Visit our Expo - Redox and Inflammation signaling 2012

Session XIV : Transcriptional and translational control Poster XIV, 44
Identification in rat of a yeast She3 homolog as interaction partner of AATF
Peter Leister, Sven Burgdorf, Andrea Felten, Lutz Uhlmann, and Karl Heinz
Scheidtmann
Institute of Genetics, University of Bonn
Roemerstr. 164, D-53117 Bonn
peterleister@uni-bonn.de
AATF, or Che-1, is a coactivator of several transcription factors including steroid hormone
receptors, E2F, and SP1. In search of novel interaction partners of AATF we identified a so
far unknown protein from rat with high degree of homology to She3p from budding yeast.
She3p is an adapter protein for myosinV type motor protein Myo4p and is involved in
selective transport of mRNA and ER vesicles. The novel protein was termed SHIA for She3
Homolog Interacting with AATF. A single transcript of SHIA mRNA of 1050 bp was highly
expressed in brain, heart, spleen, liver, testis and kidney and to a lower extent in lung,
whereas it was undetectable in skeletal muscle. However, sequence alignments with database
sequences revealed that human, mouse and rat orthologs exist in two or three isoforms
generated by alternative splicing or alternative usage of start codons, giving rize to
polypeptides of 142 and 99 residues, respectively. Strikingly, besides some variations at their
N-termini SHIA proteins are extremely conserved. A core sequence between residues 20 and
140 is strictly conserved within all vertebrates represented in the database, and certain
sequence motifs are found even in insects and C. elegans and yeast. This high degree of
conservation suggests that SHIA plays an essential role in all eukaryotes.
The rat SHIA clone isolated appears to contain an extra exon (termed exon 2b) resulting in a
protein of 168 amino acids with MW of 20 kDa. SHIA contains a She3p homology region at
its N-terminus and a leucine zipper at its C-terminus, which mediates interaction with AATF.
When expressed as GFP fusion protein, GFP-SHIA was localized in the cytoplasm,
preferentially nuclear near structures and the actin cytoskeleton. A small fraction of GFP-
SHIA was also observed within the nucleus. Overexpression of SHIA resulted in disturbed
actin fibers, and coexpression of SHIA and AATF resulted in partial relocalisation of AATF
from the nucleus to the cytoplasm. Interestingly, SHIA enhanced reporter gene activty in
androgen receptor based transactivation assays, thus, SHIA behaved like a transcriptional coactivator.
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