Classical human leukocyte antigen(HLA)molecules of the major histocompatibility classⅡ(MHCⅡ)complex present peptides for the development,surveillance and activation of CD4^(+) T cells.The nonclassical MHCⅡ-like pro...Classical human leukocyte antigen(HLA)molecules of the major histocompatibility classⅡ(MHCⅡ)complex present peptides for the development,surveillance and activation of CD4^(+) T cells.The nonclassical MHCⅡ-like protein HLA-DM(DM)catalyzes the exchange and loading of peptides onto MHCⅡmolecules,thereby shaping MHCⅡimmunopeptidomes.Natural variations of DM in both chains of the protein(DMA and DMB)have been hypothesized to impact peptide presentation,but no evidence for altered function has been reported.Here we define the presence of DM allotypes in human populations covered by the 1000 Genomes Project and probe their activity.The functional properties of several allotypes are investigated and show strong enhancement of peptide-induced T cell activation for a particular combination of DMA and DMB.Biochemical evidence suggests a broader pH activity profile for the new variant relative to that of the most commonly expressed DM allotype.Immunopeptidome analysis indicates that the compartmental activity of the new DM heterodimer extends beyond the late endosome and suggests that the natural variation of DM has profound effects on adaptive immunity when antigens bypass the canonical processing pathway.展开更多
Scaffolding proteins play pivotal roles in the assembly of macromolecular machines such as the spliceosome.The adaptor protein CD2BP2,originally identified as a binding partner of the adhesion molecule CD2,is a pre-sp...Scaffolding proteins play pivotal roles in the assembly of macromolecular machines such as the spliceosome.The adaptor protein CD2BP2,originally identified as a binding partner of the adhesion molecule CD2,is a pre-spliceosomal assembly factor that utilizes its glycine-tyrosine-phenylalanine(GYF)domain to co-localize with spliceosomal proteins.So far,its function in vertebrates is unknown.Using conditional gene targeting in mice,we show that CD2BP2 is crucial for embryogenesis,leading to growth retardation,defects in vascularization,and premature death at embryonic day 10.5 when absent.Ablation of the protein in bone marrow-derived macrophages indicates that CD2BP2 is involved in the alternative splicing of mRNA transcripts from diverse origins.At the molecular level,we identified the phosphatase PP1 to be recruited to the spliceosome via the N-terminus of CD2BP2.Given the strong expression of CD2BP2 in podocytes of the kidney,we use selective depletion of CD2BP2,in combination with next-generation sequencing,to monitor changes in exon usage of genes critical for podocyte functions,including VEGF and actin regulators.CD2BP2-depleted podocytes display foot process effacement,and cause proteinuria and ultimately lethal kidney failure in mice.Collectively,our study defines CD2BP2 as a non-redundant splicing factor essential for embryonic development and podocyte integrity.展开更多
基金supported by the Deutsche Forschungsgemeinschaft(DFG)C.F.is thankful for funding by the DFG(FR-1325/17–1,SFB958(project Z03)+1 种基金TRR186(projects A05,A11))M.A.-B.is thankful for funding from the Freie Universität Berlin Forschungskommision.
文摘Classical human leukocyte antigen(HLA)molecules of the major histocompatibility classⅡ(MHCⅡ)complex present peptides for the development,surveillance and activation of CD4^(+) T cells.The nonclassical MHCⅡ-like protein HLA-DM(DM)catalyzes the exchange and loading of peptides onto MHCⅡmolecules,thereby shaping MHCⅡimmunopeptidomes.Natural variations of DM in both chains of the protein(DMA and DMB)have been hypothesized to impact peptide presentation,but no evidence for altered function has been reported.Here we define the presence of DM allotypes in human populations covered by the 1000 Genomes Project and probe their activity.The functional properties of several allotypes are investigated and show strong enhancement of peptide-induced T cell activation for a particular combination of DMA and DMB.Biochemical evidence suggests a broader pH activity profile for the new variant relative to that of the most commonly expressed DM allotype.Immunopeptidome analysis indicates that the compartmental activity of the new DM heterodimer extends beyond the late endosome and suggests that the natural variation of DM has profound effects on adaptive immunity when antigens bypass the canonical processing pathway.
基金This work was supported by grants from the Deutsche Forschungsgemeinschaft(FG806,SFB854)to C.F.and from the Focus Area DynAge to H.S.and C.F.
文摘Scaffolding proteins play pivotal roles in the assembly of macromolecular machines such as the spliceosome.The adaptor protein CD2BP2,originally identified as a binding partner of the adhesion molecule CD2,is a pre-spliceosomal assembly factor that utilizes its glycine-tyrosine-phenylalanine(GYF)domain to co-localize with spliceosomal proteins.So far,its function in vertebrates is unknown.Using conditional gene targeting in mice,we show that CD2BP2 is crucial for embryogenesis,leading to growth retardation,defects in vascularization,and premature death at embryonic day 10.5 when absent.Ablation of the protein in bone marrow-derived macrophages indicates that CD2BP2 is involved in the alternative splicing of mRNA transcripts from diverse origins.At the molecular level,we identified the phosphatase PP1 to be recruited to the spliceosome via the N-terminus of CD2BP2.Given the strong expression of CD2BP2 in podocytes of the kidney,we use selective depletion of CD2BP2,in combination with next-generation sequencing,to monitor changes in exon usage of genes critical for podocyte functions,including VEGF and actin regulators.CD2BP2-depleted podocytes display foot process effacement,and cause proteinuria and ultimately lethal kidney failure in mice.Collectively,our study defines CD2BP2 as a non-redundant splicing factor essential for embryonic development and podocyte integrity.
