VCPIP1 Drives Diabetic Cardiomyopathy by Deubiquitinating AMPKgamma1 and Preventing AMPKalpha-gamma Subunit Assembly in Cardiomyocytes

Protein ubiquitination modifications contribute to cardiomyocyte homeostasis and pathophysiology in diabetic cardiomyopathy (DCM). Yet the roles of deubiquitinating enzymes (DUBs) in DCM remain poorly defined. Here, we aimed to clarify the regulatory function of a DUB, valosin-containing protein interacting protein 1 (VCPIP1), in DCM and uncover the molecular mechanisms. We identify VCPIP1 was significantly elevated in diabetic hearts, and upregulated VCPIP1 was mainly distributed in cardiomyocytes. Cardiomyocyte-specific VCPIP1 knockout ameliorated cardiac injury in both type 2 and type 1 diabetic mouse models. Ubiquitinome and interactome profiling revealed AMPKgamma1 as a substrate of VCPIP1 in cardiomyocytes. Mechanistically, VCPIP1 binds the cystathionine-beta-synthase 2 domain of AMPKgamma1 via its UBX-L domain and then catalyzes the K63-linked deubiquitination of AMPKgamma1-K234 site through its catalytic residue C218. This VCPIP1-mediated AMPKgamma1 deubiquitination disrupts AMPKalpha-gamma heterodimer integrity, allosterically impairing AMPKalpha2-LKB1 interaction and limiting LKB1-mediated AMPKalphaT172 phosphorylation. RNA-seq analysis showed that AMPKgamma1-K234 deubiquitination impaired mitochondrial respiratory through inactivating AMPKalpha in cardiomyocytes, while VCPIP1 deficiency reversed hyperglycemia-induced mitochondrial dysfunction. Finally, AMPKgamma1-K234R mutant phenocopied VCPIP1-mediated cardiac pathology in db/db mice. In conclusion, our findings unveil the VCPIP1-AMPKgamma1 axis as a non-canonical regulatory mechanism for AMPKalphaT172 phosphorylation in cardiomyocytes, suggesting targeting inhibition of VCPIP1 as a potential therapeutic strategy for DCM.