Hang H, He L, Fox M H
Department of Radiological Health Sciences, Colorado State University, Fort Collins 80523, USA.
J Cell Physiol. 1995 Nov;165(2):367-75. doi: 10.1002/jcp.1041650218.
The expression of the 72 kD inducible heat shock protein (hsp72) has been reported to be cell cycle associated in unheated, synchronized HeLa cells. In this study, flow cytometry was used to investigate hsp72 levels through the cell cycle in HeLa cells by dual labeling with propidium iodide and antibodies against hsp72. The entire cell cycle distribution of hsp72 could be measured in a single sample of asynchronously growing cells. For unheated cells, the level of hsp72 increased about 30% from G1 to S phase, with about a 65% increase in G2/M, probably due to cell size differences. Neither mitotic selection nor serum stimulation induced a higher level of hsp72 than in the control cells. Western blot analysis of hsp72 from Hoechst-stained cells sorted from G1, mid-S, or G2/M showed that G1 cells had the lowest level of hsp72, with about a 30% increase in S phase and a 60% increase in G2/M, in good agreement with the flow cytometry results. These data conflict with previous reports by other laboratories which showed a 3-fold higher level of hsp72 in S phase than in G1 or G2. In contrast, heat shock (both acute and chronic) led to a non-uniform increase in hsp72 through the cell cycle. Most cells in mid S phase had high levels of hsp72, and a larger range in the levels of hsp72 were found in G1 and late S/G2/M phase cells.
据报道，在未加热的、同步化的HeLa细胞中，72kD诱导型热休克蛋白（hsp72）的表达与细胞周期相关。在本研究中，通过碘化丙啶和抗hsp72抗体双重标记，利用流式细胞术研究HeLa细胞在整个细胞周期中的hsp72水平。hsp72的整个细胞周期分布可以在一个异步生长细胞的单一样本中进行测量。对于未加热的细胞，hsp72水平从G1期到S期增加约30%，在G2/M期增加约65%，这可能是由于细胞大小差异所致。有丝分裂选择和血清刺激均未诱导出比对照细胞更高水平的hsp72。对从G1期、S期中期或G2/M期分选的经Hoechst染色细胞中的hsp72进行蛋白质免疫印迹分析表明，G1期细胞的hsp72水平最低，S期增加约30%，G2/M期增加60%，与流式细胞术结果高度一致。这些数据与其他实验室先前的报道相矛盾，其他报道显示S期hsp72水平比G1期或G2期高3倍。相比之下，热休克（急性和慢性）导致hsp72在整个细胞周期中不均匀增加。S期中期的大多数细胞具有高水平的hsp72，在G1期和S期后期/G2/M期细胞中发现hsp72水平的范围更大。
