Biology subjects

Del Maestro, L.

Publications and source records attributed to Del Maestro, L..

6 recordsLinked to original sources

bioRxiv2025

Epigenetic control of nuclear mechanics and cellular migration via histone H3 lysine 9 methylation at Lamina-Associated Domains

Chromatin not only stores genetic information but also regulates nuclear mechanical properties. However, how epigenetic modifications, such as histone H3 lysine 9 trimethylation (H3K9me3), shape chromatin states at lamina-associated domains (LADs) and influence nuclear mechanics remains unclear. Here, we reveal an unexpected and paradoxical role of the pro-oncogenic H3K9 lysine methyltransferase (KMT) SETDB1, frequently overexpressed in many cancers, in LAD regulation. Rather than reinforcing heterochromatin, SETDB1 overexpression prevents SUV39H1-driven H3K9me3 accumulation at LADs, thereby disrupting the peripheral heterochromatin. Reducing SETDB1 levels, or disrupting its interaction with SUV39H1, enables SUV39H1 to restore LAD-localized H3K9me3 and re-establish an epithelial-like heterochromatin architecture. Heterochromatin reorganization upon SETDB1 reduction stiffens the nucleus and increases cell viscosity, thereby reducing cancer cell deformability and migratory capacity. Strikingly, these mechanical effects occur without major transcriptional changes, demonstrating that chromatin architecture itself critically shapes nuclear mechanics and cell motility. Our findings reveal a previously unrecognized role of the SETDB1-SUV39H1 axis in nuclear biomechanics, highlighting it as a potential determinant of cancer cell migration and metastatic processes.

molecular biology↗

bioRxiv2024

Metabolic imprint of an intracellular pathogen drives histone hypermethylation and tunes the host transcriptional response to infection

Chlamydia trachomatis, an intracellular bacterium, highjacks metabolites from the host cell for its own proliferation. We provide evidence of global hypermethylation of the host proteome, including histones, during the late stages of infection. Single cell analyses revealed co-occurrence of several methylated residues on histones. Histone hypermethylation correlated with bacterial load and was prevented by antibiotic treatment. Mapping of trimethylation of histone 3 at residues K4 and K9 revealed a broad distribution throughout the chromatin. Nuclear fractions of infected cells exhibited a four-fold decrease of demethylase activity towards H3K4me3 and a two-fold increase in succinate concentration, a competitive inhibitor for the demethylase co-factor -ketoglutarate. Supplementation of the culture medium with dimethyl-ketoglutarate (DMKG) or with iron, a second co-factor of histone lysine demethylases, reduced histone hypermethylation. DMKG supplementation modified the transcription of about one third of the infection-responsive genes, indicating that histone hypermethylation contributes to modulating the transcriptional response of the host to infection. Finally, chemical inhibition of histone demethylases in a mouse model of infection showed a moderate benefit regarding the outcome of infection. Overall, our data show that the metabolic pressure exerted by a pathogen with an intracellular lifestyle drives epigenetic changes in infected cells.

cell biology↗

bioRxiv2023

SETDB1 modulates the TGFbeta response in Duchenne muscular dystrophy myotubes

Overactivation of the TGF{beta} signaling in Duchenne muscular dystrophy (DMD) is a major hallmark of disease progression, leading to fibrosis and muscle dysfunction. Here, we investigated the role of SETDB1, a histone lysine methyltransferase involved in muscle differentiation. Our data show that, following TGF{beta} induction, SETDB1 accumulates in the nuclei of healthy myotubes, while being already present in the nuclei of DMD myotubes where TGF{beta} signaling is constitutively activated. Interestingly, transcriptomics revealed that depletion of SETDB1 in DMD myotubes leads to downregulation of TGF{beta}-target genes coding for secreted factors involved in extracellular matrix remodeling and inflammation. Consequently, SETDB1 silencing in DMD myotubes abrogates the deleterious effect of their secretome on myoblast differentiation by impairing myoblast pro-fibrotic response. Our findings indicate that SETDB1 potentiates the TGF{beta}-driven fibrotic response in DMD muscles, providing a new axis for therapeutic intervention. Key resultsO_LITGF{beta} induces nuclear accumulation of SETDB1 in healthy myotubes C_LIO_LISETDB1 is enriched in DMD myotube nuclei with intrinsic TGF{beta} pathway overactivation C_LIO_LISETDB1 LOF in DMD myotubes attenuates TGF{beta}-induced pro-fibrotic response C_LIO_LISecretome of TGF{beta}-treated DMD myotubes with SETDB1 LOF is less deleterious on myoblast differentiation C_LI

cell biology↗

bioRxiv2021

Glucose controls co-translation of structurally related mRNAs via the mTOR and eIF2 pathways in human pancreatic beta cells

Pancreatic beta cell response to glucose is critical for the maintenance of normoglycemia. A strong transcriptional response was classically described in rodent models but, interestingly, not in human cells. In this study, we exposed human pancreatic beta cells to an increased concentration of glucose and analysed at a global level the mRNAs steady state levels and their translationalability. Polysome profiling analysis showed an early acute increase in protein synthesis and a specific translation regulation of more than 400 mRNAs, independently of their transcriptional regulation. We clustered the co-regulated mRNAs according to their behaviour in translation in response to glucose and discovered common structural and sequence mRNA features. Among them mTOR- and eIF2-sensitive elements have a predominant role to increase mostly the translation of mRNAs encoding for proteins of the translational machinery. Furthermore, we show that mTOR and eIF2 pathways are independently regulated in response to glucose, participating to a translational reshaping to adapt beta cell metabolism. The early acute increase in the translation machinery components prepare the beta cell for further protein demand due to glucose-mediated metabolism changes. AUTHOR SUMMARYAdaptation and response to glucose of pancreatic beta cells is critical for the maintenance of normoglycemia. Its deregulation is associated to Diabetic Mellitus (DM), a significant public health concern worldwide with an increased incidence of morbidity and mortality. Despite extensive research in rodent models, gene expression regulation in response to glucose remains largely unexplored in human cells. In our work, we have tackled this question by exposing human EndoC-BH1 cells to high glucose concentration. Using polysome profiling, the gold standard technique to analyse cellular translation activity, we observed a global protein synthesis increase, independent from transcription activity. Among the specific differentially translated mRNAs, we found transcripts coding for ribosomal proteins, allowing the cell machinery to be engaged in a metabolic response to glucose. Therefore, the regulation in response to glucose occurs mainly at the translational level in human cells, and not at the transcriptional level as described in the classically used rodent models. Furthermore, by comparing the features of the differentially translated mRNAs, and classifying them according to their translational response, we show that the early response to glucose occurs through the coupling of mRNA structure and sequence features impacting translation and regulation of specific signalling pathways. Collectively, our results support a new paradigm of gene expression regulation on the translation level in human beta cells.

genomics↗

bioRxiv2021

Paramecium Polycomb Repressive Complex 2 physically interacts with the small RNA binding PIWI protein to repress transposable elements

Polycomb Repressive Complex 2 (PRC2) maintains transcriptionally silent genes in a repressed state via deposition of histone H3 K27 trimethyl (me3) marks. PRC2 has also been implicated in silencing transposable elements (TEs) yet how PRC2 is targeted to TEs remains unclear. To address this question, we performed tandem affinity purification combined with mass spectrometry and identified proteins that physically interact with the Paramecium Enhancer-of-zeste Ezl1 enzyme, which catalyzes H3K9me3 and H3K27me3 deposition at TEs. We show that the Paramecium PRC2 core complex comprises four subunits, each required in vivo for catalytic activity. We also identify PRC2 cofactors, including the RNA interference (RNAi) effector Ptiwi09, which are necessary to target H3K9me3 and H3K27me3 to TEs. We find that the physical interaction between PRC2 and the RNAi pathway is mediated by a RING finger protein and that small RNA recruitment of PRC2 to TEs is analogous to the small RNA recruitment of H3K9 methylation SU(VAR)3-9 enzymes.

molecular biology↗

bioRxiv2020

Endosomal trafficking defects alter neural progenitor proliferation and cause microcephaly

Primary microcephaly and megalencephaly are severe brain malformations defined by reduced and increased brain size, respectively. Whether these two pathologies arise from related alterations at the molecular level is unclear. Microcephaly has been largely associated with centrosomal defects, leading to cell death. Here, we investigated the consequences of WDR81 loss of function, which cause severe microcephaly in patients. We show that WDR81 regulates endosomal trafficking of EGFR, and that loss of function leads to reduced MAP kinase pathway activation. Mouse radial glial progenitor cells knocked-out for WDR81 display reduced proliferation rates, leading to reduced brain size. These proliferation defects are rescued in vivo by the expression of megalencephaly-causing mutated Cyclin D2. Our results identify the endosomal machinery as an important regulator of RG cell proliferation rates and brain growth. They demonstrate that microcephaly and megalencephaly can be due to opposite effects on the proliferation rate of radial glial progenitors.

neuroscience↗