Recently, through reporter gene studies, the novel BTB/POZ protein, Kaiso,
has been identified as a transcriptional repressor. The purpose of this study was
to determine if Kaiso recruited the Histone Deacetylase Complex to mediate
repression and if the previously identified Kaiso Binding Site (KBS; TCCTGCNA)
is a physiological target regulated by Kaiso. The two objectives are
complementary because an HDAC interaction identifies the mechanism of
transcriptional regulation used by Kaiso and regulation of the KBS element
identifies a novel, non-methylation dependent, physiological target under
transcriptional regulation by Kaiso. Through coimmunoprecipitation and Western
blot analyses, Kaiso does not interact with HDAC1, HDAC2 or mSIN3A. These
results were surprising since all three of these proteins are common to a variety
of repression complexes. mSIN3A is a common component of SIN3 mediated
repression and HDAC1/HDAC2 are part of various repression complexes
including SIN3, NuRD and CtBP. Although the remaining HDAC proteins were
not assayed for an interaction, Kaiso transcriptional activity was demonstrated to
be insensitive to the HDAC inhibiting drug, Trichostatin A (TSA). These results
indicate either a non-HDAC mechanism of action or alternatively, transcriptional
activation. Complementary to the observations of no Kaiso-HDAC interaction
and TSA insensitivity was the findings that Kaiso activates transcription of the
KBS cis-element in HCT116, HCA-7 and 293 cells, but not MOCK cells in
reporter gene assays. Taken together, these results indicate that Kaiso is a dual
functioning protein capable of both transcriptional activation and repression and
that the mechanism of repression is not through the direct recruitment of HDAC
proteins. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22704 |
| Date | 07 1900 |
| Creators | Baig, Akeel |
| Contributors | Daniel, Juliet, Biology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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