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Diabetes. 2019 Feb;68(2):361-376. doi: 10.2337/db18-0035. Epub 2018 Nov 19.

HSPA12A Is a Novel Player in Nonalcoholic Steatohepatitis via Promoting Nuclear PKM2-Mediated M1 Macrophage Polarization.

Author information

1
Department of Anesthesiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
2
Department of Geriatrics, First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
3
Department of Pathology, First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
4
Department of Surgery, East Tennessee State University, Johnson City, TN.
5
Department of Pathophysiology, Nanjing Medical University, Nanjing, China.
6
State Key Laboratory of Pharmaceutical Biotechnology and Jiangsu Key Laboratory of Molecular Medicine and School of Medicine, Nanjing University, Nanjing, China.
7
Medical School of Nanjing University, Nanjing, China.
8
Department of Geriatrics, First Affiliated Hospital of Nanjing Medical University, Nanjing, China zhengnianding@njmu.edu.cn liuli@njmu.edu.cn.
9
Department of Anesthesiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, China zhengnianding@njmu.edu.cn liuli@njmu.edu.cn.

Abstract

Nonalcoholic steatohepatitis (NASH) is the most prevalent cause of chronic liver disease worldwide. Macrophage-mediated inflammation plays a critical role in NASH pathogenesis; however, optimum therapies for macrophage activation and NASH remain elusive. HSPA12A encodes a novel member of the HSP70 family. Here, we report that NASH patients showed increased hepatic HSPA12A expression and serum HSPA12A contents. Intriguingly, knockout of HSPA12A (Hspa12a-/- ) in mice attenuated high-fat diet (HFD)-induced hepatic steatosis and injury. HFD-induced macrophage polarization toward an M1 phenotype and inflammatory responses in the liver of Hspa12a-/- mice were also attenuated. Loss- and gain-of-function studies revealed that the de novo lipogenesis in hepatocytes was regulated by the paracrine effects of macrophage HSPA12A rather than by hepatocyte HSPA12A. In-depth molecular analysis revealed that HSPA12A interacted with the M2 isoform of pyruvate kinase (PKM2) in macrophages and increased its nuclear translocation, thereby promoting M1 polarization and secretion of proinflammatory M1 cytokines; this led, ultimately, to hepatocyte steatosis via paracrine effects. Taken together, these findings show that HSPA12A acts as a novel regulator of M1 macrophage polarization and NASH pathogenesis by increasing nuclear PKM2. Strategies that inhibit macrophage HSPA12A might be a potential therapeutic intervention for NASH.

PMID:
30455376
DOI:
10.2337/db18-0035

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