Biology subjects

Batisse, J.

Publications and source records attributed to Batisse, J..

6 recordsLinked to original sources

bioRxiv2025

Molecular basis for the regulation of retroviral nucleosomal integration by chromatin compaction

Cellular chromatin represents the first nonreversible contact point between the genomes of incoming infectious agents, such as integrative viruses, and their hosts. The integration of retroviral genomes requires a functional association between the viral integration complex (intasome) and host chromatin, mediated through multiple interfaces between the integrase, target DNA, and histone components of the nucleosome. Previous studies have shown that these associations are regulated by cellular factors, such as LEDGF/p75 for lentiviruses, and by the degree of compaction of the chromatin surrounding the insertion site. However, the molecular mechanisms underlying the regulation of access to local nucleosomal functional interfaces remain elusive. In this study, we dissected how incoming intasomes engage nucleosome surface to achieve efficient integration. Combining biochemical approaches with molecular docking analysis, we demonstrated that HIV-1 and PFV intasomes distinctly and specifically interact with nucleosome surfaces. Mapping these interfaces onto a compacted trinucleosomal structure and simulating the dynamic docking of the intasome at these sites revealed how neighboring nucleosomes modulate the functional binding of the HIV-1 intasome to the catalytic target nucleosome by masking these functional interfaces. In contrast, the lower susceptibility of the PFV intasome to chromatin compaction was due to the persisting accessibility of active nucleosomal interfaces. Together, these data provide the first molecular and structural insights into how chromatin compaction influence retroviral integration. Our results especially show how nucleosome-intasomes docking sites participate in modulating the sensitivity of the retroviral integration to chromatin structure. Overall, our data reveal that HIV-1 and PFV integration rely on nucleosomes with distinct structural and functional properties at the insertion site to form an active strand transfer complex. This work further demonstrated that retroviruses have evolved distinct strategies to engage suitable chromatin structures for efficient integration highlighting a divergence in retroviral adaptation mechanisms.

microbiology↗

bioRxiv2023

The kinesin Kif21b regulates radial migration of cortical projection neurons through a noncanonical function on actin cytoskeleton.

Completion of neuronal migration is critical for brain development. Kif21b is a plus-end directed kinesin motor protein that promotes intracellular transport and controls microtubule dynamics in neurons. Here we report a physiological function of Kif21b during radial migration of projection neurons in the mouse developing cortex. In vivo analysis in mouse and live imaging on cultured slices demonstrate that Kif21b regulates the radial glia-guided locomotion of new-born neurons independently of its motility on microtubules. Unexpectedly we show that Kif21b directly binds and regulates the actin cytoskeleton both in vitro and in vivo in migratory neurons. We establish that Kif21b-mediated regulation of actin cytoskeleton dynamics influences branching and nucleokinesis during neuronal locomotion. Altogether, our results reveal atypical roles of Kif21b on the actin cytoskeleton during migration of cortical projection neurons.

neuroscience↗

bioRxiv2023

Biological and structural analysis of new potent Integrase-LEDGF allosteric HIV-1 inhibitors

LEDGF/p75 (LEDGF) main cellular cofactor of HIV-1 integrase (IN), acts as tethering factor to target integration of HIV in actively transcribed genes. Recently a class of IN inhibitors based on inhibition of LEDGF-IN interaction has been developed. We describe here a new series of IN-LEDGF allosteric inhibitors (INLAIs), with potent anti-HIV-1 activity in the one-digit nanomolar range. These compounds inhibited IN-LEDGF interaction while enhancing IN-IN aberrant multimerization by allosteric mechanism. Compounds of this series were fully active on HIV-1 mutants resistant to IN strand transfer inhibitors (INSTIs) and other class of anti-HIV drugs, confirming that they belong to a new class of antiretrovirals. These compounds displayed most potent antiretroviral activity at post-integration due to aberrant IN polymerization responsible of infectivity defect of viral particles produced. INLAI-resistant mutants were selected by dose escalation method and the most detrimental mutation found was T174I. The impact of these resistance mutations was analyzed by fold shift EC50 with regard to wild type virus and the replication capacity of mutated viruses were determined. Crystal structure of BDM-2, the lead compound of this series in complex with IN catalytic core domain (CCD) was elucidated. No antagonism was observed between BDM-2 and a panel of 16 antiretroviral drugs from different classes. In conclusion, the overall virologic profile of BDM-2 warrants the recently completed single ascending dose phase I trial (ClinicalTrials.gov Id: NCT03634085) and supports further clinical investigation for potential use in combination with other antiretroviral drugs. Author summaryIntegrase-LEDGF allosteric inhibitors are a new class of antiretrovirals recently developed that target the interaction of HIV-1 Integrase with its cellular cofactor LEDGF/p75 required for HIV-1 integration in actively transcribed genes. The great interest of developing such new class of antiretroviral is to add to the anti-HIV drug arsenal compounds that are fully active on resistant viruses to all other classes of drugs currently used in clinic. However, none of these inhibitors are currently in clinical use or in late clinical trials. Here we describe a series of highly potent Integrase allosteric inhibitors that can be considered as precursors of a new class of antiretroviral drugs, with fully conserved activity on viruses resistant to currently used anti-HIV drugs, and a lead compound that has no antagonism with a large panel of present anti-HIV drugs and that was successfully validated in a phase I clinical trial.

microbiology↗

bioRxiv2022

Modulation of the functional interfaces between retroviral intasomes and the human nucleosome

Retroviral integration into cell chromatin requires the formation of integrase-viral DNA complexes, called intasomes, and their interaction with the target DNA wrapped around nucleosomes. To further study this mechanism we developed an alphaLISA approach using the prototype foamy virus (PFV) intasome and human nucleosome. This system allowed us to monitor the association between both partners and investigate the protein/protein and protein/DNA interactions engaged in the association with chromatin. Using this approach, we next screened the chemical OncoSET library and selected small molecules that could modulate the intasome/nucleosome complex. Molecules were selected as acting either on the DNA topology within the nucleosome or on the integrase/histone tail interactions. Within these compounds, doxorubicin and histone binders calixarenes were characterized using biochemical, structural and cellular approaches. These drugs were shown to inhibit PFV and HIV-1 integration in vitro as well as HIV-1 infection in primary PBMCs cells. Our work provides new information about intasome-nucleosome interaction determinants and paves the way for further unedited antiviral strategies that target the final step of intasome/chromatin anchoring.

microbiology↗

bioRxiv2021

The HIV-1 Integrase C-Terminal domain induces TAR RNA structural changes promoting Tat binding.

Recent evidence indicated that HIV-1 Integrase (IN) binds genomic viral RNA (gRNA) playing a critical role in viral particle morphogenesis and gRNA stability in host cells. Combining biophysical and biochemical approaches we show that the C-terminal flexible 18-residues tail of IN acts as a sensor of the peculiar apical structure of trans-activation response element RNA (TAR), directly interacting with its hexaloop. We highlighted how the whole IN C-terminal domain, once bound to TAR, can change its structure assisting the binding of Tat, the HIV trans-activator protein, which finally displaces IN from TAR. Our results are consistent with the emerging role of IN in early stage of proviral transcription and suggest new steps of HIV-1 life cycle that can be considered as therapeutic targets.

biochemistry↗

bioRxiv2021

A conserved uORF impacts APOBEC3G translation and is essential for translational inhibition by the HIV-1 Vif protein

The HIV-1 Vif protein is essential for viral fitness and pathogenicity. Vif decreases expression of cellular restriction factors APOBEC3G (A3G), A3F, A3D and A3H, which inhibit HIV-1 replication by inducing hypermutation during reverse transcription. Vif counteracts A3G at several levels (transcription, translation and protein degradation) that together reduce the levels of A3G in cells and prevent its incorporation into viral particles. How Vif affects A3G translation remains unclear. Here, we uncovered the importance of a short conserved uORF (upstream ORF) located within two critical stem-loop structures of the 5 untranslated region (5UTR) of A3G mRNA for this process. A3G translation occurs through a combination of leaky-scanning and translation re-initiation and the presence of an intact uORF decreases the extent of global A3G translation under normal conditions. Interestingly, the uORF is also absolutely required for Vif-mediated translation inhibition and redirection of A3G mRNA into stress granules. Overall, we discovered that A3G translation is regulated by a small uORF conserved in the human population and that Vif uses this specific feature to repress its translation.

microbiology↗