Reconstitution defines the roles of p62, NBR1 and TAX1BP1 in ubiquitin condensate formation and autophagy initiation.

The autophagic degradation of misfolded and ubiquitinated proteins is important for cellular homeostasis. In this process, which is governed by cargo receptors, ubiquitinated proteins are condensed into larger structures and subsequently become targets for the autophagy machinery. Here we employ in vitro reconstitution and cell biology to define the roles of the human cargo receptors p62/SQSTM1, NBR1 and TAX1BP1 in the selective autophagy of ubiquitinated substrates.

A cross-kingdom conserved ER-phagy receptor maintains endoplasmic reticulum homeostasis during stress.

Eukaryotes have evolved various quality control mechanisms to promote proteostasis in the endoplasmic reticulum (ER). Selective removal of certain ER domains via autophagy (termed as ER-phagy) has emerged as a major quality control mechanism. However, the degree to which ER-phagy is employed by other branches of ER-quality control remains largely elusive.

Recruitment and Activation of the ULK1/Atg1 Kinase Complex in Selective Autophagy.

Autophagy is a major cellular degradation pathway, which mediates the delivery of cytoplasmic cargo material into lysosomes. This is achieved by the specific sequestration of the cargo within double-membrane vesicles, the autophagosomes, which form de novo around this material. Autophagosome formation requires the action of a conserved set of factors, which act in hierarchical manner.

How RB1CC1/FIP200 claws its way to autophagic engulfment of SQSTM1/p62-ubiquitin condensates.

Macroautophagy/autophagy mediates the degradation of ubiquitinated aggregated proteins within lysosomes in a process known as aggrephagy. The cargo receptor SQSTM1/p62 condenses aggregated proteins into larger structures and links them to the nascent autophagosomal membrane (phagophore). How the condensation reaction and autophagosome formation are coupled is unclear.

FIP200 Claw Domain Binding to p62 Promotes Autophagosome Formation at Ubiquitin Condensates.

The autophagy cargo receptor p62 facilitates the condensation of misfolded, ubiquitin-positive proteins and their degradation by autophagy, but the molecular mechanism of p62 signaling to the core autophagy machinery is unclear. Here, we show that disordered residues 326-380 of p62 directly interact with the C-terminal region (CTR) of FIP200. Crystal structure determination shows that the FIP200 CTR contains a dimeric globular domain that we designated the "Claw" for its shape.

Insights into autophagosome biogenesis from in vitro reconstitutions.

Macro-autophagy (autophagy) is a conserved catabolic pathway for the degradation of cytoplasmic material in the lysosomal system. This is achieved by the sequestration of the cytoplasmic cargo material within double membrane-bound vesicles that fuse with lysosomes, wherein the vesicle's inner membrane and the cargo are degraded. Autophagosomes form in a de novo manner and their precursors are initially detected as small membrane structures that are referred to as isolation membranes.

Oligomerization of p62 allows for selection of ubiquitinated cargo and isolation membrane during selective autophagy.

Autophagy is a major pathway for the clearance of harmful material from the cytoplasm. During autophagy, cytoplasmic material is delivered into the lysosomal system by organelles called autophagosomes. Autophagosomes form in a de novo manner and, in the course of their formation, isolate cargo material from the rest of the cytoplasm.

Monoubiquitination of histone H2B is intrinsic to the Bre1 RING domain-Rad6 interaction and augmented by a second Rad6-binding site on Bre1.

Ubiquitin signaling on chromatin is linked to diverse aspects of genome regulation, including gene expression and DNA repair. The yeast RING E3 ligase Bre1 combines with the E2 Rad6 to monoubiquitinate histone H2B during transcription. Little is known about how Bre1 directs Rad6 toward transferring only a single ubiquitin to a specific lysine residue.

Understanding the role of the Q338H MUTYH variant in oxidative damage repair.

The MUTYH DNA-glycosylase is indirectly engaged in the repair of the miscoding 7,8-dihydro-8-oxo-2'-deoxyguanine (8-oxodG) lesion by removing adenine erroneously incorporated opposite the oxidized purine. Inherited biallelic mutations in the MUTYH gene are responsible for a recessive syndrome, the MUTYH-associated polyposis (MAP), which confers an increased risk of colorectal cancer. In this study, we functionally characterized the Q338H variant using recombinant proteins, as well as cell-based assays.