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P Barrand

Publications and source records attributed to P Barrand.

10 recordsLinked to original sources
PubMed1991

Activity of the kappa B enhancer of the interleukin-2 receptor alpha chain in somatic cell hybrids is accompanied by the nuclear localization of NF-kappa B.

The two nuclear proteins NF-kappa B (consisting of subunits p50 an dp65) and the DNA-binding subunit of NF-kappa B (p50) by itself, also called KBF1, are constitutively expressed and localized in the nucleus of the human T-cell line IARC 301.5. In order to define the roles of these two factors, which bind to the same kappa B enhancers, in transcription activation we have prepared somatic cell hybrids between IARC 301.5 and a murine myeloma. Most hybrids express both KBF1 and NF-kappa B in their nuclei, but one hybrid expresses only KBF1. The kappa B enhancer of the gene encoding the interleukin-2 (IL-2) receptor alpha chain (IL-2R alpha) is functional only in the hybrids expressing nuclear NF-kappa B. These findings show that nuclear NF-kappa B is necessary to activate the kappa B enhancer, while KBF1 by itself is not sufficient. We propose that KBF1 is a competitive inhibitor of NF-kappa B and discuss how these factors may be involved in the transient expression of IL-2 and IL-2R alpha genes during the immune response.

Animals↗
PubMed1987

Retinoic acid increases the expression of NGF gene in mouse L cells.

Retinoic acid (RA), the acid form of vitamin A, is shown to enhance the synthesis of nerve growth factor (NGF) in cultures of mouse L cells. Maximal stimulation was observed in cells growing in a serum-free medium supplemented with 10(-6)M RA during 48 h. The drug increased both the level of NGF mRNA and the amount of mature NGF protein secreted by the cells. RA was previously reported to increase the number of NGF receptors on some neuroblastoma cells (Haskell et al., 1987 Cell and Tiss. Res., 247, 67-73). It seems, therefore, that RA may influence nerve cell differentiation by promoting both the synthesis of the neurotrophic factor and the responsiveness of target cells.

Animals↗
PubMed1985

Serum and thyroid hormones T3 and T4 regulate nerve growth factor mRNA levels in mouse L cells.

Mouse L cells synthesize and secrete a neurotrophic factor related to the beta subunit of the submaxillary gland nerve growth factor (NGF) of male mice. Use of a cDNA probe which encodes the beta-NGF mRNA demonstrated that L cells produce a transcript identical in size to that of the submaxillary gland. Moreover, target sites of restriction enzymes EcoRI, PstI and BamHI were not significantly rearranged in the beta-NGF gene locus of these cells. The abundance of the beta-NGF transcript was found to depend on culture conditions. Removal of serum depressed the cellular content of polyadenylated RNA by a factor of 1.7, and decreased specifically the pool of beta-NGF transcript by an additional factor of 4. The presence of 10(-7) M testosterone in the serum-free medium did not modify the level of beta-NGF mRNA, while addition of 10(-7) M T3 (or T4) increased this level by a factor of 1.5. These data provide the first evidence that the beta-NGF mRNA of L cells is subjected to regulation, but in a way apparently different from that described for the submaxillary gland.

Animals↗
PubMed1982

Mutants in the y region of bacteriophage lambda constitutive for repressor synthesis: their isolation and the characterization of the Hyp phenotype.

Bacteriophage lambdahyp mutants have been isolated as survivors of Escherichia coli K-12 bacteria lysogenic for lambda Nam7am53cI857. The hyp mutants are characterized by (i) their localization in the y region very close to the imm lambda/imm434 boundary, (ii) polarity on O gene expression, (iii) immediate recovery of lambda immunity at 30 degrees C after prolonged growth of lambda Nam7am53cI857 hyp lysogens at 42 degrees C even in the presence of an active cro gene product, (iv) ability of phage lambda v2v3vs326 but not lambda v1v2v3 to propagate on lambda cI+hyp lysogens, (v) inability to express lambda exonuclease activity after prophage induction, and (vi) inviability at any temperature of phage carrying the hyp mutation. All these properties are referred to collectively as the Hyp phenotype. We show that the Hyp phenotype is due to cII-independent constitutive cI-gene-product synthesis originating in the y region, which results in the synthesis of anti-cro RNA species, and constitutive levels of cro gene product present even in lambda cI+hyp lysogens. A model is presented which is consistent with all the experimental observations.

Antigens, Viral↗
PubMed1969

On the association of tyrocidine with acetylcholinesterase.

In studies of several polypeptide antibiotics with a high affinity for a variety of biological membranes, tyrocidine was found to bind specifically to acetylcholinesterase, an enzyme localized in excitable membranes. Several other polypeptides tested were not bound. Tyrocidine reversibly inhibits acetylcholinesterase formed by homogeneous protein, but seems to have no effect on the activity of the enzyme bound to the eel electroplax membrane. This inhibition is accompanied by a reversible association of the soluble enzyme in to ordered and rapidly sedimenting aggregates of large molecular weight. Electron micrographs of acetylcholinesterase are shown which are consistent with the chemical evidence of the existence of four subunits.

Animals↗