a1 McGill Group for Suicide Studies, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada
Alterations in the levels of spermine synthase (SMS) and spermine oxidase (SMOX), two enzymes involved in polyamine metabolism, have previously been observed in brains of suicide completers. To characterize the roles played by genetic and epigenetic factors in determining expression levels of these genes, as well as to identify potential mechanisms by which to explain our findings in suicide completers, we (1) assessed the role of promoter polymorphisms in determining expression in the brain and in vitro, and (2) examined CpG methylation and levels of methylated histone H3 lysine-27 in the promoter regions of these genes in the prefrontal cortex of suicide completers and healthy controls. We identified several promoter haplotypes in SMS and SMOX, but found no consistent effects of haplotype on expression levels in either the brain or in reporter gene assays performed in three different cell lines. We also found no overall effects of epigenetic factors in determining expression, with the exception of a relationship between CpG methylation at one site in the promoter of SMOX and its expression in Brodmann area 8/9. In conclusion, the genetic and epigenetic factors examined in this study show little influence on the expression levels of SMS and SMOX, and do not appear to be responsible for the dysregulated expression of these genes in suicide completers.
(Received August 25 2009)
(Revised August 25 2009)
(Accepted November 22 2009)
(Online publication January 11 2010)
c1 Address for correspondence: Dr G. Turecki, Douglas Mental Health University Institute, 6875 LaSalle Boulevard, Verdun, Quebec, Canada H4H 1R3. Tel.: +1514 761 6131 (ext. 2369) Fax: +1 514 762 3023 Email: firstname.lastname@example.org