The insulin-like growth factor 1 receptor induces physiological heart growth via the phosphoinositide 3-kinase(p110alpha) pathway.
Insulin-like growth factor 1 (IGF1) was considered a potential candidate for the treatment of heart failure. However, some animal studies and clinical trials have questioned whether elevating IGF1 chronically is beneficial. Secondary effects of increased serum IGF1 levels on other tissues may explain these unfavorable results. The aim of the current study was to examine the role of IGF1 in cardiac myocytes in the absence of secondary effects, and to elucidate downstream signaling pathways and transcriptional regulatory effects of the IGF1 receptor (IGF1R). Transgenic mice overexpressing IGF1R in the heart displayed cardiac hypertrophy, which was the result of an increase in myocyte size, and there was no evidence of histopathology. IGF1R transgenics also displayed enhanced systolic function at 3 months of age, and this was maintained at 12-16 months of age. The phosphoinositide 3-kinase (PI3K)-Akt-p70S6K1 pathway was significantly activated in hearts from IGF1R transgenics. Cardiac hypertrophy induced by overexpression of IGF1R was completely blocked by a dominant negative PI3K(p110alpha) mutant, suggesting IGF1R promotes compensated cardiac hypertrophy in a PI3K(p110alpha)-dependent manner. This study suggests that targeting the cardiac IGF1R-PI3K(p110alpha) pathway could be a potential therapeutic strategy for the treatment of heart failure.
Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA. jmcmulle@bidmc.harvard.edu
Julie R
JR
McMullen
Tetsuo
T
Shioi
Weei-Yuarn
WY
Huang
Li
L
Zhang
Oleg
O
Tarnavski
Egbert
E
Bisping
Martina
M
Schinke
Sekwon
S
Kong
Megan C
MC
Sherwood
Jeffrey
J
Brown
Lauren
L
Riggi
Peter M
PM
Kang
Seigo
S
Izumo
D000818:Animals; D001483:Base Sequence; D006332:Cardiomegaly / Q000209:etiology; D018076:DNA, Complementary / Q000235:genetics; D006321:Heart / Q000254:growth & development* / Q000502:physiology; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D019869:Phosphatidylinositol 3-Kinases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013599:Systole
D018076:DNA, Complementary; D011994:Recombinant Proteins; D019869:Phosphatidylinositol 3-Kinases; D017526:Receptor, IGF Type 1