Study about Tubulin protein's novel function in interphase nuclei and regulation by polycomb proteins.

在后生动物中，核膜内表面衬有核纤层（NL），主要由核纤层组成。NL和核内分子的物理相互作用参与染色体陈述和转录活性的调节。与NL相关的基因大部分被转录抑制。NL还与包括HDAC在内的多种染色质修饰因子相关。由于组蛋白乙酰化水平较低，且与NL相互作用基因的转录活性密切相关，这些分子缔合使NL近端空间成为促进组蛋白去乙酰化的微区，从而抑制转录。在这里，我们表明微管蛋白蛋白持续与NL相关，并且对于NL-染色质和NL-HDAC的缔合是必不可少的。微管蛋白从NL的丢失导致染色质和HDAC从NL脱离，以及核周边组蛋白乙酰化的上调。此外，我们发现微管蛋白和染色质的结合需要多梳组（PcG）蛋白Ring 1b，因此Ring 1b介导染色质和NL的结合。我们的数据显示微管蛋白和PcGs的新功能的分子组装决定染色体的陈述在核周围。

In metazoan, the inner surface of nuclear envelope is lined by nuclear lamina(NL), primarily consist of Lamins. Physical interaction of NL and intranuclear molecules engages in regulation of chromosome statement and of transcriptional activity. Large extent of the genes associating to NL is transcriptionally repressed. NL also associates to variety of chromatin modifying factors including HDACs. Given that histone acetylation at nuclear periphery in low level and is close involved in transcriptional activity of genes interacting to NL, these molecular associations make proximal space of NL a microdomain which promotes deacetylation of histone, and thereby transcriptional repression.However, machineries which link NL and its binding factors in living cells are yet poorly understood. Here we show Tubulin proteins persistently associate to NL, and are indispensable for association of NL-chromatin, and of NL-HDACs. Loss of Tubulin from NL results in the disengagement of chromatin and HDACs from NL, and upregulation of histone acetylation at nuclear periphery. Moreover, we found association of Tubulin and chromatin requires polycomb group(PcG) protein Ring1b, therefore Ring1b mediates binding of chromatin and NL. Our data show novel function of Tubulin proteins and PcGs for the molecular assembly determinative for chromosome statement at nuclear periphery.