Apoptosis Regulates ipRGC Spacing Necessary for Rods and Cones to Drive Circadian Photoentrainment

Shih Kuo Chen, Kylie S. Chew, David S. McNeill, Patrick W. Keeley, Jennifer L. Ecker, Buqing Q. Mao, Johan Pahlberg, Bright Kim, Sammy C.S. Lee, Michael A. Fox, William Guido, Kwoon Y. Wong, Alapakkam P. Sampath, Benjamin E. Reese, Rejji Kuruvilla, Samer Hattar

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The retina consists of ordered arrays of individual types of neurons for processing vision. Here, we show that such order is necessary for intrinsically photosensitive retinal ganglion cells (ipRGCs) to function as irradiance detectors. We found that during development, ipRGCs undergo proximity-dependent Bax-mediated apoptosis. Bax mutant mice exhibit disrupted ipRGC spacing and dendritic stratification with an increase in abnormally localized synapses. ipRGCs are the sole conduit for light input to circadian photoentrainment, and either their melanopsin-based photosensitivity or ability to relay rod/cone input is sufficient for circadian photoentrainment. Remarkably, the disrupted ipRGC spacing does not affect melanopsin-based circadian photoentrainment but severely impairs rod/cone-driven photoentrainment. We demonstrate reduced rod/cone-driven cFos activation and electrophysiological responses in ipRGCs, suggesting that impaired synaptic input to ipRGCs underlies the photoentrainment deficits. Thus, for irradiance detection, developmental apoptosis is necessary for the spacing and connectivity of ipRGCs that underlie their functioning within a neural network

Original languageEnglish (US)
Pages (from-to)503-515
Number of pages13
Issue number3
StatePublished - Feb 6 2013
Externally publishedYes

ASJC Scopus subject areas

  • Neuroscience(all)


Dive into the research topics of 'Apoptosis Regulates ipRGC Spacing Necessary for Rods and Cones to Drive Circadian Photoentrainment'. Together they form a unique fingerprint.

Cite this