Tyrosine phosphatase SHP2 in ovarian granulosa cells balances follicular development by inhibiting PI3K/AKT signaling

In mammals,the growth and maturation of oocytes within growing follicles largely depends on ovarian granulosa cells(GCs)in response to gonadotropin stimulation.Many signals have been shown to regulate GC proliferation and apoptosis.However,whether the tyrosine phosphatase SHP2 is involved remains unclear.In this study,we identified the crucial roles of SHP2 in modulating GC proliferation and apoptosis.The production of both mature oocytes and pups was increased in mice with Shp2 specifically deleted in ovarian GCs via Fshr-Cre.Shp2 deletion simultaneously promoted GC proliferation and inhibited GC apoptosis.Furthermore,Shp2 deficiency promoted,while Shp2 overexpression inhibited,the proliferation of cultured primary mouse ovarian GCs and the human ovarian granulosa-like tumor cell line KGN in vitro.Shp2 deficiency promoted follicule-stimulating hormone(FSH)-activated phosphorylation of AKT in vivo.SHP2 deficiency reversed the inhibitory effect of hydrogen peroxide(H_(2)O_(2))on AKT activation in KGN cells.H_(2)O_(2) treatment promoted the interaction between SHP2 and the p85 subunit of PI3K in KGN cells.Therefore,SHP2 in GCs may act as a negative modulator to balance follicular development by suppressing PI3K/AKT signaling.The novel function of SHP2 in modulating proliferation and apoptosis of GCs provides a potential therapeutic target for the clinical treatment of follicle developmental dysfunction.

Deletion of Gab2 in mice protects against hepatic steatosis and steatohepatitis:a novel therapeutic target for fatty liver disease

Fatty liver disease is a serious health problem worldwide and is the most common cause for chronic liver disease and metabolic disorders.The major challenge in the prevention and intervention of this disease is the incomplete understanding of the underlying mechanism and thus lack of potent therapeutic targets due to multifaceted and interdependent disease factors.In this study,we investigated the role of a signaling adaptor protein,GRB2-associated-binding protein 2(Gab2),in fatty liver using an animal disease model.Gab2 expression in hepatocytes responded to various disease factor stimulations,and Gab2 knockout mice exhibited resistance to fat-induced obesity,fat-or alcohol-stimulated hepatic steatosis,as well as methionine and choline deficiency-induced steatohepatitis.Concordantly,the forced expression or knockdown of Gab2 enhanced or diminished oleic acid(OA)-or ethanol-induced lipid production in hepatocytes in vitro,respectively.During lipid accumulation in hepatocytes,both fat and alcohol induced the recruitment of PI3K or Socs3 by Gab2 and the activation of their downstream signaling proteins AKT,ERK,and Stat3.Therefore,Gab2 may be a disease-associated protein that is induced by pathogenic factors to amplify and coordinate multifactor-induced signals to govern disease development in the liver.Our research provides a novel potential target for the prevention and intervention of fatty liver disease.