic target of multiple diseases. Understanding the role of MLKL in different cell death can lay a foundation for seeking various MLKL-related disease targets, and also guide the development and application of MLKL inhibitors.
Protein Kinases/metabolism* ; Necroptosis/physiology* ; Receptor-Interacting Protein Serine-Threonine Kinases ; Signal Transduction ; Pyroptosis ; Apoptosis

The AMP-activated protein kinase (AMPK) widely exists in skeletal muscle, liver, pancreas, adipose tissue and central nervous system. As a "cellular energy regulator", activation of AMPK can improve insulin resistance in various mechanisms. To overall understand the importance of AMPK in exercise, the article summarized the research progress on AMPK exercise activation in skeletal muscle, liver and adipose tissue as well as exercise improving cardiovascular insulin resistance by AMPK, and looked forward to the study future of AMPK exercise activation.
AMP-Activated Protein Kinases ; physiology ; Adipose Tissue ; physiology ; Exercise ; physiology ; Humans ; Insulin Resistance ; Liver ; physiology ; Muscle, Skeletal ; physiology

BACKGROUNDAdrenomedullin (ADM), a potent hypotensive small peptide, was recently found to inhibit the proliferation of glomerular mesangial cells (MsC) in vitro and to attenuate glomerular lesions in vivo, however the mechanisms remain poorly understood. In this study, we attempted to elucidate them using molecular signal transduction.

METHODSCultured rat MsC were treated with ADM and several inhibitors of signalling molecules. Methyl thiazoleterazolium (MTT) assay and BrdU incorporation method were employed for examining MsC proliferation. Western blot analysis was used for detecting total mitogen activated protein kinases (t-MAPKs) and phosphorylated MAPKs (p-MAPKs) proteins.

RESULTSADM suppressed MsC proliferation in a concentration- and time-dependent fashion. This response was inhibited by ADM receptor antagonist CGRP8-37 and a potent protein kinase-A (PKA) inhibitor, H89. Forskolin, a direct adenylate cyclase activator, also significantly inhibited MsC proliferation. SB203580, a P38MAPK inhibitor, and U0126, a MEK inhibitor, both completely blocked ADM mediated responses in MsC. However, curcumin, a SAPK/JNK inhibitor, and GF109203X, a potent protein kinase-C (PKC) inhibitor, had no effect on MsC growth. Western blot analysis showed that ADM did not change the expression of t-MAPKs but increased p-SAPK/JNK and p-P38MAPK levels and decreased p-ERK level. These responses were inhibited by CGRP8-37. All these kinase phosphorylations, except for the increase in p-SAPK/JNK, could be stimulated using forskolin. In addition, only ADM mediated changes in ERK and P38MAPK phosphorylations were inhibited by H89. GF109203X did not affect ADM induced changes in three p-MAPKs expressions.

CONCLUSIONSADM inhibits MsC proliferation possibly through cAMP-PKA pathway. Both phosphorylations of ERK and P38MAPK pathways were necessary in mediating the antiproliferative response of ADM. It does not preclude the involvement of cAMP independent pathways in the ADM mediated responses.

Adrenomedullin ; Animals ; Cell Proliferation ; drug effects ; Cells, Cultured ; Extracellular Signal-Regulated MAP Kinases ; physiology ; Glomerular Mesangium ; cytology ; drug effects ; JNK Mitogen-Activated Protein Kinases ; physiology ; Peptides ; pharmacology ; Rats ; Signal Transduction ; physiology ; p38 Mitogen-Activated Protein Kinases ; physiology

Hydrogen sulfide (H(2)S) is among a family of endogenous molecules of gas, defined as gasotransmitters. In recent years, endogenous production of H(2)S and its physiological importance have been realized. Abnormal metabolism and functions of H(2)S contribute to or participate in the pathogenesis of many diseases. This article reviews recent discoveries on the roles of H(2)S in the regulation of cell proliferation and apoptosis. The molecular mechanisms for the cellular effects of H(2)S are also recapitulated, including changes in mitogen-activated protein kinase, cell cycle-related kinase, cell death-related gene and ion channels. A better understanding of H(2)S-regualted cell growth or death will pave way for future design of novel pharmacological and therapeutic interventions for various diseases.
Animals ; Apoptosis ; physiology ; Cell Proliferation ; Cyclin-Dependent Kinases ; metabolism ; Humans ; Hydrogen Sulfide ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism

The erectile response of the penis depends on a balance between vasoconstrictor agents, which cause cavernosal smooth muscle to contract limiting blood inflow, and vasodilators, which relax cavernosal smooth muscle leading to increased blood inflow and erection. This review emphasizes the role of the RhoA/Rho-kinase pathway in the cavernosal circulation. While it is widely held that the nitric oxide-cyclic GMP-protein kinase G(NO-cGMP-PKG) pathway mediates vasorelaxation and penile erection, the vasoconstrictor actions of endothelin ET-1 and NE are reported to be mediated by the RhoA/Rho-kinase pathway in the cavernosal circulation and NO relax cavernosal smooth by inhibition of Rho-kinase. The application of Rho-kinase inhibitor on the penile erection may represent a new and promising method of treatment for erectile dysfunction.
Animals ; Erectile Dysfunction ; physiopathology ; Humans ; Intracellular Signaling Peptides and Proteins ; physiology ; Male ; Nitric Oxide ; physiology ; Penile Erection ; physiology ; Protein-Serine-Threonine Kinases ; physiology ; rho-Associated Kinases ; rhoA GTP-Binding Protein ; physiology

OBJECTIVETo investigate the expressions of cyclin E, cyclin dependent kinase 2 (CDK-2) and cyclin-dependent kinase inhibitor p57(KIP2) in human gastric cancer, and to evaluate the relationships between protein levels and clinicopathological parameters.

METHODSWestern blot was used to measure the expressions of cyclin E, CDK-2 and p57(KIP2) proteins in the surgically resected gastric carcinoma, adjacent normal mucosa and metastatic lymph nodes from 36 patients.

RESULTSCyclin E and CDK-2 protein levels were higher in gastric cancer tissues in comparison with normal tissues (P < 0.05). Overexpression of cyclin E was correlated with lymph node involvement, poor histological grade and serosa invasion (P < 0.05). Overexpression of CDK-2 was correlated with lymph nodes involvement (P < 0.05). No statistically significant difference between cyclin E and CDK-2 expression was found when samples were stratified according to tumor size (P > 0.05). Expression of cyclin E and CDK-2 showed a positive linear correlation (r = 0.451, P = 0.01). Protein levels of p57(KIP2) were lower in gastric cancer tissues than in the normal mucosa (P < 0.05). Decreased expression of p57(KIP2) was correlated with lymph node involvement (P < 0.05). No statistically significant difference in p57(KIP2) expression was found when sample were stratified according to tumor size, histological grade or serosa invasion (P > 0.05). In metastatic lymph nodes, expression of cyclin E was increased and the expression of p57(KIP2) decreased.

CONCLUSIONOverexpressions of cyclin E, CDK-2 and downregulated expression of p57(KIP2) may play important roles in tumorigenesis and metastatic potential of gastric cancer.

Blotting, Western ; CDC2-CDC28 Kinases ; Cyclin E ; analysis ; physiology ; Cyclin-Dependent Kinase 2 ; Cyclin-Dependent Kinase Inhibitor p57 ; Cyclin-Dependent Kinases ; analysis ; physiology ; Humans ; Lymphatic Metastasis ; Nuclear Proteins ; analysis ; physiology ; Protein-Serine-Threonine Kinases ; analysis ; physiology ; Stomach Neoplasms ; chemistry ; pathology

Serum and glucocorticoid-regulated kinase 1 (SGK1) plays an important role in the physiological processes of hormone release, neuronal excitation and cell proliferation. SGK1 also participates in the pathophysiological processes of inflammation and apoptosis in the central nervous system (CNS). Increasing evidence demonstrates that SGK1 may serve as a target of the intervention of neurodegenerative diseases. In this article, we summarize the recent progress on the role and molecular mechanisms of SGK1 in the regulation of the function of the CNS. We also discuss the potential of newly discovered SGK1 inhibitors in the treatment of CNS diseases.
Humans ; Cell Proliferation ; Central Nervous System Diseases/drug therapy* ; Inflammation ; Protein Serine-Threonine Kinases/physiology*

Simiao Wan (SMW) is a traditional Chinese formula, including Atractylodis Rhizoma, Achyranthis Bidentatae Radix, Phellodendri Chinensis Cortex and Coicis Semen at the ratio of 1:1:2:2. It can be used to the treatment of diabetes. However, its bioactive compounds and underlying mechanism are unclear. This study aimed to screen the antilipolytic fraction from SMW and investigate its therapeutic mechanisms on hepatic insulin resistance. Different fractions of SMW were prepared by membrane separation combined with macroporous resin and their antilipolytic activities were screened in fasted mice. The effects of 60% ethanol elution (ESMW) on lipolysis were investigated in 3T3-L1 adipocytes stimulated by palmitic acid (PA) and high fat diet (HFD)-fed mice. In our study, ESMW is the bioactive fraction responsible for the antilipolytic activity of SMW and 13 compounds were characterized from ESMW by UHPLC-QTOF-MS/MS. ESMW suppressed protein kinase A (PKA)-hormone-sensitive lipase (HSL) related lipolysis and increased AMP-activated protein kinase (AMPK) phosphorylation in PA challenged 3T3-L1 adipocytes. AMPKα knockdown abolished the inhibitory effects of ESMW on IL-6 and HSL pSer-660, revealing that the antilipolytic and anti-inflammatory activities of ESMW are AMPK dependent. Furthermore, ESMW ameliorated insulin resistance and suppressed lipolysis in HFD-fed mice. It inhibited diacylglycerol accumulation in the liver and inhibited hepatic gluconeogenesis. Conditional medium collected from ESMW-treated 3T3-L1 cells ameliorated insulin action on hepatic gluconeogenesis in liver cells, demonstrating the antilipolytic activity contributed to ESMW beneficial effects on hepatic glucose production. In conclusion, ESMW, as the antilipolytic fraction of SMW, inhibited PKA-HSL related lipolysis by activating AMPK, thus inhibiting diacylglycerol (DAG) accumulation in the liver and thereby improving insulin resistance and hepatic gluconeogenesis.
AMP-Activated Protein Kinases/metabolism* ; Animals ; Insulin/metabolism* ; Lipolysis/physiology* ; Liver/metabolism* ; Mice ; Tandem Mass Spectrometry

OBJECTIVETo investigate the MEK and ERK expression and their relationship with clinicopathological parameters in human breast carcinoma, and the effect of preoperative chemotherapy on MEK and ERK protein expression.

METHODSSamples were obtained from 56 patients with breast carcinoma and 8 patients with benign tumors. Sixteen of the 56 patients received preoperative chemotherapy. Western blot and immunohistochemistry were used to measure the expression of MEK1, MEK2 and ERK1, ERK2 protein.

RESULTSMEK2 and ERK1, ERK2 protein levels were increased in breast carcinoma tissue compared with those in adjacent normal tissues (t = 7.244, 5.959, 3.735, P < 0.01) and benign tumors (t = 2.206, P < 0.05). The levels of MEK1 were decreased. The expression of MEK2 protein in ER negative patients was higher than that in ER positive ones. MEK2 protein levels were lower in patients who received preoperative chemotherapy than in those who did not.

CONCLUSIONOverexpression of MEK-ERK may play an important role in the development of human breast carcinoma. MEK and ERK protein expressions are inhibited by preoperative chemotherapy.

Adult ; Aged ; Blotting, Western ; Breast Neoplasms ; diagnosis ; enzymology ; metabolism ; Female ; Humans ; Immunohistochemistry ; MAP Kinase Kinase 1 ; MAP Kinase Kinase 2 ; MAP Kinase Signaling System ; physiology ; Middle Aged ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinase Kinases ; metabolism ; Mitogen-Activated Protein Kinases ; metabolism ; Prognosis ; Protein Kinases ; metabolism ; Protein-Serine-Threonine Kinases ; metabolism ; Protein-Tyrosine Kinases ; metabolism