Altered monocytic phenotypes are linked with systemic inflammation and may be linked to mortality in dialysis patients

The functions and mechanisms of post-translational modification in protein regulators of RNA methylation: Current status and future perspectives

RNA methylation, an epigenetic modification that does not alter gene sequence, may be important to diverse biological processes. Protein regulators of RNA methylation include "writers," "erasers," and "readers," which respectively deposit, remove, and recognize methylated RNA. RNA methylation, particularly N6-methyladenosine (m6A), 5-methylcytosine (m5C), N3-methylcytosine (m3C), N1-methyladenosine (m1A) and N7-methylguanosine (m7G), has been suggested as disease therapeutic targets. Despite advances in the structure and pharmacology of RNA methylation regulators that have improved drug discovery, regulating these proteins by various post-translational modifications (PTMs) has received little attention. PTM modifies protein structure and function, affecting all aspects of normal biology and pathogenesis, including immunology, cell differentiation, DNA damage repair, and tumors. It is becoming evident that RNA methylation regulators are also regulated by diverse PTMs. PTM of RNA methylation regulators induces their covalent linkage to new functional groups, hence modifying their activity and function. Mass spectrometry has identified many PTMs on protein regulators of RNA methylation. In this review, we describe the functions and PTM of protein regulators of RNA methylation and summarize the recent advances in the regulatory mode of human disease and its underlying mechanisms.

Hemodialysis-Associated Immune Dysregulation in SARS-CoV-2-Infected End-Stage Renal Disease Patients

Patients on hemodialysis show dysregulated immunity, basal hyperinflammation and a marked vulnerability to COVID-19. We evaluated the immune profile in COVID-19 hemodialysis patients and the changes associated with clinical deterioration after the hemodialysis session. Recruited patients included eight hemodialysis subjects with active, PCR-confirmed SARS-CoV-2 infection, five uninfected hemodialysis patients and five healthy controls. In SARS-CoV-2-infected hemodialysis patients TNF-α, IL-6 and IL-8 were particularly increased. Lymphopenia was mostly due to reduction in CD4+ T, B and central memory CD8+ T cells. There was a predominance of classical and intermediate monocytes with reduced HLA-DR expression and enhanced production of pro-inflammatory molecules. Immune parameters were analysed pre- and post-hemodialysis in three patients with COVID-19 symptoms worsening after the hemodialysis session. There was a higher than 2.5-fold increase in GM-CSF, IFN-γ, IL-1β, IL-2, IL-6, IL-17A and IL-21 in serum, and augmentation of monocytes-derived TNF-α, IL-1β and IL-8 and CXCL10 (p < 0.05). In conclusion, COVID-19 in hemodialysis patients associates with alteration of lymphocyte subsets, increasing of pro-inflammatory cytokines and monocyte activation. The observed worsening during the hemodialysis session in some patients was accompanied by augmentation of particular inflammatory cytokines, which might suggest biomarkers and therapeutic targets to prevent or mitigate the hemodialysis-related deterioration during SARS-CoV-2 infection.

Old known and possible new biomarkers of ANCA-associated vasculitis

Antineutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) comprises a group of multisystem disorders involving severe, systemic, small-vessel vasculitis with short- and long term serious and life-threating complications. Despite the simplification of treatment, fundamental aspects concerning assessment of its efficacy and its adaptation to encountered complications or to the relapsing/remitting/subclinical disease course remain still unknown. The pathogenesis of AAV is complex and unique, and despite the progress achieved in the last years, much has not to be learnt. Foremost, there is still no accurate marker enabling us to monitoring disease and guide therapy. Therefore, the disease management relays often on clinical judgment and follows a" trial and error approach". In the recent years, an increasing number of new molecules s have been explored and used for this purpose including genomics, B- and T-cell subpopulations, complement system factors, cytokines, metabolomics, biospectroscopy and components of our microbiome. The aim of this review is to discuss both the role of known historical and clinically established biomarkers of AAV, as well as to highlight potential new ones, which could be used for timely diagnosis and monitoring of this devastating disease, with the goal to improve the effectiveness and ameliorate the complications of its demanding therapy.

YB1 dephosphorylation attenuates atherosclerosis by promoting CCL2 mRNA decay

Chronic inflammation is a key pathological process in atherosclerosis. RNA binding proteins (RBPs) have been reported to play an important role in atherosclerotic plaque formation, and they could regulate the expression of inflammatory factors by phosphorylation modification. Y-box binding protein 1 (YB1) is an RBP that has participated in many inflammatory diseases. Here, we found an increased expression of phosphorylated YB1 (pYB1) in atherosclerotic plaques and demonstrated that YB1 dephosphorylation reduced lipid accumulation and lesion area in the aorta in vivo. Additionally, we found that inflammatory cytokines were downregulated in the presence of YB1 dephosphorylation, particularly CCL2, which participates in the pathogenesis of atherosclerosis. Furthermore, we demonstrated that CCL2 mRNA rapid degradation was mediated by the glucocorticoid receptor-mediated mRNA decay (GMD) process during YB1 dephosphorylation, which resulted in the downregulation of CCL2 expression. In conclusion, YB1 phosphorylation affects the development of atherosclerosis through modulating inflammation, and targeting YB1 phosphorylation could be a potential strategy for the treatment of atherosclerosis by anti-inflammation.

RNA-binding proteins and their role in kidney disease

RNA-binding proteins (RBPs) are of fundamental importance for post-transcriptional gene regulation and protein synthesis. They are required for pre-mRNA processing and for RNA transport, degradation and translation into protein, and can regulate every step in the life cycle of their RNA targets. In addition, RBP function can be modulated by RNA binding. RBPs also participate in the formation of ribonucleoprotein complexes that build up macromolecular machineries such as the ribosome and spliceosome. Although most research has focused on mRNA-binding proteins, non-coding RNAs are also regulated and sequestered by RBPs. Functional defects and changes in the expression levels of RBPs have been implicated in numerous diseases, including neurological disorders, muscular atrophy and cancers. RBPs also contribute to a wide spectrum of kidney disorders. For example, human antigen R has been reported to have a renoprotective function in acute kidney injury (AKI) but might also contribute to the development of glomerulosclerosis, tubulointerstitial fibrosis and diabetic kidney disease (DKD), loss of bicaudal C is associated with cystic kidney diseases and Y-box binding protein 1 has been implicated in the pathogenesis of AKI, DKD and glomerular disorders. Increasing data suggest that the modulation of RBPs and their interactions with RNA targets could be promising therapeutic strategies for kidney diseases.

YB-1 Interferes with TNFα-TNFR Binding and Modulates Progranulin-Mediated Inhibition of TNFα Signaling

Inflammation and an influx of macrophages are common elements in many diseases. Among pro-inflammatory cytokines, tumor necrosis factor α (TNFα) plays a central role by amplifying the cytokine network. Progranulin (PGRN) is a growth factor that binds to TNF receptors and interferes with TNFα-mediated signaling. Extracellular PGRN is processed into granulins by proteases released from immune cells. PGRN exerts anti-inflammatory effects, whereas granulins are pro-inflammatory. The factors coordinating these ambivalent functions remain unclear. In our study, we identify Y-box binding protein-1 (YB-1) as a candidate for this immune-modulating activity. Using a yeast-2-hybrid assay with YB-1 protein as bait, clones encoding for progranulin were selected using stringent criteria for strong interaction. We demonstrate that at physiological concentrations, YB-1 interferes with the binding of TNFα to its receptors in a dose-dependent manner using a flow cytometry-based binding assay. We show that YB-1 in combination with progranulin interferes with TNFα-mediated signaling, supporting the functionality with an NF-κB luciferase reporter assay. Together, we show that YB-1 displays immunomodulating functions by affecting the binding of TNFα to its receptors and influencing TNFα-mediated signaling via its interaction with progranulin.

Y-Box Binding Proteins in mRNP Assembly, Translation, and Stability Control

Y-box binding proteins (YB proteins) are DNA/RNA-binding proteins belonging to a large family of proteins with the cold shock domain. Functionally, these proteins are known to be the most diverse, although the literature hardly offers any molecular mechanisms governing their activities in the cell, tissue, or the whole organism. This review describes the involvement of YB proteins in RNA-dependent processes, such as mRNA packaging into mRNPs, mRNA translation, and mRNA stabilization. In addition, recent data on the structural peculiarities of YB proteins underlying their interactions with nucleic acids are discussed.