Molecular cloning and functional expression of zfCx52.6: a novel connexin with hemichannel-forming properties expressed in horizontal cells of the zebrafish retina.
Gap junction-mediated electrical coupling contributes to synchronous oscillatory activities of neurons, and considerable progress has been made in defining the molecular composition of gap junction channels. In particular, cloning and functional expression of gap junction proteins (connexins (Cx)) from zebrafish retina have shown that this part of the brain possesses a high degree of connexin diversity that may account for differential functional properties of electrical synapses. Here, we report the cloning and functional characterization of a new connexin, designated zebrafish Cx52.6 (zfCx52.6). This connexin shows little similarity to known connexins from fish and higher vertebrates. By combining in situ hybridization with Laser Capture Microdissection and RT-PCR, we found that this novel fish connexin is expressed in horizontal cells in the inner nuclear layer of the retina. Functional expression of zfCx52.6 in neuroblastoma cells and Xenopus oocytes led to functional gap junctional channels and, in single oocytes, induced large non-junctional membrane currents indicative of the formation of hemichannels, which were inhibited in reversible fashion by raising extracellular Ca(2+) concentrations.
Zoidl
Georg
G
Department of Neuroanatomy and Molecular Brain Research, Ruhr-University-Bochum, University Street 150, D-44801 Bochum, Germany.
Bruzzone
Roberto
R
Weickert
Svenja
S
Kremer
Marian
M
Zoidl
Christiane
C
Mitropoulou
Georgia
G
Srinivas
Miduturu
M
Spray
David C
DC
Dermietzel
Rolf
R
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D017630:Connexins / Q000235:genetics* / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D012160:Retina / Q000378:metabolism*; D016415:Sequence Alignment; D014981:Xenopus; D015027:Zebrafish / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000378:metabolism
D017630:Connexins; C483906:Cx52.6 protein, zebrafish; D029961:Zebrafish Proteins