Biology subjects

Bouhaddou, M.

Publications and source records attributed to Bouhaddou, M..

At least 19 recordsLinked to original sources

bioRxiv2026

The Global Phosphorylation Landscape of Acute Heat Stress in Reef-Building Corals

Warming oceans disrupt the coral-algal symbiosis that sustains reefs, yet the signaling mechanisms initiating bleaching remain poorly understood. Integrating global phosphoproteomics across three reef-building corals with protein structure modeling revealed conservation between coral and human kinases, enabling inference of coral kinase activities and uncovering a shared signaling program induced by acute heat stress. Heat rapidly activated ERK, JNK, and p38 MAP kinases, suppressed cell cycle signaling, and remodeled pathways controlling chromatin, RNA processing, and metabolism. Most strikingly, thermal stress rewired immune receptor signaling networks associated with non-self recognition, suggesting that heat shifts the coral host from tolerance to immune recognition of its algal symbionts. These findings define conserved signaling mechanisms that precede bleaching, revealing actionable molecular targets for enhancing coral resilience.

systems biology↗

bioRxiv2026

The p53-p21-Cyclin D2 regulatory axis drives metabolic reprogramming and a distinct senescent macrophage senotype during aging and MASLD.

Aging drives chronic disease in part through senescent cells, including macrophages, which fuel inflammation. Senescent macrophages are functionally heterogeneous: canonical p16-high macrophages promote tumorigenesis or, in other contexts, disease tolerance, whereas we previously identified a distinct p21-high, p16-low senotype that drives metabolic dysfunction-associated steatotic liver disease (MASLD). The molecular basis of this senotype has remained undefined. Using genetic and multi-omic approaches, we show that a p53-p21-dependent program actively represses p16 and is required for senescent macrophage viability. We identify Cyclin D2 as a non-canonical downstream effector that redistributes from the nucleus to mitochondria and lipid droplets, where it partners with MIC60 to drive metabolic reprogramming and modulates AKT1-mTORC1 signaling that sustains the SASP. Cyclin D2-p21 double-positive macrophages accumulate with aging and MASLD in mice and in human liver cirrhosis, and can be selectively depleted by senolytic treatment. Together, these findings define a druggable p53-p21-Cyclin D2 axis that specifies macrophage senotype.

immunology↗

bioRxiv2026

Multi-omics Reveals Divergent Endothelial Molecular Responses to New and Old World Hantaviruses

Hantaviruses cause vascular leakage syndromes that vary in clinical manifestation and severity. Although tissue tropism contributes to these differences, both Old and New World hantaviruses infect endothelial cells, where species-specific disease phenotypes remain poorly understood. Here we integrated time-resolved global RNA sequencing, mass spectrometry proteomics, and phosphoproteomics of human endothelial cells infected with New World Andes virus (ANDV) or Old World Hantaan virus (HTNV). Despite equivalent early viral RNA and protein levels, ANDV elicited a stronger innate immune protein response, preceding its restriction while HTNV replication continued. At later stages of infection, HTNV induced downregulation of cytoskeletal and junctional protein phosphorylation, accompanied by visual disruption of cellular actin architecture. Additionally, ANDV induced heightened activity of ERBB-family kinases, whose chemical inhibition by neratinib and afatinib reduced viral replication. Together, these data define species-specific responses in endothelial cells, identify druggable host targets, and reveal mechanisms with relevance to divergent vascular leakage symptomology.

systems biology↗

bioRxiv2026

From SCUBA to spectra: Broadly applicable methods for coral metabolomics research

Corals represent a complex assemblage consisting of a host cnidarian, symbiotic dinoflagellate microalgae, and associated microbiomes and viromes, collectively called the coral holobiont. Corals are foundational to tropical reefs, yet their global decline due to climate change and other stressors creates an uncertain future for this valuable ecosystem. Metabolomics is a powerful means to unravel biochemical interactions within the holobiont that underpin coral resilience and adaptation. However, the remote nature of reefs and the analytical demands of this technique often limit its application. Untargeted metabolomics presents analytical challenges that are amplified in complex samples like corals, such as identifying the biological source of metabolites. Here, we evaluate how different sample fixation methods and time delays before storage--unavoidable in field contexts--affect coral metabolome profiles. We further present a framework for mapping metabolites in holobiont samples to their coral host and algal symbiont origins and introduce a spectral library to improve and automate annotation of coral lipids. Additionally, we demonstrate how single samples can be used concurrently for metabolomics, DNA amplification, and proteomics. Together, our study provides a streamlined, field-adaptable workflow for coral metabolomics that enables larger-scale studies and broader adoption of metabolomics in coral reef research and conservation.

biochemistry↗

bioRxiv2025

Spatial regulation of AMPK activity under oxidative stress requires LKB1

AMP-activated protein kinase (AMPK) is a central regulator of cellular energy homeostasis, with over 100 identified downstream targets throughout the cell. In response to cellular stress, including energetic stress, AMPK is activated via binding of AMP and phosphorylation by upstream kinases, including liver kinase B1 (LKB1). We and others have found that the activation of AMPK in response to cellular stress has distinct subcellular mechanisms, indicating compartmentalized regulation of AMPK signaling. Oxidative stress is known to stimulate AMPK activity, but how AMPK is spatially regulated by oxidative stress is underexplored. Using a single-fluorophore excitation-ratiometric AMPK activity reporter (ExRai AMPKAR), we find that oxidative stress induced by hydrogen peroxide (H2O2) results in AMPK activity with distinct spatiotemporal dynamics. We found that in the cytoplasm, nucleus, outer mitochondrial membrane, and cytosolic lysosomal surface, phosphorylation of AMPK by LKB1 is required for AMPK activity. Using a biosensor for ATP, we found at the cytoplasm and lysosome local ATP depletion dictates kinetics of AMPK activity. Using a multi- omics approach, we discover that in response to oxidative stress, AMPK mediates significant metabolic and gene expression changes, including upregulation of oxidative stress response through nuclear factor erythroid 2-related factor 2 (NRF2). Expanding on this identified mechanism, we find that non-small cell lung cancers harboring Kelch-like ECH-associated protein 1 (KEAP1) mutations have a functionally deficient LKB1-AMPK signaling network in response to oxidative stress. Altogether, this work provides new insights into how the subcellular environment influences localized AMPK activity, and identifies how AMPK regulates the cellular response to oxidative stress.

biochemistry↗

bioRxiv2025

HIV-1 latency reversing agents converge on phosphoregulation of nuclear protein complexes

Despite the success of antiretroviral therapy (ART), HIV-1 persists in latently infected cells, posing a central barrier to a cure. "Shock-and-kill" strategies using latency-reversing agents (LRAs) have shown some promise in reactivating viral gene expression ex vivo, but have yielded little clinical efficacy, underscoring the need for deeper insight into the molecular mechanisms that govern reactivation. Here, we performed deep quantitative phosphoproteomics of J-Lat 10.6 cells treated with diverse LRAs: SAHA, PMA, or prostratin. We identified 48,476 confidently localized phosphorylation sites mapping to 6,672 proteins, with SAHA inducing the most extensive changes. Regulated phosphoproteins were enriched in chromatin organization, transcription, RNA processing, nuclear transport, and cytoskeletal remodeling. Although LRAs regulated overlapping pathways, they elicited divergent kinase activities and site-specific phosphorylation patterns. A reproducible core of 3,502 phosphorylation sites on 1,432 proteins mapped to 39 nuclear protein complexes, including the spliceosome, Mediator, NF-{kappa}B, and RNA polymerase II. Remarkably, 20 protein complexes were phosphoregulated by all three LRAs, but at distinct sites, revealing convergence on shared nuclear machinery through distinct mechanisms. This study provides a comprehensive map of protein complex phosphorylation remodeling during HIV-1 reactivation and highlights signaling mechanisms that could guide the rational design of next-generation LRAs with improved efficacy and reduced toxicity.

microbiology↗

bioRxiv2025

SARS-CoV-2 nucleocapsid induces hyperinflammation and vascular leakage through the Toll-like receptor signaling axis in macrophages

Tens of thousands of severe COVID-19 cases are hospitalized weekly in the U.S., often driven by an imbalance between antiviral responses and inflammatory signaling, leading to uncontrolled cytokine secretion. The SARS-CoV-2 nucleocapsid (N) protein is a known immune antagonist, but its role in macrophage-driven cytokine storms is unclear. We demonstrate that N functions in a pathway-specific manner, specifically amplifying nuclear factor {kappa}B-related transcripts upon Toll-like receptor 7/8 stimulation. Moreover, we show that this is a conserved feature of pathogenic coronaviruses, with the delta variant N being the most pro-inflammatory. Our interaction networks suggest the delta variant N drives inflammation through interactions with several stress granule-related proteins. Profiling of secreted cytokines revealed that supernatants from the delta variant N-expressing macrophages disrupt brain and heart endothelial barriers, implicating N in COVID-19-associated cognitive and cardiac complications. Our findings highlight N-mediated immune imbalance as a driver of severe COVID-19 and identify N as a promising therapeutic target to mitigate hyperinflammation.

microbiology↗

bioRxiv2025

Paracrine Signals from HIV-1 Infected Immune Cells Reprogram Cervical Cancer Pathways

Persistent infection with human papillomavirus (HPV) is the primary cause of cervical cancer worldwide. Notably, women co-infected with HPV and human immunodeficiency virus type 1 (HIV-1) have a six-fold higher lifetime risk of developing cervical cancer compared to those without HIV, even when adhering to antiretroviral therapy (ART) and achieving T-cell reconstitution. While chronic HIV-1 infection is known to cause inflammation, how paracrine signals from immune cells alter signaling in cervical cells remain poorly understood. To address this, we conducted global transcriptomics analysis on cervical swabs from Kenyan women with HPV, stratified by HIV-1 and cancer status. Strikingly, women with HIV-1 showed cancer-like gene expression patterns in non-cancerous cervical epithelial cells. Complementary global mass spectrometry (MS) proteomics of cervical cells exposed to the secretome of HIV-1 infected primary CD4+ T-cells revealed altered expression of proteins in MAPK, PI3K-AKT, and {beta}-catenin signaling pathways. Integrative network analyses of transcriptomic and proteomic datasets revealed that HIV-1 altered gene expression in key pathways known to drive cervical cancer, including genes commonly mutated in HIV-1-naive disease. Notably, IRS-1, a key PI3K-AKT pathway activator, was found to be consistently upregulated in both participant samples and cell culture models, as were interferon-stimulated genes. Phosphoproteomics MS analysis confirmed PI3K-AKT pathway activation in cervical cells exposed to conditioned media from HIV-1-infected T-cells. Together, our findings uncover how HIV-1 reshapes cervical cell signaling via paracrine mechanisms and highlights the PI3K pathway as a potential therapeutic target in HIV-associated cervical cancer.

cancer biology↗

bioRxiv2025

Global Landscape of Human Kinase Motifs in Viral Proteomes

Viruses are classically viewed as targets of host sensing, yet whether they also sense and respond to host cues remains largely unexplored. We propose that host-driven post-translational modification of viral proteins allows viruses to dynamically sense host cellular states. We annotated human kinase motifs in 1,505 viral proteomes and discovered an enrichment for stress, inflammation, and cell-cycle kinases. Mapping kinase motifs onto 21,606 viral protein structures and integrating with phosphoproteomics of infected cells revealed surface-accessible residues were preferentially phosphorylated, showed greater kinase specificity, and were under positive selection for stress and immune kinase motifs. Temporal phosphoproteomics of alphavirus-infected cells confirmed stress kinase activation and viral protein phosphorylation, and MAP kinase inhibition reduced alphavirus replication and phosphorylation of ERK and JNK motifs on viral proteins. Our findings suggest that viruses evolved as biosensors of the host signaling state, unveiling new antiviral opportunities aimed at disrupting virus decision-making.

microbiology↗

bioRxiv2025

Drug screen reveals new potent host-targeted antivirals against Mpox virus

Mpox virus (MPXV), a re-emerging zoonotic threat, has caused outbreaks in non-endemic regions through respiratory, sexual, and close-contact transmission. The increased transmissibility of Clade IIb fueled the 2022 global outbreak, with 2024 Clade Ib spread in the Democratic Republic of Congo further escalating concern. Both outbreaks were declared public health emergencies by the WHO. Although tecovirimat (TPOXX) has been used off-label for Mpox, its limited effectiveness highlights the critical need for newer antivirals for MPXV. We conducted high- throughput antiviral drug screening using a host-directed kinase inhibitor library composed of 2,750 compounds against 2022 Clade IIb MPXV. Our primary screen identified 138 compounds preventing MPXV cytopathic effects, including multiple inhibitors of EGFR, PI3K-mTOR, and Ras/Raf, as well as apoptosis and autophagy regulators. Secondary and tertiary screenings yielded a shortlist of potent, nontoxic antiviral compounds that inhibited MPXV replication. Three selected compounds, IRAK4-IN-6, SM-7368, and KRAS inhibitor-10, reduced MPXV-induced cell death in primary human epidermal keratinocytes. IRAK4-IN-6 and SM-7368 were also found to modulate NF-{kappa}B and STING signaling. Furthermore, these compounds were found effective in reducing skin lesions and viral burden in a mouse model of MPXV skin infection. Together, our study reveals new classes of antiviral compounds against MPXV, offering promising candidates for future clinical development.

microbiology↗

bioRxiv2025

Old World alphaviruses use distinct mechanisms to infect brain microvascular endothelial cells for neuroinvasion

Several alphaviruses bypass the blood-brain barrier (BBB), causing debilitating or fatal encephalitis. Sindbis virus (SINV) has been extensively studied in vivo to understand alphavirus neuropathogenesis; yet the molecular details of neuroinvasion at the BBB remain poorly understood. We investigated alphavirus-BBB interactions by pairing a physiologically relevant, human pluripotent stem cell derived model of brain microvascular endothelial cells (BMECs) with SINV strains of opposite neuroinvasiveness. Our system demonstrates that SINV neuroinvasion correlates with robust infection of the BBB. Specifically, SINV genetic determinants of neuroinvasion enhance viral entry into BMECs. We also identify solute carrier family 2 member 3 (SLC2A3, also named GLUT3) as a potential BMEC-specific entry factor exploited for neuroinvasion. Strikingly, efficient BBB infection is a conserved phenotype that correlates with the neuroinvasive capacity of several Old World alphaviruses, including chikungunya virus. Here, we reveal BBB infection as a shared pathway for alphavirus neuroinvasion that can be targeted for preventing alphavirus-induced encephalitis.

microbiology↗

bioRxiv2024

HIV Vpr activates a nucleolar-specific ATR pathway to degrade the nucleolar stress sensor CCDC137

The lentiviral accessory protein Vpr engages an extensive network of cellular pathways to drive diverse host consequences. Of its many phenotypes, CRL4A-E3 ubiquitin ligase complex co-option, DNA damage response (DDR) engagement, and G2/M arrest are conserved and thus proposed to be functionally important. How Vpr effects these functions and whether they explain how Vpr dysregulates additional cellular pathways remain unclear. Here we leverage the ability of Vpr to deplete the nucleolar protein CCDC137 to understand how Vpr-induced DDR activation impacts nucleolar processes. We characterize CCDC137 as an indirect Vpr target whose degradation does not correlate with Vpr-induced G2/M arrest. Yet, degradation is conserved among Vpr from the pandemic HIV-1 and related SIVcpz/SIVgor, and it is triggered by genomic insults that activate a nucleolar ATR pathway in a manner similar to camptothecin. We determine that Vpr causes ATR-dependent features of nucleolar stress that correlate with CCDC137 degradation, including redistribution of nucleolar proteins, altered nucleolar morphology, and repressed ribosome biogenesis. Together, this data distinguishes CCDC137 as a non-canonical Vpr target that may serve as a sensor of nucleolar disruption, and in doing so, identifies a novel role for Vpr in nucleolar stress. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/612530v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@d43859org.highwire.dtl.DTLVardef@bf95f4org.highwire.dtl.DTLVardef@dec82org.highwire.dtl.DTLVardef@22802c_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

A foundational atlas of autism protein interactions reveals molecular convergence

Translating high-confidence (hc) autism spectrum disorder (ASD) genes into viable treatment targets remains elusive. We constructed a foundational protein-protein interaction (PPI) network in HEK293T cells involving 100 hcASD risk genes, revealing over 1,800 PPIs (87% novel). Interactors, expressed in the human brain and enriched for ASD but not schizophrenia genetic risk, converged on protein complexes involved in neurogenesis, tubulin biology, transcriptional regulation, and chromatin modification. A PPI map of 54 patient-derived missense variants identified differential physical interactions, and we leveraged AlphaFold-Multimer predictions to prioritize direct PPIs and specific variants for interrogation in Xenopus tropicalis and human forebrain organoids. A mutation in the transcription factor FOXP1 led to reconfiguration of DNA binding sites and altered development of deep cortical layer neurons in forebrain organoids. This work offers new insights into molecular mechanisms underlying ASD and describes a powerful platform to develop and test therapeutic strategies for many genetically-defined conditions.

systems biology↗

bioRxiv2022

Global landscape of the host response to SARS-CoV-2 variants reveals viral evolutionary trajectories

A series of SARS-CoV-2 variants of concern (VOCs) have evolved in humans during the COVID-19 pandemic--Alpha, Beta, Gamma, Delta, and Omicron. Here, we used global proteomic and genomic analyses during infection to understand the molecular responses driving VOC evolution. We discovered VOC-specific differences in viral RNA and protein expression levels, including for N, Orf6, and Orf9b, and pinpointed several viral mutations responsible. An analysis of the host response to VOC infection and comprehensive interrogation of altered virus-host protein-protein interactions revealed conserved and divergent regulation of biological pathways. For example, regulation of host translation was highly conserved, consistent with suppression of VOC replication in mice using the translation inhibitor plitidepsin. Conversely, modulation of the host inflammatory response was most divergent, where we found Alpha and Beta, but not Omicron BA.1, antagonized interferon stimulated genes (ISGs), a phenotype that correlated with differing levels of Orf6. Additionally, Delta more strongly upregulated proinflammatory genes compared to other VOCs. Systematic comparison of Omicron subvariants revealed BA.5 to have evolved enhanced ISG and proinflammatory gene suppression that similarly correlated with Orf6 expression, effects not seen in BA.4 due to a mutation that disrupts the Orf6-nuclear pore interaction. Our findings describe how VOCs have evolved to fine-tune viral protein expression and protein-protein interactions to evade both innate and adaptive immune responses, offering a likely explanation for increased transmission in humans. One sentence summarySystematic proteomic and genomic analyses of SARS-CoV-2 variants of concern reveal how variant-specific mutations alter viral gene expression, virus-host protein complexes, and the host response to infection with applications to therapy and future pandemic preparedness.

systems biology↗

bioRxiv2021

Hepatitis C Virus Infects and Perturbs Liver Stem Cells

Hepatitis C virus (HCV) is the leading cause of death from liver disease. How HCV infection causes lasting liver damage and increases cancer risk beyond viral clearance remains unclear. We identify bipotent liver stem cells as novel targets for HCV infection, and their erroneous differentiation as the potential cause of impaired liver regeneration and cancer development. We show 3D organoids generated from liver stem cells from actively HCV-infected individuals carry replicating virus and maintain low-grade infection over months. Organoids can be infected with a primary HCV isolate. Virus-inclusive single-cell RNA-sequencing uncovered extensive transcriptional reprogramming in HCV+ cells supporting hepatocytic differentiation, cancer stem cell development and viral replication while stem cell proliferation and interferon signaling are disrupted. Our data adds a pathogenesis factor - infection of liver stem cells - to the biology of HCV infection that explains persistent liver damage and enhanced cancer risk through an altered stem cell state.

microbiology↗

bioRxiv2021

SARS-CoV-2 variants of concern have acquired mutations associated with an increased spike cleavage

For efficient cell entry and membrane fusion, SARS-CoV-2 spike (S) protein needs to be cleaved at two different sites, S1/S2 and S2 by different cellular proteases such as furin and TMPRSS2. Polymorphisms in the S protein can affect cleavage, viral transmission, and pathogenesis. Here, we investigated the role of arising S polymorphisms in vitro and in vivo to understand the emergence of SARS-CoV-2 variants. First, we showed that the S:655Y is selected after in vivo replication in the mink model. This mutation is present in the Gamma Variant Of Concern (VOC) but it also occurred sporadically in early SARS-CoV-2 human isolates. To better understand the impact of this polymorphism, we analyzed the in vitro properties of a panel of SARS-CoV-2 isolates containing S:655Y in different lineage backgrounds. Results demonstrated that this mutation enhances viral replication and spike protein cleavage. Viral competition experiments using hamsters infected with WA1 and WA1-655Y isolates showed that the variant with 655Y became dominant in both direct infected and direct contact animals. Finally, we investigated the cleavage efficiency and fusogenic properties of the spike protein of selected VOCs containing different mutations in their spike proteins. Results showed that all VOCs have evolved to acquire an increased spike cleavage and fusogenic capacity despite having different sets of mutations in the S protein. Our study demonstrates that the S:655Y is an important adaptative mutation that increases viral cell entry, transmission, and host susceptibility. Moreover, SARS-COV-2 VOCs showed a convergent evolution that promotes the S protein processing.

microbiology↗

bioRxiv2021

Evolution of enhanced innate immune evasion by the SARS-CoV-2 B.1.1.7 UK variant

Emergence of SARS-CoV-2 variants, including the globally successful B.1.1.7 lineage, suggests viral adaptations to host selective pressures resulting in more efficient transmission. Although much effort has focused on Spike adaptation for viral entry and adaptive immune escape, B.1.1.7 mutations outside Spike likely contribute to enhance transmission. Here we used unbiased abundance proteomics, phosphoproteomics, mRNA sequencing and viral replication assays to show that B.1.1.7 isolates more effectively suppress host innate immune responses in airway epithelial cells. We found that B.1.1.7 isolates have dramatically increased subgenomic RNA and protein levels of Orf9b and Orf6, both known innate immune antagonists. Expression of Orf9b alone suppressed the innate immune response through interaction with TOM70, a mitochondrial protein required for RNA sensing adaptor MAVS activation, and Orf9b binding and activity was regulated via phosphorylation. We conclude that B.1.1.7 has evolved beyond the Spike coding region to more effectively antagonise host innate immune responses through upregulation of specific subgenomic RNA synthesis and increased protein expression of key innate immune antagonists. We propose that more effective innate immune antagonism increases the likelihood of successful B.1.1.7 transmission, and may increase in vivo replication and duration of infection.

microbiology↗

bioRxiv2021

CryoEM and AI reveal a structure of SARS-CoV-2 Nsp2, a multifunctional protein involved in key host processes.

The SARS-CoV-2 protein Nsp2 has been implicated in a wide range of viral processes, but its exact functions, and the structural basis of those functions, remain unknown. Here, we report an atomic model for full-length Nsp2 obtained by combining cryo-electron microscopy with deep learning-based structure prediction from AlphaFold2. The resulting structure reveals a highly-conserved zinc ion-binding site, suggesting a role for Nsp2 in RNA binding. Mapping emerging mutations from variants of SARS-CoV-2 on the resulting structure shows potential host-Nsp2 interaction regions. Using structural analysis together with affinity tagged purification mass spectrometry experiments, we identify Nsp2 mutants that are unable to interact with the actin-nucleation-promoting WASH protein complex or with GIGYF2, an inhibitor of translation initiation and modulator of ribosome-associated quality control. Our work suggests a potential role of Nsp2 in linking viral transcription within the viral replication-transcription complexes (RTC) to the translation initiation of the viral message. Collectively, the structure reported here, combined with mutant interaction mapping, provides a foundation for functional studies of this evolutionary conserved coronavirus protein and may assist future drug design.

biophysics↗