Morcillo G, Diez J L, Carbajal M E, Tanguay R M
Centro de Investigaciones Biologicas, CSIC, Madrid, Spain.
Chromosoma. 1993 Nov;102(9):648-59. doi: 10.1007/BF00352313.
The heat shock protein HSP90, which is mainly cytoplasmic, has recently been reported to be present in the nucleus. We have found a specific chromosomal localization of HSP90 in different species of Drosophila and Chironomus using immunocytochemical techniques with different mono- and polyclonal antibodies for this hsp. HSP90 was found associated with heat shock-induced puffs at 93D and 48B in salivary gland chromosomes of Drosophila melanogaster and Drosophila hydei, respectively. The localization of HSP90 to locus 93D occurred rapidly after the onset of heat shock and disappeared during recovery, concomitant with puff regression. The association of HSP90 with the 93D locus was strictly heat shock dependent as shown by the absence of HSP90 in puff 93D induced by either benzamide or colchicine. No specific nuclear staining was observed in unstressed control cells. HSP90 was also found in the temperature-induced telomeric Balbiani ring puffs (T-BRs) in Chironomus thummi and in one heat shock puff at I-1C in Chironomus tentans. Other heat shock puffs also appeared lightly stained with the HSP90 polyclonal antibody in both species of Chironomus. HSP90 was absent from the T-BRs when RNA synthesis was inhibited with Actinomycin D suggesting that the localization of HSP90 is dependent on transcription. Inhibition of protein synthesis did not prevent association of this hsp with the T-BRs, indicating that pre-existing HSP90 can associate with this locus. HSP90 did not associate with any telomeric chromosomal regions of unstressed cells. The present observations suggest that heat shock gene products such as HSP90 may somehow be involved in the regulation at the chromosomal level of other members of the heat shock gene family. Puffs 93D (D. melanogaster) and 48B (D. hydei) are equivalent and correspond to homologous gene loci (hsr omega) that have unusual features that distinguish them from other heat shock puffs. The binding of HSP90 at T-BRs and at puff I-1C in the genus Chironomus is the first demonstration, albeit indirect, of the existence of hsr omega analogous loci in species other than Drosophila.
热休克蛋白HSP90主要存在于细胞质中，但最近有报道称其也存在于细胞核中。我们使用针对该热休克蛋白的不同单克隆和多克隆抗体，通过免疫细胞化学技术，在果蝇和摇蚊的不同物种中发现了HSP90的特定染色体定位。在黑腹果蝇和海德氏果蝇的唾液腺染色体中，分别发现HSP90与热休克诱导的位于93D和48B处的胀泡相关。热休克开始后，HSP90迅速定位于93D位点，并在恢复过程中消失，同时胀泡消退。HSP90与93D位点的关联严格依赖于热休克，如苯甲酰胺或秋水仙碱诱导的93D胀泡中不存在HSP90所示。在未受应激的对照细胞中未观察到特异性核染色。在图氏摇蚊的温度诱导端粒巴尔比亚尼环胀泡（T-BRs）以及细毛摇蚊I-1C处的一个热休克胀泡中也发现了HSP90。在两种摇蚊中，其他热休克胀泡用HSP90多克隆抗体染色也较浅。当用放线菌素D抑制RNA合成时，T-BRs中不存在HSP90，这表明HSP90的定位依赖于转录。蛋白质合成的抑制并未阻止该热休克蛋白与T-BRs的关联，表明预先存在的HSP90可以与该位点结合。HSP90不与未受应激细胞的任何端粒染色体区域结合。目前的观察结果表明，热休克基因产物如HSP90可能以某种方式参与热休克基因家族其他成员在染色体水平的调控。93D（黑腹果蝇）和48B（海德氏果蝇）胀泡是等效的，对应于具有不同于其他热休克胀泡的异常特征的同源基因位点（hsr omega）。HSP90在摇蚊属的T-BRs和I-1C胀泡处的结合，首次间接证明了除果蝇外的其他物种中存在hsr omega类似位点。
