TY - JOUR
T1 - Role of A-Kinase Anchoring Protein Phosphorylation in Alcohol-Induced Liver Injury and Hepatic Stellate Cell Activation
AU - Ramani, Komal
AU - Tomasi, Maria Lauda
AU - Berlind, Joshua
AU - Mavila, Nirmala
AU - Sun, Zhaoli
N1 - Funding Information:
Supported by NIH grant 5R00AA017774-05, Applied Cell Biology and Physiology Division seed funding, Biomedical Sciences Department, Cedars-Sinai Medical Center (K.R.); NIH grant K01AA022372 (M.L.T.); liver research group core support, Division of Digestive and Liver Diseases, Department of Medicine, Cedars-Sinai Medical Center (K.R. and J.B.); Applied Cell Biology and Physiology division seed funding, Biomedical Sciences Department, Cedars-Sinai Medical Center (N.M.); and grant R24AA025017, National Institute on Alcohol Abuse and Alcoholism–supported Clinical Resource for Alcoholic Hepatitis Investigations, Johns Hopkins University (Z.S.).
Publisher Copyright:
© 2018 American Society for Investigative Pathology
PY - 2018/3
Y1 - 2018/3
N2 - Alcoholic liver injury is associated with hepatic stellate cell (HSC) activation. A-kinase anchoring protein 12 (AKAP12) scaffolds protein kinase C and cyclin-D1, which is regulated by its phosphorylation, and spatiotemporally controls cell proliferation, invasiveness, and chemotaxis. HSC activation induces AKAP12 expression, but the role of AKAP12's scaffolding activity in liver function is unknown. Because AKAP12 phosphorylation is enhanced in ethanol-treated HSCs, we examined AKAP12's scaffolding functions in alcohol-mediated HSC activation and liver injury. AKAP12 expression, interaction, and phosphorylation were assayed in in vitro and in vivo ethanol models and human subjects by real-time PCR, coimmunoprecipitation, immunoblotting, and phosphorylated proteomics/Phos-tag. Ethanol induced AKAP12 phosphorylation in the liver and in primary HSCs, but not in hepatocytes. AKAP12's scaffolding activity for protein kinase C/cyclin-D1 decreased in ethanol-treated HSCs but not hepatocytes. AKAP12 negatively regulated HSC activation, which was reversed by ethanol-mediated AKAP12 phosphorylation. AKAP12 interacted with heat shock protein 47 (HSP47), which chaperones collagen and induces its secretion. Ethanol inhibited AKAP12-HSP47 and induced HSP47-collagen interaction. Ethanol-induced phosphorylated AKAP12 was unable to bind to HSP47 compared with its unphosphorylated counterpart, thereby proving that ethanol-mediated phosphorylation of AKAP12 inhibited the HSP47-AKAP12 scaffold. Silencing AKAP12 facilitated the chaperoning of collagen by HSP47. Hence, AKAP12 scaffolds HSP47 and regulates collagen-HSP47 interaction. Ethanol quenches AKAP12's scaffolding activity through phosphorylation and facilitates HSC activation.
AB - Alcoholic liver injury is associated with hepatic stellate cell (HSC) activation. A-kinase anchoring protein 12 (AKAP12) scaffolds protein kinase C and cyclin-D1, which is regulated by its phosphorylation, and spatiotemporally controls cell proliferation, invasiveness, and chemotaxis. HSC activation induces AKAP12 expression, but the role of AKAP12's scaffolding activity in liver function is unknown. Because AKAP12 phosphorylation is enhanced in ethanol-treated HSCs, we examined AKAP12's scaffolding functions in alcohol-mediated HSC activation and liver injury. AKAP12 expression, interaction, and phosphorylation were assayed in in vitro and in vivo ethanol models and human subjects by real-time PCR, coimmunoprecipitation, immunoblotting, and phosphorylated proteomics/Phos-tag. Ethanol induced AKAP12 phosphorylation in the liver and in primary HSCs, but not in hepatocytes. AKAP12's scaffolding activity for protein kinase C/cyclin-D1 decreased in ethanol-treated HSCs but not hepatocytes. AKAP12 negatively regulated HSC activation, which was reversed by ethanol-mediated AKAP12 phosphorylation. AKAP12 interacted with heat shock protein 47 (HSP47), which chaperones collagen and induces its secretion. Ethanol inhibited AKAP12-HSP47 and induced HSP47-collagen interaction. Ethanol-induced phosphorylated AKAP12 was unable to bind to HSP47 compared with its unphosphorylated counterpart, thereby proving that ethanol-mediated phosphorylation of AKAP12 inhibited the HSP47-AKAP12 scaffold. Silencing AKAP12 facilitated the chaperoning of collagen by HSP47. Hence, AKAP12 scaffolds HSP47 and regulates collagen-HSP47 interaction. Ethanol quenches AKAP12's scaffolding activity through phosphorylation and facilitates HSC activation.
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U2 - 10.1016/j.ajpath.2017.11.017
DO - 10.1016/j.ajpath.2017.11.017
M3 - Article
C2 - 29305319
AN - SCOPUS:85042295683
SN - 0002-9440
VL - 188
SP - 640
EP - 655
JO - American Journal of Pathology
JF - American Journal of Pathology
IS - 3
ER -