Structural basis for RING-Cys-Relay E3 ligase activity and its role in axon integrity.

MYCBP2 is a ubiquitin (Ub) E3 ligase (E3) that is essential for neurodevelopment and regulates axon maintenance. MYCBP2 transfers Ub to nonlysine substrates via a newly discovered RING-Cys-Relay (RCR) mechanism, where Ub is relayed from an upstream cysteine to a downstream substrate esterification site. The molecular bases for E2-E3 Ub transfer and Ub relay are unknown.

Tug of War in the Xenophagy World.

Xenophagy, the process of eliminating intracellular pathogens through the autophagy machinery, is an important defense mechanism against infectious disease, yet the underlying molecular mechanisms remain incompletely understood. Recent work (Xu et al., Cell, 2019) used the discovery of an inhibitor of xenophagy, SopF, to identify a SopF-sensitive mechanism that allows mammalian cells to detect invading bacteria.

Activity-based E3 ligase profiling uncovers an E3 ligase with esterification activity.

Ubiquitination is initiated by transfer of ubiquitin (Ub) from a ubiquitin-activating enzyme (E1) to a ubiquitin-conjugating enzyme (E2), producing a covalently linked intermediate (E2-Ub) . Ubiquitin ligases (E3s) of the 'really interesting new gene' (RING) class recruit E2-Ub via their RING domain and then mediate direct transfer of ubiquitin to substrates . By contrast, 'homologous to E6-AP carboxy terminus' (HECT) E3 ligases undergo a catalytic cysteine-dependent transthiolation reaction with E2-Ub, forming a covalent E3-Ub intermediate.

Probes of ubiquitin E3 ligases enable systematic dissection of parkin activation.

E3 ligases represent an important class of enzymes, yet there are currently no chemical probes for profiling their activity. We develop a new class of activity-based probe by re-engineering a ubiquitin-charged E2 conjugating enzyme and demonstrate the utility of these probes by profiling the transthiolation activity of the RING-in-between-RING (RBR) E3 ligase parkin in vitro and in cellular extracts. Our study provides valuable insight into the roles, and cellular hierarchy, of distinct phosphorylation events in parkin activation.

A Versatile Strategy for the Semisynthetic Production of Ser65 Phosphorylated Ubiquitin and Its Biochemical and Structural Characterisation.

Ubiquitin phosphorylation is emerging as an important regulatory layer in the ubiquitin system. This is exemplified by the phosphorylation of ubiquitin on Ser65 by the Parkinson's disease-associated kinase PINK1, which mediates the activation of the E3 ligase Parkin. Additional phosphorylation sites on ubiquitin might also have important cellular roles.

Di-(2-ethylhexyl) phthalate accelerates atherosclerosis in apolipoprotein E-deficient mice.

Di-(2-ethylhexyl) phthalate (DEHP) is associated with atherosclerosis-related cardiovascular disease complications, but we lack direct evidence of its unfavorable effect on atherogenesis. In this study, we aimed to clarify in vivo and in vitro the contribution of DEHP to the development of atherosclerosis and its underlying mechanisms. Apolipoprotein E-deficient (apoE(-/-)) mice chronically treated with DEHP for 4 weeks showed exacerbated hyperlipidemia, systemic inflammation, and atherosclerosis.

Hepatocellular carcinoma targeting agents: conjugates of nitroimidazoles with trimethyl nordihydroguaiaretic acid.

Cancer has been a primary global health issue for decades, with hepatocellular carcinoma (HCC) resulting in more than half a million new cases annually. With survival rates as low as <5% after five years, it remains a poorly treated cancer. Nordihydroguaiaretic acid (NDGA), an antioxidant, was previously proven effective against cancer cells.

Microwave assistance of labeling hippuric acid by I-131.

This work presents a novel approach for labeling hippuric acid with I-131 using microwaves. It utilizes copper(II) acetate as a catalyst of the labeling. The process involves the use of this catalytic copper(II) acetate at low dilutions that were nevertheless sufficient to produce labeled hippuric acid with high radiochemical purity in a short time.

Development of erlotinib derivatives as CIP2A-ablating agents independent of EGFR activity.

Cancerous inhibitor of PP2A (CIP2A) is a novel human oncoprotein that inhibits PP2A, contributing to tumor aggressiveness in various cancers. Several studies have shown that downregulation of CIP2A by small molecules reduces PP2A-dependent phosphorylation of Akt and induces cell death. Here, a series of mono- and di-substituted quinazoline and pyrimidine derivatives based on the skeleton of erlotinib (an EGFR inhibitor) were synthesized and their bioactivities against hepatocellular carcinoma were evaluated.