NCBI Summary:
This gene product is a member of the Vanin family of proteins that share extensive sequence similarity with each other, and also with biotinidase. The family includes secreted and membrane-associated proteins, a few of which have been reported to participate in hematopoietic cell trafficking. No biotinidase activity has been demonstrated for any of the vanin proteins, however, they possess pantetheinase activity, which may play a role in oxidative-stress response. The encoded protein is a GPI-anchored cell surface molecule that plays a role in transendothelial migration of neutrophils. This gene lies in close proximity to, and in same transcriptional orientation as two other vanin genes on chromosome 6q23-q24. Alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, May 2011]
General function
Enzyme
Comment
Cellular localization
Plasma membrane
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Ovarian function
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Expression, Regulation, and Promoter Activation of Vanin-2 (VNN2) in Bovine Follicles Prior to Ovulation. Sayasith K 2013 et al.
Vanin-2 (VNN2) is known to be involved in inflammation and leukocyte migration, but its regulation in follicles remains unknown. The objectives of this work were to study the regulation of VNN2 transcripts in bovine follicles prior to ovulation, and to characterize the control of its expression in bovine granulosa cells. VNN2 expression was studied using total RNA extracted from granulosa cells of small follicles (2-4 mm in diameter), dominant follicles obtained on day 5 of the estrous cycle, ovulatory follicles obtained 0-24 h after human chorionic gonadotropin (hCG), and corpora lutea on day 5 of the cycle. Results from RT-PCR analyses showed that levels of VNN2 mRNA were high in ovulatory follicles 24 h post-hCG but low in other tissues. In ovulatory follicles, levels of VNN2 mRNA were low at 0 h but significantly upregulated 12-24 h post-hCG. To determine factors controlling VNN2 gene expression, established primary cultures of granulosa cells isolated from bovine dominant follicles were used. Treatment with forskolin elevated VNN2 mRNA expression as observed in vivo. Mutation studies identified the minimal region conferring basal and forskolin-stimulated VNN2 promoter activities, which were dependent on chicken ovalbumin upstream promoter-transcription factor (COUP-TF), GATA and Ebox cis-elements. EMSAs identified COUP-TF, GATA4, and upstream stimulating factor (USF) proteins as key factors interacting with these elements. Chromatin immunoprecipitation assays confirmed basal and forskolin-induced interactions between these proteins and the VNN2 promoter in bovine granulosa cell cultures. VNN2 promoter activity and mRNA expression were markedly stimulated by forskolin and overexpression of the catalytic subunit of PKA, but inhibited by PKA and ERK1/2 inhibitors. Collectively, findings from this study describe for the first time the gonadotropin/forskolin-dependent up-regulation of VNN2 transcripts in granulosa cells of preovulatory follicles, and provide insights into some of the molecular basis of VNN2 gene expression in follicular cells.
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Expression regulated by
LH
Comment
Ovarian localization
Granulosa, Luteal cells
Comment
The effect of energy balance on the transcriptome of bovine granulosa cells at 60 days postpartum. Girard A et al. (2015) Dairy cows expend great amounts of energy during the lactation peak to cope with milk production. A state of negative energy balance (NEB) was suggested as a cause for the suboptimal fertility observed during this period, via an interaction with ovarian function. The objective of this study was to identify the impact of NEB on gene expression in granulosa cells of dairy cows at 60 days postpartum and to suggest a potential treatment to improve ovarian function. Dairy cows at 60 days postpartum from 10 typical medium-sized farms were synchronized using a single injection of prostaglandin. Dominant follicles were collected 42 hours later by transvaginal aspiration. Blood concentrations of beta-hydroxybutyrate (BHB) on the day of aspiration were used to classify animals into two groups: severe NEB (high BHB, n = 12) and mild NEB (low BHB, n = 12). The transcriptomes of granulosa cells from both groups were contrasted using microarrays, and the differentially expressed genes were analyzed using Ingenuity Pathway Analysis to identify affected functions and potential upstream regulators. Genes linked with cellular organization (KRT4 and PPL), proliferation (TACSTD2), and fatty acids metabolism (VNN2) were downregulated in granulosa cells from animals with severe NEB. Several genes linked to decitabine, a hypomethylating agent, and with beta-estradiol, were downregulated in the severe NEB group. Numerous genes linked to vitamins A and D were also downregulated in this group of cows, suggesting a potential deficiency of these vitamins in dairy cows during the postpartum period. This study supports the idea that energy balance has an impact on follicular dynamics which could be detrimental to resumption of fertility after calving.//////////////////