Role of YAP Activation in Nuclear Receptor CAR-Mediated Proliferation of Mouse Hepatocytes

Taiki Abe, Yuto Amaike, Ryota Shizu, Miki Takahashi, Makoto Kano, Takuomi Hosaka, Takamitsu Sasaki, Susumu Kodama, Atsushi Matsuzawa, Kouichi Yoshinari

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Abstract

Constitutive androstane receptor (CAR) is a xenobiotic-responsive nuclear receptor that is highly expressed in the liver. CAR activation induces hepatocyte proliferation and hepatocarcinogenesis in rodents, but the mechanisms remain unclear. In this study, we investigated the association of CAR-dependent cell proliferation with Yes-associated protein (YAP), which is a transcriptional cofactor controlling organ size and cell growth through the interaction with various transcriptional factors including TEA domain family member (TEAD). In mouse livers, 1,4-bis-(2-[3,5-dichloropyridyloxy])benzene (TCPOBOP) (a mouse CAR [mCAR] activator) treatment increased the nuclear YAP accumulation and mRNA levels of YAP target genes as well as cell-cycle related genes along with liver hypertrophy and verteporfin (an inhibitor of YAP/TEAD interaction) cotreatment tended to attenuate them. Furthermore, in cell-based reporter gene assays, CAR activation enhanced the YAP/TEAD-dependent transcription. To investigate the role of YAP/TEAD activation in the CAR-dependent hepatocyte proliferation, we sought to establish an in vitro system completely reproducing CAR-dependent cell proliferation. Since CAR was only slightly expressed in cultured mouse primary hepatocytes compared with mouse livers and no proliferation was observed after treatment with TCPOBOP, we overexpressed CAR using mCAR expressing adenovirus (Ad-mCAR-V5) in mouse primary hepatocytes. Ad-mCAR-V5 infection and TCPOBOP treatment induced hepatocyte proliferation. Similar results were obtained with immortalized normal mouse hepatocytes as well. In the established in vitro system, CAR-dependent proliferation was strongly inhibited by Yap knockdown and completely abolished by verteporfin treatment. Our present results obtained in in vivo and in vitro experiments suggest that YAP/TEAD activation plays key roles in CAR-dependent proliferation of murine hepatocytes.

Original languageEnglish
Pages (from-to)408-419
Number of pages12
JournalToxicological Sciences
Volume165
Issue number2
DOIs
Publication statusPublished - Oct 1 2018
Externally publishedYes

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Keywords

  • CAR
  • hepatocyte proliferation
  • Hippo pathway
  • liver hypertrophy
  • nuclear receptor

ASJC Scopus subject areas

  • Toxicology

Cite this

Abe, T., Amaike, Y., Shizu, R., Takahashi, M., Kano, M., Hosaka, T., Sasaki, T., Kodama, S., Matsuzawa, A., & Yoshinari, K. (2018). Role of YAP Activation in Nuclear Receptor CAR-Mediated Proliferation of Mouse Hepatocytes. Toxicological Sciences, 165(2), 408-419. https://doi.org/10.1093/toxsci/kfy149