Biology subjects

Rivaldi, A.

Publications and source records attributed to Rivaldi, A..

3 recordsLinked to original sources

bioRxiv2026

Somatic variants activating the RAS-MAPK pathway confer susceptibility to hippocampal sclerosis in drug-resistant epilepsy

Hippocampal sclerosis is a frequent finding in pediatric epilepsy surgery and has traditionally been regarded as an acquired lesion. It commonly co-occurs with focal cortical dysplasia (FCD IIIa), yet whether hippocampal injury is secondary to seizures or reflects a shared underlying etiology remains unresolved. Here we identified somatic variants activating the RAS-MAPK pathway in 40% of patients with hippocampal sclerosis, but in none with non-sclerotic hippocampus. Gain-of-function variants in PTPN11 were the most common finding, with mutations present in both cortex and hippocampus and enriched in hippocampal neurons, consistent with a shared developmental origin. In mice, Ptpn11D61Y mutants developed profound hippocampal degeneration and gliosis following subthreshold kainic acid exposure, whereas wild-type controls were unaffected. p38-dependent stress pathways were upregulated in patients and mice, suggesting a mechanism through which ERK-p38 crosstalk lowers the threshold for seizure-induced injury. These results provide a genetic explanation for FCD IIIa, elucidate the role of somatic mutations within the RAS-MAPK pathway in driving hippocampal sclerosis, and provide a target for pathway-specific interventions for intractable seizures.

neuroscience↗

bioRxiv2025

PEDIA-BRAIN: A single nuclei multiomic encyclopedia of the human pons provides a resource for normal development and disease vulnerability

The human pons relays information between the brain and the body. It is affected by pathological processes, including diffuse midline gliomas (DMGs) and multiple sclerosis (MS) which predominantly arise in childhood and middle age, respectively. Although multiple studies address these disease states, a comprehensive resource for normal pons development is lacking. Here we present the first installment of PEDIA-BRAIN, an encyclopedia of gene expression and chromatin accessibility from 140,771 human pons nuclei spanning the first trimester to early adulthood, as a resource for the scientific community. Exploration of the encyclopedia identified two trajectories to mature oligodendrocytes and developmental restriction of genes for neuron to oligodendrocyte progenitor cell synapses. To illustrate the utility of the resource, we compared single cell transcriptomes from DMG and MS tissues to the encyclopedia and identified perturbation of oligodendrocyte subtypes in both diseases. Data may be accessed at https://pediabrain.nchgenomics.org.

neuroscience↗

bioRxiv2024

Single Nuclei Sequencing Reveals Replication Stress in Adrenocortical Carcinoma

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with a poor prognosis and limited treatment options. Bulk genomic characterization of ACC has not yielded obvious therapeutic or immunotherapeutic targets, yet novel therapies are needed. We hypothesized that elucidating the intratumoral cellular heterogeneity by single nuclei RNA sequencing analyses would yield insights into potential therapeutic vulnerabilities of this disease. In addition to characterizing the immune cell and fibroblast landscape, our analyses of single nuclei gene expression profiles identified an adrenal cortex cell cluster exhibiting a program of replication stress and DNA damage response in primary and metastatic ACC. In vitro assessment of replication stress and DNA damage response using an ACC cell line and a series of newly-derived hormonally active patient-derived tumor organoids revealed ATR sensitivity. These findings provide novel mechanistic insight into ACC biology and suggest that an underlying dependency on ATR may be leveraged therapeutically in advanced ACC.

cancer biology↗