Lens epithelium-derived growth factor p75 splice variant (LEDGF) is a chromatin-binding protein known for its antiapoptotic activity and ability to direct human immunodeficiency virus into active transcription units. Here we show that LEDGF promotes the repair of DNA double-strand breaks (DSBs) by the homologous recombination repair pathway. Depletion of LEDGF impairs the recruitment of C-terminal binding protein interacting protein (CtIP) to DNA DSBs and the subsequent CtIP-dependent DNA-end resection. LEDGF is constitutively associated with chromatin through its Pro-Trp-Trp-Pro (PWWP) domain that binds preferentially to epigenetic methyl-lysine histone markers characteristic of active transcription units. LEDGF binds CtIP in a DNA damage-dependent manner, thereby enhancing its tethering to the active chromatin and facilitating its access to DNA DSBs. These data highlight the role of PWWP-domain proteins in DNA repair and provide a molecular explanation for the antiapoptotic and cancer cell survival-activities of LEDGF.

• MeSH
• adaptorové proteiny signální transdukční * antagonisté a inhibitory   genetika   metabolismus   MeSH
• apoptóza MeSH
• chromatin metabolismus   MeSH
• dvouřetězcové zlomy DNA MeSH
• HeLa buňky MeSH
• HIV genetika   MeSH
• jaderné proteiny metabolismus   MeSH
• lidé MeSH
• malá interferující RNA genetika   MeSH
• nádorové buněčné linie MeSH
• rekombinační oprava DNA * fyziologie   MeSH
• RNA interference MeSH
• transkripční faktory * antagonisté a inhibitory   genetika   metabolismus   MeSH
• transportní proteiny metabolismus   MeSH
• viabilita buněk MeSH
• Check Tag
• lidé MeSH

The pl6INK4a tumor suppressor negatively regulates progression through the G1 phase of the mammalian cell cycle. To mimic the downmodulation of p16INK4a commonly seen in cancer, we designed and characterized a hammerhead ribozyme against exon E1alpha of the murine pl6INK4a transcript. Stable expression of the ribozyme in murine erythroleukemia (MEL) cells reduced the endogenous pl6INK4a protein by more than 70% and significantly accelerated cell cycle progression. The specificity and efficiency of our new ribozyme suggest its possible application in elucidating the role of p16INK4a in fundamental biological processes including homeostatic tissue renewal, protection against oncogenic transformation, and cellular senescence.

• MeSH
• akutní erytroblastická leukemie genetika   metabolismus   patologie   MeSH
• buněčné dělení MeSH
• buněčné klony MeSH
• down regulace MeSH
• genetická transkripce MeSH
• inhibitor p16 cyklin-dependentní kinasy genetika   metabolismus   MeSH
• messenger RNA MeSH
• molekulární sekvence - údaje MeSH
• myši MeSH
• nádorové buňky kultivované MeSH
• proteosyntéza MeSH
• rekombinantní proteiny genetika   metabolismus   MeSH
• RNA katalytická genetika   metabolismus   MeSH
• sekvence nukleotidů MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The product of the retinoblastoma susceptibility gene, pRb, is a negative regulator of cell growth. It functions by regulating the activity of transcription factors. Rb represses some genes by sequestering or inactivating the positive transcription factor E2F and seems to activate some others by interacting with factors like Sp1 or ATF-2. However, there are only a few examples of genes which are positively regulated by pRb. In order to find out if there are common mechanisms for promoter regulation by pRb, we were interested to identify more genes which are either stimulated or repressed by pRb. Using the method of differential display (DDRT-PCR) in combination with nuclear run-on analyses we were able to detect a number of genes which are upregulated by ectopic expression of the Rb gene in Rb-deficient mammary carcinoma cells. We could demonstrate not only stimulation of the endogenous mutant Rb gene but also positive regulation of genes coding for diverse classes of proteins, including the endothelial growth regulator endothelin-1 and the proteoglycans versican and PG40. As a second approach, we investigated gene expression in cell lines established from Rb deficient heterozygous and homozygous knockout mouse embryos and normal mice. We have identified several genes the expression of which correlates positively or negatively with the presence of Rb. These data provide further evidence for pRb being a master regulator of a complex network of gene activities defining the difference between dividing and resting or differentiated cells.

• MeSH
• endoteliny biosyntéza   genetika   MeSH
• geny retinoblastomu fyziologie   MeSH
• lidé MeSH
• molekulární sekvence - údaje MeSH
• myši knockoutované MeSH
• myši MeSH
• nádorové buňky kultivované MeSH
• polymerázová řetězová reakce metody   MeSH
• proteoglykany biosyntéza   genetika   MeSH
• regulace genové exprese * MeSH
• retinoblastomový protein genetika   fyziologie   MeSH
• sekvence nukleotidů MeSH
• transfekce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH