QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, September 24, 2008, 28(39):9769-9789; doi:10.1523/JNEUROSCI.2137-08.2008

This Article Full Text Full Text (PDF) Supplemental Data Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Li, X. Articles by Nagy, J. I. Search for Related Content PubMed PubMed Citation Articles by Li, X. Articles by Nagy, J. I.

 Previous Article  |  Next Article 

Cellular/Molecular
Connexin45-Containing Neuronal Gap Junctions in Rodent Retina Also Contain Connexin36 in Both Apposing Hemiplaques, Forming Bihomotypic Gap Junctions, with Scaffolding Contributed by Zonula Occludens-1

Xinbo Li,^1 * Naomi Kamasawa,^2,3 * Cristina Ciolofan,¹ Carl O. Olson,¹ Shijun Lu,¹ Kimberly G. V. Davidson,³ Thomas Yasumura,³ Ryuichi Shigemoto,² John E. Rash,^3,4 and James I. Nagy¹

¹Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada R3E 3J7, ²Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki 444-8787, Japan, and ³Department of Biomedical Sciences and ⁴Program in Molecular, Cellular, and Integrative Neurosciences, Colorado State University, Fort Collins, Colorado 80523

Correspondence should be addressed to either of the following: Dr. John E. Rash, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, Email: john.rash{at}colostate.edu (regarding FRIL); or Dr. James I. Nagy, Department of Physiology, Faculty of Medicine, University of Manitoba, 730 William Avenue, Winnipeg, Manitoba, Canada R3E 3J7, E-mail: Email: nagyji{at}ms.umanitoba.ca (regarding immunofluorescence, molecular approaches, and cell culture)

Mammalian retinas contain abundant neuronal gap junctions, particularly in the inner plexiform layer (IPL), where the two principal neuronal connexin proteins are Cx36 and Cx45. Currently undetermined are coupling relationships between these connexins and whether both are expressed together or separately in a neuronal subtype-specific manner. Although Cx45-expressing neurons strongly couple with Cx36-expressing neurons, possibly via heterotypic gap junctions, Cx45 and Cx36 failed to form functional heterotypic channels in vitro. We now show that Cx36 and Cx45 coexpressed in HeLa cells were colocalized in immunofluorescent puncta between contacting cells, demonstrating targeting/scaffolding competence for both connexins in vitro. However, Cx36 and Cx45 expressed separately did not form immunofluorescent puncta containing both connexins, supporting lack of heterotypic coupling competence. In IPL, 87% of Cx45-immunofluorescent puncta were colocalized with Cx36, supporting either widespread heterotypic coupling or bihomotypic coupling. Ultrastructurally, Cx45 was detected in 9% of IPL gap junction hemiplaques, 90–100% of which also contained Cx36, demonstrating connexin coexpression and cotargeting in virtually all IPL neurons that express Cx45. Moreover, double replicas revealed both connexins in separate domains mirrored on both sides of matched hemiplaques. With previous evidence that Cx36 interacts with PDZ1 domain of zonula occludens-1 (ZO-1), we show that Cx45 interacts with PDZ2 domain of ZO-1, and that Cx36, Cx45, and ZO-1 coimmunoprecipitate, suggesting that ZO-1 provides for coscaffolding of Cx45 with Cx36. These data document that in Cx45-expressing neurons of IPL, Cx45 is almost always accompanied by Cx36, forming "bihomotypic" gap junctions, with Cx45 structurally coupling to Cx45 and Cx36 coupling to Cx36.

Key words: double replica; FRIL; heterotypic coupling; homotypic coupling; PDZ domains; SDS-FRL

---

Received May 8, 2008; revised July 17, 2008; accepted Aug. 13, 2008.

Correspondence should be addressed to either of the following: Dr. John E. Rash, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, Email: john.rash{at}colostate.edu (regarding FRIL); or Dr. James I. Nagy, Department of Physiology, Faculty of Medicine, University of Manitoba, 730 William Avenue, Winnipeg, Manitoba, Canada R3E 3J7, E-mail: Email: nagyji{at}ms.umanitoba.ca (regarding immunofluorescence, molecular approaches, and cell culture)

This article has been cited by other articles:

				C. Puller, L. P. de Sevilla Muller, U. Janssen-Bienhold, and S. Haverkamp ZO-1 and the Spatial Organization of Gap Junctions and Glutamate Receptors in the Outer Plexiform Layer of the Mammalian Retina J. Neurosci., May 13, 2009; 29(19): 6266 - 6275. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help