Biology subjects

Todaro, M.

Publications and source records attributed to Todaro, M..

4 recordsLinked to original sources

bioRxiv2026

Activating Ras-MAPK pathway variants drive hippocampal clonal competition in human epilepsy

Mesial (a.k.a., medial) temporal lobe epilepsy (MTLE) is the most common focal epilepsy1,2 and, in drug-resistant cases, is treated by surgical removal of the anterior temporal lobe, which often shows neuronal loss and gliosis consistent with hippocampal sclerosis (HS)2. MTLE with HS has minimal contribution from germline genetic variation3, and is associated with prior precipitating insults such as prolonged childhood seizures and head trauma4-6. Somatic variants in Ras-MAPK pathway genes were recently reported in a few MTLE surgical specimens7,8, but their prevalence, clinical relevance, and underlying biological mechanisms remain unknown. Targeted duplex sequencing of hippocampal DNA from 462 surgical resections revealed significant enrichment of deleterious somatic variants in MTLE versus controls, with >40% of MTLE specimens harboring activating Ras-MAPK variants in PTPN11, NF1, BRAF, KRAS, and twelve genes not previously associated with focal epilepsy. Eight Ras-MAPK genes showed positive clonal selection in MTLE. Increased somatic variant burden predicted worse surgical outcome. Somatic Ras-MAPK variants at ultra-low (<0.5%) variant allele fractions were associated with older seizure onset and HS pathology, supporting a late prenatal or postnatal origin. Ras-MAPK variants in MTLE were enriched in cells derived from hippocampal progenitors--neurons, astrocytes, oligodendrocytes--in line with the known neuronal hyperexcitability and seizures induced by Ras-MAPK overactivation9,10; in contrast, Alzheimer disease hippocampi exhibited microglial enrichment of Ras-MAPK variants, consistent with prior reports11. Single-nucleus RNA sequencing showed increased expression of Ras-MAPK genes in neurons and upregulation of pathways mediating neurogenesis and neural development in MTLE. Functional validation of novel, recurrent PTPN11 variants confirmed gain-of-function, while cellular modeling in induced pluripotent stem cells demonstrated proliferative/survival advantages for mutant cells in mosaic culture. Overall, our data suggest that somatic Ras-MAPK variants and acquired risk factors may converge on clonal competition in the hippocampus to modulate epilepsy risk.

genetics↗

bioRxiv2024

ANP32E drives vulnerability to ATR inhibitors by inducing R-loops-dependent Transcription Replication Conflicts in Triple Negative Breast Cancer

Oncogene-induced replicative stress (RS) plays a central role in tumor progression, leading to genomic instability by eliciting transcription replication conflicts (TRCs), which represent the major source of R-loops, that ultimately favors the onset of the DNA damage response (DDR). We investigated the pathogenic contribution of chromatin factors in increasing TRCs and R-loop frequencies in cancer. We found that in breast cancer patients the concomitant upregulation of MYC and the H2A.Z-specific chaperone ANP32E correlated with an increase genome instability. Genome-wide profiling revealed that the ANP32E-dependent increases turnover of H2A.Z altered RNApol II processivity, leading to accumulation of long R-loops at TRCs. We showed that ANP32E upregulation increases TRCs and activates an ATR-dependent DDR, which predispose cancer cells to R-loop-mediated genomic fragility. By exploiting the vulnerability of ANP32E-expressing cancer cells to ATR inhibitors, we found that tumors relied on this DDR pathway, whose inhibition halted their pro-metastatic capacity.

cancer biology↗

bioRxiv2022

Lipid Droplets Fuel Small Extracellular Vesicle Biogenesis

Despite an increasing gain of knowledge regarding small extracellular vesicle (sEV) composition and functions in cell-cell communication, the mechanism behind their biogenesis remains unclear. Here, we revealed for the first time that the sEV biogenesis and release into the microenvironment are tightly connected with another important organelle: Lipid Droplets (LD). We have observed this correlation using different human cancer cell lines as well as patient-derived colorectal cancer stem cells (CR-CSCs). Our results showed that the use of external stimuli such as radiation, pH, hypoxia, or lipid interfering drugs, known to affect the LD content, had a similar effect in terms of sEV secretion. Additional validations were brought using multiple omics data, at the mRNA and protein levels. Altogether, the possibility to fine-tune sEV biogenesis by targeting LDs, could have a massive impact on the amount, the cargos and the properties of those sEVs, paving the way for new clinical perspectives. Significance Statement

cancer biology↗

bioRxiv2017

MYC-driven epigenetic reprogramming favors the onset of tumorigensis by inducing a stem cell-like state

Breast cancer consists of highly heterogeneous tumors, whose cell of origin and driver oncogenes resulted difficult to be uniquely defined. Here we report that MYC acts as tumor reprogramming factor in mammary epithelial cells by inducing an alternative epigenetic program, which triggers loss of cell identity and activation of oncogenic pathways. Over-expression of MYC induces transcriptional repression of lineage-specifying transcription factors, causing decommissioning of luminal-specific enhancers. MYC-driven dedifferentiation supports the onset of a stem cell-like state by inducing the activation of de novo enhancers, which drive the transcriptional activation of oncogenic pathways. Furthermore, we demonstrate that the MYC-driven epigenetic reprogramming favors the formation and maintenance of tumor initiating cells endowed with metastatic capacity. This study supports the notion that MYC-driven tumor initiation relies on cell reprogramming, which is mediated by the activation of MYC-dependent oncogenic enhancers, thus establishing a therapeutic rational for treating basal-like breast cancers.

cancer biology↗