Reversible changes in the nuclear lamina induced by hyperthermia

The nuclear matrix (NM) has been identified as a potential target for heat‐induced cell killing. Previous studies have shown that heat‐shock may significantly modulate lamin B content. Since changes in NM structure have often been accompanied by changes in protein composition, we investigated whether hyperthermia induced changes in nuclear lamina (NL) structure in non‐tolerant and thermotolerant cells, and the implications of these changes on cell survival. Using indirect immunofluorescence techniques and confocal microscopy, we found that heating cells at 42 or 45.5°C caused invaginations and other distortions of the peripheral NL. While hyperthermia did not alter the number or structure of internal lamin B foci, heat‐induced alterations to the peripheral NL were dose‐dependent. Interestingly, NL structure recovered with time after heating in cells that were destined to live or die. Thermotolerant cells heated at 45.5°C showed similar initial changes in the NL compared to non‐tolerant cells, but recovery occurred much faster. Taken together, these results suggest that the amount of initial damage to the peripheral NL is not correlated with heat‐induced cell killing. However, the possibility that an increased rate of recovery might confer a survival advantage cannot be discounted. J. Cell. Biochem. 86: 451–460, 2002. © 2002 Wiley‐Liss, Inc.