Calcium-binding proteins in the retina of a calbindin-null mutant mouse.
Calcium-binding proteins are abundantly expressed in many neurons of mammalian retinae. Their physiological roles are, however, largely unknown. This is particularly true for calcium-modulating proteins ("calcium buffers") such as calbindin D28k. Here, we have studied retinae of wildtype (+/+) and calbindin-null mutant (-/-) mice by using immunocytochemical methods. Although calbindin immunoreactivity was completely absent in the calbindin (-/-) retinae, those cells that express the protein in wildtype retinae, such as horizontal cells, were still present and appeared normal. This was verified by immunostaining horizontal cells for various neurofilament proteins. In order to assess whether other calcium-binding proteins are upregulated in the mutant mouse and may thus compensate for the loss of calbindin, mouse retinae were also immunolabeled for parvalbumin, calretinin, and a calmodulin-like protein (CALP). In no instance could a change in the expression pattern of these proteins be detected by immunocytochemical methods. Thus, our results show that calbindin is not required for the maintenance of the light-microscopic structure of the differentiated retina and suggest roles for this protein in retinal function.
Wässle
H
H
Max-Planck-Institut für Hirnforschung, Neuroanatomie, Deutschordenstrasse 46, D-60528 Frankfurt a.M., Germany. waessle@mpih-frankfurt.mpg.de
Peichl
L
L
Airaksinen
M S
MS
Meyer
M
M
D000818:Animals; D064092:Calbindin 1; D064032:Calbindin 2; D064026:Calbindins; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D007124:Immunoenzyme Techniques; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D010320:Parvalbumins / Q000378:metabolism; D012160:Retina / Q000378:metabolism* / Q000648:ultrastructure; D064030:S100 Calcium Binding Protein G / Q000235:genetics / Q000378:metabolism*
C576499:Calb1 protein, mouse; C576511:Calb2 protein, mouse; D064092:Calbindin 1; D064032:Calbindin 2; D064026:Calbindins; D002135:Calcium-Binding Proteins; D005136:Eye Proteins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G