4E-BP1 counteracts human mesenchymal stem cell senescence via maintaining mitochondrial homeostasis

Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders, the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown. Here, we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem cells (hMSCs). Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration, increases mitochondrial reactive oxygen species (ROS) production, and accelerates cellular senescence. Mechanistically, the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes, especially several key subunits of complex III including UQCRC2. Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs. These f indings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis, particularly for the mitochondrial respiration complex III, thus providing a new potential target to counteract human stem cell senescence.

Inhibition of LIM kinase reduces contraction and proliferation in bladder smooth muscle

Overactive bladder (OAB) is the most bothersome symptom in lower urinary tract symptoms (LUTS). Current pharmacologic treatment aims to inhibit detrusor contraction; however, shows unsatisfied efficacy and high discontinuation rate. LIM kinases (LIMKs) promote smooth muscle contraction in the prostate; however, their function in the bladder smooth muscle remains unclear. Here, we studied effects of the LIMK inhibitors on bladder smooth muscle contraction and proliferation both

Analysis on Role of mTORC1/4E-BP1 Axis in Idiopathic Pulmonary Fibrosis and Research Progress of Bupleuri Radix on Its Intervention / 中国实验方剂学杂志

Idiopathic pulmonary fibrosis （IPF） is a common， lethal interstitial lung disease characterized by airway remodeling， inflammation， alveolar destruction， and fibrosis. The mammalian target of rapamycin complex 1/4E binding protein 1 （mTORC1/4E-BP1） axis is closely related to the expression of collagen by fibroblasts， and its role in pulmonary fibrosis remains to be further elucidated. Traditional Chinese medicine （TCM） has shown promising efficacy in improving the lung function， exercise capacity， and quality of life in patients with IPF. The theory of "same treatment for different diseases" provides a TCM theoretical basis for the treatment of pulmonary fibrosis with Bupleuri Radix， while the research in western medicine has preliminarily shown that both the formulation and single herb as well as the active ingredients of Bupleuri Radix have good therapeutic effects on pulmonary fibrosis. Therefore， this review will elaborate on the role of the mTORC1/4E-BP1 axis in the pathomechanism of IPF， as well as the research results of the active components of Bupleuri Radix on the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin protein（PI3K/AKT/mTOR） pathway， so as to provide a reference for the treatment and drug development of IPF.

Overexpression of CLPTM1L inhibits the sensitivity of 95-D lung cancer cells to gemcitabine / 实用肿瘤学杂志

Objective This study aimed to investigate the relationship between CLPTM1L gene and lung cancer 95-D cells sensitivity to gemcitabine,and to explore its potential mechanism of action. Methods Overexpression of lentivirus against CLPTM1L gene was constructed and infected with lung cancer 95-D cells;Cells were divided into the CLPTM1L overexpression group and con-trol group;The proliferation of cells in the overexpressing and control groups after gemcitabine treatment was detected by CCK-8;The changes of CLPTM1L gene and protein were detected by real-time PCR,Western blot and immunochemiluminescence;The changes of caspase-3/7 and caspase-9 activities were detected by bioluminescence;Western blot was used to detect the changes of p-4E-BP1 protein. Results The expression of CLPTM1L gene( P =0. 036) and its protein ( P <0. 01) was significantly increased after CLPTM1L overexpressed lentivirus-infected 95 -D cells;Compared with the control group,the proliferation of CLPTM1L overex-pressing group after gemcitabine treatment was increased(P <0. 01);The activity of caspase activity showed that the activities of caspase-3/7 and caspase-9 in the CLPTM1L overexpression group were significantly lower than those in the control group(P<0. 01);The phosphorylated level of 4E-BP1 protein in the CLPTM1L overexpression group was significantly higher than that in the control group. Conclusion Overexpression of CLPTM1L can reduce the sensitivity of lung cancer cells to gemcitabine. Its mechanism may be to increase the phosphorylation level of 4E-BP1.

Improving Effect of L-leucine on Memory Impairment in Plateau / 医药导报

Objective To explore the improving effect of L-leucine on memory impairment in plateau and the mecha-nism. Methods After successfully trained in the 8-arm radial maze,50 male Kunming mice were selected and randomly divid-ed into normoxic control group (NC group),model group,and L-leucine (low,medium and high dose) groups.Animals in L-leu-cine groups were intragastrically given 0.473 g?kg-1 ,0.945 g?kg-1 and 1.89 g?kg-1 L-leucine for 7 days and those in NC and model control groups were administered the same volume of purified water for the same period of time.At the 4th day of the treat-ment,the mice in the model control group and L-leucine groups were placed in a large low-pressure and low-oxygen chamber to simulate low-pressure hypoxic environment of the plateau (7 500 m,3 d).The 8-arm radial maze was used to measure the spatial learning and memory ability of mice and dry-wet method to measure the water content of brain tissue.HE staining was employed to observe the cell morphological changes in CA1 region of the hippocampus.The expression levels of mTOR,P70S6K and 4E-BP1 mRNA in the hippocampus were detected by SYBR Green real-time PCR. Results The reference memory error ( RME) ,total error ( TE) ,testing time ( TT) ,and water content of brain tissue were significantly increased,the neuron injury was exacerbated in CA1 region of the hippocampus,and the expression levels of mTOR and P70S6K mRNA were markedly decreased in model control group when compared with those in NC group (P<0.05 or P<0.01).These indexes,however,were significantly improved in L-leu-cine groups,especially in high-dose group. Conclusion L-leucine can improve memory impairment in plateau,and the mecha-nism may involve the activation of mTOR and its downstream substrates (4E-BP1 and P70S6K).

HIF-1α pathway: role, regulation and intervention for cancer therapy

Hypoxia-inducible factor-1 (HIF-1) has been recognized as an important cancer drug target. Many recent studies have provided convincing evidences of strong correlation between elevated levels of HIF-1 and tumor metastasis, angiogenesis, poor patient prognosis as well as tumor resistance therapy. It was found that hypoxia (low O2 levels) is a common character in many types of solid tumors. As an adaptive response to hypoxic stress, hypoxic tumor cells activate several survival pathways to carry out their essential biological processes in different ways compared with normal cells. Recent advances in cancer biology at the cellular and molecular levels highlighted the HIF-1α pathway as a crucial survival pathway for which novel strategies of cancer therapy could be developed. However, targeting the HIF-1α pathway has been a challenging but promising progresses have been made in the past twenty years. This review summarizes the role and regulation of the HIF-1α in cancer, and recent therapeutic approaches targeting this important pathway.

Rapamycin inhibits the growth and mTOR/4E-BP1 signalling pathway in xenograft of esophageal squamous cell carcinoma / 基础医学与临床

Objective To investigate the effects of rapamycin on tumor growth and mTOR/4E-BP1 signaling pathway in xenograft of esophageal squamous cell carcinoma ( ESCC ) EC9706 cells. Methods The expression of factors in mTOR/4E-BP1 signaling pathway of the tumor tissues was analyzed by RT-PCR and Western blot. Results Both rapamycin and cisplatin significantly inhibited the growth of transplantable tumors as compared to control group ( P < 0. 05 ) and their combination had a synergestic effect. The results of RT-PCR and Western blot show that rapamycin significantly decreased the expression of Mtor and p-4E-BP1 but increased the expression of 4E-BP1. Conclusion Rapamycin inhibits the mTOR/4E-BP1 signalling pathway, resulting in the growth inhibition of xenograft of EC9706 cells.