STAT1-mediated Bim expression promotes the apoptosis of retinal pericytes under high glucose conditions.

Hyperglycemia impacts different vascular cell functions and promotes the development and progression of various vasculopathies including diabetic retinopathy. Although the increased rate of apoptosis in pericytes (PCs) has been linked to increased oxidative stress and activation of protein kinase C-δ (PKC-δ) and SHP-1 (Src homology region 2 domain-containing phosphatase-1) tyrosine phosphatase during diabetes, the detailed mechanisms require further elucidation. Here we show that the rate of apoptosis and expression of proapoptotic protein Bim were increased in the retinal PCs of diabetic Akita/+ mice and mouse retinal PCs cultured under high glucose conditions. Increased Bim expression in retinal PCs under high glucose conditions required the sustained activation of signal transducer and activator of transcription 1 (STAT1) through production of inflammatory cytokines. PCs cultured under high glucose conditions also exhibited increased oxidative stress and diminished migration. Inhibition of oxidative stress, PKC-δ or Rho-associated protein kinase I/II was sufficient to protect PCs against apoptosis under high glucose conditions. Furthermore, PCs deficient in Bim expression were protected from high glucose-mediated increased oxidative stress and apoptosis. However, only inhibition of PKC-δ lowered Bim levels. N-acetylcysteine did not affect STAT1 levels, suggesting that oxidative stress is downstream of Bim. PCs cultured under high glucose conditions disrupted capillary morphogenesis of retinal endothelial cells (ECs) in coculture experiments. In addition, conditioned medium prepared from PCs under high glucose conditions attenuated EC migration. Taken together, our results indicate that Bim has a pivotal role in the dysfunction of retinal PCs under high glucose conditions by increasing oxidative stress and death of PCs.

Lack of sigma-1 receptor exacerbates ALS progression in mice.

The function of the sigma-1 receptor (S1R) has been implicated in modulating the activity of various ion channels. In the CNS S1R is enriched in cholinergic postsynaptic densities in spinal cord motoneurons (MNs). Mutations in S1R have been found in familial cases of amyotrophic lateral sclerosis (ALS). In this study we show that a knockout of S1R in the SOD1*G93A mouse model of ALS significantly reduces longevity (end stage). Electrophysiological experiments demonstrate that MN of mice lacking S1R exhibit increased excitability. Taken together the data suggest the S1R acts as a brake on excitability, an effect that might enhance longevity in an ALS mouse model.

Altered neuronal density and neurotransmitter expression in the ganglionated region of Ednrb null mice: implications for Hirschsprung's disease.

BACKGROUND: Hirschsprung's disease (HSCR) is a congenital condition in which enteric ganglia, formed from neural crest cells (NCC), are absent from the terminal bowel. Dysmotility and constipation are common features of HSCR that persist following surgical intervention. This persistence suggests that the portion of the colon that remains postoperatively is not able to support normal bowel function. To elucidate the defects that underlie this condition, we utilized a murine model of HSCR. METHODS: Mice with NCC-specific deletion of Ednrb were used to measure the neuronal density and neurotransmitter expression in ganglia. KEY RESULTS: At the site located proximal to the aganglionic region of P21 Ednrb null mice, the neuronal density is significantly decreased and the expression of neurotransmitters is altered compared with het animals. The ganglia in this colonic region are smaller and more isolated while the size of neuronal cell bodies is increased. The percentage of neurons expressing neuronal nNOS and VIP is significantly increased in Ednrb nulls. Conversely, the percentage of choline acetyltransferase (ChAT) expressing neurons is decreased, while Substance P is unchanged between the two genotypes. These changes are limited to the colon and are not detected in the ileum. CONCLUSIONS & INFERENCES: We demonstrate changes in neuronal density and alterations in the balance of expression of neurotransmitters in the colon proximal to the aganglionic region in Ednrb null mice. The reduced neuronal density and complementary changes in nNOS and ChAT expression may account for the dysmotility seen in HSCR.

Comparative genomic imprinting and expression analysis of six cattle genes.

Imprinted genes are monoallelically expressed in a parent-of-origin-specific manner under epigenetic regulation. Although it is generally believed that genomic imprinting is conserved among mammalian species, there is accumulating evidence that suggests such an assumption is false. Identification of species-specific imprinted genes is necessary to understand the evolution of genomic imprinting and to elucidate mechanisms leading to allele-specific expression. In this study, we analyzed the imprinting status of the CD81, target of antiproliferation antibody 1 (TSSC4), and oxysterol-binding protein homologue 1 (OBPH1) genes clustered on bovine chromosome 29; the paternally expressed gene 10 and ankyrin repeat and suppressor of cytokine signaling box-containing protein 4 genes clustered on bovine chromosome 4; and the 5-hydroxytryptamine (serotonin) 2A receptor microdomain gene on bovine chromosome 12 using a sequencing-based approach. It was found that CD81 and OBPH1 showed biallelic expression in all cattle tissues examined, whereas TSSC4 showed monoallelic expression in placental tissues, like its mouse ortholog. Comparative expression analysis showed that the imprinting pattern of the CD81, TSSC4, and OBPH1 cluster was not conserved among mouse, human, and cattle. None of these genes were imprinted in all 3 species. The the paternally expressed gene 10 gene was imprinted in all 3 species, whereas ankyrin repeat and suppressor of cytokine signaling box-containing protein 4 gene, reported to be imprinted in mouse, was not imprinted in cattle. The the 5-hydroxytryptamine (serotonin) 2A receptor gene was not imprinted in cattle, and human imprinting data has shown conflicting results. It is more likely that imprinting in the genes examined in this study is species-specific. In addition, we studied the expression and tissue distribution of transcripts of these genes in 174 fetal and adult cattle tissues.

The association of bovine PPARGC1A and OPN genes with milk composition in two independent Holstein cattle populations.

Many studies have reported quantitative trait loci on chromosome 6 that affect milk production traits in dairy cattle. Osteopontin (OPN) and peroxisome proliferator activated receptor gamma coactivator 1 alpha (PPARGC1A) are located in the middle of chromosome 6 about 6 Mb apart, which is approximately 12 cM. The objective of this study was to investigate the association of OPN and PPARGC1A variants with milk production traits in 2 independent Holstein cattle populations: the University of Wisconsin (UW) daughter design and the Cooperative Dairy DNA Repository (CDDR) granddaughter design resource populations. For OPN, 891 cows from the UW resource population were genotyped for the C/T polymorphism reported previously in the CDDR population. Additive effects were significant for fat percentage, protein percentage, and fat yield in the UW resource population. These results are consistent with previous studies that have shown significant association of OPN variants with milk composition traits. The association between PPARC1A variants was investigated in UW and CDDR resource populations using 2 single nucleotide polymorphisms. For the UW resource population, additive effects were significantly increased for protein percentage and decreased for milk yield. Dominance effects were not significant for any of the examined traits. For the CDDR population, PPARGC1A was associated with a significant increase in milk protein percentage and in SCS. Thus, in UW and CDDR populations, PPARGC1A was associated with a significant increase in milk protein percentage in contrast to association results previously reported for the German Holstein population.

Evaluation of association between polymorphism within the thyroglobulin gene and milk production traits in dairy cattle.

In dairy cattle, many studies have reported quantitative trait loci (QTL) on the centromeric end of chromosome 14 that affect milk production traits. One of the candidate genes in this QTL region - thyroglobulin (TG) - was previously found to be significantly associated with marbling in beef cattle. Thus, based on QTL studies in dairy cattle and because of possible effects of this gene on fat metabolism, we investigated the association of TG with milk yield and composition in Holstein dairy cattle. A total of 1279 bulls from the Cooperative Dairy DNA Repository Holstein population were genotyped for a single nucleotide polymorphism in TG used previously in beef cattle studies. Analysis of 29 sire families showed no significant association between TG variants and milk production traits. Within-sire family analysis suggests that TG is neither the responsible gene nor a genetic marker in association with milk production traits.

Effects of the signal transducer and activator of transcription 1 (STAT1) gene on milk production traits in Holstein dairy cattle.

A functional candidate gene approach was used to search for genes affecting milk production traits in Holstein dairy cattle. Signal transducer and activator of transcription 1 (STAT1) was chosen because of its involvement in the development of the mammary gland. Using the pooled genomic DNA sequencing approach, we identified a single nucleotide polymorphism. Genomic DNA was extracted from 1,292 sons obtained from the Cooperative Dairy DNA Repository and from 715 blood samples of daughters of 12 bulls obtained from the University of Wisconsin resource population. Daughter yield deviation data for the sons and yield deviation for the daughters were obtained for milk production traits from the USDA Animal Improvement Programs Laboratory. For the Repository population, allele C was associated with significant increases in milk fat and protein percentages. For the University of Wisconsin population, genotypes CC and CT were associated with significant increases in milk, fat, and protein yields. Results from this study are consistent with previous studies on the role of STAT1 in regulating the transcription of genes involved in milk protein synthesis and fat metabolism.