Integrator complex subunit 6 promotes hepatocellular steatosis via β-catenin-PPARγ axis

Shiozaki Minami

Kanno Keishi

Yonezawa Sayaka

Otani Yuichiro

Shigenobu Yuya

Haratake Daisuke

Murakami Eisuke

Oka Shiro

Ito Masanori

Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids

Hepatic adipogenesis has common mechanisms with adipocyte differentiation such as PPARγ involvement and the induction of adipose tissue-specific molecules. A previous report demonstrated that integrator complex subunit 6 (INTS6) is required for adipocyte differentiation. This study aimed to investigate INTS6 expression and its role in hepatic steatosis progression. The expression of INTS6 and PPARγ was examined in the liver of a mouse model of steatohepatitis and in paired liver biopsy samples from 11 patients with severe obesity and histologically proven metabolic dysfunction associated steatohepatitis (MASH) before and one year after bariatric surgery. To induce hepatocellular steatosis in vitro, an immortalized human hepatocyte cell line Hc3716 was treated with free fatty acids. In the steatohepatitis mouse model, we observed hepatic induction of INTS6, PPARγ, and adipocyte-specific genes. In contrast, β-catenin which negatively regulates PPARγ was reduced. Biopsied human livers demonstrated a strong positive correlation (r2 = 0.8755) between INTS6 and PPARγ mRNA levels. After bariatric surgery, gene expressions of PPARγ, FABP4, and CD36 were mostly downregulated. In our in vitro experiments, we observed a concentration-dependent increase in Oil Red O staining in Hc3716 cells after treatment with the free fatty acids. Alongside this change, the expression of INTS6, PPARγ, and adipocyte-specific genes was induced. INTS6 knockdown using siRNA significantly suppressed cellular lipid accumulation together with induction of β-catenin and PPARγ downregulation. Collectively, INTS6 expression closely correlates with PPARγ. INTS6 suppression significantly reduced hepatocyte steatosis via β-catenin-PPARγ axis, indicating that INTS6 could be a novel therapeutic target for treating MASH.

Metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatohepatitis

Integrator complex subunit 6

Lipid metabolism

Adipogenesis

eng

Elsevier

© 2024. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/

This is not the published version. Please cite only the published version.

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[DOI] https://doi.org/10.1016/j.bbalip.2024.159532 isVersionOf