V(D)J recombination activates a p53-dependent DNA damage checkpoint in scid lymphocyte precursors.

Double-stranded DNA breaks (DSBs) trigger p53-mediated cell cycle arrest or apoptosis pathways that limit the oncogenic consequences of exposure to genotoxic agents, but p53-mediated responses to DSB generated by normal physiologic events have not been documented. "Broken" V(D)J coding ends accumulate in scid lymphocyte precursors as a consequence of a mutation in DNA-dependent protein kinase (DNA-PK). The ensuing failure to rearrange efficiently antigen receptors arrests lymphoid development.

Localization, interaction, and RNA binding properties of the V(D)J recombination-activating proteins RAG1 and RAG2.

The RAG1 and RAG2 gene products are indispensable for activating somatic rearrangement of antigen receptor gene segments. The two proteins form a stable complex in primary thymocytes as well as when expressed in adherent cells. In both cell types, most cells localize RAG proteins at the periphery of the nucleus.

A dominant T cell receptor beta-chain in response to a short ragweed allergen, Amb a 5.

HLA-DR alpha, beta 1 *1501 (and the closely related DR alpha, beta 1 *1502) heterodimers are the primary class II MHC restriction elements controlling T cell responses to a ragweed pollen allergen, Amb a 5 (M(r) = 5000). Using a novel, quantitative, competitive PCR (QC-PCR) assay and a TCR beta-gene internal standard (IS), we have examined the TCR beta-gene use in Amb a 5-specific T cells. Multiple TCR V beta (and V alpha) genes were found in polyclonal T cell lines from two unrelated subjects, and 30% of the cells were stained positive for V beta 5.

Identification of the substrate and pseudosubstrate binding sites of phosphorylase kinase gamma-subunit.

Using site-directed mutagenesis, we proposed that an autoinhibitory domain(s) is located at the C-terminal region (301-386) of the phosphorylase kinase gamma-subunit (Huang, C.-Y.F.

Over-expression of CD3 epsilon transgenes blocks T lymphocyte development.

We have reported previously that mice carrying > 30 copies of the human CD3 epsilon transgene completely lose their T lymphocytes and NK cells (36). Here we demonstrate by immunohistology that in the most severely immunodeficient mouse, tg epsilon 26, the thymus is very small, has sizeable vacuoles and does not contain recognizable T lymphocytes except for a small percentage of Thy-1+ cells and B cells. Cell surface phenotyping and TCR alpha and -beta rearrangement studies confirm that the arrest in T lymphocyte development precedes the arrest in rag-1null, rag-2null and TCR beta nuli mice.

Role of TCR zeta chain in T cell development and selection.

Signals mediated by the T cell receptor (TCR) are required for thymocyte maturation and selection. To examine the role of TCR zeta chain signals in development, TCR expression was restored in zeta-deficient mice with transgenic zeta chains that partially or completely lacked sequences required for signal transduction. The zeta chain played a role in thymic development by promoting TCR surface expression, but zeta-mediated signals were not essential because TCRs that contained signaling-deficient zeta chains promoted T cell maturation and transduced signals associated with thymic selection.

An active v-abl protein tyrosine kinase blocks immunoglobulin light-chain gene rearrangement.

Lymphoid cells transformed by Abelson murine leukemia virus have provided one of the classic models for study of early B-cell development and immunoglobulin rearrangement. Most of these cells have rearranged their heavy-chain locus but not their light chain genes, suggesting that an active v-abl protein interferes with this differentiation step. To test this hypothesis, light-chain gene structure was examined in pre-B cells transformed by temperature-sensitive mutants of the Abelson virus and in derivatives that survive at the nonpermissive temperature because they express a human BCL-2 gene.

Solution structure of the exocyclic 1,N2-propanodeoxyguanosine adduct opposite deoxyadenosine in a DNA nonamer duplex at pH 8.9. model of pH-dependent conformational transition.

The solution structure of the complementary d(C1-A2-T3-G4-X5-G6-T7-A8-C9).d(G10-T11-A12-C13-A14-C15-A16-T17-G18) DNA duplex (designated X.A 9-mer), which contains a 1,N2-propanodeoxyguanosine exocyclic adduct X5 opposite deoxyadenosine A14 at the center, is pH dependent [Kouchakdjian, M.

The three-dimensional structure in solution (pH 5.8) of a DNA 9-mer duplex containing 1,N2-propanodeoxyguanosine opposite deoxyadenosine. Restrained molecular dynamics and NOE-based refinement calculations.

The solution structure of the complementary d(C1-A2-T3-G4-X5-G6-T7-A8-C9).d(G10-T11-A12-C13-A14-C15-A 16-T17-G18) nonanucleotide duplex (designated X.A 9-mer) that contains a 1,N2-propanodeoxyguanosine exocyclic adduct, X5, opposite deoxyadenosine A14 in the center of the helix at pH 5.

Electroacupuncture in rats: evidence for naloxone and naltrexone potentiation of analgesia.

Low frequency electroacupuncture (EA) analgesia has been thought to be mediated by endogenous opioids. Among other lines of evidence, it has been reported that EA stimulation delivered at 2 and 2-15 Hz in rats could be blocked or partially antagonized by naloxone (NAL) and naltrexone (NTX). In contrast, experiments in one of our laboratories (D.