Biological and Biochemical Properties of Two KDM1A Associated Alternatively Spliced SWIRM Domains

Abstract

LSD1 is the first described histone demethylase which demethylates H3K4me1/2 (Shi et el., 2004), thus, causing transcriptional repression. Alternatively, LSD1 was demonstrated to have H3K9me1/2 demethylase activity when bound by androgen receptor, hence, causing transcriptional activation (Schule et al., 2005). LSD1 is commonly recruited by the so called CoREST core complex including: RCOR1, HDAC1 and HDAC2 among others and therefore is coupled with histone deacetylation and transcriptional repression (Foster et al., 2010). It is an important regulator of pluripotency in early development and it occupies, along with pluripotency factors NANOG and OCT4, the promoters of major lineage determining genes that are poised for activation in the pluripotent state, (Adamo et al., 2011). There are four described isoforms for LSD1: LSD1, LSD1-E2a, LSD1-8a and LSD1-E2a/E8a (Zibetti et al., 2010). While the Cterminus of LSD1 is extensively studied and the function of the isoforms LSD1-E8a and LSD1-E8aE2a is described, there is scarce knowledge on LSD1 N-terminus unstructured region and the SWIRM domain. In this project I examined the role of the differently spliced exon 2a on the function of the SWIRM domain through generation of eight constructs coding for the N-terminal portion of LSD1 SV1 and SV2 fused with a C- or N-terminus FLAG tag. I then performed an immunoprecipitation experiment followed by mass spectrometry and proteomics analysis that led to the identification of previously unknown binding partners to the LSD1 SWIRM domain: NONO and IGF2B3.