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Identification of the minimal promoter for specific expression of the GABA ρ1 receptor in retinal bipolar cells
Author(s) -
MachucaParra Arturo Israel,
Miledi Ricardo,
MartínezTorres Ataúlfo
Publication year - 2013
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/jnc.12067
Subject(s) - receptor , microbiology and biotechnology , retinal , neuroscience , identification (biology) , chemistry , biology , biochemistry , botany
γ‐aminobutyric acid (GABA)ρ receptors regulate rapid synaptic ion currents in the axon end of retinal ON bipolar neurons, acting as a point of control along the visual pathway. In the GABAρ1 subunit knock out mouse, inhibition mediated by this receptor is totally eliminated, showing its role in neural transmission in retina. GABAρ1 mRNA is expressed in mouse retina after post‐natal day 7, but little is known about its transcriptional regulation. To identify the GABA ρ1 promoter, in silico analyses were performed and indicated that a 0.290‐kb fragment, flanking the 5′‐end of the GABA ρ1 gene, includes putative transcription factor‐binding sites, two Inr elements, and lacks a TATA ‐box. A rapid amplification of cDNA ends ( RACE ) assay showed three transcription start sites ( TSS ) clustered in the first exon. Luciferase reporter assays indicated that a 0.232‐kb fragment upstream from the ATG is the minimal promoter in transfected cell lines and in vitro electroporated retinae. The second Inr and AP 1 site are important to activate transcription in secretin tumor cells (STC‐1) and retina. Finally, the 0.232‐kb fragment drives green fluorescent protein ( GFP ) expression to the inner nuclear layer, where bipolar cells are present. This first work paves the way for further studies of molecular elements that control GABA ρ1 transcription and regulate its expression during retinal development.