Disease relevance of hsp90a

• Hsp90alpha, Hsp90beta, and heat shock factor 1a (Hsf1a) were expressed in all three tissues, but were not upregulated in response to heat stress [1].

High impact information on hsp90a

• In particular, hsp90alpha is expressed during the normal differentiation of striated muscle fibres, and hsp70-4 is expressed during normal lens development in the eye [2].
• Furthermore, development of the notochord, which provides many of the signals required for proper somite patterning and which does not express detectable levels of either hsp90alpha or hsp90beta mRNA, was similarly unaffected in geldanamycin-treated embryos [3].
• Both the hsp47 and hsp90 genes are expressed in a highly tissue-restricted manner during normal development [4].
• Specific localization of zebrafish hsp90 alpha mRNA to myoD-expressing cells suggests a role for hsp90 alpha during normal muscle development [5].
• We show that constitutive hsp90 alpha mRNA in zebrafish embryos is restricted primarily to a subset of cells within the somites and pectoral fin buds which also express myoD [5].

Biological context of hsp90a

• In expression studies using Northern blot analysis, hsp 90 beta mRNA was found to be present at control temperatures throughout normal embryonic development whereas hsp 90 alpha mRNA was barely detectable [6].
• In this study, we provide the first in vivo evidence that the hsp90 alpha gene may play a role in the process of myogenesis [5].
• We have previously shown that hsp90alpha gene expression in early zebrafish embryos is restricted to a subgroup of paraxial-mesoderm derived somitic cells prior to muscle formation and that the gene is downregulated in mature trunk and tail muscle fibers [7].

Anatomical context of hsp90a

• Finally, expression of hsp90alpha is downregulated in slow muscle fibers by 24 h of age but becomes detectable in the later developing fast fibers at this time [7].

Regulatory relationships of hsp90a

• Thus, the hsp 90 alpha gene is strongly upregulated during heat shock in zebrafish embryos whereas expression of the hsp 90 beta gene appears to be weakly induced [6].
• Furthermore, expression of the hsp90 alpha gene is down-regulated along with myoD in differentiated muscles of the trunk at a time when levels of mRNA encoding the muscle structural protein alpha-tropomyosin remain high [5].
• Expression of hsp90alpha is also activated in the midline of flh mutants when these cells switch from a notochord to a muscle fate [7].

Other interactions of hsp90a

• HSP 90 alpha and HSP 90 beta genes are present in the zebrafish and are differentially regulated in developing embryos [6].
• We have cloned members of the zebrafish hsp47, hsp70, and hsp90 gene families and shown them to be closely related to their counterparts in higher vertebrates [8].

References