Abstract
Abstract: :
Purpose: We have previously shown that there is a critical temporal difference in CRX gene expression between the human and mouse gene. We have now characterized these genes at the genomic and transcriptional level and expand on this earlier report by obtaining the entire sequence of human and mouse CRX, including the promoters and untranslated sequence. Methods: 5' and 3' RACE and RT-PCR was performed from human retinal and C57BL/6 mouse eye cDNA. Products were cloned and sequenced. Results: Human CRX spans 25 kilobases and has six exons. Mouse Crx has four exons spanning 15 kilobases. Seven human and two mouse mRNAs generated by alternative splicing of a variable 5' untranslated region were isolated. The genes share an evolutionary conserved promoter that drives expression of two similar transcripts. In addition, human CRX has a second promoter that drives expression of five other transcripts, one of which contains a novel internal exon that introduces a stop codon into the CRX reading frame, generating a protein of 34 residues with no known functional domains Conclusion: The human and mouse CRX genes have a complex genomic and transcriptional structure that is related. However, in addition the human specific transcripts may explain the differences we have detected in the expression profile of these genes.
Keywords: 555 retina: distal(photoreceptors, horizontal cells, bipolar cells) • 605 transcription factors • 528 proteins encoded by disease genes