The linear ubiquitin-specific deubiquitinase gumby regulates angiogenesis

Abstract

A complex interplay of signaling events, including the Wnt pathway, regulates sprouting of blood vessels from preexisting vasculature during angiogenesis. Here we show that two distinct mutations in the (uro)chordate-specific Gumby/Fam105b gene cause an embryonic angiogenic phenotype in gumby mice. Gumby interacts with Disheveled 2 (Dvl2), is expressed in canonical Wnt-responsive endothelial cells and encodes an Ovarian Tumor Domain (OTU) class of deubiquitinase (DUB) that specifically cleaves linear ubiquitin linkages. A crystal structure of Gumby in complex with linear di-ubiquitin reveals how the identified mutations adversely impact substrate binding and catalytic function in line with the severity of their angiogenic phenotypes. Gumby interacts with HOIP/Rnf31, a key component of the linear ubiquitin assembly complex (LUBAC), decreases linear ubiquitination and activation of NFκB dependent transcription. This work provides support for the biological importance of linear (de)ubiquitination in angiogenesis, craniofacial and neural development and in modulating Wnt signaling.

Biallelic hypomorphic mutations in a linear deubiquitinase define otulipenia, an early-onset autoinflammatory disease

“…Mice deficient in LUBAC subunits have variable degrees of inflammation, from a mild phenotype in HOIL-1-deficient mice (16) to more severe inflammation and dermatitis in SHARPIN KO (2,17) to defective vascularization and embryonic lethality in HOIP KO (18). Consistent with the essential function of OTULIN in regulation of multiple signaling pathways, OTULINdeficient mice (gumby/gumby) are embryonic lethal due to vascular and neuronal defects caused by dysregulation in canonical Wnt signaling (8).…”

“…Although OTULIN functions exclusively as a Met1 deubiquitinase (7,8), CYLD may also hydrolyze Lys63-linked ubiquitin (9). OTULIN is an evolutionarily highly conserved protein, and in mice complete deficiency is embryonically lethal (8). Recently, we reported patients with heterozygous germline mutations in TNFAIP3/ A20 (10), which has DUB activity for K63-linked polyubiquitin chains.…”

“…OTULIN and CYLD are deubiquitinases (DUBs) that cleave Met1-linked chains (6). Although OTULIN functions exclusively as a Met1 deubiquitinase (7,8), CYLD may also hydrolyze Lys63-linked ubiquitin (9). OTULIN is an evolutionarily highly conserved protein, and in mice complete deficiency is embryonically lethal (8).…”

OTULIN deficiency causes auto-inflammatory syndrome

“…Previous studies have revealed that OTULIN exclusively hydrolyzes Met1-Ub, prevents accumulation of Met1-Ub on LUBAC components under basal conditions, and restricts ubiquitination of LUBAC substrates after receptor stimulation [2][3][4]. However, the contribution of OTULIN to regulation of physiological immune responses had not been investigated.…”

“…Met1-Ub chains are assembled by the linear ubiquitin chain assembly complex (LU-BAC), composed of HOIP, HOIL-1, and SHARPIN [1]. LUBAC function is regulated by the deubiquitinases (DUBs) OTULIN [2-4] and CYLD [5][6][7], which both associate with the catalytic subunit HOIP [5][6][7][8].Previous studies have revealed that OTULIN exclusively hydrolyzes Met1-Ub, prevents accumulation of Met1-Ub on LUBAC components under basal conditions, and restricts ubiquitination of LUBAC substrates after receptor stimulation [2][3][4]. However, the contribution of OTULIN to regulation of physiological immune responses had not been investigated.…”