Biology subjects

Toubia, J.

Publications and source records attributed to Toubia, J..

5 recordsLinked to original sources

bioRxiv2026

Tumor Protein D54 (TPD54) regulates intracellular protein trafficking, cellular function and disease progression in melanoma

To facilitate survival, migration and evasion of immune surveillance, cancer cells tightly coordinate the synthesis and trafficking of a diverse repertoire of proteins to their cell surface and the surrounding tumor microenvironment. A key mechanism underlying this process is the intracellular membrane trafficking pathways, including vesicular transport systems. There remains a paucity of mechanistic insight into the regulatory components that mediate nascent protein trafficking and their dysregulation in cancer. Herein, we investigate Tumor Protein D54 (TPD54) as a central regulator of intracellular protein transport that is exploited by melanoma cells to promote disease progression. Integrative analyses of patient-derived tumor tissue specimens show that the expression of TPD52L2 (the gene encoding TPD54) is frequently overexpressed in melanoma and correlates with adverse clinical outcomes, including reduced responses to immune checkpoint blockade. Mechanistic investigations further revealed that TPD54 maintains Golgi integrity and orchestrates trafficking of early endosomes, anterograde vesicles and extracellular vesicles. Functionally, TPD54 augments the secretion of pro-cancerous cytokines, increases the cell surface expression of adhesion-signaling receptors (e.g. integrin-{beta}1 and desmoglein-2), promotes melanoma cell migration and elevates their capability to undergo vasculogenic mimicry. Targeting TPD52L2 in two mouse models of melanoma (B16-F10 and HCmel12) showed significant attenuation of tumor growth, disrupted tumor vasculature, enhanced anti-tumor immunity with infiltration of CD8+ T cells and reduced metastatic disease. Collectively, these findings establish TPD54 as a critical and previously underappreciated regulator of protein trafficking in cancer cells that directly contributes to disease progression and highlights its potential as a novel therapeutic target to combat melanoma.

cancer biology↗

bioRxiv2025

Neural crest cell derived DKK1 modulates Wnt signalling in the second heart field to orchestrate cardiac outflow tract development

Heart morphogenesis is highly complex, and depends on the generation of diverse cell types which interact with each other in an orchestrated manner to remodel the primitive heart tube into a functional organ. Cardiac outflow tract formation critically depends on continued contribution of cardiac progenitor cells from the anterior second heart field to ensure proper growth of the outflow tract. Prior to entering the outflow tract, neural crest cells migrate in close apposition to the second heart field and may play important roles in regulating second heart field growth dynamics, however the molecular mechanisms by which neural crest cells interact with the second heart field have remained elusive. Here, we discover that neural crest cells are a primary source of Dickkopf1 (DKK1), a secreted Wnt signalling inhibitor, which modulates Wnt signalling activity in the second heart field to impose a balance between progenitor maintenance and differentiation. Further, we identify the ubiquitin ligase NEDD4 as a critical regulator of DKK1 levels, with disruption of Nedd4 activity leading to outflow tract defects. In the context of disease pathogenicity, we show a novel human congenital heart disease variant of NEDD4 has lost the ability to ubiquitinate DKK1, and is associated with heart defects in a mouse model of the genetic variant. Our findings point to an unexpected role for neural crest cells acting as a rheostat of Wnt signalling activity in cardiac progenitors, identifying a new molecular pathway underpinning correct outflow tract morphogenesis, and a new causative factor of congenital heart disease.

developmental biology↗

bioRxiv2020

capCLIP: a new tool to probe protein synthesis in human cells through capture and identification of the eIF4E-mRNA interactome.

Translation of eukaryotic mRNAs starts with binding of the m7G cap to the protein eIF4E followed by recruitment of other translation initiation factors. eIF4Es essential role in translation suggests the cellular eIF4E-mRNA interactome (or eIF4E cap-ome) may serve as a faithful proxy of cellular translational activity. Here we describe capCLIP, a novel method to systematically capture and quantify the eIF4E cap-ome. To validate capCLIP, we identified the cap-omes in human cells {+/-} the partial mTORC1 inhibitor rapamycin. As expected, TOP (terminal oligopyrimidine) mRNA representation is systematically reduced in rapamycin-treated cells. capCLIP tag data permits refinement of a 7-nucleotide TOP motif (5'-CUYUYYC-3'). We also apply capCLIP to probe the consequences of phosphorylation of eIF4E, whose function had remained unclear. eIF4E phosphorylation drives an overall reduction in eIF4E-mRNA association; strikingly, mRNAs most sensitive to phosphorylation possess short 5'-UTRs. capCLIP provides a sensitive and comprehensive measure of cellular translational activity. We foresee its application as a high-throughput way to assess translation in contexts not amenable to existing methodologies.

biochemistry↗

bioRxiv2019

MicroRNA-194 promotes lineage plasticity in advanced prostate cancer

MicroRNA-194 (miR-194) promotes prostate cancer metastasis, but the precise molecular mechanisms by which it achieves this are unknown. Here, by integrating Argonaute high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation (Ago-HITS-CLIP) with RNA sequencing and exon-intron split analysis, we defined a 163-gene miR-194 \"targetome\" in prostate cancer. These target genes were predominantly down-regulated through canonical 3UTR recognition sites and were enriched within pathways involved in cytoskeletal organisation and cell movement. In clinical prostate cancer samples, miR-194 activity was inversely correlated with the androgen receptor (AR) signalling axis. At a mechanistic level, this inverse correlation was explained by down-regulation of miR-194 expression by AR. Accordingly, miR-194 expression and activity was significantly elevated in neuroendocrine prostate cancer (NEPC), an aggressive AR-independent disease subtype. MiR-194 enhanced the transdifferentiation of prostate adenocarcinoma cells to a neuroendocrine-like state, at least in part by targeting FOXA1, a transcription factor with a key role in maintaining the prostate epithelial lineage. Importantly, a miR-194 inhibitor effectively inhibited the growth of cell lines and patient-derived organoids with neuroendocrine features. Overall, our study reveals a novel post-transcriptional mechanism regulating the plasticity of prostate cancer cells and provides a rationale for targeting miR-194 in this NEPC.

cancer biology↗

bioRxiv2017

Post-Transcriptional Control Of EMT Is Coordinated Through Combinatorial Targeting By Multiple microRNAs

Epithelial-mesenchymal transition (EMT) is a process whereby cells undergo reversible phenotypic change, losing epithelial characteristics and acquiring mesenchymal attributes. While EMT underlies normal, physiological programs in embryonic tissue development and adult wound healing, it also contributes to cancer progression by facilitating metastasis and altering drug sensitivity. Using a cell model of EMT (human mammary epithelial (HMLE) cells), we show that miRNAs act as an additional regulatory layer over and above the activity of the transcription factors with which they are closely associated. In this context, miRNAs serve to both enhance expression changes for genes with EMT function, whilst simultaneously reducing transcriptional noise in non-EMT genes. We find that members of the polycistronic miR-200c~141 and miR-183~182 clusters (which are decreased during HMLE cell EMT and are associated with epithelial gene expression in breast cancer patients) co-regulate common targets and pathways to enforce an epithelial phenotype. We demonstrate their combinatorial effects are apparent much closer to endogenous expression levels (and orders of magnitude lower than used in most studies). Importantly, the low levels of combinatorial miRNAs that are required to exert biological function ameliorate the \"off-target\" effects on gene expression that are a characteristic of supra-physiologic miRNA manipulation. We argue that high levels of over-expression characteristic of many miRNA functional studies have led to an over-estimation of the effect of many miRNAs in EMT regulation, with over 130 individual miRNAs directly implicated as drivers of EMT. We propose that the functional effects of co-regulated miRNAs that we demonstrate here more-accurately reflects the endogenous post-transcriptional regulation of pathways, networks and processes, and illustrates that the post-transcriptional miRNA regulatory network is fundamentally cooperative.

molecular biology↗