The coiled body is a specific intranuclear structure of unknown function that is enriched in splicing small nuclear ribonucleoproteins (snRNPs). Because adenoviruses make use of the host cell-splicing machinery and subvert the normal subnuclear organization, we initially decided to investigate the effect of adenovirus infection on the coiled body. The results indicate that adenovirus infection induces the disassembly of coiled bodies and that this effect is probably secondary to the block of host protein synthesis induced by the virus. Furthermore, coiled bodies are shown to be very labile structures, with a half-life of -2 h after treatment of HeLa cells with protein synthesis inhibitors. After blocking of protein synthesis, p80 coilin was detected in numerous microfoci that do not concentrate snRNP. These structures may represent precursor forms of the coiled body, which goes through a rapid cycle of assembly/disassembly in the nucleus and requires ongoing protein synthesis to reassemble.

Isolated cells from the proximal tubule have previously been used to study specific renal physiological processes. Here we analysed the structural changes induced by mechanical isolation on rat proximal tubule cells. As major modifications we detected: 1) a redistribution of brush border microvilli, which spread out over all the cell surface immediately after isolation; 2) a rapid redistribution of the apical membrane enzyme markers aminopeptidase N and isomaltase; and 3) a striking decrease of membrane surface amplification factor. The results show that cells isolated from the proximal tubule rapidly loose their characteristic polarized membrane structure. Loss of epithelial polarity implies loss of several vectorial transports and should thus be cautiously taken into account when working with this model system.