Molecular and functional diversity of neural connexins in the retina.

Abstract

Electrical synapses (gap junctions) in neuronal circuits have become a major focus in the study of network properties such as synchronization and oscillation (Galarreta and Hestrin, 1999; Gibson et al., 1999). Despite the recent progress made in unraveling the contribution of gap junctions to network behavior, little is known about the molecular composition of the junctional constituents. By cloning gap junction proteins [connexins (Cxs)] from zebrafish retina and through functional expression, we demonstrate that the retina possesses a high degree of connexin diversity, which may account for differential functional properties of electrical synapses. Three new Cxs, designated as zebrafish Cx27.5 (zfCx27.5), zfCx44.1, and zfCx55.5, and the carp ortholog of mammalian Cx43 were cloned. By in situ hybridization and in situ RT-PCR, we demonstrate that the four fish connexin mRNAs show differential localization in the retina. Transient functional expression in paired Xenopus oocytes and in the neuroblastoma N2A cell line indicate an extreme range of electrophysiological properties of these connexins in terms of voltage dependence and unitary conductance. For instance, the new zfCx44.1 exhibited high sensitivity to voltage-induced closure with currents decaying rapidly for transjunctional potentials >10 mV, whereas zfCx55.5 channels showed an opposite voltage dependence in response to voltage steps of either polarity. Moreover, although zfCx44.1 channels showed unitary conductance as high as any previously reported for junctional channels (nearly 300 pS), zfCx55. 5 and zfCx27.5 exhibited much lower unitary conductances (<60 pS).

• Authors: R Dermietzel, M Kremer, G Paputsoglu, A Stang, I M Skerrett, D Gomes, M Srinivas, U Janssen-Bienhold, R Weiler, B J Nicholson, R Bruzzone, D C Spray
• Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience (J Neurosci) Vol. 20 Issue 22 Pg. 8331-43 (Nov 15 2000) ISSN: 1529-2401 [Electronic] United States
• PMID: 11069940 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Connexin 43
• Connexins
• Eye Proteins
• RNA, Messenger
• Zebrafish Proteins
• connexin 50
• cx27.5 protein, zebrafish
• cx55.5 protein, zebrafish
• Connexin 26

Topics

• Animals
• Carps
• Cells, Cultured
• Cloning, Molecular
• Connexin 26
• Connexin 43 (genetics, metabolism)
• Connexins (genetics, metabolism)
• Conserved Sequence
• Eye Proteins (genetics, metabolism)
• Female
• Gap Junctions (metabolism)
• Gene Expression
• In Situ Hybridization
• Microinjections
• Molecular Sequence Data
• Neurons (cytology, metabolism)
• Oocytes (cytology, metabolism)
• Organ Specificity (genetics)
• Patch-Clamp Techniques
• RNA, Messenger (metabolism)
• Retina (metabolism)
• Reverse Transcriptase Polymerase Chain Reaction
• Sequence Alignment
• Synapses (metabolism)
• Xenopus laevis
• Zebrafish
• Zebrafish Proteins