Tbx1 regulates Vegfr3 and is required for lymphatic vessel development

Defects in lymphangiogenesis are added to the broad clinical manifestations of DiGeorge syndrome, caused by deletion of the T box transcription factor Tbx1

Differential Specificity of Endocrine FGF19 and FGF21 to FGFR1 and FGFR4 in Complex with KLB

Background: Recent studies suggest that betaKlotho (KLB) and endocrine FGF19 and FGF21 redirect FGFR signaling to regulation of metabolic homeostasis and suppression of obesity and diabetes. However, the identity of the predominant metabolic tissue in which a major FGFR-KLB resides that critically mediates the differential actions and metabolism effects of FGF19 and FGF21 remain unclear. Methodology/Principal Findings: We determined the receptor and tissue specificity of FGF21 in comparison to FGF19 by using direct, sensitive and quantitative binding kinetics, and downstream signal transduction and expression of early response gene upon administration of FGF19 and FGF21 in mice. We found that FGF21 binds FGFR1 with much higher affinity than FGFR4 in presence of KLB; while FGF19 binds both FGFR1 and FGFR4 in presence of KLB with comparable affinity. The interaction of FGF21 with FGFR4-KLB is very weak even at high concentration and could be negligible at physiological concentration. Both FGF19 and FGF21 but not FGF1 exhibit binding affinity to KLB. The binding of FGF1 is dependent on where FGFRs are present. Both FGF19 and FGF21 are unable to displace the FGF1 binding, and conversely FGF1 cannot displace FGF19 and FGF21 binding. These results indicate that KLB is an indispensable mediator for the binding of FGF19 and FGF21 to FGFRs that is not required for FGF1. Although FGF19 can predominantly activate the responses of the liver and to a less extent the adipose tissue, FGF21 can do so significantly only in the adipose tissue an

Identification of variables contributing to superovulation efficiency for production of transgenic prairie voles (<it>Microtus ochrogaster</it>)

Abstract Background The prairie vole (Microtus ochrogaster) is an emerging animal model for biomedical research because of its rich sociobehavioral repertoire. Recently, lentiviral transgenic technology has been used to introduce the gene encoding the green fluorescent protein (GFP) into the prairie vole germline. However, the efficiency of transgenesis in this species is limited by the inability to reliably produce large numbers of fertilized embryos. Here we examined several factors that may contribute to variability in superovulation success including, age and parentage of the female, and latency to mating after being placed with the male. Methods Females produced from 5 genetically distinct breeder lines were treated with 100 IU of pregnant mare serum gonadotrophin (PMSG) and immediately housed with a male separated by a perforated Plexiglas divider. Ovulation was induced 72 hr later with 30 IU of human chorionic gonadotropin (hCG) and 2 hrs later mating was allowed. Results Superovulation was most efficient in young females. For example, females aged 6-11 weeks produced more embryos (14 +/- 1.4 embryos) as compared to females aged 12-20 weeks (4 +/- 1.6 embryos). Females aged 4-5 weeks did not produce embryos. Further, females that mated within 15 min of male exposure produced significantly more embryos than those that did not. Interestingly, there was a significant effect of parentage. For example, 12 out of 12 females from one breeder pair superovulated (defined as producing 5 or more embryos), while only 2 out of 10 females for other lines superovulated. Conclusions The results of this work suggest that age and genetic background of the female are the most important factors contributing to superovulation success and that latency to mating is a good predictor of the number of embryos to be recovered. Surprisingly we found that cohabitation with the male prior to mating is not necessary for the recovery of embryos but is necessary to recover oocytes. This information will dramatically reduce the number of females required to generate embryos for transgenesis in this species.</p

Control of lipid metabolism by adipocyte FGFR1-mediated adipohepatic communication during hepatic stress

Abstract Background Endocrine FGF19 and FGF21 exert their effects on metabolic homeostasis through fibroblast growth factor receptor (FGFR) and co-factor betaKlotho (KLB). Ileal FGF19 regulates bile acid metabolism through specifically FGFR4-KLB in hepatocytes where FGFR1 is not significant. Both FGF19 and FGF21 activate FGFR1-KLB whose function predominates in adipocytes. Recent studies using administration of FGF19 and FGF21 and genetic ablation of KLB or adipocyte FGFR1 indicate that FGFR1-KLB mediates the response of adipocytes to both FGF21 and FGF19. Here we show that adipose FGFR1 regulates lipid metabolism through direct effect on adipose tissue and indirect effects on liver under starvation conditions that cause hepatic stress. Methods We employed adipocyte-specific ablations of FGFR1 and FGFR2 genes in mice, and analyzed metabolic consequences in adipose tissue, liver and systemic parameters under normal, fasting and starvation conditions. Results Under normal conditions, the ablation of adipose FGFR1 had little effect on adipocytes, but caused shifts in expression of hepatic genes involved in lipid metabolism. Starvation conditions precipitated a concurrent elevation of serum triglycerides and non-esterified fatty acids, and increased hepatic steatosis and adipose lipolysis in the FGFR1-deficient mice. Little effect on glucose or ketone bodies due to the FGFR1 deficiency was observed. Conclusions Our results suggest an adipocyte-hepatocyte communication network mediated by adipocyte FGFR1 that concurrently dampens hepatic lipogenesis and adipocyte lipolysis. We propose that this serves overall to mete out and extend lipid reserves for neural fuels (glucose and ketone bodies), while at the same time governing extent of hepatosteatosis during metabolic extremes and other conditions causing hepatic stress.</p

Differential tissue-specific responses to FGF21 and FGF19 as measured by the expression level of early responsive gene c-Fos.

<p>Thirty age- and weight-matched mice (2×3×5) were fasted for 24 hrs with water freely available, and then injected intraperitoneally with FGF21, FGF19 (0.5 mg/Kg body weight) and PBS vesicle control as indicated. After 20 min, liver and adipose tissue (A) and several other endocrine and metabolic tissues (B) were isolated and processed for RNA purification. Quantitative PCR was used to assess the expression of c-Fos in response to different treatments (n = 5).</p

Dose-dependent differential binding of FGF21, FGF19 and FGF1 to KLB or FGFR4 alone.

<p>(A) Interaction of FGF21, FGF19 and FGF1 with KLB. Graded concentrations as indicated for FGF21 (open square), FGF19 (not shown) and FGF1 (filled circle) were added together with 2 ng/ml ¹²⁵I-FGF19 to the cells expressing KLB alone, and the remaining specific bindings of ¹²⁵I-FGF1 under these conditions were then determined. (B) Competitive binding of FGF21 and FGF1 with FGF19 to FGFR4 alone. Graded concentrations as indicated for FGF21 (open square), FGF19 (not shown) and FGF1 (filled circle) were added together with 2 ng/ml ¹²⁵I-FGF19 to the cells expressing FGFR4 alone, and the remaining specific bindings of ¹²⁵I-FGF1 under these conditions were then determined.</p

Dose-dependent differential binding of FGF21, FGF19 and FGF1 to FGFR1-KLB and FGFR4-KLB.

<p>(A) Competition ability of FGF21 and FGF1 with FGF19 to bind FGFR-KLB. Graded concentrations as indicated for FGF21 (open square), FGF19 (filled triangle) and FGF1 (filled circle) were added together with 2 ng/ml ¹²⁵I-FGF19 to the cells expressing FGFR1-KLB (solid line) or FGFR4-KLB (dot line) after 30 ng/ml Tet induction overnight, the remaining specific bindings of ¹²⁵I-FGF19 were determined as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0033870#pone-0033870-g001" target="_blank">Figure 1A</a>. (B) Competition ability of FGF21 with FGF1 to bind FGFR1-KLB. Graded concentrations as indicated for FGF21 (open square), FGF19 (not shown) and FGF1 (filled circle) were added together with 2 ng/ml ¹²⁵I-FGF1 to the cells expressing FGFR1-KLB (solid line) or FGFR4-KLB (Inset), the remaining specific bindings of ¹²⁵I-FGF1 under these conditions were determined as described above.</p