Myosin in hepatocytes is essential for bile canalicular contraction.
Active dynamic contraction of bile canaliculi has been observed in cultured doublet hepatocytes using time-lapse cinephotomicrography. This contractile movement plays an important role in normal bile formation. The mechanism of bile canalicular contraction has been proved to involve the Ca(2+)-calmodulin system and pericanalicular actin filaments. However, the role of myosin in this system is still unknown. In this study, using the newly synthesized myosin light-chain kinase inhibitor ML-9, we found that the treatment of cultured doublet hepatocytes with ML-9 inhibited canalicular contraction. This inhibitory effect suggests that myosin is involved in this complex cellular function and that the integrity of the actin-myosin system, as well as the Ca(2+)-calmodulin system is essential for normal bile canalicular contraction.
Watanabe
S
S
Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan.
Miyazaki
A
A
Hirose
M
M
Takeuchi
M
M
Ohide
H
H
Kitamura
T
T
Ueno
T
T
Kominami
E
E
Sato
N
N
D000199:Actins / Q000378:metabolism; D000818:Animals; D001381:Azepines; D001648:Bile Canaliculi / Q000502:physiology*; D002478:Cells, Cultured; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009219:Myosin-Light-Chain Kinase / Q000037:antagonists & inhibitors; D009218:Myosins / Q000378:metabolism / Q000502:physiology*; D013194:Staining and Labeling; D014743:Videotape Recording
D000199:Actins; D001381:Azepines; C056218:ML 9; D009219:Myosin-Light-Chain Kinase; D009218:Myosins