RESUMO
pre-mRNA splicing is a critical feature of eukaryotic gene expression. Both cis- and trans-splicing rely on accurately recognising splice site sequences by spliceosomal U snRNAs and associated proteins. Spliceosomal snRNAs carry multiple RNA modifications with the potential to affect different stages of pre-mRNA splicing. Here, we show that the conserved U6 snRNA m6A methyltransferase METT-10 is required for accurate and efficient cis- and trans-splicing of C. elegans pre-mRNAs. The absence of METT-10 in C. elegans and METTL16 in humans primarily leads to alternative splicing at 5' splice sites with an adenosine at +4 position. In addition, METT-10 is required for splicing of weak 3' cis- and trans-splice sites. We identified a significant overlap between METT-10 and the conserved splicing factor SNRNP27K in regulating 5' splice sites with +4A. Finally, we show that editing endogenous 5' splice site +4A positions to +4U restores splicing to wild-type positions in a mett-10 mutant background, supporting a direct role for U6 snRNA m6A modification in 5' splice site recognition. We conclude that the U6 snRNA m6A modification is important for accurate and efficient pre-mRNA splicing.
Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Metiltransferases , Precursores de RNA , Sítios de Splice de RNA , Splicing de RNA , RNA Nuclear Pequeno , RNA Nuclear Pequeno/genética , RNA Nuclear Pequeno/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Animais , Precursores de RNA/metabolismo , Precursores de RNA/genética , Humanos , Metiltransferases/metabolismo , Metiltransferases/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Adenosina/análogos & derivados , Adenosina/metabolismo , Adenosina/genética , Processamento Alternativo , Spliceossomos/metabolismo , Spliceossomos/genéticaRESUMO
Research has shown that during the COVID-19 pandemic, approximately 20% of children and adolescents in the United States experienced mental health issues that became a significant social concern. However, recent studies have demonstrated that the majority of adolescents maintain positive emotions despite the crisis. This cross-sectional and descriptive study delves into the emotional states of adolescents during the pandemic, considering the viewpoints of both adolescents and their parents, with a specific focus on Hispanic adolescents. Survey results revealed that most adolescents reported positive and happy moods. However, a percentage of adolescents experienced worry, significant changes in feelings, and loneliness as a result of the physical and social isolation associated with virtual learning. Unfortunately, most surveyed Hispanic parents did not adequately recognize their adolescents' mood changes well. This lack of awareness, caused by factors such as an insufficient understanding about the importance of adolescent mental health, cultural reasons, language barriers, low education, unstable jobs, and more, could lead to missed opportunities for timely mental health interventions. This study seeks to provide a comprehensive discussion on the mental health of adolescents, while also advocating for the emotional wellbeing of Hispanic adolescents.
RESUMO
pre-mRNA splicing is a critical feature of eukaryotic gene expression. Many eukaryotes use cis-splicing to remove intronic sequences from pre-mRNAs. In addition to cis-splicing, many organisms use trans-splicing to replace the 5' ends of mRNAs with a non-coding spliced-leader RNA. Both cis- and trans-splicing rely on accurately recognising splice site sequences by spliceosomal U snRNAs and associated proteins. Spliceosomal snRNAs carry multiple RNA modifications with the potential to affect different stages of pre-mRNA splicing. Here, we show that m6A modification of U6 snRNA A43 by the RNA methyltransferase METT-10 is required for accurate and efficient cis- and trans-splicing of C. elegans pre-mRNAs. The absence of U6 snRNA m6A modification primarily leads to alternative splicing at 5' splice sites. Furthermore, weaker 5' splice site recognition by the unmodified U6 snRNA A43 affects splicing at 3' splice sites. U6 snRNA m6A43 and the splicing factor SNRNP27K function to recognise an overlapping set of 5' splice sites with an adenosine at +4 position. Finally, we show that U6 snRNA m6A43 is required for efficient SL trans-splicing at weak 3' trans-splice sites. We conclude that the U6 snRNA m6A modification is important for accurate and efficient cis- and trans-splicing in C. elegans.
RESUMO
Transporters belonging to the Resistance-Nodulation-cell Division (RND) superfamily of proteins such as Mycobacterium tuberculosis MmpL3 and its analogs are the focus of intense investigations due to their importance in the physiology of Corynebacterium-Mycobacterium-Nocardia species and antimycobacterial drug discovery. These transporters deliver trehalose monomycolates, the precursors of major lipids of the outer membrane, to the periplasm by a proton motive force-dependent mechanism. In this study, we successfully purified, from native membranes, the full-length and the C-terminal truncated M. tuberculosis MmpL3 and Corynebacterium glutamicum CmpL1 proteins and reconstituted them into proteoliposomes. We also generated a series of substrate mimics and inhibitors specific to these transporters, analyzed their activities in the reconstituted proteoliposomes, and carried out molecular dynamics simulations of the model MmpL3 transporter at different pH. We found that all reconstituted proteins facilitate proton translocation across a phospholipid bilayer, but MmpL3 and CmpL1 differ dramatically in their responses to pH and interactions with substrate mimics and indole-2-carboxamide inhibitors. Our results further suggest that some inhibitors abolish the transport activity of MmpL3 and CmpL1 by inhibition of proton translocation.
Assuntos
Proteínas de Bactérias , Proteínas de Membrana Transportadoras , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/química , Corynebacterium , Transporte de Íons , Bicamadas Lipídicas/química , Proteínas de Membrana Transportadoras/química , Ácidos Micólicos/metabolismo , Prótons , Especificidade por SubstratoRESUMO
IL10 plays a dual role in supporting humoral immunity and inhibiting inflammatory conditions. B cells producing IL10 are thought to play a key regulatory role in maintaining self-tolerance and suppressing excessive inflammation during autoimmune and infectious diseases, primarily by inhibiting associated T cell responses. The extent to which B cells, through the provision of IL10, might function to sustain or inhibit autoantibody production is less clear. We previously described transgenic mice expressing catalytically inactive RAG1 (dnRAG1 mice), which show expansion of an IL10-compentent CD5+ B cell subset that phenotypically resembles B10 B cells, hypogammaglobulinemia, and a restricted B cell receptor repertoire with features indicative of impaired B cell receptor editing. We show here that B10-like B cells in dnRAG1 mice bind the membrane-associated autoantigen phosphatidylcholine (PtC), and that in vitro lipopolysaccharide (LPS) stimulation of dnRAG1 splenocytes induces a robust IgM response enriched in reactivity toward lupus-associated autoantigens. This outcome was correlated with detection of sIgMhi B cell populations that were distinct from, but in addition to, sIgMint populations observed after similar treatment of wild-type splenocytes. Loss of IL10 expression in dnRAG1 mice had no significant effect on B10-like B cell expansion or the frequency of PtC+ B cells. Compared to IL10+/+ dnRAG1 mice, levels of serum IgM, but not serum IgG, were highly elevated in some naïve IL10-/- dnRAG1 mice, and was correlated with a significant increase in serum BAFF levels. Differentiation of sIgMint B cells from LPS-stimulated dnRAG1 splenocytes was enhanced by loss of IL10 expression and IL10 blockade, but was suppressed by treatment with recombinant IL10. In vitro LPS-induced differentiation and antibody production was inhibited by treatment with JAK/STAT inhibitors or a synthetic corticosteroid, independent of IL10 expression and genotype. Taken together, these data suggest that IL10 expression in dnRAG1 mice maintains suppression of IgM levels in part by inhibiting BAFF production, and that regulatory B10-like B cells, through the provision of IL10, constrains B cell differentiation in response to mitogenic stimuli. Furthermore, autoantibody profiling raises a possible link between CD5+ B cell expansion, mitogenic stimulation, and autoantibodies associated with autoimmune complications observed in lupus and lupus-related disorders.
Assuntos
Autoantígenos/imunologia , Linfócitos B/imunologia , Proteínas de Homeodomínio/imunologia , Interleucina-10/imunologia , Animais , Fator Ativador de Células B/imunologia , Fator Ativador de Células B/metabolismo , Subpopulações de Linfócitos B/citologia , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Linfócitos B/citologia , Linfócitos B/metabolismo , Antígenos CD5/imunologia , Antígenos CD5/metabolismo , Diferenciação Celular/imunologia , Proliferação de Células , Células Cultivadas , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Interleucina-10/genética , Interleucina-10/metabolismo , Camundongos Knockout , Camundongos Transgênicos , Tolerância a Antígenos Próprios/imunologia , Baço/citologia , Baço/imunologia , Baço/metabolismoRESUMO
Adhesion in cephalopods is either mechanical, involving a reduced-pressure system of the arm and tentacle suckers, or is chemically mediated by special adhesive gland structures (as proposed for Euprymna, Idiosepius, and Nautilus). Four species of Sepia (S. typica, S. papillata, S. pulchra, and S. tuberculata) possess grooved structures on the ventral mantle surface and on the fourth arm pair, which are used to attach mechanically to the substratum. Because these areas are often partly covered with sand or debris, it has been hypothesized that chemical substances were involved in this attachment process. This study provides a histochemical and ultrastructural description of the glandular epithelium in the adhesive area of Sepia tuberculata. Two specific glandular cells (Type 1 and Type 2) are present in the epithelium, which differ clearly in their granule size and cellular structure. The aggregation of both cell types and their simultaneous secretion suggest that the secretions of both cell types work synergistically providing a two-component adhesive system which supports the primarily mechanical sucker adhesion by making the arm surface sticky.