CLONING AND CHROMOSOMAL MAPPING OF THE MURINE NOREPINEPHRINE TRANSPORTER

The norepinephrine (NE) transporter (NET), a target of many clinically prescribed antidepressants, regulates noradrenergic neurotransmission by efficiently clearing NE from synaptic spaces after release. To adv ance our understanding of NET gene structure, regulation, and potentia l associations with complex behavioral trait loci, we amplified a mous e norepinephrine transporter (mNET) cDNA from placenta total RNA and u tilized mNET probes to isolate and characterize the mNET gene. Inferre d translation of the major open reading frame of the mNET cDNA predict s a 617-amino acid protein with 12 putative membrane-spanning regions and 94% identity to human NET. The coding exons of the mNET cDNA were found to be spread across >36 kb of 129/Svj genomic DNA, with exon-int ron boundaries bearing consensus gt/ag splice sites. Sequence upstream (202 bp) of the inferred translation initiation site matched the sequ ence of 5' rapid amplification of cDNA ends products from brain mRNA w ith no evidence for intervening introns and is preceded by a TATA box and canonical transcriptional regulatory elements that may play a role in mNET expression in vivo. Probes derived from mNET cDNA identified species-specific Msp1 restriction fragment length variations within th e mNET gene that were utilized to position the gene (Slc6a5) to murine chromosome 8, one recombinant distal to D8Mit15. This site is within a recently defined quantitative trait locus defined for ethanol sensit ivity in LSXSS recombinant inbred mice, Lore4. The status of Slc6a5 as a candidate gene for alcohol sensitivity is discussed with respect to studies noting ethanol-induced alterations in brain NE receptors, NE receptor-linked adenylate cyclase, and NE transport.