Genomic alterations in patients with somatic loss of the Y chromosome as the sole cytogenetic finding in bone marrow cells

Loss of the Y chromosome (LOY) is one of the most common somatic genomic alterations in hematopoietic cells in men. However, due to the high prevalence of LOY as the sole cytogenetic finding in the healthy older population, differentiating isolated LOY associated with clonal hematologic processes from aging-associated mosaicism can be difficult in the absence of definitive morphological features of disease. In the past, various investigators have proposed that a high percentage of metaphases with LOY is more likely to represent expansion of a clonal myeloid disease-associated population. It is unknown whether the proportion of metaphases with LOY is associated with the incidence of myeloid neoplasia-associated genomic alterations. To address this question, we identified marrow samples with LOY as isolated cytogenetic finding and used targeted next generation sequencing-based molecular analysis to identify common myeloid neoplasia-associated somatic mutations. Among 73 patients with median age of 75 years (range 29-90), the percentage of metaphases with LOY was <25% in 23 patients, 25-49% in 10, 50-74% in 8 and ≥75% in 32. A threshold of ≥75% LOY was significantly associated with morphologic diagnosis of myeloid neoplasm (p = 0.004). Further, ≥75% LOY was associated with a higher lifetime incidence of diagnosis of myelodysplastic syndromes (MDS; p < 0.0001), and in multivariate analysis ≥75% LOY was a statistically significant independent predictor of myeloid neoplasia [OR 6.17; 95% CI = 2.15-17.68; p = 0.0007]. Higher LOY percentage (≥75%) was associated with greater likelihood of having somatic mutations (p = 0.0009) and a higher number of these mutations (p = 0.0002). Our findings indicate that ≥75% LOY in marrow is associated with increased likelihood of molecular alterations in genes commonly seen in myeloid neoplasia and with morphologic features of MDS. These observations suggest that ≥75% LOY in bone marrow should be considered an MDS-associated cytogenetic aberration

Autophagy Is Induced Upon Platelet Activation and Is Essential for Hemostasis and Thrombosis

Autophagy is important for maintaining cellular homeostasis, and thus its deficiency is implicated in a broad spectrum of human diseases. Its role in platelet function has only recently been examined. Our biochemical and imaging studies demonstrate that the core autophagy machinery exists in platelets, and that autophagy is constitutively active in resting platelets. Moreover, autophagy is induced upon platelet activation, as indicated by agonist-induced loss of the autophagy marker LC3II. Additional experiments, using inhibitors of platelet activation, proteases, and lysosomal acidification, as well as platelets from knockout mouse strains, show that agonist-induced LC3II loss is a consequence of platelet signaling cascades and requires proteases, acidic compartments, and membrane fusion. To assess the physiological role of platelet autophagy, we generated a mouse strain with a megakaryocyte- and platelet-specific deletion of Atg7, an enzyme required for LC3II production. Ex vivo analysis of platelets from these mice shows modest defects in aggregation and granule cargo packaging. Although these mice have normal platelet numbers and size distributions, they exhibit a robust bleeding diathesis in the tail-bleeding assay and a prolonged occlusion time in the FeCl3-induced carotid injury model. Our results demonstrate that autophagy occurs in platelets and is important for hemostasis and thrombosis

Canonical and Atypical E2Fs Regulate the Mammalian Endocycle

SUMMARY The endocycle is a variant cell cycle consisting of successive DNA synthesis and Gap phases that yield highly polyploid cells. Although essential for metazoan development, relatively little is known about its control or physiologic role in mammals. Using novel lineage-specific cre mice we identified two opposing arms of the E2F program, one driven by canonical transcription activation (E2F1, E2F2 and E2F3) and the other by atypical repression (E2F7 and E2F8), that converge on the regulation of endocycles in vivo. Ablation of canonical activators in the two endocycling tissues of mammals, trophoblast giant cells in the placenta and hepatocytes in the liver, augmented genome ploidy, whereas ablation of atypical repressors diminished ploidy. These two antagonistic arms coordinate the expression of a unique G2/M transcriptional program that is critical for mitosis, karyokinesis and cytokinesis. These results provide in vivo evidence for a direct role of E2F family members in regulating non-traditional cell cycles in mammals

EGCG, a Green Tea Catechin, as a Potential Therapeutic Agent for Symptomatic and Asymptomatic SARS-CoV-2 Infection

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has emerged to be the greatest threat to humanity in the modern world and has claimed nearly 2.2 million lives worldwide. The United States alone accounts for more than one fourth of 100 million COVID-19 cases across the globe. Although vaccination against SARS-CoV-2 has begun, its efficacy in preventing a new or repeat COVID-19 infection in immunized individuals is yet to be determined. Calls for repurposing of existing, approved, drugs that target the inflammatory condition in COVID-19 are growing. Our initial gene ontology analysis predicts a similarity between SARS-CoV-2 induced inflammatory and immune dysregulation and the pathophysiology of rheumatoid arthritis. Interestingly, many of the drugs related to rheumatoid arthritis have been found to be lifesaving and contribute to lower COVID-19 morbidity. We also performed in silico investigation of binding of epigallocatechin gallate (EGCG), a well-known catechin, and other catechins on viral proteins and identified papain-like protease protein (PLPro) as a binding partner. Catechins bind to the S1 ubiquitin-binding site of PLPro, which might inhibit its protease function and abrogate SARS-CoV-2 inhibitory function on ubiquitin proteasome system and interferon stimulated gene system. In the realms of addressing inflammation and how to effectively target SARS-CoV-2 mediated respiratory distress syndrome, we review in this article the available knowledge on the strategic placement of EGCG in curbing inflammatory signals and how it may serve as a broad spectrum therapeutic in asymptomatic and symptomatic COVID-19 patients

Autoimmune Disease in Patients With Advanced Thymic Epithelial Tumors.

INTRODUCTION: Paraneoplastic autoimmune diseases (ADs)&nbsp;are a hallmark of thymic epithelial tumors (TETs) and affect treatment management in patients with advanced-stage tumors, yet the risk factors for development of AD in advanced TET remain poorly understood. METHODS: All patients with advanced TET treated at Stanford University between 2006 and 2020 were included. Charts were retrospectively reviewed for the presence of AD, demographic information, and treatment history. Next-generation sequencing was performed on available TET tissue. Multivariate regression was used to evaluate variables associated with AD. RESULTS: A total of 48 patients were included in the analysis with a median follow-up of 5.4 years. One-third (n&nbsp;= 16, 33%) were diagnosed with having ADs, with 28 distinct ADs identified. The only significant difference observed in the AD cohort compared with the non-AD cohort was a higher proportion of thymoma histotype (81% versus 47%, p&nbsp;= 0.013). The most common AD events were myasthenia gravis (n&nbsp;= 7, 44%) followed by pure red cell aplasia (n&nbsp;= 5, 31%). In the multivariate models, there were no independent factors associated with AD, either at TET diagnosis or subsequent to TET diagnosis. Genomic data were available on 18 patients, and there were no overlapping mutations identified in the nine patients with AD. CONCLUSIONS: ADs are common in patients with advanced TETs. Prior total thymectomy does not affect the development of subsequent AD. Patients who developed AD other than myasthenia gravis were more likely to do so several years after TET diagnosis. Additional work, including multiomic analyses, is needed to develop predictive markers for AD in advanced TET

E2f1–3 switch from activators in progenitor cells to repressors in differentiating cells

In the established model of mammalian cell cycle control, the retinoblastoma protein (Rb) functions to restrict cells from entering S phase by binding and sequestering E2f activators (E2f1, E2f2 and E2f3), which are invariably portrayed as the ultimate effectors of a transcriptional program that commit cells to enter and progress through S phase(1,2). Using a panel of tissue-specific cre-transgenic mice and conditional E2f alleles we examined the effects of E2f1, E2f2 and E2f3 triple deficiency in murine embryonic stem cells, embryos and small intestines. We show that in normal dividing progenitor cells E2f1-3 function as transcriptional activators, but contrary to the current view, are dispensable for cell division and instead are necessary for cell survival. In differentiating cells E2f1-3 function in a complex with Rb as repressors to silence E2f targets and facilitate exit from the cell cycle. The inactivation of Rb in differentiating cells resulted in a switch of E2f1-3 from repressors to activators, leading to the superactivation of E2f responsive targets and ectopic cell divisions. Loss of E2f1-3 completely suppressed these phenotypes caused by Rb deficiency. This work contextualizes the activator versus repressor functions of E2f1-3 in vivo, revealing distinct roles in dividing versus differentiating cells and in normal versus cancer-like cell cycles