Transcriptional regulation of the Drosophila melanogaster ERG potassium channel locus: Transgenic analysis of promoter elements.

摘要

Herg encodes a voltage-gated potassium channel that is expressed in the cardiac and nervous systems and has been implicated in familial Long QT syndrome. A homolog of the Herg gene has been characterized in Drosophila melanogaster . Transcriptional regulation of the erg gene has not been examined. 5' RACE of Derg was performed and demonstrated the presence of three distinct promoter regions. To ascertain the spatial and temporal expression pattern of Derg, we have isolated a 1 Kb genomic DNA fragment. After close analysis of the Derg promoter regions, the gamma-SNAP gene was found just downstream of Derg, on the opposite strand of the DNA. The gamma-SNAP gene has been minimally characterized and consequently the shared untranslated regions bring up some interesting regulatory questions. A 1 Kb DNA fragment has been isolated from just upstream of the gamma-SNAP coding region. The genomic fragments were cloned into pPTGAL, a reporter plasmid that drives expression of yeast Gal4 transcription factor, which can activate expression of UAS-regulated reporter genes. Two sets of independent transgenic lines were isolated and characterized. Expression of enhanced yellow fluorescent protein reporter enzyme suggested that Derg is expressed in the nervous system, ring gland, dorsal vessel, gut and eye; whereas, the gamma-SNAP gene seems to be expressed in ring gland, brain, dorsal vessel, gut, and peripheral nervous system.