Developmentally-regulated expression of tissue-specific splice variant of rat vesicular glutamate transporter 1 in retina and pineal gland.
Three distinct subtypes of vesicular glutamate transporters (VGLUTs) have been identified to date that are expressed basically in a cell type-specific manner. We have found a splice variant of VGLUT1 mRNA that is expressed almost exclusively in photosensitive tissues, i.e. the retina and the pineal gland. The variant mRNA, termed VGLUT1v, contains an additional 75 base pair sequence derived from part of a second intron (designated as exon IIa) between exons 2 and 3. The variant accounted for approximately 70% and 25%of VGLUT1 mRNA in the adult retina and pineal gland, respectively. The expression of VGLUT1v was developmentally regulated in both tissues. Organ culture showed that expression of the variant in the retina increased in association with the development of rod cells, suggesting that VGLUT1v is expressed in rod cells. In situ hybridization with variant-specific probes showed expression of VGLUT1v in the inner segment layer of photoreceptor cells. On the other hand, variant expression did not parallel the development of rhodopsin-positive cells in the pineal gland. As rod cells and pinealocytes are known to release glutamate continuously at ribbon synapses, it is possible that the variant has some functional advantage over the wild-type transporter in such a specialized manner of glutamate release.
Nogami
Haruo
H
Laboratory of Neuroendocrinology, Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba, Japan. hnogami@md.tsukuba.ac.jp
Ogasawara
Kiyomoto
K
Mimura
Yuka
Y
Mogi
Koichi
K
Shutoh
Fumihiro
F
Hisano
Setsuji
S
D017398:Alternative Splicing; D000818:Animals; D001921:Brain / Q000502:physiology; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D017931:DNA Primers; D018507:Gene Expression Regulation, Developmental; D014644:Genetic Variation; D009928:Organ Specificity; D010870:Pineal Gland / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012160:Retina / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050598:Vesicular Glutamate Transport Protein 1 / Q000235:genetics*
D017931:DNA Primers; D012333:RNA, Messenger; C493466:Slc17a7 protein, rat; D050598:Vesicular Glutamate Transport Protein 1; D004247:DNA