title: Physiological ranges of matrix rigidity modulate primary mouse hepatocyte function in part through hepatocyte nuclear factor 4 alpha.
abstract: Matrix rigidity has important effects on cell behavior and is increased during liver fibrosis; however, its effect on primary hepatocyte function is unknown. We hypothesized that increased matrix rigidity in fibrotic livers would activate mechanotransduction in hepatocytes and lead to inhibition of liver-specific functions. To determine the physiologically relevant ranges of matrix stiffness at the cellular level, we performed detailed atomic force microscopy analysis across liver lobules from normal and fibrotic livers. We determined that normal liver matrix stiffness was around 150 Pa and increased to 1-6 kPa in areas near fibrillar collagen deposition in fibrotic livers. In vitro culture of primary hepatocytes on collagen matrix of tunable rigidity demonstrated that fibrotic levels of matrix stiffness had profound effects on cytoskeletal tension and significantly inhibited hepatocyte-specific functions. Normal liver stiffness maintained functional gene regulation by hepatocyte nuclear factor 4 alpha (HNF4α), whereas fibrotic matrix stiffness inhibited the HNF4α transcriptional network. Fibrotic levels of matrix stiffness activated mechanotransduction in primary hepatocytes through focal adhesion kinase. In addition, blockade of the Rho/Rho-associated protein kinase pathway rescued HNF4α expression from hepatocytes cultured on stiff matrix.
  
  
  
  Fibrotic levels of matrix stiffness significantly inhibit hepatocyte-specific functions in part by inhibiting the HNF4α transcriptional network mediated through the Rho/Rho-associated protein kinase pathway. Increased appreciation of the role of matrix rigidity in modulating hepatocyte function will advance our understanding of the mechanisms of hepatocyte dysfunction in liver cirrhosis and spur development of novel treatments for chronic liver disease. (Hepatology 2016;64:261-275).
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, CA.
authors.forename: Seema S
authors.initials: SS
authors.lastname: Desai
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, CA.|Center for Bioengineering and Tissue Regeneration, University of California, San Francisco, San Francisco, CA.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Tung
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, CA.
authors.forename: Vivian X
authors.initials: VX
authors.lastname: Zhou
authors.affiliation: Department of Pathology, University of California, San Francisco, San Francisco, CA.|Liver Center, and, University of California, San Francisco, San Francisco, CA.
authors.forename: James P
authors.initials: JP
authors.lastname: Grenert
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, CA.
authors.forename: Yann
authors.initials: Y
authors.lastname: Malato
authors.affiliation: Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA.
authors.forename: Milad
authors.initials: M
authors.lastname: Rezvani
authors.affiliation: Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA.
authors.forename: Regina
authors.initials: R
authors.lastname: Español-Suñer
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, CA.|Liver Center, and, University of California, San Francisco, San Francisco, CA.|Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA.
authors.forename: Holger
authors.initials: H
authors.lastname: Willenbring
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, CA.|Center for Bioengineering and Tissue Regeneration, University of California, San Francisco, San Francisco, CA.
authors.forename: Valerie M
authors.initials: VM
authors.lastname: Weaver
authors.affiliation: Department of Surgery, University of California, San Francisco, San Francisco, CA.|Liver Center, and, University of California, San Francisco, San Francisco, CA.
authors.forename: Tammy T
authors.initials: TT
authors.lastname: Chang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology; D005109:Extracellular Matrix / Q000502:physiology*; D015870:Gene Expression; D051557:Hepatocyte Nuclear Factor 4 / Q000378:metabolism*; D022781:Hepatocytes / Q000502:physiology*; D008103:Liver Cirrhosis / Q000378:metabolism; D040542:Mechanotransduction, Cellular; D008810:Mice, Inbred C57BL; D018625:Microscopy, Atomic Force; D054460:rho-Associated Kinases / Q000378:metabolism
chemical_list: D051557:Hepatocyte Nuclear Factor 4; C496593:Hnf4a protein, mouse; D054460:rho-Associated Kinases