Corporeau C D, Angelier N, Penrad-Mobayed M
Groupe Gènes et Développement, UMR 7622, Laboratoire de Biologie Moléculaire et Cellulaire du Développement, Bât. C, Université P. et M. Curie, CNRS, 6(ème) étage, Case 16, 9 quai Saint-Bernard, Paris cedex 05, 75252, France.
Exp Cell Res. 2000 Nov 1;260(2):222-32. doi: 10.1006/excr.2000.5003.
The amphibian oocyte represents an excellent model for the study of transcription regulation. Indeed, any modification of transcriptional activity is directly reflected in lampbrush chromosome structure by concomitant morphological changes. Previous studies have led to the hypothesis of a putative role for heat-shock proteins HSP70 and/or HSC70 in transcriptional processes in the oocyte. In order to dissect out the relative role of HSP70 or HSC70 in these processes, we used an oligo-antisense strategy to specifically inhibit the function of the targeted protein. Effects of hsc70 and hsp70 antisense oligodeoxynucleotides were analyzed in terms of both mRNA quantity and protein synthesis. Their effects on oocyte transcription were analyzed at the level of structural organization of lampbrush chromosomes and nucleolar transcriptional activity. Our results show that specific inactivation of hsc70 mRNA by hsc70 antisense oligos led to a reversible inhibition of lampbrush chromosome transcription. However, such reversible inhibition of transcription is considered non-sequence specific since it is also induced by any oligo. In contrast, specific inactivation of hsp70 mRNA by hsp70 antisense oligos, which is correlated with a drop of HSP70 neosynthesis, results in an irreversible inhibition of lampbrush chromosome transcription. Furthermore, our results show that the inactivation of hsp70 or hsc70 mRNAs does not affect nucleolar transcription. Such data suggest a role for HSP70 in the control of chromatin modifications related to RNA polymerase II transcriptional activity.
两栖类卵母细胞是研究转录调控的优秀模型。实际上，转录活性的任何改变都会通过伴随的形态变化直接反映在灯刷染色体结构上。先前的研究提出了热休克蛋白HSP70和/或HSC70在卵母细胞转录过程中可能发挥作用的假说。为了剖析HSP70或HSC70在这些过程中的相对作用，我们采用了寡核苷酸反义策略来特异性抑制目标蛋白的功能。从mRNA数量和蛋白质合成两方面分析了hsc70和hsp70反义寡脱氧核苷酸的作用。在灯刷染色体的结构组织和核仁转录活性水平上分析了它们对卵母细胞转录的影响。我们的结果表明，hsc70反义寡核苷酸使hsc70 mRNA特异性失活，导致灯刷染色体转录受到可逆抑制。然而，这种转录的可逆抑制被认为是非序列特异性的，因为任何寡核苷酸都能诱导这种抑制。相反，hsp70反义寡核苷酸使hsp70 mRNA特异性失活，这与HSP70新合成的下降相关，导致灯刷染色体转录受到不可逆抑制。此外，我们的结果表明，hsp70或hsc70 mRNA的失活不影响核仁转录。这些数据表明HSP70在与RNA聚合酶II转录活性相关的染色质修饰控制中发挥作用。
