Explore the vast range of titles available.

Introduction: The multifaceted impact of COVID-19 extends beyond the respiratory system, encompassing intricate interactions with various physiological systems. This study elucidates the potential association between SARS-CoV-2 infection and anemia, with a particular emphasis on the deformability of red blood cells (RBCs), stability of hemoglobin, enzymatic activities, and proteomic profiles. Methods: The study encompasses a cohort of 74 individuals, including individuals positive for COVID-19, a control group, and patients with other viral infections to discern the specific effects attributable to COVID-19. The analysis of red blood cells was focused on deformability measured by osmotic gradient ektacytometry, hemoglobin stability, and glycolytic enzyme activity. Furthermore, membrane proteins were examined using advanced proteomics techniques to capture molecular-level changes. Results: Findings from the study suggest a correlation between anemia and exacerbated outcomes in COVID-19 patients, marked by significant elevations in d-dimer, serum procalcitonin, creatinine, and blood urea nitrogen (BUN) levels. These observations suggest that chronic kidney disease (CKD) may play a role in the development of anemia in COVID-19 patients, particularly those of advanced age with comorbidities. Furthermore, the proteomic analyses have highlighted a complex relationship between omics data and RBC parameters, enriching our understanding of the mechanisms underlying the disease. Conclusions: This research substantiates the complex interrelationship between COVID-19 and anemia, with a specific emphasis on the potential repercussions of SARS-CoV-2 infection on RBCs. The findings contribute to the growing body of evidence supporting the extensive impact of COVID-19 on RBCs.

The overactivation of the HERs, a family of tyrosine kinase receptors, leads to the development of cancer. Although the canonical view contemplates HER receptors restricted to the secretory and endocytic pathways, full‐length HER1, HER2 and HER3 have been detected in the nucleoplasm. Furthermore, limited proteolysis of HER4 generates nuclear C‐terminal fragments (CTFs). Using cells expressing a panel of deletion and point mutants, here we show that HER2 CTFs are generated by alternative initiation of translation from methionines located near the transmembrane domain of the full‐length molecule. In vitro and in vivo , HER2 CTFs are found in the cytoplasm and nucleus. Expression of HER2 CTFs to levels similar to those found in human tumors induces the growth of breast cancer xenografts in nude mice. Tumors dependent on CTFs are sensitive to inhibitors of the kinase activity but do not respond to therapeutic antibodies against HER2. Thus, the kinase domain seems necessary for the activity of HER2 CTFs and the presence of these HER2 fragments could account for the resistance to treatment with antibodies.

Exposure to ultraviolet (UV) radiation from sunlight accounts for 90% of the symptoms of premature skin aging and skin cancer. The tumor suppressor serine-threonine kinase LKB1 is mutated in Peutz-Jeghers syndrome and in a spectrum of epithelial cancers whose etiology suggests a cooperation with environmental insults. Here we analyzed the role of LKB1 in a UV-dependent mouse skin cancer model and show that LKB1 haploinsufficiency is enough to impede UVB-induced DNA damage repair, contributing to tumor development driven by aberrant growth factor signaling. We demonstrate that LKB1 and its downstream kinase NUAK1 bind to CDKN1A. In response to UVB irradiation, LKB1 together with NUAK1 phosphorylates CDKN1A regulating the DNA damage response. Upon UVB treatment, LKB1 or NUAK1 deficiency results in CDKN1A accumulation, impaired DNA repair and resistance to apoptosis. Importantly, analysis of human tumor samples suggests that LKB1 mutational status could be a prognostic risk factor for UV-induced skin cancer. Altogether, our results identify LKB1 as a DNA damage sensor protein regulating skin UV-induced DNA damage response.

Background The lack of dystrophin expression in Duchenne muscular dystrophy (DMD) induces muscle fibre and replacement by fibro‐adipose tissue. Although the role of some growth factors in the process of fibrogenesis has been studied, pathways activated by PDGF‐AA have not been described so far. Our aim was to study the molecular role of PDGF‐AA in the fibrotic process of DMD. Methods Skeletal muscle fibro‐adipogenic progenitor cells (FAPs) from three DMD treated with PDGF‐AA at 50 ng/mL were analysed by quantitative mass spectrometry‐based proteomics. Western‐blot, immunofluorescence, and G‐LISA were used to confirm the mass spectrometry results. We evaluated the effects of PDGF‐AA on the activation of RhoA pathway using two inhibitors, C3‐exoenzyme and fasudil. Cell proliferation and migration were determined by BrdU and migration assay. Actin reorganization and collagen synthesis were measured by phalloidin staining and Sircol assay, respectively. In an in vivo proof of concept study, we treated dba/2J‐mdx mice with fasudil for 6 weeks. Muscle strength was assessed with the grip strength. Immunofluorescence and flow cytometry analyses were used to study fibrotic and inflammatory markers in muscle tissue. Results Mass spectrometry revealed that RhoA pathway proteins were up‐regulated in treated compared with non‐treated DMD FAPs (n = 3, mean age = 8 ± 1.15 years old). Validation of proteomic data showed that Arhgef2 expression was significantly increased in DMD muscles compared with healthy controls by a 7.7‐fold increase (n = 2, mean age = 8 ± 1.14 years old). In vitro studies showed that RhoA/ROCK2 pathway was significantly activated by PDGF‐AA (n = 3, 1.88‐fold increase, P < 0.01) and both C3‐exoenzyme and fasudil blocked that activation (n = 3, P < 0.05 and P < 0.001, respectively). The activation of RhoA pathway by PDGF‐AA promoted a significant increase in proliferation and migration of FAPs (n = 3, P < 0.001), while C3‐exoenzyme and fasudil inhibited FAPs proliferation at 72 h and migration at 48 and 72 h (n = 3, P < 0.001). In vivo studies showed that fasudil improved muscle function (n = 5 non‐treated dba/2J‐mdx and n = 6 treated dba/2J‐mdx, 1.76‐fold increase, P < 0.013), and histological studies demonstrated a 23% reduction of collagen‐I expression area (n = 5 non‐treated dba/2J‐mdx and n = 6 treated dba/2J‐mdx, P < 0.01). Conclusions Our results suggest that PDGF‐AA promotes the activation of RhoA pathway in FAPs from DMD patients. This pathway could be involved in FAPs activation promoting its proliferation, migration, and actin reorganization, which represents the beginning of the fibrotic process. The inhibition of RhoA pathway could be considered as a potential therapeutic target for muscle fibrosis in patients with muscular dystrophies.

Conditionally disordered proteins are either ordered or disordered depending on the environmental context. The substrates of the mitochondrial intermembrane space (IMS) oxidoreductase Mia40 are synthesized on cytosolic ribosomes and diffuse as intrinsically disordered proteins to the IMS, where they fold into their functional conformations; behaving thus as conditionally disordered proteins. It is not clear how the sequences of these polypeptides encode at the same time for their ability to adopt a folded structure and to remain unfolded. Here we characterize the disorder-to-order transition of a Mia40 substrate, the human small copper chaperone Cox17. Using an integrated real-time approach, including chromatography, fluorescence, CD, FTIR, SAXS, NMR, and MS analysis, we demonstrate that in this mitochondrial protein, the conformational switch between disordered and folded states is controlled by the formation of a single disulfide bond, both in the presence and in the absence of Mia40. We provide molecular details on how the folding of a conditionally disordered protein is tightly regulated in time and space, in such a way that the same sequence is competent for protein translocation and activity.

B lymphopoiesis is orchestrated by lineage-specific transcription factors. In B cell progenitors, lineage commitment is mediated by Pax5, which is commonly mutated in B cell acute lymphoblastic leukemia. Despite its essential role in immunity, the mechanisms regulating Pax5 function remain largely unknown. Here, we found that the NAD + -dependent enzyme SIRT7 coordinates B cell development through deacetylation of Pax5 at K198, which promotes Pax5 protein stability and transcriptional activity. Neither Pax5 K198 deacetylated nor acetylated mimics rescued B cell differentiation in Pax5 −/− pro-B cells, suggesting that B cell development requires Pax5 dynamic deacetylation. The Pax5 K198 deacetylation mimic restored lineage commitment in Pax5 −/− pro-B cells and B cell differentiation in Sirt7 −/− pro-B cells, suggesting the uncoupling of differentiation from lineage commitment. The SIRT7–Pax5 interplay was conserved in B cell acute lymphoblastic leukemia, where SIRT7 expression correlated with good prognosis. Our findings reveal a crucial mechanism for B lymphopoiesis and highlight the relevance of sirtuins in immune function. Gámez-García et al. show that the deacetylase SIRT7 modulates the acetylation of Pax5 and its ability to repress alternate lineage programs and promote B cell differentiation and commitment in B cell progenitor cells.

UM is an aggressive intraocular tumor characterized by high plasticity and a propensity to metastasize in the liver. However, the underlying mechanisms governing liver tropism remain poorly understood. Given the emerging significance of exosomes, we sought to investigate the contribution of UM-derived exosomes to specific steps of the metastatic process. Firstly, we isolated exosomes from UM cells sharing a common genetic background and different metastatic properties. A comparison of protein cargo reveals an overrepresentation of proteins related to cytoskeleton remodeling and actin filament-based movement in exosomes derived from the parental cells that may favor the detachment of cells from the primary site. Secondly, we assessed the role of macrophages in reprogramming the HHSCs by exosomes. The activation of HHSCs triggered a pro-inflammatory and pro-fibrotic environment through cytokine production, upregulation of extracellular matrix molecules, and the activation of signaling pathways. Finally, we found that activated HHSCs promote increased adhesion and migration of UM cells. Our findings shed light on the pivotal role of exosomes in pre-metastatic niche construction in the liver.

Porcine intestinal mucosa hydrolysates (PIMHs) are by-products of heparin production obtained through a specific enzymatic hydrolysis process, which can theoretically generate bioactive peptides (BAPs). This study aimed to identify, characterize, and quantify BAPs in two Palbio products manufactured by Bioiberica S.A.U. (Palafolls, Spain), which are PIMH protein sources used for animal feed: Palbio® HP (PHP) and Palbio® 62 SP® (P62). Using mass spectrometry (MS)-based peptidomics, we analyzed three samples from each product, fractionated based on molecular weight (<3 kDa, 3 to 10 kDa, and >10 kDa). The <3 kDa fraction was analyzed directly, while the other two fractions were enzymatically digested before MS analysis. The workflow identified 961 peptides in PHP and 1134 in P62. Subsequent bioinformatic analysis using public databases (APD2, StraPep, AHTPDB, and BIOPEP-UWM) led to the identification of six significant BAPs in both PHP and P62, with respective quantified amounts (pg peptide/μg sample): DAVEDLESVGK (0.1626, 0.1939), EGIPPDQQRLIFAGK (0.2637, 0.1852), TITLEVEPSDTIENVK (0.3594, 0.4327), TNVPRASVPDGFLS (1.4596, 0.1898), TNVPRASVPDGFLSEL (8.0500, 0.9224), and VHVVPDQLMAF (0.0310, 0.0054). The first three BAPs are related to antimicrobial activity, while the latter three are associated with cytokine/growth factor-like, antioxidant, and immunomodulatory activities. These bioactivities align with previously reported in vivo benefits observed in animal nutrition using Palbio products. Our findings demonstrate that PHP and P62 are valuable sources of BAPs, supporting their potential role in improving animal health and performance.

Plitidepsin is an antitumoral compound safe for treating COVID-19 that targets the translation elongation factor eEF1A. Here we detect that plitidepsin decreases de novo cap-dependent translation of SARS-CoV-2 and non-viral RNAs but affects less than 13% of the host proteome, thus preserving cellular viability. In response to plitidepsin, cells upregulate EIF2AK3 and proteins that reduce translation, but also proteins that support proteostasis via ribosome synthesis and cap-independent translation by eIF4G2 and IGF2BP2. While plitidepsin inhibits cap- or internal ribosome entry sites (IRES)-mediated translation, its impact on N6-methyladenosine (m 6 A) translation is limited. In agreement, plitidepsin blocks members of Coronaviridae , Flaviviridae , Pneumoviridae and Herpesviridae families. Yet, it fails to inhibit retroviruses that exploit m 6 A synthesis routes and are blocked by drugs targeting IGF2BP2 m 6 A reader. By deciphering the molecular fingerprint of cells treated with therapies targeting translation we identify a rational approach to select broad-spectrum antivirals with potential to counteract future pandemic viruses. By deciphering the molecular fingerprint of cells treated with host-directed therapies targeting protein translation, the authors identified a rational approach to select for broad-spectrum antivirals with potential to counteract future pandemic viruses.

Extracellular vesicles (EVs) released by virus-infected cells have the potential to encapsulate viral peptides, a characteristic that could facilitate vaccine development. Furthermore, plasma-derived EVs may elucidate pathological changes occurring in distal tissues during viral infections. We hypothesized that molecular characterization of EVs isolated from COVID-19 patients would reveal peptides suitable for vaccine development. Blood samples were collected from three cohorts: severe COVID-19 patients (G1), mild/asymptomatic cases (G2), and SARS-CoV-2-negative healthcare workers (G3). Samples were obtained at two time points: during the initial phase of the pandemic in early 2020 (m0) and eight months later (m8). Clinical data analysis revealed elevated inflammatory markers in G1. Notably, non-vaccinated individuals in G1 exhibited increased levels of neutralizing antibodies at m8, suggesting prolonged exposure to viral antigens. Proteomic profiling of EVs was performed using three distinct methods: immunocapture (targeting CD9), ganglioside-capture (utilizing Siglec-1) and size-exclusion chromatography (SEC). Contrary to our hypothesis, this analysis failed to identify viral peptides. These findings were subsequently validated through Western blot analysis targeting the RBD of the SARS-CoV-2 Spike protein’s and comparative studies using samples from experimentally infected Syrian hamsters. Furthermore, analysis of the EV cargo revealed a diverse molecular profile, including components involved in the regulation of viral replication, systemic inflammation, antigen presentation, and stress responses. These findings underscore the potential significance of EVs in the pathogenesis and progression of COVID-19.