Abstract
Spliceosomal components, U class snRNA and SC-35, were investigated using anti-2, 2, 7-trimethylguanosine (m3G) antibody for snRNA and anti-SC-35 antibody by immunofluorescence and immunoelectron microscopy in normal and apoptotic ameloblasts. Nuclear substructures, interchromatin granule clusters (IGCs) and perichromatin fibrils (PFs), were positive to anti-m3G antibody and anti-SC-35 antibody. Most of the apoptotic nuclei were not labeled by either antibody, although some were labeled by immunofluorescence microscopy. In earlier apoptotic nuclei, antim3G localized in a scattered pattern in the interchromatin space in immunoelectron microscopy. TIAR, a member of the RNA binding proteins with an RNA recognition motif and an effector of apoptosis, localized in the normal ameloblast nucleus, but was mostly lacking in the apoptotic nuclei, excepting occasional diffuse labeling in immunofluorescence microscopy. These results suggest that in addition to nuclear chromatin condensation, rearrangement of interchromatin space including IGCs and PFs occurs during apoptosis, further implying that the modulation of gene transcription and splicing may be accompanied by nuclear changes during the process.
