AUTHOR=Di Schiavi Elia , Vistoli Giulio , Moretti Roberta Manuela , Corrado Ilaria , Zuccarini Giulia , Gervasoni Silvia , Casati Lavinia , Bottai Daniele , Merlo Giorgio Roberto , Maggi Roberto 

TITLE=Anosmin-1-Like Effect of UMODL1/Olfactorin on the Chemomigration of Mouse GnRH Neurons and Zebrafish Olfactory Axons Development

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2022.836179

DOI=10.3389/fcell.2022.836179

ISSN=2296-634X

ABSTRACT=<p>The impairment of development/migration of hypothalamic gonadotropin-releasing hormone (GnRH) neurons is the main cause of Kallmann's syndrome (KS), an inherited disorder characterized by hypogonadism, anosmia, and other developmental defects. Olfactorin is an extracellular matrix protein encoded by the <italic>UMODL1</italic> (uromodulin-like 1) gene expressed in the mouse olfactory region along the migratory route of GnRH neurons. It shares a combination of WAP and FNIII repeats, expressed in complementary domains, with anosmin-1, the product of the <italic>ANOS1</italic> gene, identified as the causative of KS. In the present study, we have investigated the effects of olfactorin <italic>in vitro</italic> and <italic>in vivo</italic> models. The results show that olfactorin exerts an anosmin-1-like strong chemoattractant effect on mouse-immortalized GnRH neurons (GN11 cells) through the activation of the FGFR and MAPK pathways. <italic>In silico</italic> analysis of olfactorin and anosmin-1 reveals a satisfactory similarity at the N-terminal region for the overall arrangement of corresponding WAP and FNIII domains and marked similarities between WAP domains’ binding modes of interaction with the resolved FGFR1–FGF2 complex. Finally, <italic>in vivo</italic> experiments show that the down-modulation of the zebrafish <italic>z-umodl1</italic> gene (orthologous of <italic>UMODL1</italic>) in both GnRH3:GFP and <italic>omp</italic><sup><italic>2k</italic></sup><italic>:gap-CFP</italic><sup><italic>rw034</italic></sup> transgenic zebrafish strains leads to a clear disorganization and altered fasciculation of the neurites of GnRH3:GFP neurons crossing at the anterior commissure and a significant increase in olfactory CFP + fibers with altered trajectory. Thus, our study shows olfactorin as an additional factor involved in the development of olfactory and GnRH systems and proposes <italic>UMODL1</italic> as a gene worthy of diagnostic investigation in KS.</p>