Plexin-B2, but not Plexin-B1, critically modulates neuronal migration and patterning of the developing nervous system in vivo

Semaphorins and their receptors, plexins, have emerged as important cellular cues regulating key developmental processes. B-type plexins directly regulate the actin cytoskeleton in a variety of cell types. Recently, B-type plexins have been shown to be expressed in striking patterns in the nervous system over critical developmental windows. However, in contrast to the well characterized plexin-A family, the functional role of plexin-B proteins in neural development and organogenesis in vertebrates in vivo is not known. Here, we have elucidated the functional contribution of the two neuronally expressed plexin-B proteins, Plexin-B1 or Plexin-B2, toward the development of the peripheral nervous system and the CNS by generating and analyzing constitutive knock-out mice. The development of the nervous system was found to be normal in mice lacking Plexin-B1, whereas mice lacking Plexin-B2 demonstrated defects in closure of the neural tube and a conspicuous disorganization of the embryonic brain. After analyzing mutant mice, which bypassed neural tube defects, we observed a key requirement for Plexin-B2 in proliferation and migration of granule cell precursors in the developing dentate gyrus, olfactory bulb, and cerebellum. Furthermore, we identified semaphorin 4C as a high-affinity ligand for Plexin-B2 in binding and functional assays. Semaphorin 4C stimulated activation of ErbB-2 and RhoA via Plexin-B2 and enhanced proliferation and migration of granule cell precursors. Semaphorin 4C-induced proliferation of ventricular zone neuroblasts was abrogated in mice lacking Plexin-B2. These genetic and functional analyses reveal a key requirement for Plexin-B2, but not Plexin-B1, in patterning of the vertebrate nervous system in vivo

The role of community social capital in the relationship between socioeconomic status and adolescent life satisfaction: mediating or moderating? Evidence from Czech data

This work was supported by the Ministry of Education, Youth and Sports (MEYS) under contracts No. LG14042 and No. LG 14043.Background. The concept of social capital has been extensively used to explain the relationship between socioeconomic status (SES) and adolescent health and well-being. Much less is known about the specific mechanism through which social capital impacts the relationship. This paper investigates whether an individual’s perception of community social capital moderates or mediates the association between SES and life satisfaction. Methods. This study employs cross-sectional data from the 2009–2010 Czech Health Behaviour in School-Aged Children survey: a WHO Collaborative Cross-National Study (HBSC). A sample of 4425 adolescents from the 5th, 7th and 9th grade (94.5% school response rate, 87% student response) was used to perform multilevel analysis. Results. We found that pupils’ life satisfaction was positively related to both family affluence and perceived wealth. Moreover, we found the cognitive component of social capital to be positively associated with life satisfaction. Additionally, a significant interaction was found, such that the social gradient in life satisfaction was flattened when pupils reported high levels of perceived community social capital. Conclusions. The present findings suggest that community social capital acts as an unequal health resource for adolescents, but could potentially represent opportunities for public health policy to close the gap in socioeconomic disparities.Publisher PDFPeer reviewe