Immunocytochemical detection of structural and regulatory proteins in rat adrenal nuclear matrix

The nuclear matrix is a specific cell structure consisting of a residual nu cleoskeleton that extends from the nucleoli to the nuclear envelope. The nu clear matrix of steroidogenic cells was isolated previously from a purified nuclear fraction. We present here an in situ extraction method, modified L utz's method, for rat glandular adrenal cell nuclear matrix. This residual organelle was characterized and studied using immunocytochemical methods, T he adrenal glands were removed, the cells prepared in suspension and deposi ted by cytospin onto Poly-L-lysine glass slides. The nuclear matrix was ext racted with Nonidet P-40, DNase I and high and low ionic strength buffers. Structural proteins, nuclear lamins, coilin and fibrillarin were detected i mmunocytochemically. The adrenal fasciculata cells were easily identified b y this method because of their large nuclei and abundant lipid droplets in the cytoplasm, After immunocytochemical detection by antibodies against lam ins A and C, a marked brown layer at the periphery of the nucleus was obser ved. The intensity of the staining was lower using the antibody against nuc lear lamin B, Immunocytochemical detection of the protein coilin revealed p unctuated stained areas, 2-6 per nucleus, that probably correspond to the c oiled bodies. The protein fibrillarin was detected at the nucleolus and coi led bodies, Our technique is simple, reveals well preserved adrenal nuclear matrices, and may be a useful method for immunocytochemical analysis and i n situ hybridization.