HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 99/5/2522    most recent 01066.2007v1 Alert me when this article is cited 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 (1) Citing Articles via Google Scholar Google Scholar Articles by Graham, D. M. Articles by Berson, D. M. Search for Related Content PubMed PubMed Citation Articles by Graham, D. M. Articles by Berson, D. M.

Melanopsin Ganglion Cells Use a Membrane-Associated Rhabdomeric Phototransduction Cascade

Department of Neuroscience, Brown University, Providence, Rhode Island

Submitted 25 September 2007; accepted in final form 22 February 2008

Intrinsically photosensitive retinal ganglion cells (ipRGCs) are photoreceptors of the mammalian eye that drive pupillary responses, synchronization of circadian rhythms, and other reflexive responses to daylight. Melanopsin is the ipRGC photopigment, but the signaling cascade through which this invertebrate-like opsin triggers the photocurrent in these cells is unknown. Here, using patch-clamp recordings from dissociated ipRGCs in culture, we show that a membrane-associated phosphoinositide cascade lies at the heart of the ipRGC phototransduction mechanism, similar to the cascade in rhabdomeric photoreceptors of invertebrate eyes. When ipRGCs were illuminated, melanopsin activated a G protein of the G_q/11 class, stimulating the effector enzyme phospholipase C. The presence of these signaling components in ipRGCs was confirmed by single-cell RT-PCR and immunofluorescence. The photoresponse was fully functional in excised inside-out patches of ipRGC membrane, indicating that all core signaling components are within or tightly coupled to the plasma membrane. The striking similarity of phototransduction in ipRGCs and invertebrate rhabdomeric photoreceptors reinforces the emerging view that these cells have a common evolutionary origin.

This article has been cited by other articles:

				P. Vopalensky and Z. Kozmik Eye evolution: common use and independent recruitment of genetic components Phil Trans R Soc B, October 12, 2009; 364(1531): 2819 - 2832. [Abstract] [Full Text] [PDF]

				M. del Pilar Gomez, J. M. Angueyra, and E. Nasi Light-transduction in melanopsin-expressing photoreceptors of Amphioxus PNAS, June 2, 2009; 106(22): 9081 - 9086. [Abstract] [Full Text] [PDF]

				M. D. Rollag Does Melanopsin Bistability Have Physiological Consequences? J Biol Rhythms, October 1, 2008; 23(5): 396 - 399. [PDF]

				D.-G. Luo, T. Xue, and K.-W. Yau How vision begins: An odyssey PNAS, July 22, 2008; 105(29): 9855 - 9862. [Abstract] [Full Text] [PDF]