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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20180907T111447Z
DTSTART:20181011T120000Z
DTEND:20181011T130000Z
SUMMARY:GECS Seminar:  Patrick Heun "Epigenetic inheritance and maintenan
 ce of centromere identity"
UID:{http://www.columbasystems.com/customers/uom/gpp/eventid/}vzs-jlrwlki
 n-mnz5qi
DESCRIPTION:Gene Expression\, Chromatin and Signalling Seminar Programme 
 Autumn 2018\n\nHost:  Dave Gerrard\n\nSpeaker:  Dr Patrick Heun\, Univer
 sity of Edinburgh\n\nAbstract:\nCentromeres are specific chromatin domai
 ns essential for genome stability and proper segregation of mitotic chro
 mosomes. In mitosis\, centromeres constitute the chromatin foundation fo
 r the kinetochore\, a multi-protein complex that mediates the attachment
  of the sister chromatids to the mitotic spindle. Centromeric identity i
 s defined and inherited in most organisms by an epigenetic mechanism bas
 ed on the incorporation of a centromere-specific histone H3 variant (CEN
 P-A/cenH3/CID). We find that in fly tissue culture cells that centromere
 s are transcribed in Drosophila from mitosis into G1\, which temporally 
 coincides with the deposition of new dCENP-A. Interestingly\, transcript
 ional inhibition prevents full chromatin incorporation of new dCENP-A\, 
 although an initial recruitment of new dCENP-A to centromeres is unaffec
 ted. As transcription is able to expel nucleosomes from DNA\, we propose
  that transcription is repurposed at the centromere for the removal of ‘
 placeholder’ nucleosomes. However\, this also implies that transcription
  poses a potential danger to epigenetic centromere identity due to the u
 nintentional eviction of old dCENP-A nucleosomes. We found that loss of 
 parental dCENP-A is counteracted the transcription elongation factor and
  histone chaperone Spt6 that we recently found to be associated with dCE
 NP-A. Localization of Spt6 to centromeres is largely restricted to mitos
 is and G1 and a lower salt sensitivity indicates that it binds dCENP-A w
 ith higher specificity than canonical histone H3. In the genome\, Spt6 i
 s known to prevent transcription-coupled loss of nucleosomes through nuc
 leosome re-incorporation. Accordingly\, parental dCENP-A nucleosomes are
  specifically lost in Spt6 depleted cells during the dCENP-A loading pro
 cess indicating that the ability of Spt6 to recycle expelled nucleosomes
  is required for the long-term stability of the centromeric mark. Theref
 ore\, Spt6 is a dCENP-A maintainance factor and centromeric transcriptio
 n and Spt6 co-operate to ensure stable inheritance of dCENP-A at the cen
 tromere.
STATUS:TENTATIVE
TRANSP:TRANSPARENT
CLASS:PUBLIC
LOCATION:Michael Smith Lecture Theatre\, Michael Smith Building\, Manches
 ter
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