Expression of rigf, a member of avian VEGF family, correlates with vascular patterning in the developing chick limb bud

Association of genetic polymorphisms in vascular endothelial growth factor with susceptibility to coronary artery disease: a meta-analysis

Background

Single nucleotide polymorphisms (SNPs) located in the vascular endothelial growth factor (VEGF) gene may be correlated with the susceptibility to coronary artery disease (CAD) – although results have been controversial. The aim of this meta–analysis is to clarify the effects of VEGF –2578A/C (rs699947), −1154G/A (rs1570360), +405C/G (rs2010963), and + 936C/T (rs3025039) polymorphisms on CAD risk.

Methods

Pooled odds ratio (OR) and corresponding 95% confidence intervals (CIs) were calculated to estimate the strength of the association between VEGF gene polymorphisms and CAD risk. Fixed- or random-effects model was used depending on the heterogeneity between studies.

Results

In total, 13 eligible articles containing 29 studies were analysed. The pooled analysis indicated that the VEGF gene polymorphisms of rs699947, rs2010963, and rs3025039 were associated with an increased risk of CAD, whereas no significant associations were observed with the rs1570360 polymorphism. A subgroup analysis stratified by ethnicity revealed that the rs699947 and rs3025039 polymorphisms were associated with CAD risk in Asian populations. In addition, stratification by control source indicated an increased risk of CAD susceptibility with the rs699947 polymorphism for population–based studies of reduced heterogeneity.

Conclusions

In summary, we concluded that the VEGF gene polymorphisms rs699947, rs2010963, and rs3025039 are correlated with an elevated CAD risk.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0628-3) contains supplementary material, which is available to authorized users.

Retinol-binding protein 4 is expressed in chondrocytes of developing mouse long bones: implications for a local role in formation of the secondary ossification center

Retinol-binding protein 4 (Rbp4) is the major carrier of retinol in the bloodstream, a retinoid whose metabolites influence osteogenesis, chondrogenesis and adipogenesis. Rbp4 is mainly produced in the liver where it mobilizes hepatic retinol stores to supply other tissues. However, Rbp4 is also expressed in several extrahepatic tissues, including limbs, where its role is largely unknown. This study aimed to identify the cellular localization of Rbp4 to gain insight into its involvement in limb development and bone growth. Using immunohistochemistry, we discovered that Rbp4 was present in a variety of locations in developing embryonic and postnatal mouse hindlimbs. Rbp4 was present in a restricted population of epiphyseal chondrocytes and perichondral cells correlating to the future region of secondary ossification. With the onset of secondary ossification, Rbp4 was detected in chondrocytes of the resting zone and in chondrocytes that bordered invading cartilage canals and the expanding front of ossification. Rbp4 was less abundant in proliferating chondrocytes involved in primary ossification. Our data implicate the involvement of chondrocytic Rbp4 in bone growth, particularly in the formation of the secondary ossification center of the limb.

Essential role of heparan sulfate 2-O-sulfotransferase in chick limb bud patterning and development

The interactions of heparan sulfate (HS) with heparin-binding growth factors, such as fibroblast growth factors (FGFs), depend greatly on the chain structures. O-Sulfations at various positions on the chain are major factors determining HS structure; therefore, O-sulfation patterns may play a crucial role in controlling the developmental and morphogenetic processes of various tissues and organs by spatiotemporally regulating the activities of heparin-binding growth factors. In a previous study, we found that HS-2-O-sulfotransferase is strongly expressed throughout the mesoderm of chick limb buds during the early stages of development. Here we show that inhibition of HS-2-O-sulfotransferase in the prospective limb region by small inhibitory RNA resulted in the truncation of limb buds and reduced Fgf-8 expression in the apical ectodermal ridge. The treatment also reduced Fgf-10 expression in the mesenchyme. Moreover 2-O-sulfated HS, normally abundant in the basement membranes and mesoderm under ectoderm in limb buds, was significantly reduced in the treated buds. Phosphorylation levels of ERK and Akt were up-regulated in such truncated buds. Thus, we have shown for the first time that 2-O-sulfation of HS is essential for the FGF signaling required for limb bud development and outgrowth.

Analysis of talpid3 and wild-type chicken embryos reveals roles for Hedgehog signalling in development of the limb bud vasculature

Chicken talpid(3) mutant embryos have a wide range of Hedgehog-signalling related defects and it is now known that the talpid(3) gene product encodes a novel protein essential for Hedgehog signalling which is required for both activator and repressor functions of Gli transcription factors (Davey, M.G., Paton, I.R., Yin, Y., Schmidt, M., Bangs, F.K., Morrice, D.R., Gordon-Smith, T., Buxton, P., Stamataki, D., Tanaka, M., Münsterberg, A.E., Briscoe, J., Tickle, C., Burt, D.W. (2006). The chicken talpid(3) gene encodes a novel protein essential for Hedgehog signalling. Genes Dev 20 1365-77). Haemorrhaging, oedema and other severe vascular defects are a central aspect of the talpid(3) phenotype (Ede, D.A. and Kelly, W.A (1964a). Developmental abnormalities in the head region of the talpid(3) mutant fowl. J. Embryol. exp. Morp. 12:161-182) and, as Hedgehog (Hh) signalling has been implicated in every stage of development of the vascular system, the vascular defects seen in talpid(3) are also likely to be attributable to abnormal Hedgehog signalling. Gene expression of members of the VEGF and Angiopoietin families of angiogenic growth factors has been linked to haemorrhaging and oedema and we find widespread expression of VEGF-D, rigf and Ang2a in the talpid(3) limb. Furthermore, ectopic expression of these genes in talpid(3) limbs points to regulation via Gli repression rather than activation. We monitored specification of vessel identity in talpid(3) limb vasculature by examining expression of artery-specific genes, Np1 and EphrinB2, and the vein-specific genes, Np2a and Tie2. We show that there are supernumerary subclavian arteries in talpid(3) limb buds and abnormal expression of an artery-specific gene in the venous submarginal sinus, despite the direction of blood flow being normal. Furthermore, we show that Shh can induce Np1 expression but has no effect on Np2a. Finally, we demonstrate that induction of VEGF and Ang2a expression by Shh in normal limb buds is accompanied by vascular remodelling. Thus Hedgehog signalling has a pivotal role in the cascade of angiogenic events in a growing embryonic organ which is similar to that proposed in tumours.

Region-specific expression ofmario reveals pivotal function of the anterior nondigit region on digit formation in chick wing bud

We report the region-specific expression of a novel gene, named mario, whose expression domain is in the distal tip of the presumptive and developing digit 2 region in the developing chick wing bud. The anterior region-specific expression of mario corresponds well with the presence of digit 2, and fate map analysis showed that mario expression at early stages represents the presumptive digit 2 region. Using mario expression as a region-specific marker for the digit 2 region, several surgical operations were performed to obtain insights into digit 2 development in the chick wing. Cell fate tracing concomitant with a zone of polarizing activity (ZPA) implantation revealed that an additional digit 2 in the ZPA implantation into the anterior or middle region of wing bud is derived from the original digit 2 region (mario-positive region). Surgical manipulations revealed that the anterior nondigit region has an inhibitory effect on digit 2 formation. Taken together, these results suggest that the most-anterior region, including the anterior necrotic zone, restricts the position of digit 2 region by limiting the anterior border of the digit 2 region and preventing its expansion.