The calmodulin-stimulated adenylate cyclase ADCY8 sets the sensitivity of zebrafish retinal axons to midline repellents and is required for normal midline crossing.
The chemokine SDF1 activates a cAMP-mediated signaling pathway that antagonizes retinal responses to the midline repellent slit. We show that knocking down the calmodulin-activated adenylate cyclase ADCY8 makes retinal axons insensitive to SDF1. Experiments in vivo using male and female zebrafish (Danio rerio) confirm a mutual antagonism between slit signaling and ADCY8-mediated signaling. Unexpectedly, knockdown of ADCY8 or another calmodulin-activated cyclase, ADCY1, induces ipsilateral misprojections of retinal axons that would normally cross the ventral midline. We demonstrate a cell-autonomous requirement for ADCY8 in retinal neurons for normal midline crossing. These findings are the first to show that ADCY8 is required for axonal pathfinding before axons reach their targets. They support a model in which ADCY8 is an essential component of a signaling pathway that opposes repellent signaling. Finally, they demonstrate that ADCY8 helps regulate retinal sensitivity to midline guidance cues.
Xu
Hong
H
Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Leinwand
Sarah G
SG
Dell
Alison L
AL
Fried-Cassorla
Emma
E
Raper
Jonathan A
JA
D000262:Adenylyl Cyclases / Q000235:genetics / Q000502:physiology*; D000818:Animals; D030801:Animals, Genetically Modified; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D017690:Cell Transplantation; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000494:pharmacology; D002642:Chick Embryo; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D018274:Electroporation / Q000379:methods; D004625:Embryo, Nonmammalian; D005260:Female; D007839:Functional Laterality; D019922:GAP-43 Protein / Q000235:genetics; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000378:metabolism; D020320:Oligoribonucleotides, Antisense / Q000494:pharmacology; D012160:Retina / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D014162:Transfection; D015027:Zebrafish; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism; D000098552:Slit Homolog 2 Protein
D054377:Chemokine CXCL12; D019922:GAP-43 Protein; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D020320:Oligoribonucleotides, Antisense; D029961:Zebrafish Proteins; D049452:Green Fluorescent Proteins; D005576:Colforsin; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; C118292:adenylyl cyclase 8; D000098552:Slit Homolog 2 Protein