2025 CONVENTION
Tripartite motif containing 44 (TRIM44) is part of the TRIM protein family, which participates in the ubiquitination and subsequent degradation of target proteins through the regulation of E3 ubiquitin ligases. Chaperone-mediated autophagy (CMA) represents a selective form of autophagy that directs specific cytosolic proteins to lysosomes for their breakdown. Recent studies have indicated that CMA dysfunction contributes to the development of metabolic dysfunction-associated steatohepatitis (MASH). In this study, we investigated how CMA regulates the degradation of TRIM44 in the liver. Analysis of the TRIM44 amino acid sequence revealed the presence of a KFERQ-like motif. We confirmed the interaction between TRIM44 and HSC70 in HEK293, suggesting that CMA facilitates the degradation of TRIM44. Mutations in the KFERQ-like motif weakened the interaction between TRIM44 and HSPA8, demonstrating the importance of this motif in CMA recognition. Silencing lysosome-associated protein 2A (LAMP2A) or heat shock protein family A (Hsp70) member 8 (HSPA8/HSC70) using siRNA led to increased protein levels of TRIM44. TRIM44 was found to accumulate in lysosomes following leupeptin treatment, and this accumulation was modulated when co-treated with siLAMP2A, suggesting that TRIM44 degradation relies on CMA. Additionally, in a mouse model of MASH, we observed decreased LAMP2A expression along with TRIM44 accumulation. Taken together, these results identify TRIM44 as a CMA substrate and suggest that impaired CMA-mediated degradation of TRIM44 may play a role in the development of MASH.