Biology subjects

Franco, P.

Publications and source records attributed to Franco, P..

6 recordsLinked to original sources

bioRxiv2025

Breaking new ground into RAD51-BRC repeats interplay in Homologous Recombination

Homologous recombination (HR) is a critical repair pathway involving numerous proteins that ensure error-free DNA double-strand breaks (DSBs) repair. Dysfunction in HR components can compromise genome integrity. Despite advances, many aspects of HR remain poorly understood. Notably, even one of the earliest identified and most critical interactions, between RAD51 and BRCA2, remains incompletely characterized, mainly due to the lack of structural data. This study presents a comprehensive biophysical analysis of the RAD51-BRC repeats interaction, integrating computational and experimental approaches. Starting with assessing the correlation between the binding affinities of individual BRC repeats and their impact on RAD51 disassembly, our investigation extends to larger BRCA2 truncations, offering unprecedented insights into the molecular determinants of RAD51 recognition. As mutations in the BRC repeats impair RAD51 recruitment and are associated with cancer, these results provide a valuable framework for interpreting pathogenic variants and guiding precision medicine therapies. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/688182v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@8c5cc9org.highwire.dtl.DTLVardef@11f9066org.highwire.dtl.DTLVardef@14159bdorg.highwire.dtl.DTLVardef@16ac161_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2025

A Quest for a Histaminergic or Orexinergic Biomarker for Sudden Infant Death Syndrome

AimsThis study aimed to investigate the role of the Hypocretin/Orexin (Ox) and Histamine (HA) systems--two key regulators of wakefulness --in sudden infant death syndrome (SIDS), a condition characterized by impaired arousal responses during sleep. MethodsCerebrospinal fluid (CSF) Ox levels were measured in 61 healthy controls, 70 Sudden Unexpected Death Infants (SUDI) (38 SIDS cases and 32 explained deaths (ED). HA and its metabolite, tele-methylhistamine (t-MeHA), were analysed in an additional 46 SUDI (34 SIDS, 12 ED) and 42 controls. Immunocytochemistry was performed on hypothalamic tissue from 11 SIDS and 13 ED cases to assess the number of Ox and HA neurons, using markers for Orexin-A and histidine decarboxylase (HDC), respectively. ResultsOverall CSF Ox levels did not differ significantly between groups. However, while an age-related decline in Ox levels was observed in controls (0-2 vs. 2-6 months), this pattern was absent in deceased infants, resulting in relatively higher Ox concentrations in the 2-6 month age group. HA and t-MeHA levels were significantly elevated in both SIDS and ED cases, likely due to postmortem release. Immunohistochemical analysis revealed an increased number of Ox-immunoreactive neurons in the rostral and caudal dorsolateral hypothalamus in SIDS cases compared to EDs. No differences were observed in the number or morphology of HA neurons. ConclusionFindings suggest increased Ox activity in SIDS cases, potentially reflecting repeated exposure to stress or hypoxia prior to death. In contrast, HA neurons do not appear to play a role in the pathophysiology of SIDS. Further research is needed to identify more specific biomarkers for assessing SIDS risk.

neuroscience↗

bioRxiv2025

Integrating computational and experimental biophysics reveals novel insights into the RAD51-BRC4 interaction

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=63 SRC="FIGDIR/small/642044v1_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@32e13org.highwire.dtl.DTLVardef@c60a6forg.highwire.dtl.DTLVardef@1d6fdceorg.highwire.dtl.DTLVardef@1b10541_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGRAPHICAL ABSTRACTC_FLOATNO C_FIG The interaction between the RAD51 and BRCA2 proteins is central for homologous recombination, a crucial pathway ensuring high-fidelity DNA repair. Recruitment of RAD51 involves eight highly conserved regions on BRCA2, named BRC repeats. To date, only the interaction between the fourth BRC repeat (BRC4) and the RAD51 C-terminal domain has been structurally characterized, while the complex of full-length RAD51 with the peptide still remains elusive. Here, we report an integrative experimental and in silico approach to reconstruct the conformational ensemble in solution for full length RAD51 in complex with BRC4. We combined AlphaFold2, crosslinking mass spectrometry (XL-MS) and small angle x-ray scattering (SAXS) data with molecular dynamics simulations (MD). These data show that the full-length RAD51-BRC4 complex is a mixture of compact and elongated conformations. Detailed analysis of the reweighted ensemble, achieved through the maximum entropy principle, identifies key residues at the N-terminal-BRC4 interface mediating complex conformational dynamics. Our evidence provides robust atomic-level insights into the interaction of RAD51 and BRC4. These findings are crucial for understanding the molecular features underlying the recognition between RAD51 and BRCA2, which are essential for developing therapeutic intervention strategies in cancer treatment.

biophysics↗

bioRxiv2021

Spatiotemporal heterogeneity of glioblastoma is dictated by microenvironmental interference

Glioblastomas are highly malignant tumors of the central nervous system. Evidence suggests that these tumors display large intra- and inter-patient heterogeneity hallmarked by subclonal diversity and dynamic adaptation amid developmental hierarchies1-3. However, the source for dynamic reorganization of cellular states within their spatial context remains elusive. Here, we in-depth characterized glioblastomas by spatially resolved transcriptomics, metabolomics and proteomics. By deciphering exclusive and shared transcriptional programs across patients, we inferred that glioblastomas develop along defined neural lineages and adapt to inflammatory or metabolic stimuli reminiscent of reactive transformation in mature astrocytes. Metabolic profiling and imaging mass cytometry supported the assumption that tumor heterogeneity is dictated by microenvironmental alterations. Analysis of copy number variation (CNV) revealed a spatially cohesive organization of subclones associated with reactive transcriptional programs, confirming that environmental stress gives rise to selection pressure. Deconvolution of age-dependent transcriptional programs in malignant and non-malignant specimens identified the aging environment as the major driver of inflammatory transformation in GBM, suggesting that tumor cells adopt transcriptional programs similar to inflammatory transformation in astrocytes. Glioblastoma stem cells implanted into human neocortical slices of varying age levels, independently confirmed that the ageing environment dynamically shapes the intratumoral heterogeneity towards reactive transcriptional programs. Our findings provide insights into the spatial architecture of glioblastoma, suggesting that both locally inherent tumor as well as global alterations of the tumor microenvironment shape its transcriptional heterogeneity. Global age-related inflammation in the human brain is driving distinct transcriptional transformation in glioblastomas, which requires an adjustment of the currently prevailing glioma models.

cancer biology↗

bioRxiv2020

Lineage and Spatial Mapping of Glioblastoma-associated Immunity

The diversity of molecular states and cellular plasticity of immune cells in the glioblastoma environment is still poorly understood. Here, we performed scRNA sequencing of the immune compartment and mapped potential cellular interactions leading to an immunosuppressive microenvironment and dysfunction of T cells. Through inferring the dynamic adaptation during T cell activation, we identified three different terminal states with unique transcriptional programs. Modeling of driver genes for terminal T cell fate identified IL-10 signaling alterations in a subpopulation of HAVCR2(+) T cells. To explore in depth cellular interactions, we established an in-silico model by the integration of spatial transcriptomic and scRNA-sequencing, and identified a subset of HMOX1+ myeloid cells defined by IL10 release leading to T cell exhaustion. We found a spatial overlap between HMOX(+) myeloid and HAVCR2(+) T cells, suggesting that myeloid-lymphoid interaction causes immunosuppression present in tumor regions with enriched mesenchymal gene expression. Using human neocortical GBM model, coupled with patient-derived T cells, we confirmed that the functional interaction between myeloid and lymphoid cells, leads to a dysfunctional state of T cells. This IL-10 driven T cell exhaustion was found to be rescued by JAK/STAT inhibition. A comprehensive understanding of the cellular states and plasticity of lymphoid cells in GBM will aid towards successful immunotherapeutic approaches.

cancer biology↗

bioRxiv2020

Only 40% of the world's forests are in good health

Many global environmental agendas, including halting biodiversity loss, reversing land degradation, and limiting climate change, depend upon retaining forests with high ecological integrity, yet the scale and degree of forest modification remains poorly quantified and mapped. By integrating data on observed and inferred human pressures and an index of lost connectivity, we generate the first globally-consistent, continuous index of forest condition as determined by degree of anthropogenic modification. Globally, only 17.4 million km2 of forest (40.5%) have high landscape level integrity (mostly found in Canada, Russia, the Amazon, Central Africa and New Guinea) and only 27% of this area is found in nationally-designated protected areas. Of the forest in protected areas, only 56% has high landscape level integrity. Ambitious policies that prioritize the retention of forest integrity, especially in the most intact areas, are now urgently needed alongside current efforts aimed at halting deforestation and restoring the integrity of forests globally.

ecology↗