TY  - GEN
N2  - Centromeres are specialized chromatin domains present on each chromosome, which 
determine the location of kinetochore formation ? the multiprotein platform for spindle 
microtubule attachment during mitosis. Since the underlying centromeric DNA sequence is not 
conserved, centromere inheritance and function rely on the conserved epigenetic marker 
CENP-A (also known as CID in Drosophila). CENP-A is highly enriched in centromeric 
chromatin and partially replaces canonical histone H3. Specific loading and stabilization of 
CENP-A at the centromere is ensured by a concert of different factors such as its dedicated 
chaperone called CAL1 in Drosophila. Whereas the primary DNA sequence is dispensable for 
centromere formation, CENP-A is both absolutely essential and sufficient to maintain and 
establish functional centromeres. When overabundant due to transcriptional upregulation for 
example in cancer cells, CENP-A escapes the endogenous loading pathway and hijacks other 
histone loading machineries, which leads to promiscuous non-centromeric CENP-A 
incorporation throughout the genome with detrimental effects for genome stability. 
Even though ectopic CENP-A accumulation existentially threatens cellular and 
organismal viability, CENP-A is distributed at basal levels throughout the genome under 
physiological conditions. The function and mechanistic details of genome-wide CENP-A 
loading remain elusive, but the field speculates, that low levels of ectopic CENP-A confer 
epigenetic plasticity and prime chromatin for neocentromere formation in the event of ancestral 
centromere loss. Previous work in our lab identified the histone fold protein CHRAC-14 as an 
important regulator of ectopic CENP-A incorporation and as a new DNA damage factor in 
Drosophila melanogaster. CHRAC-14 depletion leads to the increase of CENP-A levels, 
increased CENP-A ectopic loading ? possibly at telomeric DNA repair sites ? and to DNA repair 
defects accompanied by G2/M checkpoint failure. 
Since we lacked detailed mechanistic insights and clear data whether ectopic CENP-A 
localizes to and has a role at DNA lesions, I set out to further elucidate this pathway. Employing 
a portfolio of biochemical and molecular biological techniques such as CUT&Tag-Seq, RNA-Seq and immunoprecipitation combined with mass spectrometry analysis, I report in this thesis, 
that CHRAC-14 knockdown leads to the accumulation of CENP-A at centromeres and 
genome-wide. In addition, altered expression of genes associated with gene ontology 
categories such as ?mitotic progression? and ?DNA damage response? was observed. 
Furthermore, I identified candidate genes, which are mis-expressed whilst showing increased 
CENP-A binding. Moreover, I found, that both CHRAC-14 and CENP-A interact with Casein 
kinase 2 (CK2) and are phosphorylation substrates thereof. Interestingly, CK2 phosphorylation 
of CHRAC-14 seems to promote the turnover of a post translationally modified version of 
CENP-A, whereas CK2 phosphorylation of endogenous CENP-A itself seems to be essential 
for protein stability. 
Taken together, my study provides new insights into CHRAC-14 mediated CENP-A 
titration in chromatin and opens up a novel direction involving CK2 as a key regulator in this 
pathway.
ID  - heidok31436
AV  - public
TI  - The histone fold protein CHRAC-14 controls CENP-A loading and 
gene expression in Drosophila melanogaster
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/31436/
CY  - Heidelberg
Y1  - 2022///
A1  - Doppler, Sarah
ER  -