Polypyrimidine tract binding protein 1 regulates the activation of mouse CD8 T cells.

The RNA-binding protein polypyrimidine tract binding protein 1 (PTBP1) has been found to have roles in CD4 T-cell activation, but its function in CD8 T cells remains untested. We show it is dispensable for the development of naïve mouse CD8 T cells, but is necessary for the optimal expansion and production of effector molecules by antigen-specific CD8 T cells in vivo. PTBP1 has an essential role in regulating the early events following activation of the naïve CD8 T cell leading to IL-2 and TNF production.

Essential requirement for polypyrimidine tract binding proteins 1 and 3 in the maturation and maintenance of mature B cells in mice.

The maturation of immature B cells and the survival of mature B cells is stringently controlled to maintain a diverse repertoire of antibody specificities while avoiding self-reactivity. At the molecular level this is regulated by signaling from membrane Ig and the BAFF-receptor that sustain a pro-survival program of gene expression. Whether and how posttranscriptional mechanisms contribute to B cell maturation and survival remains poorly understood.

Transcriptome Analysis of Infected and Bystander Type 2 Alveolar Epithelial Cells during Influenza A Virus Infection Reveals Wnt Pathway Downregulation.

Influenza virus outbreaks remain a serious threat to public health. A greater understanding of how cells targeted by the virus respond to the infection can provide insight into the pathogenesis of disease. Here we examined the transcriptional profile of -infected and uninfected type 2 alveolar epithelial cells (AEC) in the lungs of influenza virus-infected mice.

The RNA-binding protein PTBP1 is necessary for B cell selection in germinal centers.

Antibody affinity maturation occurs in germinal centers (GCs), where B cells cycle between the light zone (LZ) and the dark zone. In the LZ, GC B cells bearing immunoglobulins with the highest affinity for antigen receive positive selection signals from helper T cells, which promotes their rapid proliferation. Here we found that the RNA-binding protein PTBP1 was needed for the progression of GC B cells through late S phase of the cell cycle and for affinity maturation.

Characterization of the B Cell Transcriptome Bound by RNA-Binding Proteins with iCLIP.

Posttranscriptional regulation of gene expression shapes the B cell transcriptome and controls messenger RNA (mRNA) translation into protein. Recent reports have highlighted the importance of RNA binding proteins (RBPs) for mRNA splicing, subcellular location, stability, and translation during B lymphocyte development, activation, and differentiation. Here we describe individual-nucleotide resolution UV cross-linking and immunoprecipitation (iCLIP) in primary lymphocytes, a method that maps RNA-protein interactions in a genome-wide scale allowing mechanistic analysis of RBP function.

RNA-binding proteins ZFP36L1 and ZFP36L2 promote cell quiescence.

Progression through the stages of lymphocyte development requires coordination of the cell cycle. Such coordination ensures genomic integrity while cells somatically rearrange their antigen receptor genes [in a process called variable-diversity-joining (VDJ) recombination] and, upon successful rearrangement, expands the pools of progenitor lymphocytes. Here we show that in developing B lymphocytes, the RNA-binding proteins (RBPs) ZFP36L1 and ZFP36L2 are critical for maintaining quiescence before precursor B cell receptor (pre-BCR) expression and for reestablishing quiescence after pre-BCR-induced expansion.

The Forgotten: Identification and Functional Characterization of MHC Class II Molecules H2-Eb2 and RT1-Db2.

In this article, we report the complete coding sequence and to our knowledge, the first functional analysis of two homologous nonclassical MHC class II genes: RT1-Db2 of rat and H2-Eb2 of mouse. They differ in important aspects compared with the classical class II β1 molecules: their mRNA expression by APCs is much lower, they show minimal polymorphism in the Ag-binding domain, and they lack N-glycosylation and the highly conserved histidine 81. Also, their cytoplasmic region is completely different and longer.

Generation of functionally distinct isoforms of PTBP3 by alternative splicing and translation initiation.

Polypyrimidine tract binding protein (PTBP1) is a widely expressed RNA binding protein that acts as a regulator of alternative splicing and of cytoplasmic mRNA functions. Vertebrates contain two closely-related paralogs with >75% amino acid sequence identity. Early replacement of PTBP1 by PTBP2 during neuronal differentiation causes a concerted set of splicing changes.

The hypervariable region 4 (HV4) and position 93 of the α chain modulate CD1d-glycolipid binding of iNKT TCRs.

TCRs of invariant NKT (iNKT) cells bind α-galactosylceramide (αGC) loaded CD1d in a highly conserved fashion and show a characteristic TCR gene usage: An "invariant" α chain with a canonical AV14/AJ18 rearrangement in mice (AV24/AJ18 in humans) is paired with β chains containing characteristic Vβ segments. In the rat, a multimember AV14 gene family increases the variability within this system. This study characterizes CD1d binding of rat AV14 gene segments in TCR transductants as well as CD1d binding and iNKT TCR expression of expanded polyclonal F344 rat iNKT populations.

The RNA-binding protein HuR is essential for the B cell antibody response.

Post-transcriptional regulation of mRNA by the RNA-binding protein HuR (encoded by Elavl1) is required in B cells for the germinal center reaction and for the production of class-switched antibodies in response to thymus-independent antigens. Transcriptome-wide examination of RNA isoforms and their abundance and translation in HuR-deficient B cells, together with direct measurements of HuR-RNA interactions, revealed that HuR-dependent splicing of mRNA affected hundreds of transcripts, including that encoding dihydrolipoamide S-succinyltransferase (Dlst), a subunit of the 2-oxoglutarate dehydrogenase (α-KGDH) complex. In the absence of HuR, defective mitochondrial metabolism resulted in large amounts of reactive oxygen species and B cell death.

Direct identification of rat iNKT cells reveals remarkable similarities to human iNKT cells and a profound deficiency in LEW rats.

iNKT cells are a particular lymphocyte population with potent immunomodulatory capa-city; by promoting or suppressing immune responses against infections, tumors, and autoimmunity, iNKT cells are a promising target for immunotherapy. The hallmark of iNKT cells is the expression of a semiinvariant TCR (with an invariant α-chain comprising AV14 and AJ18 gene segments), which recognizes glycolipids presented by CD1d. Here, we identified iNKT cells for the first time in the rat using rat CD1d-dimers and PLZF staining.

CD1d expression in paneth cells and rat exocrine pancreas revealed by novel monoclonal antibodies which differentially affect NKT cell activation.

Background: CD1d is a nonpolymorphic MHC class I-like molecule which presents nonpeptide ligands, e.g. glycolipids, to NKT cells.

Superantigen-presentation by rat major histocompatibility complex class II molecules RT1.Bl and RT1.Dl.

Rat major histocompatibility complex (MHC) class II molecules RT1.B(l) (DQ-like) and RT1.D(l) (DR-like) were cloned from the LEW strain using reverse transcription-polymerase chain reaction and expressed in mouse L929 cells.