ROCK1 and LIM kinase modulate retrovirus particle release and cell-cell transmission events.
The assembly and release of retroviruses from the host cells require dynamic interactions between viral structural proteins and a variety of cellular factors. It has been long speculated that the actin cytoskeleton is involved in retrovirus production, and actin and actin-related proteins are enriched in HIV-1 virions. However, the specific role of actin in retrovirus assembly and release remains unknown. Here we identified LIM kinase 1 (LIMK1) as a cellular factor regulating HIV-1 and Mason-Pfizer monkey virus (M-PMV) particle release. Depletion of LIMK1 reduced not only particle output but also virus cell-cell transmission and was rescued by LIMK1 replenishment. Depletion of the upstream LIMK1 regulator ROCK1 inhibited particle release, as did a competitive peptide inhibitor of LIMK1 activity that prevented cofilin phosphorylation. Disruption of either ROCK1 or LIMK1 led to enhanced particle accumulation on the plasma membrane as revealed by total internal reflection fluorescence microscopy (TIRFM). Electron microscopy demonstrated a block to particle release, with clusters of fully mature particles on the surface of the cells. Our studies support a model in which ROCK1- and LIMK1-regulated phosphorylation of cofilin and subsequent local disruption of dynamic actin turnover play a role in retrovirus release from host cells and in cell-cell transmission events.


OBJECTIVE
Viruses often interact with the cellular cytoskeletal machinery in order to deliver their components to the site of assembly and budding. This study indicates that a key regulator of actin dynamics at the plasma membrane, LIM kinase, is important for the release of viral particles for HIV as well as for particle release by a distantly related retrovirus, Mason-Pfizer monkey virus. Moreover, disruption of LIM kinase greatly diminished the spread of HIV from cell to cell. These findings suggest that LIM kinase and its dynamic modulation of the actin cytoskeleton in the cell may be an important host factor for the production, release, and transmission of retroviruses.
Department of Pediatrics, Children's Healthcare of Atlanta and Emory University School of Medicine, Atlanta, Georgia, USA.
Xiaoyun
X
Wen
Department of Pediatrics, Children's Healthcare of Atlanta and Emory University School of Medicine, Atlanta, Georgia, USA.
Lingmei
L
Ding
Department of Pediatrics, Children's Healthcare of Atlanta and Emory University School of Medicine, Atlanta, Georgia, USA.
Jaang-Jiun
JJ
Wang
Department of Pediatrics, Children's Healthcare of Atlanta and Emory University School of Medicine, Atlanta, Georgia, USA.
Mingli
M
Qi
Department of Pediatrics, Children's Healthcare of Atlanta and Emory University School of Medicine, Atlanta, Georgia, USA.
Jason
J
Hammonds
Department of Microbiology, Queen Mary Hospital, The University of Hong Kong, Hong Kong Special Administrative Region, China.
Hin
H
Chu
Department of Pediatrics, Children's Healthcare of Atlanta and Emory University School of Medicine, Atlanta, Georgia, USA.
Xuemin
X
Chen
Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA.
Eric
E
Hunter
Department of Pediatrics, Children's Healthcare of Atlanta and Emory University School of Medicine, Atlanta, Georgia, USA paul.spearman@emory.edu.
Paul
P
Spearman
D000199:Actins / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D015658:HIV Infections / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D054461:Lim Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012190:Retroviridae / Q000502:physiology; D012192:Retroviridae Infections / Q000201:enzymology / Q000235:genetics / Q000821:virology; D057074:Virus Release; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism*
D000199:Actins; C515892:LIMK1 protein, human; D054461:Lim Kinases; C515851:ROCK1 protein, human; D054460:rho-Associated Kinases