VCP is an ATPase involved in a number of cellular activities, including homotypic membrane fusion, transcription activation, nuclear envelope reconstruction, post-mitotic organelle reassembly, cell cycle control, apoptosis and endoplasmic reticulum associated degradation of proteins [34] [37].
Clathrin has been implicated in a number of nonendocytic functions including the maintenance of basolateral polarity involving the regulation of protein exit from the Golgi [15], and post-mitotic Golgi reassembly [16].
It has been suggested to be involved in a number of cellular activities, including homotypic membrane fusion, transcription activation, nuclear envelope reconstruction, post-mitotic organelle reassembly, cell cycle control, apoptosis and endoplasmic reticulum associated degradation of proteins (ERAD [20] [23]].
These results indicate that the nuclear defects in NPM-depleted cells were independent from the post-mitotic nuclear reassembly.
Interestingly, Spt6, a histone chaperone involved in post-elongation nucleosomal reassembly is necessary for H3 K36 trimethylation [ 67, 68], indicating that the addition of this mark occurs in conjunction with nucleosomal reassembly following the passage of RNAPII.
The two GRASP proteins, GRASP65 (65 kDa) and GRASP55 (55 kDa), were first identified as Golgi stacking factors in an in vitro system that reconstitutes mitotic Golgi disassembly and post-mitotic Golgi reassembly (Barr et al., 1997; Shorter et al., 1999).
Interestingly, H3 K36 di- and trimethylation prevent the interaction of Asf1 with histones over coding regions [ 61], indicating that the H3 K36 methyl mark may prevent histone exchange by interfering with the binding of histone chaperones involved in post-transcriptional chromatin reassembly [ 61, 66].
VCP is known to play an important role in cellular activities including ubiquitin (Ub) -dependent protein degradation [ 1], chromatin-associated protein degradation [ 2], messenger ribonucleic acid (mRNA) metabolism [ 3], autophagy [ 4], anti-apoptotic function [ 5], and post-mitotic Golgi apparatus reassembly [ 6].
How might this reassembly take place?
The cross-linked dimer remains clearly detected even when the reassembly took place at pH 5.0.
Mitotic chromosome condensation and intrinsic structure appear normal in the absence of the perichromosomal compartment but significant differences in nucleolar reassembly and nuclear organisation are observed in post-mitotic cells.
