Abstract
Chronic liver disease affects over a billion people worldwide. Despite diverse etiologies, a unifying feature of chronic liver disease is the liver’s impaired ability to regenerate during progression to cirrhosis, but no common molecular mechanism has been identified. Hepatocyte proliferation and liver regeneration depend on nucleoplasmic calcium (Ca2+) signals, and Ca2+ signals in hepatocytes depend on the type 2 inositol trisphosphate receptor (ITPR2) calcium release channel. Here, we found that ITPR2 was localized in part to the hepatocyte nucleus, and this localization depended on the presence of nucleoporin 62 (NUP62). Loss of either ITPR2 or NUP62 disrupted nuclear Ca2+ signaling, and impaired Ca2+ signals in the nucleus blunted nuclear entry of β-catenin. Remarkably, both ITPR2 and NUP62 are progressively lost from hepatocytes in patients with the four most common types of chronic liver disease. These findings identify a microdomain regulating Ca2+ signaling in the hepatocyte nucleus that becomes progressively disrupted as liver disease progresses. Preservation of this nuclear microdomain may be a novel approach to maintain liver regeneration and slow the progression to cirrhosis in chronic liver disease.
Authors
Jittima Weerachayaphorn, Mateus T. Guerra, Naotaka Kugiyama, Emma Kruglov, Dejian Zhao, Piyachat Chansela, Vitoon Saengsirisuwan, Marie E. Robert, Teruo Utsumi, Yasuko Iwakiri, Michael H. Nathanson
