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Myocardial YY1 activity is decreased as an early adaptation to exercise training
Author(s) -
Edwards John G,
Rafalski Karolin,
Abdourahman Aicha
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a394-d
Subject(s) - medicine , yy1 , endocrinology , major histocompatibility complex , gene expression , biology , immunology , gene , immune system , genetics , promoter
Chronic exercise increases the functional capacity of the cardiovascular system, in part by increasing αMHC expression. YY1 is a ubiquitous transcription factor that has been shown to repress αMHC expression in response to pathological forms of cardiac overload. What role YY1 may have in regulating exercise‐induced αMHC expression remains unclear. We are interested in studying the early responses to exercise training because it is during this period that the heart has yet to compensate with significant growth and the imbalance between functional capacity and increased demand is greatest. Purpose: To determine if exercise will alter myocardial YY1 activity. Methods: Rats were exercise trained for one or ten weeks or assigned to sedentary control groups. Results: Plantaris cytochrome oxidase activities were significantly (p<.05) increased following one (+28%) or ten (+32%) weeks of training. 10 weeks of training significantly increased (+7.7%) the LV/BW ratio. LV αMHC‐mRNA and protein were significantly increased after both one or ten weeks of training, whereas no changes in βMHC were observed. To determine if one week of training altered YY1 activity, we examined the DNA‐protein interactions using a gel mobility shift assay. Binding of the YY1 probe was significantly decreased (p<.05) in LV nuclear extracts from exercise trained animals compared to sedentary animals (control; 100±16%, train; 30±12%). Quantification of YY1‐mRNA levels found no differences between the control and exercise training groups. Conclusion: Exercise training increased αMHC expression and this was associated with a significant decrease in YY1 activity suggesting a significant role for this transcription factor in mediating early changes in exercise‐induced modifications of the myocardial phenotype. Supported in part by NIH HL59417 and PO‐43023.