OTUB1 Catalytic-Independently Deubiquitinates TGFBI and Mediates the Angiogenesis in Infantile Hemangioma by Regulating Glycolysis

Abstract

Background: Infantile hemangioma (IH) arises as a result of dysregulation of both angiogenesis and vasculogenesis. The deubiquitylase OTUB1 (OTU domain, ubiquitin aldehyde binding 1) has been reported to play an essential role in multiple cancers; however, its function in the progression of IH and the underlying mechanisms regulating angiogenesis remain unclear. Methods: Transwell assays, EdU assays, and tube formation assays were performed to investigate the biological behavior of IH in vitro. IH animal models were established to estimate the progression of IH in vivo. Mass spectrometric analysis were conducted to detect the downstream of OTUB1 and ubiquitination sites of transforming growth factor beta induced (TGFBI). Half-life assays and ubiquitination test were performed to investigate the interaction between TGFBI and OTUB1. Extracellular acidification rate assays were employed to estimate the glycolysis level in IH. Results: The expression of OTUB1 was obviously increased in proliferating IH as compared to the involuting and involuted IH tissues. Through in vitro experiments, the knockdown of OTUB1 inhibited the proliferation, migration and tube formation of human hemangioma endothelial cells, while the overexpression of OTUB1 promoted the proliferation, migration and angiogenic abilities of human hemangioma endothelial cells. The knockdown of OTUB1 significantly suppressed IH progression in vivo. Furthermore, TGFBI was predicted as a functional downstream target of OTUB1 in IH by mass spectrometry. Mechanistically, OTUB1 interacted with and deubiquitylated TGFBI on the K22 and K25 residues, which was demonstrated to be independent of the catalytic activity of OTUB1. The inhibitory effects of OTUB1 knockdown on cell proliferation, migration and tube formation ability of human hemangioma endothelial cells were reversed by TGFBI overexpression. Further, we found that OTUB1 mediated glycolysis by regulating TGFBI in infantile hemangioma. Conclusions: OTUB1 deubiquitinates TGFBI in a catalytic-independent manner and promotes angiogenesis in infantile hemangioma by regulating glycolysis. Targeting OTUB1 might be an effective therapeutic strategy for inhibiting IH progression and tumor angiogenesis.