Leu27IGF2 plays an opposite role to IGF1 to induce H9c2 cardiomyoblast cell apoptosis via Gαq signaling


Chen Ray-Jade,Wu His-Chin,Chang Mu-Hsin,Lai Chao-Hung,Tien Yun-Chen,Hwang Jin-Ming,Kuo Wu-Hsien,Tsai Fuu-Jen,Tsai Chang-Hai,Chen Li-Mien,Huang Chih-Yang,Chu Chun-Hsien


This study examines the role of IGF2/mannose 6-phosphate receptor (IGF2R) signaling in the signaling transduction regulation and cell apoptosis in H9c2 cardiomyoblast cells. However, it is difficult to recognize the distinct activation of IGF2 signaling without interfacing with IGFI receptor (IGF1R) after exposure to IGF2. Leu27IGF2, an analog of IGF2 that interacts selectively with the IGF2R, was used to specifically activate IGF2R signaling in this study. DNA fragmentation and TUNEL assay revealed that in contrast to IGF1 treatment preventing angiotensin II and AG1024-induced cell apoptosis, Leu27IGF2 appears to synergistically increase apoptosis in those cells. We further found cell apoptosis induction and an increase in the active form of caspase 3 in the treatment of cells with Leu27IGF2, but not IGF1. To detect the interaction between IGF2R and Gαq using the immunoprecipitation assay, we found that IGF2R could directly interact with Gαq and after treatment with Leu27IGF2 the binding ability of Gαq to IGF2R had increased. This sequentially resulted in the phosphorylation of phospholipase C-β, a key downstream modulator of Gαq, on serine 537. Moreover, disruption of the Gαq protein by small interferon RNA reduced the cell apoptosis induced by Leu27IGF2. Our findings demonstrate that IGF2R activation appears to induce cell apoptosis via Gαq-deriving signaling cascades and its effect is completely different from IGF1R survival signaling.




Endocrinology,Molecular Biology








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