K63-polyubiquitinated HAUSP deubiquitinates HIF-1α and dictates H3K56 acetylation promoting hypoxia-induced tumour progression.

Han-Tsang Wu,Jung-Jyh Hung,Shu-Chun Teng,Chi-Hung Huang,Yi-Ju Chen,Wei-Chung Cheng,Yi-Chih Kuo,Yeh Chen,Teh-Ying Chou,Yu-Ju Chen,Wei-Yi Chen,Kou-Juey Wu

doi:10.1038/ncomms13644

Abstract

Intratumoural hypoxia induces HIF-1α and promotes tumour progression, metastasis and treatment resistance. HIF-1α stability is regulated by VHL-E3 ligase-mediated ubiquitin-dependent degradation; however, the hypoxia-regulated deubiquitinase that stabilizes HIF-1α has not been identified. Here we report that HAUSP (USP7) deubiquitinase deubiquitinates HIF-1α to increase its stability, induce epithelial-mesenchymal transition and promote metastasis. Hypoxia induces K63-linked polyubiquitinated HAUSP at lysine 443 to enhance its functions. Knockdown of HAUSP decreases acetylation of histone 3 lysine 56 (H3K56Ac). K63-polyubiquitinated HAUSP interacts with a ubiquitin receptor CBP to specifically mediate H3K56 acetylation. ChIP-seq analysis of HAUSP and HIF-1α binding reveals two motifs responsive to hypoxia. HectH9 is the E3 ligase for HAUSP and a prognostic marker together with HIF-1α. This report demonstrates that hypoxia-induced K63-polyubiquitinated HAUSP deubiquitinates HIF-1α and causes CBP-mediated H3K56 acetylation on HIF-1α target gene promoters to promote EMT/metastasis, further defining HAUSP as a therapeutic target in hypoxia-induced tumour progression.

Highlights

Intratumoural hypoxia induces hypoxia-inducible factor-1a (HIF-1a) and promotes tumour progression, metastasis and treatment resistance
HAUSP interacts with and deubiquitinates HIF-1a. Since both HAUSP and HIF-1a play a significant role in tumour progression and aggressiveness[3,15], we evaluated whether HAUSP could deubiquitinate HIF-1a through interacting with HIF-1a
A domain mapping experiment showed that the N-terminal (a.a. 1–400) domain of HIF-1a immunoprecipitated with HAUSP (Supplementary Fig. 1b)

Summary

Introduction

Intratumoural hypoxia induces HIF-1a and promotes tumour progression, metastasis and treatment resistance. We report that HAUSP (USP7) deubiquitinase deubiquitinates HIF-1a to increase its stability, induce epithelial-mesenchymal transition and promote metastasis. This report demonstrates that hypoxia-induced K63-polyubiquitinated HAUSP deubiquitinates HIF-1a and causes CBP-mediated H3K56 acetylation on HIF-1a target gene promoters to promote EMT/metastasis, further defining HAUSP as a therapeutic target in hypoxia-induced tumour progression. K63-linked polyubiquitinated signalling molecules that play a significant role in signal transduction occur in NF-kB, T-cell receptor, Toll-like receptor, RIG-1-like receptor, NOD-like receptor, DNA damage response pathways and Akt activation[24,25] Among these examples, K63-linked polyubiquitin chains serve as a scaffold to facilitate assembly of a protein complex[27]. Whether there is a master scaffold that can receive the inputs from HIF-1a, CBP (a co-activator of HIF-1a), the CDK8-Mediator complex, and the elongation complex under hypoxia and convert them into fully active HIF-1a-induced gene transcription remains to be demonstrated

Methods

Results

Conclusion