IDENTIFICATION OF MEMBERS OF THE HSP30 SMALL HEAT-SHOCK PROTEIN FAMILY AND CHARACTERIZATION OF THEIR DEVELOPMENTAL REGULATION IN HEAT-SHOCKED XENOPUS-LAEVIS EMBRYOS
Y. Tam et Jj. Heikkila, IDENTIFICATION OF MEMBERS OF THE HSP30 SMALL HEAT-SHOCK PROTEIN FAMILY AND CHARACTERIZATION OF THEIR DEVELOPMENTAL REGULATION IN HEAT-SHOCKED XENOPUS-LAEVIS EMBRYOS, Developmental genetics, 17(4), 1995, pp. 331-339
In the present study we have characterized the synthesis of members of
the HSP30 family during Xenopus laevis development using a polyclonal
antipeptide antibody derived from the carboxyl end of HSP30C. Two-dim
ensional PAGE/immunoblot analysis was unable to detect any heat-induci
ble small HSPs in cleavage, blastula, gastrula, or neurula stage embry
os. However, heat-inducible accumulation of a single protein was first
detectable in early tailbud embryos with an additional 5 HSPs at the
late tailbud stage and a total of 13 small HSPs al the early tadpole s
tage. In the Xenopus A6 kidney epithelial cell line, a total of eight
heat-inducible small HSPs were detected by this antibody. Comparison o
f the pattern of protein synthesis in embryos and somatic cells reveal
ed a number of common and unique heat inducible proteins in Xenopus em
bryos and cultured kidney epithelial cells. To specifically identify t
he protein product of the HSP30C gene, we made a chimeric gene constru
ct with the Xenopus HSP30C coding sequence under the control of a cons
titutive promoter. This construct was microinjected into fertilized eg
gs and resulted in the premature and constitutive synthesis of the HSP
30C protein in gastrula stage embryos. Through a series of mixing expe
riments, we were able to specifically identify the protein encoded by
the HSP30C gene in embryos and somatic cells and to conclude that HSP3
0C synthesis was first heat-inducible at the early tailbud stage of de
velopment. The differential pattern of heat-inducible accumulation of
members of the HSP30 family during Xenopus development suggests that t
hese proteins may have distinct functions at specific embryonic stages
during a stress response. (C) 1995 Wiley-Liss, Inc.