Biology subjects

Lungu, C.

Publications and source records attributed to Lungu, C..

8 recordsLinked to original sources

bioRxiv2026

DLC1 loss drives multicellular streaming invasion by enforcing spatially coordinated Rho and β1 integrin signaling

Efficient cancer cell invasion requires coordinated control of actomyosin contractility, extracellular matrix (ECM) engagement and remodeling, yet how these processes are integrated in complex, three-dimensional (3D) environments remains unclear. Here, we identify the tumor suppressor and RhoGAP protein DLC1 as molecular brake on multicellular streaming invasion in collagen-rich ECM. Using CRISPRoff-engineered breast cancer spheroids, DLC1 reconstitution models and patient-derived organoids embedded in collagen gels, we show that DLC1 downregulation promotes an efficient multicellular streaming phenotype. This invasion program requires matrix metalloproteinase activity, {beta}1 integrin engagement and Rho-ROCK-dependent actomyosin contractility. Mechanistically, DLC1 downregulation stabilized the rear-polarization of RhoA activity and increased {beta}1 integrin abundance, plasma membrane localization and activation. Separation-of-function mutants revealed that DLC1 restrains invasion through a dual mechanism: its RhoGAP activity limited actomyosin-driven streaming, whereas its LD-like talin-binding motif controlled {beta}1 integrin enrichment at the plasma membrane. Together, our findings provide a molecular basis for the prominent role of DLC1 as a metastasis suppressor.

Cancer Biology↗

bioRxiv2026

Larger inducible reservoir and higher abundance of exhausted CD8+ T cells in people treated after late versus non-late diagnosis of chronic HIV one year after ART initiation

Background Despite effective antiretroviral therapy, HIV-1 remains a global health challenge. Most people living with HIV (PWH) are diagnosed in the chronic stage and around half are diagnosed late globally. Insight into the effect of time of diagnosis and therapy initiation on reservoir dynamics and immune reconstitution within the group with a chronic diagnosis is limited. Methods In this prospective cohort study, PWH diagnosed during the chronic stage (from Fiebig VI) were stratified into late (<350 CD4+ T cells/mm3 or an AIDS-defining illness) or non- late diagnosis subgroups. We analyzed the viral reservoir by IPDA, SQuHIVLa and FISH-Flow, and the immune compartment with the HIV-specific AIM assay and a 45-color spectral flow cytometry panel in the first year after ART initiation. Findings Although proviral DNA decreased during the first year of ART, the inducible reservoir remained stable. One year after ART initiation, exhausted CD8+ T cell abundance correlated significantly with CD4+ T cell count pre-ART. PWH with a late diagnosis had a significantly higher inducible reservoir and lower CD4+ T-cell counts than the non-late HIV diagnosis subgroup. Moreover, the subgroup with a late diagnosis showed higher abundance of exhausted CD8+ T cells, higher expression of activation/exhaustion markers, and lower naive CD4+ T-cell abundance than the non-late diagnosis subgroup. Interpretation Our results show that late diagnosis is associated with a persistently higher inducible viral reservoir and impaired immune recovery. These findings underline the importance of early diagnosis and treatment, and rationalize the use of late diagnosis as a covariate in future cure and reservoir studies.

immunology↗

bioRxiv2025

PHF19 drives PRC2 sub-nuclear compartmentalization to promote motility in TNBC cells

Polycomb Repressive Complex 2 (PRC2) is a key regulator of chromatin architecture and transcriptional repression, playing essential roles in development and disease. While its enzymatic activity is well characterized, the molecular factors governing PRC2 subnuclear organization, particularly in cancer cells, are largely unknown. Here, we integrate high-resolution in situ spatial proteomics, imaging, and functional genomics to investigate PRC2 compartmentalization in triple-negative breast cancer (TNBC) cells. We identify PHF19, a sub-stoichiometric PRC2 accessory subunit upregulated in TNBC, as a key factor driving the formation of micron-sized nuclear PRC2 bodies. These structures act as functional hubs that stabilize PRC2 occupancy and reinforce H3K27me3 domain organization. Mechanistically, we identify an intrinsically disordered region (IDR) within PHF19 that is essential for its clustering behavior in cells and link this property to the role of PHF19 in promoting cancer cell motility. Our findings uncover a non-enzymatic layer of PRC2 regulation, whereby its local compartmentalization through accessory subunits directly impinges on cellular behavior. These insights expand our understanding of PRC2 spatial biology with implications for both normal development and disease progression.

molecular biology↗

bioRxiv2025

HIV-specific CD8+ T-cell responses soon after treatment initiation during acute HIV infection are associated with viral reservoir decline

Antiretroviral therapy (ART) initiated in the acute phase of HIV infection (AHI) results in a smaller viral reservoir. However, the impact of early HIV-specific T-cell responses on long- term reservoir dynamics is less well characterized. Therefore, we measured the size of the viral reservoir and functionality of HIV-specific CD8+ T-cell responses after the acute phase at 24 and 156 weeks after ART initiation in individuals who started treatment during AHI. A significant reduction in total and defective HIV DNA and a trend towards a reduction in intact HIV DNA were observed between 24 and 156 weeks. Functional CD8+ T-cell responses against HIV peptides Env, Gag, Nef, and Pol were maintained over three years after treatment initiation. The proliferative capacity of HIV-specific CD8+ T cells at 24 weeks of ART was predictive of the degree of reduction in total and defective HIV DNA between 24 and 156 weeks, suggesting HIV-specific CD8+ T-cells may at least partially drive the decline of the viral reservoir. Therefore, enforcing HIV-specific immune responses as early as possible after diagnosis of AHI should be a central focus of HIV cure strategies.

immunology↗

bioRxiv2023

SQuHIVLa: A novel assay for Specific Quantification of inducible HIV-1 reservoir by LAMP

Strategies toward HIV-1 cure aim to clear, inactivate, reduce or immunologically control the virus from a pool of latently infected cells such that combination antiretroviral therapy (cART) can be safely interrupted. In order to assess the impact of any putative curative interventions on the size and inducibility of the latent HIV-1 reservoir, robust and scalable assays are needed to precisely quantify the frequency of infected cells containing inducible replication competent HIV-1. Here, we present Specific Quantification of Inducible HIV-1 by LAMP (SQuHIVLa), a novel assay that leverages the high sensitivity and specificity of RT-LAMP, performed in a single reaction, to detect and quantify cells expressing Tat/Rev msRNA upon activation. Our LAMP primer/probe design exclusively detects subtype-specific HIV-1 Tat/Rev msRNA and exhibits high sensitivity, specificity, and reproducibility. Using SQuHIVLa we quantified the inducible viral reservoir in CD4+ T cells from a diverse group of people living with HIV-1 subtypes B and C on cART. SQuHIVLa presents a high throughput, scalable and specific HIV-1 reservoir quantification tool that is amenable to resource limited settings.

microbiology↗

bioRxiv2022

The GEF-GAP pair Solo and DLC3 balances Rho activity during endocytic transport

The control of intracellular membrane trafficking by Rho GTPases is central to cellular homeostasis. How defined pairs of guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) come together to locally balance GTPase activation cycles in this process is nevertheless largely unclear. By performing a microscopy-based RNAi screen we here identify the RhoGEF protein Solo as a counterpart of DLC3, a RhoGAP protein with established roles in membrane trafficking. Biochemical, imaging and optogenetics assays further uncover Solo as a novel regulator of endosomal RhoB. Remarkably, we find that the interplay between Solo and DLC3 controls not only the activity but also total protein levels of RhoB. Together, the results of our study uncover the first functionally connected RhoGAP-RhoGEF pair at endomembranes and place the Solo-DLC3 axis at the core of endocytic trafficking.

cell biology↗

bioRxiv2020

Induction of selective cell death in HIV-1-infected cells by DDX3 inhibitors leads to depletion of the inducible reservoir

An innovative approach to eliminate HIV-1-infected cells emerging out of latency, the major hurdle to HIV-1 cure, is to pharmacologically reactivate viral expression and concomitantly trigger intracellular pro-apoptotic pathways in order to selectively induce cell death (ICD) of infected cells, without reliance on the extracellular immune system. In this work we demonstrate the effect of DEAD-box polypeptide 3, X-Linked (DDX3) inhibitors on selectively inducing cell death in latent HIV-1-infected cell lines, primary CD4+ T cells and in CD4+ T cells from cART-suppressed people living with HIV-1 (PLWHIV). RNA sequencing analysis revealed that while overall gene expression was minimally dysregulated, DDX3 inhibition in independent donor CD4+ T cells led to significant downregulation of BIRC5 and HSPB1A, genes critical to cell survival during HIV-1 infection. We used single-cell FISH-Flow technology to characterise latency reversal and the contribution of viral RNA to inducing cell death; pharmacological targeting of DDX3 induced HIV-1 RNA expression, resulting in phosphorylation of IRF3, upregulation of IFN{beta} and selective induction of apoptosis in viral RNA-expressing CD4+ T cells from PLWHIV but not bystander cells. DDX3 inhibitor treatment of CD4+ T cells from PLWHIV in an in vitro culture model over five days resulted in an approximately 50% reduction of the inducible latent HIV-1 reservoir as determined by quantitation of CA HIV-1 RNA, by TILDA, as well as by FISH-Flow technology. Our data support the translation of DDX3 inhibitor class compounds into HIV-1 curative strategies and provide proof of concept for pharmacological reversal of latency coupled to induction of apoptosis towards elimination of the inducible reservoir.

microbiology↗

bioRxiv2018

Prenatal exposure to household air pollution and adverse birth outcomes among newborns in Sri Lanka

BackgroundAbout 74% of the Sri Lankan population use biomass in the form of unprocessed wood as the primary cooking fuel. A growing body of evidence from meta-analyses and individual studies although limited by few prospective studies, report that prenatal exposure to particulate matter of size 2.5 {micro}m (PM2.5) emissions from biomass fuel burning may be associated with low birth weight (LBW) (<2500 grams). We present results examining the association between PM2.5 and LBW in context of a birth cohort study in Sri Lanka. MethodsWe followed 545 pregnant women from their first trimester until delivery and assessed outcomes at birth. Exposure to household air pollution (HAP) from biomass smoke was assessed using detailed questionnaire about fuel type, kitchen characteristics and cooking practices; two-hour measurements of kitchen PM2.5 were collected in a subset of households (n=304, 56%). Data from questionnaires and measured PM2.5 were used to estimate two-hour kitchen PM2.5 concentrations in unmeasured households. Data on covariates related to household characteristics, socio-demographic, maternal health and lifestyle factors were collected from baseline interviews. We performed linear and logistic regression analysis to evaluate the association between HAP exposure, and birth weight and LBW. ResultsOf the total, 78% of the households used wood as primary or secondary fuel (n=425); households using wood had four-fold higher PM2.5 levels compared to those using LPG. In linear regression models, we found an inverse association between a 10-unit increase in PM2.5 and birth weight ({beta},-0.03; SE, 0.02; p, 0.06) adjusted for covariates. Similarly, categorical HAP exposure (>50% wood use) was significantly associated with birth weight as compared to LPG users ({beta}, -0.13; SE, 0.06; p, 0.0331). In logistic regression models, a 10-unit increase in PM2.5 was associated with increased odds for LBW (OR, 1.26; 95%CI, 1.02-1.55; p, 0.0355), while the prevalence of LBW was highest among >50% wood users (OR, 2.82; 95%CI, 1.18-6.73; p, 0.0124), as compared to those using >50% LPG with wood and only LPG users. The association between HAP exposure and birth weight/LBW were consistent among term births (n=486). ConclusionsThe finding of a significant association between prenatal PM2.5 exposure and LBW in a low-middle income country (LMIC) setting where competing risk factors are minimal fills a gap in the body of evidence linking HAP from biomass smoke to LBW. These results underscore the crucial need to implement prevention and reduction of HAP exposure in LMICs where the HAP burden is high.

epidemiology↗