Exp Mol Med.  1998 Jun;30(2):73-79.

Rapid increase of cytosolic content of acetyl-CoA carboxylase isoforms in H9c2 cells by short-term treatment with insulin and okadaic acid

• Park CE
• Ko SM
• Kim JM
• Yoon MY
• Kim JY
• Kang IS
• Kim SS
• Ha JH

Abstract

Mammalian acetyl-CoA carboxylase (ACC) is present in two isoforms, alpha and beta, both of which catalyze formation of malonyl-CoA by fixing CO2 into acetyl-CoA. ACC-alpha is highly expressed in lipogenic tissues whereas ACC-beta is a predominant form in heart and skeletal muscle tissues. Even though the tissue-specific expression pattern of two ACC isoforms suggests that each form may have a distinct function, existence of two isoforms catalyzing the identical reaction in a same cell has been a puzzling question. As a first step to answer this question and to identify the possible role of ACC isoforms in myogenic differentiation, we have investigated in the present study whether the expression and the subcellular distribution of ACC isoforms in H9c2 cardiac myocyte change so that malonyl-CoA produced by each form may modulate fatty acid oxidation. We have observed that the expression levels of both ACC forms were correlated to the extent of myogenic differentiation and that they were present not only in cytoplasm but also in other subcellular compartment. Among the various tested compounds, short-term treatment of H9c2 myotubes with insulin or okadaic acid rapidly increased the cytosolic content of both ACC isoforms up to 2 folds without affecting the total cellular ACC content. Taken together, these observations suggest that both ACC isoforms may play a pivotal role in muscle differentiation and that they may translocate between cytoplasm and other subcellular compartment to achieve its specific goal under the various physiological conditions.

Keyword

acetyl-CoA carboxylase; carnitine palmitoyltransferase-I; malonyl-CoA; digitonin; H9c2 cardiac myocyte.

MeSH Terms

Acetyl-CoA Carboxylase/metabolism*
Acetyl-CoA Carboxylase/drug effects
Animal
Cell Differentiation/drug effects
Cell Line
Cell Membrane Permeability
Chromones/pharmacology
Cytosol/enzymology*
Cytosol/drug effects
Digitonin/pharmacology
Immunoblotting
Insulin/pharmacology*
Isoenzymes
Morpholines/pharmacology
Myocardium/cytology
Okadaic Acid/pharmacology*
Phosphorylation
Rats