title: Pannexin1 channel proteins in the zebrafish retina have shared and unique properties.
abstract: In mammals, a single pannexin1 gene (Panx1) is widely expressed in the CNS including the inner and outer retinae, forming large-pore voltage-gated membrane channels, which are involved in calcium and ATP signaling. Previously, we discovered that zebrafish lack Panx1 expression in the inner retina, with drPanx1a exclusively expressed in horizontal cells of the outer retina. Here, we characterize a second drPanx1 protein, drPanx1b, generated by whole-genome duplications during teleost evolution. Homology searches strongly support the presence of pannexin sequences in cartilaginous fish and provide evidence that pannexins evolved when urochordata and chordata evolution split. Further, we confirm Panx1 ohnologs being solely present in teleosts. A hallmark of differential expression of drPanx1a and drPanx1b in various zebrafish brain areas is the non-overlapping protein localization of drPanx1a in the outer and drPanx1b in the inner fish retina. A functional comparison of the evolutionary distant fish and mouse Panx1s revealed both, preserved and unique properties. Preserved functions are the capability to form channels opening at resting potential, which are sensitive to known gap junction and hemichannel blockers, intracellular calcium, extracellular ATP and pH changes. However, drPanx1b is unique due to its highly complex glycosylation pattern and distinct electrophysiological gating kinetics. The existence of two Panx1 proteins in zebrafish displaying distinct tissue distribution, protein modification and electrophysiological properties, suggests that both proteins fulfill different functions in vivo.
authors.affiliation: Neuroanatomy, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany ; Psychology, Faculty of Health, York University, Toronto, Ontario, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: Kurtenbach
authors.forename: Nora
authors.initials: N
authors.lastname: Prochnow
authors.forename: Stefan
authors.initials: S
authors.lastname: Kurtenbach
authors.forename: Jan
authors.initials: J
authors.lastname: Klooster
authors.forename: Christiane
authors.initials: C
authors.lastname: Zoidl
authors.forename: Rolf
authors.initials: R
authors.lastname: Dermietzel
authors.forename: Maarten
authors.initials: M
authors.lastname: Kamermans
authors.forename: Georg
authors.initials: G
authors.lastname: Zoidl
mesh_terms: D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017630:Connexins / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005786:Gene Expression Regulation / Q000235:genetics*; D007150:Immunohistochemistry; D007700:Kinetics; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009841:Oligonucleotides / Q000235:genetics; D018408:Patch-Clamp Techniques; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012160:Retina / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D015027:Zebrafish / Q000235:genetics* / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D017630:Connexins; D009841:Oligonucleotides; D020033:Protein Isoforms; D029961:Zebrafish Proteins; C544702:panx1a protein, zebrafish