Myosin regulatory light chains are required to maintain the stability of myosin II and cellular integrity.
Myosin II is an actin-binding protein composed of MHC (myosin heavy chain) IIs, RLCs (regulatory light chains) and ELCs (essential light chains). Myosin II expressed in non-muscle tissues plays a central role in cell adhesion, migration and division. The regulation of myosin II activity is known to involve the phosphorylation of RLCs, which increases the Mg2+-ATPase activity of MHC IIs. However, less is known about the details of RLC-MHC II interaction or the loss-of-function phenotypes of non-muscle RLCs in mammalian cells. In the present paper, we investigate three highly conserved non-muscle RLCs of the mouse: MYL (myosin light chain) 12A (referred to as MYL12A), MYL12B and MYL9 (MYL12A/12B/9). Proteomic analysis showed that all three are associated with the MHCs MYH9 (NMHC IIA) and MYH10 (NMHC IIB), as well as the ELC MYL6, in NIH 3T3 fibroblasts. We found that knockdown of MYL12A/12B in NIH 3T3 cells results in striking changes in cell morphology and dynamics. Remarkably, the levels of MYH9, MYH10 and MYL6 were reduced significantly in knockdown fibroblasts. Comprehensive interaction analysis disclosed that MYL12A, MYL12B and MYL9 can all interact with a variety of MHC IIs in diverse cell and tissue types, but do so optimally with non-muscle types of MHC II. Taken together, our study provides direct evidence that normal levels of non-muscle RLCs are essential for maintaining the integrity of myosin II, and indicates that the RLCs are critical for cell structure and dynamics.
School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Korea.
Inju
I
Park
Cecil
C
Han
Sora
S
Jin
Boyeon
B
Lee
Heejin
H
Choi
Jun Tae
JT
Kwon
Dongwook
D
Kim
Jihye
J
Kim
Ekaterina
E
Lifirsu
Woo Jin
WJ
Park
Zee Yong
ZY
Park
Do Han
DH
Kim
Chunghee
C
Cho
D000577:Amides / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D002465:Cell Movement; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D018994:Myosin Light Chains / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D024462:Myosin Type II / Q000378:metabolism*; D041681:NIH 3T3 Cells; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference
D000577:Amides; D004791:Enzyme Inhibitors; D006576:Heterocyclic Compounds, 4 or More Rings; D018994:Myosin Light Chains; D011725:Pyridines; C108830:Y 27632; C472645:blebbistatin; D024462:Myosin Type II