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Chicken T-cell receptor beta-chain diversity: an evolutionarily conserved D beta-encoded glycine turn within the hypervariable CDR3 domain.

ABSTRACT: Unlike mammals, chickens generate an immunoglobulin (Ig) repertoire by a developmentally regulated process of intrachromosomal gene conversion, which results in nucleotide substitutions throughout the variable regions of the Ig heavy- and light-chain genes. In contrast to chicken Ig genes, we show in this report that diversity of the rearranged chicken T-cell receptor (TCR) beta-chain gene is generated by junctional heterogeneity, as observed in rearranged mammalian TCR genes. This junctional diversity increases during chicken development as a result of an increasing base-pair addition at the V beta-D beta and D beta-J beta joints (where V, D, and J are the variable, diversity, and joining gene segments). Despite the junctional hypervariability, however, almost all functional V beta-D beta-J beta junctions appear to encode a glycine-containing beta-turn. Such a turn may serve to position the amino acid side chains of a hypervariable TCR beta-chain loop with respect to the antigen-binding groove of the major histocompatibility complex molecule. Consistent with this hypothesis, the germ-line D beta nucleotide sequences of chickens, mice, rabbits, and humans have been highly conserved and encode a glycine in all three reading frames.

SUBMITTER: McCormack WT

PROVIDER: S-EPMC52369 | biostudies-other | 1991 Sep

REPOSITORIES: biostudies-other

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Chicken T-cell receptor beta-chain diversity: an evolutionarily conserved D beta-encoded glycine turn within the hypervariable CDR3 domain.

McCormack W T WT Tjoelker L W LW Stella G G Postema C E CE Thompson C B CB

Proceedings of the National Academy of Sciences of the United States of America 19910901 17

Unlike mammals, chickens generate an immunoglobulin (Ig) repertoire by a developmentally regulated process of intrachromosomal gene conversion, which results in nucleotide substitutions throughout the variable regions of the Ig heavy- and light-chain genes. In contrast to chicken Ig genes, we show in this report that diversity of the rearranged chicken T-cell receptor (TCR) beta-chain gene is generated by junctional heterogeneity, as observed in rearranged mammalian TCR genes. This junctional di ...[more]

PMID: 1652759

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Project description:BackgroundshRNA lentiviral vectors are extensively used for gene knockdowns in mammalian cells, and non-target shRNAs typically are considered the proper experimental control for general changes caused by RNAi. However, the effects of non-target lentivirus controls on the modulation of cell signaling pathways remain largely unknown. In this study, we evaluated the effect of control lentiviral transduction on oxytocin receptor (OXTR) expression through the ERK/MAPK pathway in mouse and human skeletal muscle cells, on myogenic activity, and in vivo on mouse muscle regeneration. Furthermore, we mined published data for the influence of viral infections on OXTR levels in human populations and found that unrelated viral pathologies have a common consequence: diminished levels of OXTR.MethodsWe examined the change in OXTR mRNA expression upon transduction with control and Smad3-targeting viral vectors through real time RT-PCR and Western blotting, and confirmed with immunofluorescence. Changes in Smad3 and OXTR expression were examined both in vitro with mouse and human myoblasts and in vivo in mouse satellite cells. The general effects of viral infections on OXTR downregulation in humans were also examined by analyzing published Gene Expression Omnibus (GEO) datasets. The change in myoblast myogenic activity caused by the viral transduction (the percent of Pax7 + Ki67+ cells) was examined by immunofluorescence.ResultsResults shown in this work establish that lentiviral control vectors significantly downregulate OXTR expression at mRNA and protein levels and diminish key downstream effectors of OXTR, ERK signaling, reducing the myogenic proliferation of infected cells. This effect is evolutionarily conserved between mouse and human myogenic cells, and it manifests in satellite cells after control lentiviral transduction of mice in vivo. Furthermore, an examination of published datasets uncovered similar OXTR downregulation in humans that are afflicted with different viral infections. Additionally, cells transduced with Smad3-targeting shRNA downregulate OXTR even more than cells transduced with control viruses.ConclusionsOur work suggests that experimental cohorts transduced with control viruses may not behave the same as un-transduced cells and animals, specifically that control viral vectors significantly change the intensity of key cell-signaling pathways, such as OXTR/ERK. Our results further demonstrate that lentiviral transduction significantly decreases myogenic proliferation and suggest that viral infections in general may play a role in decreasing muscle health and regeneration, a decline in metabolic health, and a lower sense of well-being, as these rely on effective OXTR signaling. Additionally, our data suggest pathway crosstalk between TGF-β/pSmad3 and OXTR, implying that sustained attenuation of the TGF-β/pSmad3 pathway will reduce pro-regenerative OXTR/pERK signaling.

Dataset Information

Chicken T-cell receptor beta-chain diversity: an evolutionarily conserved D beta-encoded glycine turn within the hypervariable CDR3 domain.

Publications

Chicken T-cell receptor beta-chain diversity: an evolutionarily conserved D beta-encoded glycine turn within the hypervariable CDR3 domain.

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