UBR5 Forms Ligand-Dependent Complexes on Chromatin to Regulate Nuclear Hormone Receptor Stability

ABSTRACT: Nuclear hormone receptors (NRs) are ligand-binding transcription factors that are widely targeted therapeutically. Hormone binding triggers NR activation and their subsequent proteasomal degradation through unknown ligand-dependent ubiquitin ligase machinery. NR degradation is therapeutically relevant. Efficacy of all-trans-retinoic acid (ATRA) for the treatment of acute promyelocytic leukemia requires degradation of the oncogenic fusion between the Promyelocytic Leukemia Protein (PML) with the Retinoic Acid Receptor Alpha (RARA). Here we use CRISPR-based screens to identify the HECT E3 ubiquitin ligase UBR5 as a ligase for PML-RARA and RARA and observe an agonist-dependent association between RARA and UBR5, which occurs directly on chromatin to regulate transcription. We present the cryo-EM structure of full-length human UBR5 and identify a Leu-X-X-Leu-Leu (LxxLL) binding motif that associates with a conserved degron in RARA. A high-resolution crystal structure of the RARA ligand binding domain in complex with this LxxLL motif shows how UBR5 binding is mutually exclusive with nuclear co-activator engagement. We demonstrate that UBR5 utilizes this conserved degron to additionally regulate hormone dependent protein stability for the glucocorticoid, progesterone, and vitamin D receptors. Our work establishes UBR5-driven NR degradation as an integral regulator of transcriptional signaling by nuclear hormones.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Eric Fischer  

LAB HEAD: Eric Fischer

PROVIDER: PXD041749 | Pride | 2023-07-20

REPOSITORIES: Pride