The promyelocytic leukemia (PML) protein is expressed in the diffuse nuclear fraction of the nucleoplasm and in matrix-associated structures, known as nuclear bodies (NBs). PML NB formation requires the covalent modification of PML to SUMO. The noncovalent interactions of SUMO with PML based on the identification of a SUMO-interacting motif within PML seem to be required for further recruitment within PML NBs of SUMOylated proteins. RNA viruses whose replication takes place in the cytoplasm and is inhibited by PML have developed various strategies to counteract the antiviral defense mediated by PML NBs. We show here that primary fibroblasts derived from PML knockout mice are more sensitive to infection with encephalomyocarditis virus (EMCV), suggesting that the absence of PML results in an increase in EMCV replication. Also, we found that EMCV induces a decrease in PML protein levels both in interferon-treated cells and in PMLIIIexpressing cells. Reduction of PML was carried out by the EMCV 3C protease. Indeed, at early times postinfection, EMCV induced PML transfer from the nucleoplasm to the nuclear matrix and PML conjugation to SUMO-1, SUMO-2, and SUMO-3, leading to an increase in PML body size where the viral protease 3C and the proteasome component were found colocalizing with PML within the NBs. This process was followed by PML degradation occurring in a proteasome-and SUMO-dependent manner and did not involve the SUMOinteracting motif of PML. Together, these findings reveal a new mechanism evolved by EMCV to antagonize the PML pathway in the interferon-induced antiviral defense.The PML (promyelocytic leukemia) gene was originally identified through its fusion with the RAR␣ gene in the t(15;17) translocation found in acute promyelocytic leukemia (APL) (14). PML, also known as TRIM19, is expressed in the diffuse nuclear fraction of the nucleoplasm and in matrixassociated structures, known as nuclear bodies (NBs) (17, 30). PML functions as the organizer of PML NBs, which are dynamic structures harboring numerous transiently and permanently localized proteins (35). The RBCC/TRIM motif, which contains a C 3 HC 4 (RING finger) zinc-binding domain, two cysteine/histidine-rich motifs (the B boxes B1 and B2), an a helical coiled-coil region (RBCC), is embedded within the PML protein and is required for PML NB formation (28). Due to alternative splicing, many PML isoforms are synthesized, and they are classified into seven groups, designated PML I to PML VII (reviewed in reference 28). They share the N-terminal region (exons 1 to 3), which encodes the RBCC motif, whereas they differ in their C-terminal regions. Posttranslational modification of PML by SUMO (small ubiquitin-like modifier), a ubiquitin-like protein of 11 kDa, is another requirement for PML NB formation. SUMO is covalently coupled to PML through its lysines 65, 160, and 490 via a process called SUMOylation (29). The noncovalent interaction of SUMO with PML through a SUMO-interacting motif (SIM; also named SBD for SUMO binding domain) (46) has been sug...

Heavy metals are important regulators of cell apoptosis. Manganese (Mn 2 þ ) is a potent inducer of apoptosis in different cell types, but the precise mechanisms that mediate such effects are not well defined. We previously reported that Mn 2 þ was a potent apoptotic agent in human B cells, including lymphoma B cell lines. We show here that Mn 2 þ -induced cell death in human B cells is associated with caspase-8-dependent mitochondrial activation leading to caspase-3 activity and apoptosis. We used specific caspase-8 interfering shRNAs to reduce caspase-8 expression, and this also reduced Mn 2 þ -induced caspase-3 activation and apoptosis. Mn 2 þ -triggered caspase-8 activation is associated with a specific pathway, which is independent of Fas-associated death domain protein, and dependent on the sequential activation of p38-mitogen-activated protein kinase (p38 MAPK) and mitogen-and stress-response kinase 1 (MSK1). Inhibition of p38 activity using either pharmacological inhibitors or dominant-negative mutant forms of p38 blocked Mn 2 þ -mediated phosphorylation of MSK1 and blocked subsequent caspase-8 activation. However, specific inhibitors and the expression of a dominant-interfering mutant of MSK1 only inhibited caspase-8 activation, but not p38 activity. These findings suggest a novel model for the regulation of caspase-8 during Mn 2 þ -induced apoptosis based on the sequential activation of p38 MAPK, MSK1, caspase-8 and mitochondria, respectively.

EBV infects a large proportion of the human population worldwide and is one of the major viruses with human B lymphocyte tropism. It can immortalize human B lymphocytes and controls their resistance to apoptosis. EBV infection is associated with several lymphomas, including Burkitt’s lymphoma. In this report we show that EBV infection leads to the post-transcriptional down-regulation of expression of the proapoptotic protein Bim. This process involves the phosphorylation of BimEL by the constitutive EBV-activated kinase ERK1/2, followed by its degradation through the proteasome pathway. We also show that ectopic expression of BimEL in EBV-positive Burkitt’s lymphoma cells can enhance the sensitivity of these cells to serum deprivation-dependent apoptosis. Thus, EBV-mediated resistance to growth factor deprivation in human B lymphocytes is dependent on BimEL expression. Our data suggest that this regulatory pathway is an important contributor to the oncogenic potential of EBV.

Posttransplant lymphoproliferative disorders (PTLD) represent a spectrum of lymphoid diseases complicating the clinical course of transplant recipients. Most PTLD are Epstein-Barr virus (EBV) associated with viral latency type III. Several in vitro studies have revealed an interaction between EBV latency proteins and molecules of the apoptosis pathway. Data on human PTLD regarding an association between Bcl-2 family proteins and EBV are scarce. We analyzed 60 primary PTLD for expression of 8 anti- (Bcl-2, Bcl-XL, and Mcl-1) and proapoptotic proteins (Bak and Bax), the so-called BH3-only proteins (Bad, Bid, Bim, and Puma), as well as the apoptosis effector cleaved PARP by immunohistochemistry. Bim and cleaved PARP were both significantly (p = 0.001 and p = 5.251e-6) downregulated in EBV-positive compared to EBV-negative PTLD [Bim: 6/40 (15%), cleaved PARP: 10/43 (23%), vs. Bim: 13/16 (81%), cleaved PARP: 12/17 (71%)]. Additionally, we observed a tendency toward increased Bcl-2 protein expression (p = 0.24) in EBV-positive PTLD. Hence, we provide evidence of a distinct regulation of Bcl-2 family proteins in EBV-positive versus negative PTLD. The low-expression pattern of the proapoptotic proteins Bim and cleaved PARP together with the high-expression pattern of the antiapoptotic protein Bcl-2 by trend in EBV-positive tumor cells suggests disruption of the apoptotic pathway by EBV in PTLD, promoting survival signals in the host cells.

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Here, we describe the coding-complete sequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain HM36, identified as a strain of concern of B.1.1.529+BA (Omicron).

Background: Mutations in RAS (KRAS, NRAS) and BRAF genes are the main biomarker predicting response to anti-EGFR monoclonal antibodies in targeted therapy in colorectal cancer (CRC). Objective: Our study aims to evaluate the frequencies of KRAS, NRAS and BRAF mutations and their possible associations with clinico-pathological features in CRC patients from Morocco. Methods: DNA was extracted from 80 FFPE samples using the QIAamp DNA FFPE-kit. RAS and BRAF mutations were assessed by pyrosequencing assays using Qiagen, KRAS Pyro®kit 24.V1, Ras-Extension Pyro®kit 24.V1 and BRAF Pyro®Kit 24.V1, respectively, and carried out in the PyroMark-Q24. Results: RAS mutations were identified in 57.5% (56.2% in KRAS, 8.8% in NRAS). In KRAS gene, exon 2 mutations accounted for 93.3% (68.9% in codon 12, 24.4% in codon 13). Within codon 12, G12D was the most prevalent mutation (37.7%), followed by G12C (13.4%), G12S (8.9%) and G12V (6.6%). Within codon 13, the most frequently observed mutation was G13D (22.3%). The mutation rates of exon 3 and 4 were 15.6% and 13.3%, respectively. In exon 3 codon 61, 2.3% patients were detected with two concurrent mutations (Q61R, Q61H), and 4.4% with three concurrent mutations (Q61R, Q61H, Q61L). In NRAS gene, the mutation rates of exon 2, 3 and 4 were 57.1%, 28.6%, and 14.3%, respectively. G13A and Q61H were the most common mutations, accounting for 42.9% and 28.5%, respectively. There were 13% patients with concurrent KRAS/NRAS mutation and 4.3% wt KRAS with NRAS mutations. No mutations were identified in BRAF gene. In both sexes, KRAS codon 12 mutations were associated with higher stage III/IV tumors. Moreover, Patients whose tumor is in the proximal colon (56.3%) are more likely to harbor KRAS mutations than those tumor located in rectum (25%). Conclusion: RAS mutations could be useful in future target anti-EGFR therapy and molecular CRC screening strategy in Morocco.

Objectives This study aims to analyze the prevalence and spectrum of epidermal growth factor receptor (EGFR) mutations within the Middle East and North Africa region, compare the findings to other parts of the world, and explore the geographic disparities of EGFR mutations across the region. Methods We conducted a literature search using the terms “[EGFR] AND [mutation] AND [Non-Small Cell Lung Cancer] AND [Middle East OR North Africa]”, using PubMed, Science Direct, Web of science, Embase, Scopus, and Google scholar. Results A total of 15 eligible studies were included and 6122 patients with non-small cell lung cancer (NSCLC) were analyzed. Male patients were predominant in all of the considered studies, accounting for 70.4%. Of the included patients, 65.6% were smokers and 88.3% had been diagnosed with adenocarcinoma. Overall, EGFR mutations prevalence was 17.2%. In the Middle East, the reported frequency was 16.5%, ranging from 11.3% in Lebanon to 29.7% in the Gulf region. In North Africa, the prevalence of EGFR mutations was 18%, ranging from 17.5% in Egypt to 21.5% in Morocco. The most prevalent mutations were the exon 19 deletions (46.7%) followed by exon 21 substitutions (31.1%). Exon 20 alterations were detected in 10.8% of the analyzed cases, whereas exon 18 mutations were reported in 3.4% of the EGFR-mutated patients. There was 1.1% of patients that had concurrent EGFR mutations. Overall, EGFR mutation prevalence was higher in females [females vs males: 29.7% vs 5.9%, P<.001], non-smokers [non-smokers vs smokers: 31.3% vs 9.6%, P<.001], and patients with adenocarcinoma [adenocarcinoma vs non-adenocarcinoma: 18.8% vs 6.5%, P<.001]. Conclusion EGFR mutation prevalence among the Middle East and North Africa populations is slightly higher than that seen in NSCLC patients of Caucasian ethnicity but is lower than that identified in Asian NSCLC patients. The distribution of these mutations varies considerably throughout the region.