Deleterious GRM1 Mutations in Schizophrenia

We analysed a phenotypically well-characterised sample of 450 schziophrenia patients and 605 controls for rare non-synonymous single nucleotide polymorphisms (nsSNPs) in the GRM1 gene, their functional effects and family segregation. GRM1 encodes the metabotropic glutamate receptor 1 (mGluR1), whose documented role as a modulator of neuronal signalling and synaptic plasticity makes it a plausible schizophrenia candidate. In a recent study, this gene was shown to harbour a cluster of deleterious nsSNPs within a functionally important domain of the receptor, in patients with schizophrenia and bipolar disorder. Our Sanger sequencing of the GRM1 coding regions detected equal numbers of nsSNPs in cases and controls, however the two groups differed in terms of the potential effects of the variants on receptor function: 6/6 case-specific and only 1/6 control-specific nsSNPs were predicted to be deleterious. Our in-vitro experimental follow-up of the case-specific mutants showed that 4/6 led to significantly reduced inositol phosphate production, indicating impaired function of the major mGluR1signalling pathway; 1/6 had reduced cell membrane expression; inconclusive results were obtained in 1/6. Family segregation analysis indicated that these deleterious nsSNPs were inherited. Interestingly, four of the families were affected by multiple neuropsychiatric conditions, not limited to schizophrenia, and the mutations were detected in relatives with schizophrenia, depression and anxiety, drug and alcohol dependence, and epilepsy. Our findings suggest a possible mGluR1 contribution to diverse psychiatric conditions, supporting the modulatory role of the receptor in such conditions as proposed previously on the basis of in vitro experiments and animal studies

Active Surveillance for Influenza A Virus among Swine, Midwestern United States, 2009–2011

Veterinary diagnostic laboratories identify and characterize influenza A viruses primarily through passive surveillance. However, additional surveillance programs are needed. To meet this need, an active surveillance program was conducted at pig farms throughout the midwestern United States. From June 2009 through December 2011, nasal swab samples were collected monthly from among 540 groups of growing pigs and tested for influenza A virus by real-time reverse transcription PCR. Of 16,170 samples, 746 were positive for influenza A virus; of these, 18.0% were subtype H1N1, 16.0% H1N2, 7.6% H3N2, and 14.5% (H1N1)pdm09. An influenza (H3N2) and (H1N1)pdm09 virus were identified simultaneously in 8 groups. This active influenza A virus surveillance program provided quality data and increased the understanding of the current situation of circulating viruses in the midwestern US pig population

Multiple reassortment between pandemic (H1N1) 2009 and endemic influenza viruses in pigs, United States.

As a result of human-to-pig transmission, pandemic influenza A (H1N1) 2009 virus was detected in pigs soon after it emerged in humans. In the United States, this transmission was quickly followed by multiple reassortment between the pandemic virus and endemic swine viruses. Nine reassortant viruses representing 7 genotypes were detected in commercial pig farms in the United States. Field observations suggested that the newly described reassortant viruses did not differ substantially from pandemic (H1N1) 2009 or endemic strains in their ability to cause disease. Comparable growth properties of reassortant and endemic viruses in vitro supported these observations; similarly, a representative reassortant virus replicated in ferrets to the same extent as did pandemic (H1N1) 2009 and endemic swine virus. These novel reassortant viruses highlight the increasing complexity of influenza viruses within pig populations and the frequency at which viral diversification occurs in this ecologically important viral reservoir.As a result of human-to-pig transmission, pandemic influenza A (H1N1) 2009 virus was detected in pigs soon after it emerged in humans. In the United States, this transmission was quickly followed by multiple reassortment between the pandemic virus and endemic swine viruses. Nine reassortant viruses representing 7 genotypes were detected in commercial pig farms in the United States. Field observations suggested that the newly described reassortant viruses did not differ substantially from pandemic (H1N1) 2009 or endemic strains in their ability to cause disease. Comparable growth properties of reassortant and endemic viruses in vitro supported these observations; similarly, a representative reassortant virus replicated in ferrets to the same extent as did pandemic (H1N1) 2009 and endemic swine virus. These novel reassortant viruses highlight the increasing complexity of influenza viruses within pig populations and the frequency at which viral diversification occurs in this ecologically important viral reservoir

Functional analysis and relative plasma membrane expression of mGluR1 mutants in COS-7 cells.

<p>Cells transiently expressing mGluR1, wild-type (WT) or possessing the different mutations as indicated, were assayed for Quisqualate-induced inositol phosphate production using the IP-One assay (<b>a</b>) or plasma membrane expression using ELISA with anti-mGluR1 antibody on intact cells (<b>b</b>). With the IP-One assay, cells were stimulated with Quisqualate (10 µM) for 45 minutes and data were normalized to percentage of Quisqualate-induced IP₁ production in cells expressing mGluR1-WT (<b>a</b>). Similarly, the ELISA signals were normalized to percentage of plasma membrane expression of the mGluR1-WT (<b>b</b>). Data are Mean ± SEM of four independent experiments carried out in triplicate. *** P<0.001, ** P<0.01, * P<0.05, ns P>0.05.</p

Structure, neuropsychiatric morbidity and mutation segregation in families of schizophrenia probands with deleterious <i>GRM1</i> variants.

<p>Structure, neuropsychiatric morbidity and mutation segregation in families of schizophrenia probands with deleterious <i>GRM1</i> variants.</p

Distribution of the coding mutations in the <i>GRM1</i> gene and the encoded mGluR1 protein.

<p>(<b>a</b>) All coding mutations relative to gene structure, with <i>GRM1</i> exons 1 to 8 shown in alternating shaded bars. Top panel: changes found in patients; bottom panel: changes found in controls. Colour coding: red - rare missense variants; blue - common missense variants (MAF>1%), black- synonymous variants. (<b>b</b>) Non-synonymous coding changes relative to the mGluR1 receptor protein domains (shown as grey bars). Colour coding: red circles – case-specific, green circles – control specific, red circles with green outline – detected in cases as well as controls. Mutation predicted by bioinformatics programs to have a deleterious effect on protein function are italicised and underlined.</p