Sirtuin1-p53, forkhead box O3a, p38 and post-infarct cardiac remodeling in the spontaneously diabetic Goto-Kakizaki rat.
BACKGROUND
Diabetes is associated with changes in myocardial stress-response pathways and is recognized as an independent risk factor for cardiac remodeling. Using spontaneously diabetic Goto Kakizaki rats as a model of type 2 DM we investigated whether post-translational modifications in the Akt - FOXO3a pathway, Sirt1 - p53 pathway and the mitogen activated protein kinase p38 regulator are involved in post-infarct cardiac remodeling


METHODS
Experimental myocardial infarction (MI) was induced by left anterior descending coronary artery ligation in spontaneously diabetic Goto-Kakizaki rats and non-diabetic Wistar controls. Cardiac function was studied by echocardiography. Myocardial hypertrophy, cardiomyocyte apoptosis and cardiac fibrosis were determined histologically 12 weeks post MI or Sham operation. Western blotting was used to study Caspase-3, Bax, Sirt1, acetylation of p53 and phosphorylation of p38, Akt and FOXO3a. Electrophoretic mobility shift assay was used to assess FOXO3a activity and its nuclear localization.


RESULTS
Post-infarct heart failure in diabetic GK rats was associated with pronounced cardiomyocyte hypertrophy, increased interstitial fibrosis and sustained cardiomyocyte apoptosis as compared with their non-diabetic Wistar controls. In the GK rat myocardium, Akt- and FOXO3a-phosphorylation was decreased and nuclear localization of FOXO3a was increased concomitantly with increased PTEN protein expression. Furthermore, increased Sirt1 protein expression was associated with decreased p53 acetylation, and phosphorylation of p38 was increased in diabetic rats with MI.


CONCLUSIONS
Post-infarct heart failure in diabetic GK rats was associated with more pronounced cardiac hypertrophy, interstitial fibrosis and sustained cardiomyocyte apoptosis as compared to their non-diabetic controls. The present study suggests important roles for Akt-FOXO3a, Sirt1 - p53 and p38 MAPK in the regulation of post-infarct cardiac remodeling in type 2 diabetes.
Vahtola
Erik
E
Institute of Biomedicine, University of Helsinki, Finland.
Louhelainen
Marjut
M
Forstén
Hanna
H
Merasto
Saara
S
Raivio
Johanna
J
Kaheinen
Petri
P
Kytö
Ville
V
Tikkanen
Ilkka
I
Levijoki
Jouko
J
Mervaala
Eero
E
D000818:Animals; D003094:Collagen / Q000378:metabolism; D048909:Diabetes Complications / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D003971:Diastole / Q000502:physiology; D004452:Echocardiography; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D032383:Myocytes, Cardiac / Q000473:pathology; D011499:Protein Processing, Post-Translational; D051381:Rats; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D056564:Sirtuin 1 / Q000235:genetics / Q000378:metabolism*; D013318:Stroke Volume; D013599:Systole / Q000502:physiology
C499515:FOXO3 protein, rat; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D003094:Collagen; D056564:Sirtuin 1