Structural model of the hUbA1-UbcH10 quaternary complex: in silico and experimental analysis of the protein-protein interactions between E1, E2 and ubiquitin

Case report of a patient with VEXAS syndrome

RATIONALE

Hematological malignancies have always been a challenge for scientists because there is a constant need to better define these entities. Myelodysplastic syndromes (MDS) are clonal hematopoietic disorders characterized by ineffective hematopoiesis. Cytogenetics and molecular findings are a prerequisite for these syndromes as they confirm the clonal nature of the disease. However, MDS is often linked to autoimmunity and inflammation as part of its pathogenesis. Recently, VEXAS syndrome (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) linked these two in a single mutation, suggesting that the heterogeneity among hematological malignancies often demands a more personalized medicine by tailoring medical treatment to the individual characteristics of each patient.

PATIENT CONCERNS

We present a case of VEXAS syndrome regarding a 63-year-old male patient who initially presented with episodes of low fever, polyarthritis of the knees and ankles, polymyalgia, and fatigue. His laboratory examinations revealed increased levels of serum inflammatory markers.

DIAGNOSES

Diagnosis was based on high clinical suspicion, laboratory findings, and vacuolization of the erythroid and myeloid precursors in the bone marrow evaluation. Mutational status of ubiquitin-like modifier activating enzyme 1 gene was positive with a 68.8% allelomorph frequency (rs782416867).

INTERVENTIONS

Therapy was based on controlling inflammation with the use of glucocorticoids and treating MDS-related anemia with the use of erythropoietin.

OUTCOMES

Currently, the patient visits our department regularly. He is still receiving the aforementioned treatment. He did not mention any new incidents for the time being.

LESSONS

VEXAS syndrome as a newly identified entity might be often underestimated since its clinical presentation is notably diverse.

Adverse Reaction to COVID-19 mRNA Vaccination in a Patient With VEXAS Syndrome

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a rare genetic disorder originating from a somatic mutation in the hematopoietic stem cells. This syndrome was first described in 2020 and carries many clinical features that other conditions cannot explain. Widespread autoinflammation is the primary process the disease presents, with high morbidity and mortality in those who show signs of bone marrow failure. Treatment is complex, and response to current therapies is poor. Long-term prognosis carries a mortality of 50%. In addition, the advancement of new-generation messenger ribonucleic acid (mRNA) vaccines raises concerns about their safety in this population since it could trigger a vaccine-related autoimmune response. This case describes the hospital course of a male in his 50s exhibiting an unexplained cutaneous reaction to an mRNA COVID-19 vaccine. He was later diagnosed with VEXAS syndrome based on symptoms presentation and diagnostic workup.

DNA Homeostasis and Senescence: Lessons from the Naked Mole Rat

As we age, our bodies accrue damage in the form of DNA mutations. These mutations lead to the generation of sub-optimal proteins, resulting in inadequate cellular homeostasis and senescence. The build-up of senescent cells negatively affects the local cellular micro-environment and drives ageing associated disease, including neurodegeneration. Therefore, limiting the accumulation of DNA damage is essential for healthy neuronal populations. The naked mole rats (NMR) are from eastern Africa and can live for over three decades in chronically hypoxic environments. Despite their long lifespan, NMRs show little to no biological decline, neurodegeneration, or senescence. Here, we discuss molecular pathways and adaptations that NMRs employ to maintain genome integrity and combat the physiological and pathological decline in organismal function.

Dissecting the Specificity of Adenosyl Sulfamate Inhibitors Targeting the Ubiquitin-Activating Enzyme

Targeting the activating enzymes (E1) of ubiquitin (Ub) and ubiquitin-like modifiers (Ubls) has emerged as a promising anti-cancer strategy, possibly overcoming the ineffectiveness of proteasome inhibitors against solid tumors. Here, we report crystal structures of the yeast ubiquitin E1 (Uba1) with three adenosyl sulfamate inhibitors exhibiting different E1 specificities, which are all covalently linked to ubiquitin. The structures illustrate how the chemically diverse inhibitors are accommodated within the adenylation active site. When compared with the previously reported structures of various E1 enzymes, our structures provide the basis of the preferences of these inhibitors for different Ub/Ubl-activating enzymes. In vitro inhibition assays and molecular dynamics simulations validated the specificities of the inhibitors as deduced from the structures. Taken together, the structures establish a framework for the development of additional compounds targeting E1 enzymes, which will display higher potency and selectivity.

Ubiquitin-like Protein Conjugation: Structures, Chemistry, and Mechanism

Ubiquitin-like proteins (Ubl's) are conjugated to target proteins or lipids to regulate their activity, stability, subcellular localization, or macromolecular interactions. Similar to ubiquitin, conjugation is achieved through a cascade of activities that are catalyzed by E1 activating enzymes, E2 conjugating enzymes, and E3 ligases. In this review, we will summarize structural and mechanistic details of enzymes and protein cofactors that participate in Ubl conjugation cascades. Precisely, we will focus on conjugation machinery in the SUMO, NEDD8, ATG8, ATG12, URM1, UFM1, FAT10, and ISG15 pathways while referring to the ubiquitin pathway to highlight common or contrasting themes. We will also review various strategies used to trap intermediates during Ubl activation and conjugation.