Leu27IGF2 plays an opposite role to IGF1 to induce H9c2 cardiomyoblast cell apoptosis via Galphaq signaling.
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 Galphaq using the immunoprecipitation assay, we found that IGF2R could directly interact with Galphaq and after treatment with Leu27IGF2 the binding ability of Galphaq to IGF2R had increased. This sequentially resulted in the phosphorylation of phospholipase C-beta, a key downstream modulator of Galphaq, on serine 537. Moreover, disruption of the Galphaq protein by small interferon RNA reduced the cell apoptosis induced by Leu27IGF2. Our findings demonstrate that IGF2R activation appears to induce cell apoptosis via Galphaq-deriving signaling cascades and its effect is completely different from IGF1R survival signaling.
Chen
Ray-Jade
RJ
Trauma and Emergency Center School of Medicine, China Medical University Hospital, Taichung 404, Taiwan, ROC.
Wu
His-Chin
HC
Chang
Mu-Hsin
MH
Lai
Chao-Hung
CH
Tien
Yun-Chen
YC
Hwang
Jin-Ming
JM
Kuo
Wu-Hsien
WH
Tsai
Fuu-Jen
FJ
Tsai
Chang-Hai
CH
Chen
Li-Mien
LM
Huang
Chih-Yang
CY
Chu
Chun-Hsien
CH
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D053938:DNA Fragmentation / Q000187:drug effects; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D047468:Immunoprecipitation; D020287:In Situ Nick-End Labeling; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007335:Insulin-Like Growth Factor II; D008954:Models, Biological; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017527:Receptor, IGF Type 2 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D017527:Receptor, IGF Type 2; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D053148:Caspase 3; D043802:GTP-Binding Protein alpha Subunits, Gq-G11