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Biomedical subjects

J A Parente

Publications and source records attributed to J A Parente.

12 recordsLinked to original sources
PubMed1999

Isolation, cloning, and characterization of a new mammalian coronin family member, coroninse, which is regulated within the protein kinase C signaling pathway.

In order to understand the regulatory role of protein kinase C (PKC) in secretory epithelia, it is necessary to identify and characterize specific downstream targets. We previously identified one such protein in studies of gastric parietal cells. This protein was referred to as pp66 because it migrated with an apparent molecular mass of 66 kDa on SDS-polyacrylamide gels. The phosphorylation of pp66 is increased by the cholinergic agonist, carbachol, and by the PKC activator, phorbol-12-myristate-13-acetate, in a calcium-independent manner. In this study, we have purified pp66 to homogeneity and cloned the complete open reading frame. GenBankTM searches revealed a 45% homology with the Dictyostelium actin-binding protein, coronin, and approximately 67% homology with the previously cloned human and bovine coronin-like homologue, p57. pp66 appears to be most highly expressed in the gastrointestinal mucosa and in kidney and lung. Confocal microscopic studies of an enhanced green fluorescent protein fusion construct of pp66 in cultured parietal cells and in Madin-Darby canine kidney cells indicate that pp66 preferentially localizes in F-actin-rich regions. On the basis of our findings, we propose that pp66 may play an important, PKC-dependent role in regulating membrane/cytoskeletal rearrangements in epithelial cells. We have tentatively named this protein coroninse, because it appears to be highly expressed in secretory epithelia.

Amino Acid Sequence↗
PubMed1998

Lasp-1 is a regulated phosphoprotein within the cAMP signaling pathway in the gastric parietal cell.

Activation of the cAMP signaling pathway is correlated with increased secretory-related events in a wide variety of cell types including the gastric parietal cell. Within this pathway, as well as in other intracellular signaling pathways, protein phosphorylation serves as a major downstream regulatory mechanism. However, although agonist and cAMP-dependent activation of cAMP-dependent protein kinase (PKA) has been demonstrated, little is currently known about the downstream in vivo phosphoprotein substrates of this enzyme. Here we report the isolation, microsequencing, and cloning of a LIM and SH3 domain-containing, cAMP-responsive, 40-kDa phosphoprotein (pp40) from rabbit gastric parietal cells. The deduced amino acid sequence for pp40 is 93.5%, homologous with the putative protein product of the human gene lasp-1, which was recently identified based on its overexpression in some breast carcinomas. In addition to LIM and SH3 domains, the rabbit homolog contains two highly conserved PKA consensus sequences as well as two conserved SH2 binding motifs and several other putative protein kinase phosphorylation sites, including two for tyrosine kinase(s). Combined Northern and Western blot analyses indicate that pp40/lasp-1 is widely expressed (through a single 3.3-kb message) not only in epithelial tissues but also in muscle and brain. Furthermore, stimulation of isolated parietal cells, distal colonic crypts, and pancreatic cells with the adenylyl cyclase activator forskolin leads to the appearance of a higher molecular weight form of pp40/lasp-1, a finding which is consistent with an increase in protein phosphorylation. Thus pp40/lasp-1 appears to be regulated within the cAMP signaling pathway in a wide range of epithelial cell types. Because the cAMP-dependent increase in pp40 phosphorylation is correlated with secretory responses in the parietal cell and because pp40 appears to be widely distributed among various secretory tissues, this newly defined signaling protein may play an important role in modulating ionic transport or other secretory-related activities in many different cell types.

Adaptor Proteins, Signal Transducing↗
PubMed1997

Ca2+-independent protein kinase C isoforms may modulate parietal cell HCl secretion.

Although activation of adenosine 3',5'-cyclic monophosphate by histamine and of Ca2+-dependent signaling pathways by cholinergic agonists is a generally recognized mechanism for increasing parietal cell HCl secretion, the role of protein kinase C (PKC) in this process is controversial. In this study, acid-secretory responses of gastric glands from rabbits [measured as accumulation of aminopyrine (AP)] were found to be relatively resistant to the PKC inhibitors calphostin C, chelerythrine chloride, staurosporine, and the bisindolylmaleimide-like inhibitors Ro 31-8220, Gö 6976, and bisindolylmaleimide I hydrochloride. Western analyses of the PKC isozyme profile in highly enriched parietal cells (98% purity) indicated that this cell type expresses abundant levels of the novel isoforms PKC-epsilon and PKC-mu and abundant levels of the atypical isoforms PKC-iota, PKC-lambda, and PKC-zeta. In contrast, there appeared to be low to undetectable expression of the classical isoforms PKC-alpha and PKC-beta1/beta2, respectively. Relatively high concentrations of Ro 31-8220 potentiated both carbachol- and histamine-stimulated AP accumulation (IC50 857 +/- 100 and 910 +/- 98 nM, respectively). There was a similar dose dependence for Ro 31-8220 inhibition of in situ phosphorylation of a parietal cell phosphoprotein, pp66 (IC50 750 +/- 120 nM). Similar concentrations of Ro 31-8220 also inhibited phosphorylation of the cytoskeletal, actin membrane cross-linking phosphoprotein ezrin, but not other phosphoproteins. Ezrin phosphorylation was increased by carbachol and 12-O-tetradecanoylphorbol 13-acetate (TPA). Because carbachol and TPA stimulate pp66 phosphorylation in a Ca2+-independent manner, our results suggest that one or more novel PKC isoforms may be involved in negative regulation of HCl secretion. In related experiments, PKC-epsilon, but not PKC-mu, was immunolocalized by confocal microscopy to a parietal cell compartment that bore a striking resemblance to that containing filamentous actin. Moreover, pp66 was enriched in a Triton X-100-insoluble parietal cell fraction, suggesting a potential cytoskeletal localization for this unknown protein. Given their location and sensitivity to Ro 31-8220, it is possible that pp66 and ezrin interact in a PKC-dependent manner to regulate the well-known morphological changes that occur in concert with agonist-dependent activation of parietal cell HCl secretion.

Actins↗
PubMed1996

Purification, cloning, and expression of a novel, endogenous, calcium-sensitive, 28-kDa phosphoprotein.

In gastric parietal cells, cholinergically induced increases in intracellular free calcium concentrations have been well characterized, but little is known about the signaling events beyond the initial rise in intracellular calcium. In the present study, we report the isolation of a 28-kDa protein, which is rapidly phosphorylated in intact, enriched parietal cells in response to both the cholinergic agonist, carbachol, and the calcium ionophore, ionomycin. A combination of in situ 32P labeling and one- and two-dimensional gel electrophoresis was used to acquire sufficient quantities of protein to obtain partial amino acid sequence. Cloning of the pp28 cDNA revealed a novel protein which we have named CSPP28 based on its calcium-sensitive phosphorylation. There are three CSPP28 mRNA species (1.7, 2.2, and 3.3 kilobases) that are widely distributed throughout a variety of rabbit tissues. Recombinant CSPP28 was phosphorylated by both crude parietal cell homogenate and purified CaM kinase II in a calcium/calmodulin-dependent manner. We propose that CSPP28 may play an important and ubiquitous role in the calcium signaling pathway.

Amino Acid Sequence↗
PubMed1996

[Determinants of induced abortion among poor women admitted to hospitals in a locality of northeastern Brazil].

In Brazil, abortion is legally allowed only when it is necessary to save a woman's life or when pregnancy has occurred following rape. Despite this law, induced abortion is widely carried out. This study presents the findings as to the determinants of 2,084 abortions admitted to two major obstetric hospitals in Fortaleza, Brazil, between October 1992 and September 1993. Most of these women (2,074) have admitted an attempt to terminate pregnancy and 10 women were classified as induced abortion cases based on the findings of signs of intervention such as cervical laceration, perforation or foreign bodies in the vagina or uterus. The study findings indicate that self-administration of medicines plays an important role in terminating pregnancy. Among the 2,074 women who admitted to terminating the pregnancy 66% reported using misoprostol to induce abortion. Misoprostol, a prostaglandin E1 analogue indicated for ulcer treatment, has been widely used as an abortifacient by women in Brazil. Misoprostol has some uterine effects but it is not effective in inducing abortion. Among women who were hospitalized for complications resulting from abortion about 59.7% were 20 to 29 years old and 22.6% were aged less than 20. The majority of the women (91.6%) were Catholic and only 4.3% were illiterate. About 62% of the abortion cases lived alone or did not have a stable partner. Most of the women (59.2%) reported less than 2 live births and 11.8% had experienced a previous abortion; 61.1% of the women were not using a contraceptive method at the time of conception. The main reasons for this were "fear of side effects", "did not expect to have sexual intercourse" and "did not expect to get pregnant". The authors suggest that the situation of a high rate of self-inflicted abortion may be changed by the application of an appropriate contraceptive and reproductive health programme.

Abortion, Illegal↗
PubMed1993

Is dehydroepiandrosterone an antiobesity agent?

The steroid hormone intermediate, DHEA, has been proposed as a therapeutic agent for the treatment of obesity. Its effects on lipogenesis, substrate cycling, peroxisome proliferation, mitochondrial respiration, protein synthesis, and thyroid hormone function have been reported. The results of these studies suggest that the antiobesity function of DHEA is not simply one of inhibiting fat synthesis and deposition but is one of affecting a number of pathways that contribute to the maintenance of the isoenergetic state rather than the promotion of positive energy balance.

Animals↗
PubMed1993

Drugs that suppress hepatic fat synthesis in starved-refed BHE/cdb rats also have an effect on muscle protein synthesis.

Simultaneous lipogenesis and protein synthesis as influenced by LY79771, testosterone, or dehydroepiandrosterone in starved/refed rats were studied. Starved-refed BHE/cdb rats were injected with one of these compounds during the 2-day refeed period. Hepatic de novo fatty acid synthesis using tritium incorporation into fatty acids and protein synthesis using [14C]phenylalanine incorporation into hepatic and muscle protein were determined. Hepatic lipogenesis was decreased by all three drugs and these drugs had a differential effect on protein synthesis. We did not observe a corresponding increase in protein synthesis in the liver when fat synthesis was decreased, but we did observe a corresponding increase in muscle protein synthesis. We concluded that in the acute hyperlipogenic state induced by starvation/refeeding, these drugs induced a reciprocal increase in muscle protein synthesis along with a suppression of fatty acid synthesis.

2-Hydroxyphenethylamine↗
PubMed1976

Music preference as a factor of music distraction.

The present study is an experimental analysis of music preference as a factor of music distraction measured by the Stroop tests. Significant differences were found amoung groups given, most preferred music, least preferred music, and no music (quiet). Each group of 10 subjects were randomly chosen from 42 screened subjects. Performance was better without music and better with most preferred than with least preferred music. The results were not consistent with those previously found for the effects of noise upon Stroop test performance.

Attention↗
PubMed1976

Music preference as a factor of music distraction.

The present study is an experimental analysis of music preference as a factor of music distraction measured by the Stroop tests. Significant differences were found among groups given, most preferred music, least preferred music, and no music(quiet). Each group of 10 subjects were randomly chosen from 42 screened subjects. Performance was better without music and better with most preferred than with least preferred music. The results were not consistent with those previously found for the effects of noise upon Stroop test performance.

Attention↗
PubMed1975

Training in musical rhythm and field dependence of children.

The present experiment investigated the effects of musical rhythm training on field dependence in children. An experimental group of 12 Ss showed significant improvement on the Children's Embedded-figures Test and the Rod-and-frame Test after training, while a matched control group did not improve. Pretest scores on the children's Embedded-figures Test and the Rod-and-frame Test were not correlated.

Child↗