Adams, Grace E. Understanding the contribution of inositol phosphate signalling to class-1 HDAC complex function <div>Class 1 histone deacetylases (HDACs) regulate chromatin confirmation and gene</div><div>expression through recruitment to co-repressor complexes. Recently, it was shown</div><div>that HDAC3/SMRT binds and is regulated by inositol phosphates (IP) in vitro.</div><div>Additionally, complex activity of HDAC1/MTA1 and HDAC1/MIDEAS is enhanced by the</div><div>addition of IPs in vitro, indicating conserved regulation. In this work, I aimed to alter</div><div>the level of IPs present in the cells through overexpression of a kinase, IPMK, and two</div><div>phosphatases, PTEN and SopB, and determine the effect on HDAC activity in vivo. In</div><div>addition, I utilised an IPMK knockout embryonic stem (ES) cell line and generated</div><div>inducible rescues through a PiggyBac TET system to establish if large scale depletions</div><div>of IP levels alter HDAC activity.</div><div>We revealed that manipulation of IP through the overexpression of IPMK, PTEN and</div><div>SopB does not influence global HDAC activity or histone acetylation levels. Isolation of</div><div>overexpressed HDAC3/SMRT in concert with these enzymes, revealed differences in</div><div>HDAC3/SMRT complex activity, however, these differences did not correlate with</div><div>altered IP levels. Analysis of global HDAC activity, isolated complex activity and HDAC3</div><div>target genes in IPMK knockout and rescue ES cell lines further revealed minimal</div><div>changes. In conclusion, we were unable to show that IPs regulated the activity of class</div><div>I HDAC complexes in vivo. IPMK, HDAC1 and HDAC3 null mice all exhibit early</div><div>embryonic lethality suggesting they play essential roles in embryogenesis. Upon</div><div>differentiation of TET-IPMK cells, embryoid bodies revealed loss of IPMK leads to</div><div>increased cardiomyocyte markers and decreased formation of neuroectoderm</div><div>progenitors. Therefore, emphasizing IPMKs important role in gene regulation during</div><div>embryogenesis. Our data suggests, that this is not through direct regulation of HDAC</div><div>activity, thus highlighting an undiscovered nuclear role for IPMK.</div> Thesis 2019-11-13
    https://figshare.le.ac.uk/articles/thesis/Understanding_the_contribution_of_inositol_phosphate_signalling_to_class-1_HDAC_complex_function/10298168
10.25392/leicester.data.10298168.v1