U12-type or minor introns are found in most multicellular eukaryotes and constitute ∼0.5% of all introns in species with a minor spliceosome. Although the biological significance for evolutionary conservation of U12-type introns is debated, mutations disrupting U12 splicing cause developmental defects in both plants and animals. In human hematopoietic stem cells, U12 splicing defects disrupt proper differentiation of myeloid lineages and are associated with myelodysplastic syndrome (MDS), predisposing individuals to acute myeloid leukemia. Mutants in the maize ortholog of RNA Binding Motif Protein 48 (RBM48) have aberrant U12-type intron splicing. Human RBM48 was recently purified biochemically as part of the minor spliceosome and shown to recognize the 5’ end of the U6atac snRNA. In this report, we use CRISPR/Cas9-mediated ablation of RBM48 in human K-562 cells to show the genetic function of RBM48. RNA-seq analysis comparing wild-type and mutant K-562 genotypes found that 48% of minor intron containing genes (MIGs) have significant U12-type intron retention in RBM48 mutants. Comparing these results to maize rbm48 mutants defined a subset of MIGs disrupted in both species. Mutations in the majority of these orthologous MIGs have been reported to cause developmental defects in both plants and animals. Our results provide genetic evidence that the primary defect of human RBM48 mutants is aberrant U12-type intron splicing, while a comparison of human and maize RNA-seq data identifies candidate genes likely to mediate mutant phenotypes of U12-type splicing defects.
U12-type (minor) introns are found in most multicellular eukaryotes, and constitute ~0.5% of all introns in species with a minor spliceosome required for their splicing. However, the biological relevance of U12-type introns is not well understood. It is known that mutations resulting in aberrant U12-type intron splicing cause developmental defects in both plants and animals. We recently reported that maize RNA Binding Motif Protein 48 (RBM48) is an essential splicing factor for U12-type introns. Maize rbm48 mutants display aberrant genome-wide U12-type intron splicing. This leads to severe defects in endosperm development, resulting in non-viable seeds. In this report, we use CRISPR/Cas9-mediated ablation of RBM48 in human K-562 cells to establish the evolutionary conservation of RBM48 dependent U12-type intron splicing between maize and humans. Comparative RNA-seq analysis performed on RBM48 deficient human cell lines and maize endosperm defined a subset of orthologous minor U12-type containing genes (MIGs) displaying aberrant splicing of U12-type introns in both species. Mutations in the majority of these MIGs have been reported to cause developmental defects in both plants and animals. Thus, a comparison of RNA-seq data between distantly related species containing mutations in RBM48 identifies candidate genes likely to mediate mutant phenotypes of U12-type splicing defects. Our results elucidate deeply conserved post-transcriptional processing mechanisms that are required for normal growth and development of eukaryotes with a minor spliceosome.
Suppressor/Enhancer of Lin-12-like (Sel1L) is a critical adaptor for endoplasmic reticulum-associated degradation (ERAD), a process that maintains cellular protein quality control through degradation of misfolded proteins. Here we investigate the role of Sel1L in T cell homeostasis and function. T cell-specific deletion of Sel1L profoundly impairs peripheral T cell survival and promotes apoptotic cell death. Furthermore, Sel1L is required to maintain naive CD8+ T cell homeostasis in a cell-intrinsic manner with loss of quiescence as evidenced by increased proliferation. Sel1L-deficient T cells exhibit enhanced activation of the mammalian target of rapamycin (mTOR) pathway and altered cellular metabolism, including increased cellular reactive oxygen species, mitochondrial mass and mitochondrial membrane potential in the naive CD8+ T cell compartment. Furthermore, loss of Sel1L impaired CD8+ T cell immune responses following bacterial infection. These results demonstrate a novel role for Sel1L/ERAD in T cell homeostasis and function.
Neutrophil Extracellular Traps (NETs) are formed from dying neutrophils expelling their contents to capture pathogens and limit the spread of infection. While they are beneficial during infection, overproduction of NETs or the inability to degrade them can be pathogenic. Different inflammatory disorders and autoimmune diseases have been shown to be associated with an increase in NET production. Therefore, it is important to understand the method in which NETs are removed or broken down. Cayman Chemical has developed an imaging-based assay to sensitively assay NET uptake by phagocytic cells. Imaging was found to be an ideal method to monitor NET clearance in vitro, in part due to the ability to monitor the uptake of NETs kinetically. Both primary monocyte-derived macrophages and differentiated THP-1 cells, which are frequently used as phagocytic cell models, were shown to take up NETs. Putative modulators of NET uptake were tested in the assay. We aimed to develop a method in which the process of NET uptake can be monitored and quantified. Modulators of NET uptake can be tested in this assay, allowing for further studies toward treating autoimmune disorders that are driven by aberrant NETs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.