Modulation of cardiac Ca2+ channels in Xenopus oocytes by protein kinase C

L-Type calcium channel was expressed in Xenopus laevis oocytes injected with RNAs coding for different cardiac Cu2+ channel subunits, or with total heart RNA. The effects of activation of protein kinase C (PKC) by the phorbol ester PMA (4β-phorbol 12-myristate 13-acetate) were studied. Currents through channels composed of the main (1) subunit alone were initially increased and then decreased by PMA. A similar biphasic modulation was observed when the 1 subunit was expressed in combination with 2/δ, β and/or γ subunits, and when the channels were expressed following injection of total rat heart RNA. No effects on the voltage dependence of activation were observed. The effects of PMA were blocked by staurosporine, a protein kinase inhibitor. β subunit moderated the enhancement caused by PMA. We conclude that both enhancement and inhibition of cardiac L-type Ca2+ currents by PKC are mediated via an effect on the 1 subunit, while the β subunit may play a mild modulatory role

Comparative Functional Genomics Analysis of NNK Tobacco-Carcinogen Induced Lung Adenocarcinoma Development in Gprc5a-Knockout Mice

Background: Improved understanding of lung cancer development and progression, including insights from studies of animal models, are needed to combat this fatal disease. Previously, we found that mice with a knockout (KO) of G-protein coupled receptor 5A (Gprc5a) develop lung tumors after a long latent period (12 to 24 months). Methodology/Principal Findings: To determine whether a tobacco carcinogen will enhance tumorigenesis in this model, we administered 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) i.p. to 2-months old Gprc5a-KO mice and sacrificed groups (n = 5) of mice at 6, 9, 12, and 18 months later. Compared to control Gprc5a-KO mice, NNK-treated mice developed lung tumors at least 6 months earlier, exhibited 2- to 4-fold increased tumor incidence and multiplicity, and showed a dramatic increase in lesion size. A gene expression signature, NNK-ADC, of differentially expressed genes derived by transcriptome analysis of epithelial cell lines from normal lungs of Gprc5a-KO mice and from NNK-induced adenocarcinoma was highly similar to differential expression patterns observed between normal and tumorigenic human lung cells. The NNK-ADC expression signature also separated both mouse and human adenocarcinomas from adjacent normal lung tissues based on publicly available microarray datasets. A key feature of the signature, up-regulation of Ube2c, Mcm2, and Fen1, was validated in mouse normal lung and adenocarcinoma tissues and cells by immunohistochemistry and western blotting, respectively

Direct Interaction of Endogenous Kv Channels with Syntaxin Enhances Exocytosis by Neuroendocrine Cells

K+ efflux through voltage-gated K+ (Kv) channels can attenuate the release of neurotransmitters, neuropeptides and hormones by hyperpolarizing the membrane potential and attenuating Ca2+ influx. Notably, direct interaction between Kv2.1 channels overexpressed in PC12 cells and syntaxin has recently been shown to facilitate dense core vesicle (DCV)-mediated release. Here, we focus on endogenous Kv2.1 channels and show that disruption of their interaction with native syntaxin after ATP-dependent priming of the vesicles by Kv2.1 syntaxin–binding peptides inhibits Ca2+ -triggered exocytosis of DCVs from cracked PC12 cells in a specific and dose-dependent manner. The inhibition cannot simply be explained by the impairment of the interaction of syntaxin with its SNARE cognates. Thus, direct association between endogenous Kv2.1 and syntaxin enhances exocytosis and in combination with the Kv2.1 inhibitory effect to hyperpolarize the membrane potential, could contribute to the known activity dependence of DCV release in neuroendocrine cells and in dendrites where Kv2.1 commonly expresses and influences release

Antibiotic treatment attenuates behavioral and neurochemical changes induced by exposure of rats to group a streptococcal antigen.

Post-streptococcal A (GAS) sequelae including movement and neuropsychiatric disorders have been associated with improvement in response to antibiotic therapy. Besides eradication of infection, the underlying basis of attenuation of neuropsychiatric symptoms following antibiotic treatment is not known. The aim of the present study was to test the efficacy of antibiotic treatment in a rat model of GAS-related neuropsychiatric disorders. In the model, rats were not infected but were exposed to GAS-antigen or to adjuvants only (Control rats) and treated continuously with the antibiotic ampicillin in their drinking water from the first day of GAS-antigen exposure. Two additional groups of rats (GAS and Control) did not receive ampicillin in their drinking water. Behavior of the four groups was assessed in the forced swim, marble burying and food manipulation assays. We assessed levels of D1 and D2 dopamine receptors and tyrosine hydroxylase in the prefrontal cortex and striatum, and IgG deposition in the prefrontal cortex, striatum and thalamus. Ampicillin treatment prevented emergence of the motor and some of the behavioral alterations induced by GAS-antigen exposure, reduced IgG deposition in the thalamus of GAS-exposed rats, and tended to attenuate the increase in the level of TH and D1 and D2 receptors in their striatum, without concomitantly reducing the level of sera anti-GAS antibodies. Our results reinforce the link between exposure to GAS antigen, dysfunction of central dopaminergic pathways and motor and behavioral alterations. Our data further show that some of these deleterious effects can be attenuated by antibiotic treatment, and supports the latter's possible efficacy as a prophylactic treatment in GAS-related neuropsychiatric disorders

A Gprc5a Tumor Suppressor Loss of Expression Signature Is Conserved, Prevalent, and Associated with Survival in Human Lung Adenocarcinomas12

Increasing the understanding of the impact of changes in oncogenes and tumor suppressor genes is essential for improving the management of lung cancer. Recently, we identified a new mouse lung-specific tumor suppressor—the G protein-coupled receptor 5A (Gprc5a). Microarray analysis of the transcriptomes of lung epithelial cells cultured from normal tracheas of Gprc5a knockout and wild-type mice defined a loss-of-Gprc5a gene signature, which revealed many aberrations in cancer-associated pathways. To assess the relevance of this mouse tumor suppressor to human lung cancer, the loss-of-Gprc5a signature was cross species compared with and integrated with publicly available gene expression data of human normal lung tissue and non-small cell lung cancers. The loss-of-Gprc5a signature was prevalent in human lung adenocarcinomas compared with squamous cell carcinomas or normal lung. Furthermore, it identified subsets of lung adenocarcinomas with poor outcome. These results demonstrate that gene expression patterns of Gprc5a loss in nontumorigenic mouse lung epithelial cells are evolutionarily conserved and important in human lung adenocarcinomas

Behavioral effects of GAS exposure and ampicillin treatment.

<p>Effects of streptococcal exposure and ampicillin treatment on (A) food manipulation, (B) marble burying, and (C) forced swim test (FST). (A) The mean and SE of food manipulation scores of GAS-Water, Control-Water, GAS-ampicillin, and Control-ampicillin rats. (B) The mean and SE of number of marbles buried by GAS-Water, Control-Water, GAS-ampicillin, and Control-ampicillin rats. (C) The mean and SE of the duration of immobility time in the FST of GAS-Water, Control-Water, GAS-ampicillin, and Control-ampicillin rats. N per group  = 12–15 rats. *p<0.05, ***p<0.0001.</p