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Fast‐To‐Slow: Myosin Heavy Chain Alterations in Response to Altered Six1 Gene Expression
Author(s) -
Collins Brittany C,
Gordon Bradley S,
Kostek Matthew C
Publication year - 2012
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.26.1_supplement.1086.26
Subject(s) - myogenin , myosin , gene expression , c2c12 , skeletal muscle , myocyte , biology , regulation of gene expression , gene , expression vector , medicine , transfection , endocrinology , microbiology and biotechnology , biochemistry , myogenesis , recombinant dna
Muscle activation patterns (e.g. exercise) affect muscle fiber‐type proportions in skeletal muscle. The developmental gene, Six1's, expression is altered by exercise, and altering its expression affects fiber‐type proportions in mice, though how is unclear. PURPOSE Examine the effect of Six1 expression on the myosin heavy chain (MyHC) genes during muscle fiber formation. METHODS C2C12 mouse myoblasts were grown in standard conditions. When cells reached 80% confluence, they were transfected with Six1 over‐expression vectors or empty vector control. 24 hours later, cells were switched to differentiation medium. After four days, cells were harvested. Six1, MyHC, and Myogenin gene expression was analyzed by qRT‐PCR. RESULTS When compared to empty vector control, Six1 expression increased 700 ± 243.4 fold (p = 0.02), MyHC‐IIb expression decreased 2 ± 0.12 fold (p = 0.01), MyHC‐IIx decreased 1.5 ± 0.09 fold (p = 0.05), MyHC‐I increased 2 ± 0.24 fold (p = 0.03), and MyHC‐IIa expression did not change. Six1 over‐expression caused a Myogenin increase 2.7 ± 0.34 fold (p = 0.02). A second Six1 expression vector confirmed these results. CONCLUSION Six1 over‐expression differentially affects the muscle fiber‐type gene program during the formation of a muscle fiber. Together with our previous in‐vivo data, this suggests that Six1 expression affects the fiber‐type shift induced by muscle activation patterns.