cGAS Inhibits ALDH2 to Suppress Lipid Droplet Function and Regulate MASLD Progression

Area of Science:

• Cellular Biology
• Metabolism
• Immunology

Background:

• Cyclic GMP-AMP synthase (cGAS) is known as a cytosolic DNA sensor for innate immunity.
• Its functions beyond host defense against microbial infections are not well understood.

Purpose of the Study:

• To investigate the non-canonical roles of cGAS in metabolic regulation.
• To elucidate the molecular mechanisms linking cGAS to aldehyde metabolism and lipid homeostasis.

Main Methods:

• Biochemical assays to demonstrate direct binding of cGAS to ALDH2.
• Analysis of cGas^-/- mice to assess ethanol tolerance and lipid metabolism.
• Histological and molecular analyses of liver tissues from cGas^-/- mice and human MASLD cohorts.

Main Results:

• cGAS directly binds and suppresses aldehyde dehydrogenase 2 (ALDH2) activity.
• Loss of cGAS leads to ALDH2 activation, increased ethanol tolerance, and lipid droplet accumulation.
• cGAS deficiency exacerbates metabolic dysfunction-associated steatotic liver disease (MASLD) in mice and correlates with altered cGAS/ALDH2 expression in human MASLD patients.
• Lipid droplets induced by cGAS loss confer ferroptosis resistance but cause ER stress, impairing STING activation.

Conclusions:

• cGAS plays a critical role in regulating aldehyde metabolism and lipid homeostasis, independent of its immune function.
• The cGAS-ALDH2 interaction influences lipid biogenesis, cellular stress responses, and MASLD pathogenesis.
• Targeting the cGAS-ALDH2 pathway may offer new therapeutic strategies for metabolic liver diseases.