P. Coumailleau et al., TISSUE-SPECIFIC EXPRESSION OF AN HSC90 GENE AND NUCLEAR TRANSLOCATIONOF THE HSC90-RELATED PROTEIN DURING AMPHIBIAN EMBRYOGENESIS, Development, genes and evolution, 206(6), 1997, pp. 397-406
Expression and distribution of a constitutive member of the 90 kDa hea
t-shock protein family, named HSC90, was investigated during amphibian
embryonic development. By Northern blot analysis, two hsp90 transcrip
ts (2.5 and 3 kb) which displayed differing developmental regulation w
ere detected during embryogenesis. Expression of the larger transcript
(3 kb), which encodes an HSC90-related protein, decreased until the g
astrula stage. However, zygotic transcription for this hsc90 gene was
found to start from the neurula stage, and the corresponding zygotic h
sc90 transcript was specifically located by whole mount in situ hybrid
ization in the anterior neural tube of a late neurula embryo. Later, i
n a tailbud embryo, hsc90 transcripts were detected in the cephalic re
gion, neural tube, eye vesicles, branchial and mandibular arches and s
omites. Distribution of the HSC90-related protein was also analysed by
immunohistochemistry throughout embryogenesis. As expected, the prote
in was strongly expressed in the cytoplasm, mainly in the periplasmic
area of embryonic tissue cells. Interestingly, HSC90 was also transien
tly detected in the nuclear area, with this nuclear transfer depending
on the chromatin condensation state, up to the blastula stage. During
the process of gastrulation, nuclear translocation of HSC90 was also
observed at the level of the blastopore dorsal lip, exclusively in cel
ls undergoing invagination.