Expression of CaV3.2 T-type Ca²⁺ channels in a subpopulation of retinal type-3 cone bipolar cells.
Retinal bipolar cells and ganglion cells are known to possess voltage-gated T-type Ca(2+) channels. Previous electrophysiological recording studies suggested that there is differential expression of different T-type Ca(2+) channel α1 subunits among bipolar cells. The detailed expression patterns of the individual T-type Ca(2+) channel subunits in the retina, however, remain unknown. In this study, we examined the expression of the Ca(V)3.2 Ca(2+) channel α1 subunit in the mouse retina using immunohistochemical analysis and patch-clamp recordings together with a Ca(V)3.2 knock out (KO) mouse line. The specificity of a Ca(V)3.2 Ca(2+) channel antibody was first confirmed in recombinant T-type Ca(2+) channels expressed in human embryonic kidney (HEK) cells and in Ca(V)3.2 KO mice. Our immunohistochemical analysis indicates that the Ca(V)3.2 antibody labels a subgroup of type-3 cone bipolar cells (CBCs), the PKAβII-immunopositive type-3 CBCs. The labeling was observed throughout the cell including dendrites and axon terminals. Our patch-clamp recording results further demonstrate that Ca(V)3.2 Ca(2+) channels contribute to the T-type Ca(2+) current in a subpopulation of type-3 CBCs. The findings of this study provide new insights into understanding the functional roles of T-type Ca(2+) channels in retinal processing.
Department of Anatomy & Cell Biology, Wayne State University School of Medicine, Detroit, MI 48201, United States.
J
J
Cui
E
E
Ivanova
L
L
Qi
Z-H
ZH
Pan
D000818:Animals; D020747:Calcium Channels, T-Type / Q000096:biosynthesis*; D057809:HEK293 Cells; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018408:Patch-Clamp Techniques; D051245:Retinal Bipolar Cells / Q000378:metabolism*
C504883:Cacna1h protein, mouse; D020747:Calcium Channels, T-Type