Characterization of the neuroligin gene family expression and evolution in zebrafish

Abstract

Neuroligins constitute a family of transmembrane proteins localized at the postsynaptic side of both excitatory and inhibitory synapses of the central nervous system. They are involved in synaptic function and maturation and recent studies have linked mutations in specific human Neuroligins to mental retardation and autism. We isolated the human Neuroligin homologs in Danio rerio. Next, we studied their gene structures and we reconstructed the evolution of the Neuroligin genes across vertebrate phyla. Using reverse-transcriptase polymerase chain reaction, we analyzed the expression and alternative splicing pattern of each gene during zebrafish embryonic development and in different adult organs. By in situ hybridization, we analyzed the temporal and spatial expression pattern during embryonic development and larval stages and we found that zebrafish Neuroligins are expressed throughout the nervous system. Globally, our results indicate that, during evolution, specific subfunctionalization events occurred within paralogous members of this gene family in zebrafish. Developmental Dynamics 239:688-702,

The Synaptic Proteins β-Neurexin and Neuroligin Synergize With Extracellular Matrix-Binding Vascular Endothelial Growth Factor A During Zebrafish Vascular Development

“…16 In parallel, we identified the members of zebrafish (Danio rerio) NRXN and NLGN gene families. 17,18 To deepen the functional characterization of these 2 gene families in vascular development, we took advantage of the zebrafish model system to perform an in vivo study. Given the lack of in vivo functional data for β-NRXNs and starting from our previous findings, 16 we focused our analyses on the β-nrxn1a and nlgn1 genes.…”

“…18,19 The following lines were used: Tg(gata1:dsRed) 20 and Tg(flk1:EGFP). 21 The double transgenic line Tg(gata1:dsRed) sd2 ;(kdrl:EGFP) s843 was a generous gift from Dr Massimo Santoro (Laboratory of Cardiovascular Biology, Molecular Biotechnology Center, Torino, Italy).…”

“…23 Specific probes for nlgn1, cdh5, vsg1, flk1, tie2, and flt4 were synthesized and used, as previously described. 18,23 All the probes were purified using Spin Post-Reaction Clean-Up Columns ( Sigma-Aldrich, St Louis, MO) before use. We used 2 different probes for the nrxn1a gene: a probe specific for both α-and β-forms and a second probe specific only for β-forms.…”

Nervous vascular parallels: axon guidance and beyond

“…Both gene families present a high degree of evolutionary conservation that can be explained by the action of a positive selective pressure which in turn suggests a conservation of their functions across vertebrate evolution (Rissone et al, 2007;Rissone et al, 2010) Neurexins, which are produced as a long (a) and a short (b) forms by each of their genes, have been widely studied because of their exceptionally extended alternative splicing (Rissone et al, 2007;Tabuchi and Sudhof, 2002) and have been indirectly localized at the pre-synaptic membrane (Sudhof, 2001). Thousands of different isoforms were predicted to be produced by the three mammalian neurexin genes, so that they were proposed as molecular codes for the specific reciprocal neuronal recognition (Missler and Sudhof, 1998).…”

Neurexins and neuroligins: synapses look out of the nervous system

“…Generally, vertebrates present three different Neurexin genes and at least four Neuroligins. Different studies indicated that vertebrate Neurexins and Neuroligins are strongly conserved from fish to human [6,[39][40][41][42]. The comparison of human Neurexin genes indicated a strong preservation of gene structure and a high degree of sequence conservation in the introns flanking alternative splicing sites, in particular between Neurexin 1 and 3 [33,43].…”