LEVELS OF 70-KDA HEAT-SHOCK PROTEIN THROUGH THE CELL-CYCLE IN SEVERALMAMMALIAN-CELL LINES

Seven different cell lines were analyzed by now cytometry to evaluate the variation in heat shock protein hsp70 through the cell cycle, Indu cible (hsp72) or both constitutive and inducible (hsp70) heat shock pr oteins were measured with monoclonal antibodies, and the cell cycle di stribution was simultaneously measured with propidium iodide, Cell lin es analyzed were Rat-1, HR-24 (Rat-1 transfected with human hsp72 gene ), CHO (Chinese hamster ovary), C3H-10T1/2, AG1522 (normal human fores kin), GM2149 (normal human female skin), and Hela, None of the cell li nes had a substantial variation in hsp72 or hsp70 levels through the c ell cycle if they were not heated, In contrast, after chronic heating at 42.0 degrees C for 7.5 h, different cell lines had different patter ns of hsp72 or hsp70 through the cell cycle, These results demonstrate that the level of hsp70 is not regulated differentially through the c ell cycle in a variety of mammalian cell lines under normal unheated c onditions, However, heat shock does induce cell-cycle-specific regulat ion of hsp70, which varies for different cell lines. (C) 1996 Wiley-Li ss, Inc.