TY  - UNPB
PB  - UCL (University College London)
N1  - Authorisation for digitisation not received
TI  - A functional RNAi screen for regulators of the serum response factor (SRF)
M1  - Doctoral
Y1  - 2009/12//
A1  - Grüner, T.
UR  - https://discovery.ucl.ac.uk/id/eprint/19000/
AV  - none
N2  - Serum response factor (SRF) controls transcription of numerous immediate early
and muscle-specific genes by its association with diverse co-activators. Amongst the
SRF binding regulators are the TCF family proteins, including Elk1, SAP1 and SAP2
and the myocardin-related transcription factor (MRTF) family proteins including MAL
and MAL16. Both types of transcriptional coactivators form a complex with SRF,
which binds to serum response elements (SREs) upon serum activation by different
upstream signal transduction pathways. While SRF activation by TCFs occur through
the MAP kinase pathway, MRTFs regulate SRF specifically through the RhoA
pathway.
MAL, a G-actin binding protein, continuously shuttles between cytoplasm and
nucleus in many unstimulated cells and appears cytoplasmic. Upon RhoA-induced actin
polymerization, MAL nuclear export is blocked due to disruption of the MAL-actin
interaction. MAL accumulates in the nucleus where it binds to SRF, which results in
target gene expression.
Although many of the pathway components are already known, it is probable that
there are still uncharacterized factors that regulate SRF. Therefore this thesis addresses
the identification of new regulators of SRF that are specifically dependent on the RhoA
pathway.
Since the interaction of MAL with SRF and actin represents an evolutionarily
conserved regulatory mechanism between Drosophila and human and the Drosophila
genome lacks much of the genetic redundancy observed in human, a genome-wide
RNA interference (RNAi) screen in cultured Drosophila cells was performed to identify
key regulators of SRF.
Using RNAi, 295 proteins in Drosophila cells were identified, of which 50 were
further validated in human cells. Amongst the final confirmed hits, eukaryotic
elongation translation factor (eEF1A) was a promising regulator for RhoA induced SRF
activation. eEF1A2 was shown to interact with MAL and depletion of eEF1A2 in
unstimulated cells led to nuclear accumulation of MAL, suggesting its role as a MAL
regulator. Potential roles of the remaining hits confirmed in the rescreen are also
discussed in this thesis.
EP  - 284
ID  - discovery19000
ER  -