Compromised COPII vesicle trafficking leads to glycogenic hepatopathy

Area of Science:

• Cell Biology
• Metabolic Homeostasis
• Zebrafish Models

Background:

• Coat protein complex II (COPII) vesicle trafficking is essential for cellular processes and liver metabolism.
• The precise role and mechanisms of COPII trafficking in systemic metabolic homeostasis remain incompletely understood.

Purpose of the Study:

• To investigate the functional consequences of compromised COPII vesicle trafficking in liver metabolism using a novel zebrafish model.
• To elucidate the molecular pathways and systemic interactions underlying metabolic dysregulation due to impaired vesicle transport.

Main Methods:

• Generation and characterization of a gene trap zebrafish line (sec31anju221) with compromised COPII trafficking.
• Epistasis analysis to identify key signaling pathways involved in hepatic steatosis.
• Proteomic profiling and biochemical assays to assess metabolic status and thyroid function.
• Investigation of thyroid hormone's effect on metabolic defects.

Main Results:

• Compromised COPII trafficking in zebrafish larvae leads to unfolded protein response activation and hepatic steatosis, mediated by the eIF2α-ATF4 pathway.
• In adult zebrafish, hepatic steatosis is reversed, manifesting as glycogenic hepatopathy.
• Proteomic and biochemical data reveal hypothyroidism in affected zebrafish, with thyroid hormone treatment ameliorating metabolic defects.

Conclusions:

• Impaired COPII vesicle trafficking induces biphasic hepatic metabolic abnormalities, involving distinct larval and adult phenotypes.
• The eIF2α-ATF4 pathway is a critical mediator of COPII-dependent hepatic steatosis.
• Thyroid hormone signaling is intricately linked to liver metabolic health in the context of vesicle trafficking dysfunction.