Photoreceptor degeneration and Ca2+ influx through light-activated channels of Drosophila.
We discuss in this chapter the role of Ca2+ homeostasis in maintaining the structural integrity of photoreceptor cells in Drosophila. Both insufficient and excessive amounts of Ca2+ in photoreceptor cells appear to lead to cell degeneration. Because one of the two classes of light-sensitive channels in Drosophila photoreceptors is highly Ca2+-permeable, how well this class of channels functions can profoundly affect Ca2+ homeostasis. We will begin by reviewing Drosophila phototransduction, emphasizing what is known about the mechanism of activation of light-sensitive channels. We will then describe Ca2+ entry through light-sensitive channels and the presumed mechanisms by which too little and too much Ca2+ entry can both cause photoreceptor degeneration. We will conclude the chapter with discussions of two examples of mutations known to cause unregulated Ca2+ entry through light-sensitive channels, leading to massive photoreceptor degeneration.
Geng
Chaoxian
C
Department of Biological Sciences, Purdue University, West Lafayette, IN 47907-1392, USA. cgeng@bilbo.bio.purdur.edu
Pak
William L
WL
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000502:physiology; D004330:Drosophila; D029721:Drosophila Proteins; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology; D008027:Light; D008854:Microscopy, Electron; D009154:Mutation; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D013997:Time Factors; D050051:Transient Receptor Potential Channels
D015220:Calcium Channels; D029721:Drosophila Proteins; D019476:Insect Proteins; D050051:Transient Receptor Potential Channels; C063169:trp protein, Drosophila; D002118:Calcium