Biomedical subjects

Cheryl Bock

Publications and source records attributed to Cheryl Bock.

3 recordsLinked to original sources

PubMed2005

Regulation of T cell receptor alpha gene assembly by a complex hierarchy of germline Jalpha promoters.

Assembly of the gene encoding T cell receptor alpha (Tcra) is characterized by an orderly progression of primary and secondary V(alpha)-to-J(alpha) recombination events across the J(alpha) array, but the targeting mechanisms responsible for this progression are mostly unknown. Studies have shown that the T early-alpha promoter is important in targeting primary Tcra rearrangements. We found that T early-alpha and a previously unknown promoter associated with J(alpha)49 targeted primary recombination to discrete sets of constant alpha region (C(alpha))-distal J(alpha) segments and together directed nearly all normal primary recombination events. Furthermore, deletion of the T early-alpha promoter activated previously suppressed downstream promoters and stimulated primary rearrangement to centrally located J(alpha) segments. Central promoter derepression also occurred after primary rearrangement, thereby providing a mechanism to target secondary recombination events.

Acetylation↗

PubMed2004

Cloning of Brassica napus phospholipase C2 (BnPLC2), phosphatidylinositol 3-kinase (BnVPS34) and phosphatidylinositol synthase1 (BnPtdIns S1)--comparative analysis of the effect of abiotic stresses on the expression of phosphatidylinositol signal transduction-related genes in B. napus.

The cloning and identification of full-length cDNA fragments coding for the Brassica napus phosphatidylinositol-specific phospholipase C2 (BnPLC2), phosphatidylinositol 3-kinase (BnVPS34) and phosphatidylinositol synthase (BnPtdIns S1) is described. In addition, two complementary fragments (120 nucleotides long) corresponding to Arabidopsis PtdIns 4-kinase (PtdIns 4-K) and PtdIns-4-phosphate 5-kinase (PtdIns4P 5-K) sequences were chemically synthesized. These, as well as the cDNA clones, were used as probes to study the corresponding steady state mRNA levels in different tissues and developmental stages of B. napus, as well as in response to different environmental conditions. Transcripts corresponding to BnPLC2, BnPtdIns S1, BnVPS34 and PtdIns 4-K were found constitutively expressed at different levels in most tissues, with young leaves, siliques, and developing seeds showing the lowest levels. No detectable PtdIns4P 5-K transcripts were found in buds or flowers. Up-regulation of BnPLC2 was seen in response to low temperature stress, which was notably accompanied by a parallel down-regulation of BnPtdIns S1, while BnVPS34 and PtdIns 4-K remained at control levels. A moderate increase in PtdIns4P 5-K levels was noted. In high salinity conditions BnPtdIns S1, BnVPS34 and BnPLC2 transcripts had similar responses but at different levels, with no major changes detected for PtdIns 4-K or PtdIns4P 5-K. Significantly, all five transcripts increased under drought stress conditions and all stressed plants clearly showed relatively higher levels of total inositol trisphosphate.

Brassica napus↗

PubMed2002

CD83 expression influences CD4+ T cell development in the thymus.

T lymphocyte selection and lineage commitment in the thymus requires multiple signals. Herein, CD4+ T cell generation required engagement of CD83, a surface molecule expressed by thymic epithelial and dendritic cells. CD83-deficient (CD83-/-) mice had a specific block in CD4+ single-positive thymocyte development without increased CD4+CD8+ double- or CD8+ single-positive thymocytes. This resulted in a selective 75%-90% reduction in peripheral CD4+ T cells, predominantly within the naive subset. Wild-type thymocytes and bone marrow stem cells failed to differentiate into mature CD4+ T cells when transferred into CD83-/- mice, while CD83-/- thymocytes and stem cells developed normally in wild-type mice. Thereby, CD83 expression represents an additional regulatory component for CD4+ T cell development in the thymus.

Adoptive Transfer↗