| Popis: |
(in English) The phosphatidylinositols are a subclass of glycerophospholipids with their inositol head group linked to the diacylglycerol backbone. The differential phosphorylation of the inositol head group yields seven different phosphoinositide phosphates (PIPs) which can be mono-, bis,- or tris-phosphorylated. The roles of the cytoplasmic PIPs have been extensively studied in vesicular trafficking, ion channels, generating second messengers and, membrane and cytoskeletal dynamics. While their cytoplasmic functions are very well described, the molecular mechanism of their nuclear functions are still poorly understood. From the nuclear PIPs, the Phosphatidylinositol 4,5-bisphosphate (PIP2) is the most abundant phosphoinositide in the cell nucleus and it participates to the nuclear architecture by regulating processes such as chromatin remodeling, DNA-damage response and gene expression. In the cell nucleus, it localizes mostly to nuclear speckles where it interacts with the splicing machinery. In nucleolus, PIP2 is involved in the RNA Polymerase I machinery to regulate rDNA transcription. Recently, we have defined a nucleoplasmic pool of PIP2 which is observed in 40 to 100nm foci. The nascent transcripts of RNA Polymerase II (RNAPII) were visualized at their periphery and RNA was shown to be... |
