The transcriptional co-activator lens epithelium-derived growth factor/p75 (LEDGF/p75) plays an important role in the biology of the cell and in several human diseases, including MLL-rearranged acute leukemia, autoimmunity, and HIV-1 infection. In both health and disease, LEDGF/p75 functions as a chromatin tether that interacts with proteins such as MLL1 and HIV-1 integrase via its integrase-binding domain (IBD) and with chromatin through its N-terminal PWWP domain. Recently, dimerization of LEDGF/p75 was shown, mediated by a network of electrostatic contacts between amino acids from the IBD and the C-terminal α6-helix. Here, we investigated the functional impact of LEDGF/p75 variants on the dimerization using biochemical and cellular interaction assays. The data demonstrate that the C-terminal α6-helix folds back in cis on the IBD of monomeric LEDGF/p75. We discovered that the presence of DNA stimulates LEDGF/p75 dimerization. LEDGF/p75 dimerization enhances binding to MLL1 but not to HIV-1 integrase, a finding that was observed in vitro and validated in cell culture. Whereas HIV-1 replication was not dependent on LEDGF/p75 dimerization, colony formation of MLLr-dependent human leukemic THP-1 cells was. In conclusion, our data indicate that intricate changes in the quaternary structure of LEDGF/p75 modulate its tethering function.

• MeSH
• chromatin * MeSH
• dimerizace MeSH
• DNA metabolismus   MeSH
• lidé MeSH
• mezibuněčné signální peptidy a proteiny * metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

[Figure: see text].

• MeSH
• adaptorové proteiny signální transdukční chemie   metabolismus   MeSH
• DNA vazebné proteiny chemie   metabolismus   MeSH
• elongace genetické transkripce * MeSH
• exprese genu MeSH
• interakční proteinové domény a motivy genetika   MeSH
• lidé MeSH
• mapy interakcí proteinů MeSH
• molekulární modely MeSH
• mutace MeSH
• nádorové buněčné linie MeSH
• proteinové domény MeSH
• proteiny vázající RNA chemie   genetika   metabolismus   MeSH
• RNA-polymerasa II chemie   metabolismus   MeSH
• transkripční elongační faktory chemie   metabolismus   MeSH
• transkripční faktory chemie   genetika   metabolismus   MeSH
• vazba proteinů MeSH
• vnitřně neuspořádané proteiny chemie   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

HDGF-related protein 2 (HRP-2) is a member of the Hepatoma-Derived Growth Factor-related protein family that harbors the structured PWWP and Integrase Binding Domain, known to associate with methylated histone tails or cellular and viral proteins, respectively. Interestingly, HRP-2 is a paralog of Lens Epithelium Derived Growth Factor p75 (LEDGF/p75), which is essential for MLL-rearranged (MLL-r) leukemia but dispensable for hematopoiesis. Sequel to these findings, we investigated the role of HRP-2 in hematopoiesis and MLL-r leukemia. Protein interactions were investigated by co-immunoprecipitation and validated using recombinant proteins in NMR. A systemic knockout mouse model was used to study normal hematopoiesis and MLL-ENL transformation upon the different HRP-2 genotypes. The role of HRP-2 in MLL-r and other leukemic, human cell lines was evaluated by lentiviral-mediated miRNA targeting HRP-2. We demonstrate that MLL and HRP-2 interact through a conserved interface, although this interaction proved less dependent on menin than the MLL-LEDGF/p75 interaction. The systemic HRP-2 knockout mice only revealed an increase in neutrophils in the peripheral blood, whereas the depletion of HRP-2 in leukemic cell lines and transformed primary murine cells resulted in reduced colony formation independently of MLL-rearrangements. In contrast, primary murine HRP-2 knockout cells were efficiently transformed by the MLL-ENL fusion, indicating that HRP-2, unlike LEDGF/p75, is dispensable for the transformation of MLL-ENL leukemogenesis but important for leukemic cell survival.

• MeSH
• adaptorové proteiny signální transdukční genetika   metabolismus   MeSH
• HEK293 buňky MeSH
• histonlysin-N-methyltransferasa genetika   metabolismus   MeSH
• karcinogeneze genetika   metabolismus   patologie   MeSH
• leukemie genetika   metabolismus   patologie   MeSH
• lidé MeSH
• myši knockoutované MeSH
• myši MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• protoonkogenní protein MLL genetika   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• viabilita buněk MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Dimerization of many eukaryotic transcription regulatory factors is critical for their function. Regulatory role of an epigenetic reader lens epithelium-derived growth factor/p75 (LEDGF/p75) requires at least two copies of this protein to overcome the nucleosome-induced barrier to transcription elongation. Moreover, various LEDGF/p75 binding partners are enriched for dimeric features, further underscoring the functional regulatory role of LEDGF/p75 dimerization. Here, we dissected the minimal dimerization region in the C-terminal part of LEDGF/p75 and, using paramagnetic NMR spectroscopy, identified the key molecular contacts that helped to refine the solution structure of the dimer. The LEDGF/p75 dimeric assembly is stabilized by domain swapping within the integrase binding domain and additional electrostatic "stapling" of the negatively charged α helix formed in the intrinsically disordered C-terminal region. We validated the dimerization mechanism using structure-inspired dimerization defective LEDGF/p75 variants and chemical crosslinking coupled to mass spectrometry. We also show how dimerization might affect the LEDGF/p75 interactome.

• MeSH
• lidé MeSH
• mezibuněčné signální peptidy a proteiny chemie   metabolismus   MeSH
• multimerizace proteinu * MeSH
• proteinové domény MeSH
• statická elektřina MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

HIV-1 persists lifelong in memory cells of the immune system as latent provirus that rebounds upon treatment interruption. Therefore, the latent reservoir is the main target for an HIV cure. Here, we studied the direct link between integration site and transcription using LEDGINs and Barcoded HIV-ensembles (B-HIVE). LEDGINs are antivirals that inhibit the interaction between HIV-1 integrase and the chromatin-tethering factor LEDGF/p75. They were used as a tool to retarget integration, while the effect on HIV expression was measured with B-HIVE. B-HIVE tracks insert-specific HIV expression by tagging a unique barcode in the HIV genome. We confirmed that LEDGINs retarget integration out of gene-dense and actively transcribed regions. The distance to H3K36me3, the marker recognized by LEDGF/p75, clearly increased. LEDGIN treatment reduced viral RNA expression and increased the proportion of silent provirus. Finally, silent proviruses obtained after LEDGIN treatment were located further away from epigenetic marks associated with active transcription. Interestingly, proximity to enhancers stimulated transcription irrespective of LEDGIN treatment, while the distance to H3K36me3 only changed after treatment with LEDGINs. The fact that proximity to these markers are associated with RNA expression support the direct link between provirus integration site and viral expression.

• MeSH
• buněčné linie MeSH
• chromatin metabolismus   MeSH
• histony metabolismus   MeSH
• HIV-1 účinky léků   genetika   metabolismus   MeSH
• inhibitory HIV-integrasy farmakologie   MeSH
• integrace viru * účinky léků   MeSH
• lidé MeSH
• mezibuněčné signální peptidy a proteiny MeSH
• proviry genetika   MeSH
• regulace exprese virových genů * účinky léků   MeSH
• RNA virová metabolismus   MeSH
• umlčování genů * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Lens epithelium-derived growth factor/p75 (LEDGF/p75, or PSIP1) is a transcriptional coactivator that tethers other proteins to gene bodies. The chromatin tethering function of LEDGF/p75 is hijacked by HIV integrase to ensure viral integration at sites of active transcription. LEDGF/p75 is also important for the development of mixed-lineage leukemia (MLL), where it tethers the MLL1 fusion complex at aberrant MLL targets, inducing malignant transformation. However, little is known about how the LEDGF/p75 protein interaction network is regulated. Here, we obtained solution structures of the complete interfaces between the LEDGF/p75 integrase binding domain (IBD) and its cellular binding partners and validated another binding partner, Mediator subunit 1 (MED1). We reveal that structurally conserved IBD-binding motifs (IBMs) on known LEDGF/p75 binding partners can be regulated by phosphorylation, permitting switching between low- and high-affinity states. Finally, we show that elimination of IBM phosphorylation sites on MLL1 disrupts the oncogenic potential of primary MLL1-rearranged leukemic cells. Our results demonstrate that kinase-dependent phosphorylation of MLL1 represents a previously unknown oncogenic dependency that may be harnessed in the treatment of MLL-rearranged leukemia.

• MeSH
• adaptorové proteiny signální transdukční genetika   metabolismus   MeSH
• aminokyselinové motivy MeSH
• fosforylace genetika   MeSH
• histonlysin-N-methyltransferasa genetika   metabolismus   MeSH
• HIV-integrasa genetika   metabolismus   MeSH
• HIV enzymologie   genetika   MeSH
• lidé MeSH
• mediátorový komplex - podjednotka 1 genetika   metabolismus   MeSH
• nádorové buněčné linie MeSH
• protoonkogenní protein MLL genetika   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Protein-protein interactions are involved in most if not all pathogenic and pathophysiological processes and represent attractive therapeutic targets. Extensive biological and clinical research efforts have led to the identification and validation of several cellular hubs that are crucially involved in disease pathogenesis. An interesting example of such a hub is the lens epithelium-derived growth factor (LEDGF/p75), a protein that tethers multiple unrelated proteins and protein complexes to the chromatin. Its chromatin-tethering ability is linked to at least two unrelated diseases-HIV infection and MLL-rearranged acute leukemia. In this review we discuss recent progress in our understanding of the interaction of LEDGF/p75 with its binding partners and focus on the first steps towards therapies targeting protein-protein interactions of LEDGF/p75.

• MeSH
• adaptorové proteiny signální transdukční genetika   metabolismus   MeSH
• cílená molekulární terapie MeSH
• histonlysin-N-methyltransferasa genetika   metabolismus   MeSH
• HIV infekce farmakoterapie   genetika   metabolismus   MeSH
• individualizovaná medicína metody   MeSH
• interakční proteinové domény a motivy MeSH
• knihovny malých molekul farmakologie   MeSH
• kontraindikace MeSH
• leukemie farmakoterapie   genetika   metabolismus   MeSH
• lidé MeSH
• molekulární modely MeSH
• protoonkogenní protein MLL genetika   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Lens epithelium-derived growth factor (LEDGF/p75) is an epigenetic reader and attractive therapeutic target involved in HIV integration and the development of mixed lineage leukaemia (MLL1) fusion-driven leukaemia. Besides HIV integrase and the MLL1-menin complex, LEDGF/p75 interacts with various cellular proteins via its integrase binding domain (IBD). Here we present structural characterization of IBD interactions with transcriptional repressor JPO2 and domesticated transposase PogZ, and show that the PogZ interaction is nearly identical to the interaction of LEDGF/p75 with MLL1. The interaction with the IBD is maintained by an intrinsically disordered IBD-binding motif (IBM) common to all known cellular partners of LEDGF/p75. In addition, based on IBM conservation, we identify and validate IWS1 as a novel LEDGF/p75 interaction partner. Our results also reveal how HIV integrase efficiently displaces cellular binding partners from LEDGF/p75. Finally, the similar binding modes of LEDGF/p75 interaction partners represent a new challenge for the development of selective interaction inhibitors.

• MeSH
• dimerizace MeSH
• Escherichia coli MeSH
• histonlysin-N-methyltransferasa metabolismus   MeSH
• HIV-integrasa metabolismus   MeSH
• konsenzuální sekvence MeSH
• Lentivirus enzymologie   MeSH
• lidé MeSH
• mezibuněčné signální peptidy a proteiny metabolismus   MeSH
• molekulární sekvence - údaje MeSH
• proteiny metabolismus   MeSH
• protoonkogenní protein MLL metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• sekvence aminokyselin MeSH
• terciární struktura proteinů MeSH
• transposasy metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH