title: Distinct expression and localization of diacylglycerol kinase isozymes in rat retina.
abstract: Recent studies have revealed that phosphoinositide (PI) signaling molecules are expressed in mammalian retinas, suggesting their importance in its signal transduction. We previously showed that diacylglycerol kinase (DGK) isozymes are expressed in distinct patterns in rat retina at the mRNA level. However, little is known about the nature and morphological aspects of DGKs in the retina. For this study, we performed immunohistochemical analyses to investigate in the retina the expression and localization of DGK isozymes at the protein level. Here, we show that both DGKβ and DGKι localize in the outer plexiform layer, within which photoreceptor cells make contact with bipolar and horizontal cells. These isozymes exhibit distinct subcellular localization patterns: DGKι localizes to the synaptic area of bipolar cells in a punctate manner, whereas DGKβ distributes diffusely in the subsynaptic and dendritic regions of bipolar and horizontal cells. However, punctate labeling for DGKε is evident in the outer limiting membrane. DGKζ and DGKα localize predominantly to the nucleus of ganglion cells. These findings show distinct expression and localization of DGK isozymes in the retina, suggesting a different role of each isozyme.
authors.affiliation: Department of Anatomy and Cell Biology, Yamagata University School of Medicine, Yamagata, Japan. yahodumi@med.id.yamagata-u.ac.jp
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Hozumi
authors.forename: Hirooki
authors.initials: H
authors.lastname: Matsui
authors.forename: Fumio
authors.initials: F
authors.lastname: Sakane
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Kaoru
authors.initials: K
authors.lastname: Goto
mesh_terms: D000818:Animals; D019852:Diacylglycerol Kinase / Q000032:analysis* / Q000235:genetics* / Q000378:metabolism; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000201:enzymology* / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D007527:Isoenzymes; D012333:RNA, Messenger; D019852:Diacylglycerol Kinase
keywords: bipolar cells; diacylglycerol kinase; horizontal cells; immunohistochemistry; phosphoinositide cycle; photoreceptor cells; retina