NUCLEAR LAMIN EXPRESSION IN CHRONIC HIBERNATING MYOCARDIUM IN MAN

Cardiomyocytes of chronic hibernating myocardium are known to undergo structural changes, indicative of dedifferentiation. Amongst these are changes in nuclear shape and chromatin distribution. Nuclear A-type l amins are known to be expressed in a differentiation-related fashion a nd to contribute to nuclear integrity and chromatin organization, Lami n expression was investigated with immunocytochemical staining procedu res in biopsies from patients with chronic hibernating myocardium, The expression of A-type (lamin A and C) were shown to be downregulated d uring hibernation, while lamin B2 remained present in hibernating card iomyocytes in a way similar to embryonic muscle cells. All heart muscl e cells were shown to be negative for lamin B1. The absence of A-type lamins in chronic hibernating cardiomyocytes could be taken as an addi tional argument for the dedifferentiation state of these cells. The ab sence of A-type lamins was accompanied by dispersion of the nuclear he terochromatin, in a way similar to nuclei of embryonic cardiomyocytes. (C) 1996 Academic Press Limited