Enhancement of gamma-actin protein during liver regeneration: its accumulation in a region adjacent to the hepatocyte plasma membrane.
We identified a protein with a molecular weight of about 44 kDa in an extract of rat regenerating liver. This protein was undetectable in normal, sham-operated, and completely regenerated liver. We also purified this 44-kDa protein from an extract of rat liver remnant after partial hepatectomy. The partial amino acid sequences of the purified protein were identical to those of gamma-actin in non-muscle cells. In addition, anti-pan actin antibody recognized the purified 44-kDa protein, whereas anti-muscle actin and anti-beta-actin antibodies did not. Thus, we concluded that the 44-kDa protein was non-muscle gamma-actin. An immunohistochemical study revealed that the non-muscle gamma-actin accumulated next to the plasma membrane of liver parenchymal cells during regeneration. Moreover, the gamma-actin level was augmented in primary cultured rat hepatocytes prior to DNA synthesis. Intracellular gamma-actin in cultured hepatocytes was distributed across the entire basal plane after stimulation with hepatocyte mitogens. This change in the distribution of gamma-actin correlated with the cell spreading that occurred during the G1/S phase transition. These findings indicated that gamma-actin plays specific roles in the growth of liver parenchymal cells during liver regeneration.
Cell Biology Laboratory, National Institute of Bioscience and Human-Technology, Ibaraki.
T
T
Tanahashi
M
M
Suzuki
N
N
Itoh
Y
Y
Mitsui
D000199:Actins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D008099:Liver / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D008115:Liver Regeneration; D008969:Molecular Sequence Data; D051381:Rats; D017208:Rats, Wistar
D000199:Actins