Identification of the minimal promoter for specific expression of the GABAρ1 receptor in retinal bipolar cells. (30th November 2012)

• Record Type: Journal Article
• Authors: Machuca‐Parra, Arturo Israel; Miledi, Ricardo; Martínez‐Torres, Ataúlfo
• Is Part Of: Journal of neurochemistry. Volume 124:Number 2(2013:Jan.)
• Page Start: 175
• Page End: 188
• Publication Date: 2012-11-30
• Subjects: Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.12067
• Languages: English
• ISSNs: 0022-3042

Abstract

<abstract abstract-type="main" id="jnc12067-abs-0001"> <title>Abstract</title> <p>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 GABAρ1 promoter, <italic>in silico</italic> analyses were performed and indicated that a 0.290‐kb fragment, flanking the 5′‐end of the <italic>GABAρ1</italic> 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 <italic>in vitro</italic> electroporated retinae. The second Inr and AP1 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 GABAρ1 transcription and regulate its expression during retinal development.</p> </abstract>