2. Academic Validation
  3. USP24 upregulation stabilizes PKA-Cα to promote lipogenesis, inflammation, and fibrosis during MASH progression

USP24 upregulation stabilizes PKA-Cα to promote lipogenesis, inflammation, and fibrosis during MASH progression

  • J Biomed Sci. 2025 May 30;32(1):54. doi: 10.1186/s12929-025-01148-4.
Beh Ning # 1 2,  Shao-An Wang # 3,  Ming-Jer Young # 1,  Yung-Ching Chen 1 2,  Yun Hung 3,  Tran Thu Huong 1,  Wen-Chang Chang 2,  Yi-Ching Wang 4,  Ming-Lung Yu 5,  Kai-Cheng Hsu 6,  Jan-Jong Hung 7
Affiliations

Affiliations

  • 1 Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 701, Taiwan.
  • 2 Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
  • 3 School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan.
  • 4 Institute of Pharmacology, National Cheng Kung University, Tainan, Taiwan.
  • 5 Center of Excellence for Metabolic Associated Fatty Liver Disease, National Sun Yat-Sen University, Kaohsiung, Taiwan.
  • 6 Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
  • 7 Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 701, Taiwan. petehung@mail.ncku.edu.tw.
  • # Contributed equally.
PMID: 40448065 DOI: 10.1186/s12929-025-01148-4
Abstract

Background: Ubiquitin-specific peptidase 24 (USP24), a deubiquitinating enzyme, regulates protein stability by removing ubiquitin. This study investigates the role of UPS24 in lipid metabolism, inflammation, and fibrosis. It also explores the effect of targeting USP24 on metabolic disorders, focusing on high-fat diet (HFD)-induced obesity and liver diseases.

Methods: This study utilized CRISPR/Cas9 to create functional knockout mice (USP24C1695A) and treated HFD-fed mice with USP24 inhibitor (USP24-i-101). The effects of USP24 inhibition or knockout on 3T3-L1 derived adipocytes, primary hepatocytes, hepatic stellate cells, and murine hepatocyte cell line AML12 (alpha mouse liver 12) cells were assessed with RNA-sequencing. Molecular mechanisms and the interaction between USP24 and PKA-Cα were studied with co-immunoprecipitation. Downstream signaling pathways involving CREB, SREBP1, PPARγ, and C/EBPβ, as well as USP24 role in liver inflammation and fibrosis, were studied using western blot and Real-Time PCR. Clinical and animal tissue samples were examined with immunohistochemistry to identify the correlations between USP24 and metabolic-associated liver diseases.

Results: Knockout or inhibition of USP24 reduced body weight, lipid accumulation, inflammation, and fibrosis in HFD-fed mice. The expression of genes related to lipogenesis, inflammation, and fibrosis was downregulated in USP24C1695A mice and those treated with USP24 inhibitor (USP24-i-101). USP24 inhibition decreased lipid droplet accumulation in adipocytes and hepatocytes, suppressed inflammation in hepatocytes and AML12 cells, and reduced fibrosis in hepatic stellate cells. Mechanistically, USP24 expression was upregulated by PKA activation during adipocyte differentiation, leading to increased PKA-Cα stability and CREB phosphorylation, which promoted lipogenic gene expression. Free fatty acids (FFA) increased USP24 expression, activating NF-κB and TGFβ pathways to induce inflammation (Cox2) and fibrosis (α-SMA). USP24 was highly expressed in patients with metabolic dysfunction-associated steatohepatitis (MASH) and correlated with Cox2 and α-SMA levels.

Keywords

Lipogenesis; MASH; PKA-Cα; USP24; p-CREB.

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