Characterization of cellular morphological alterations related to TSC pathogenic variants

Service de génétique médicale (CHU d’Angers) et faculté de Santé & Equipe MITOLAB, Laboratoire MITOVASC, UMR Inserm U1083 - CNRS 6015

Scientific context

Tuberous Sclerosis complex (TSC) is a rare, autosomal dominant, multisystemic disease characterized by the development of tumors in various organs, most commonly affecting the skin, brain, kidneys, lungs, eyes and heart, and it is frequently associated with neuropsychiatric disorders (Winden et al. 2026). The disease results from pathogenic variants in the TSC1 or TSC2 genes, which act as regulators of the mTOR pathway. Loss of function of the TSC complex induces constitutive activation of mTORC1, leading to metabolic reprogramming involving mitochondria. Although the disease is multisystemic and phenotypic variability can be considerable, severe epilepsy occurs in 70–90% of affected individuals and is responsible for major morbidity and neuropsychiatric complications. Moreover, despite advances in epilepsy treatment, about 40% of TSC patients present with refractory epilepsy, with limited therapeutic options to handle this kind of crisis (Vitale et al. 2023). Mitochondrial dysfunctions have been reported in neuronal mouse and human in vitro models of TSC (Ebrahimi-Fakhari et al. 2016; Kalf et al. 2026; Niu et al. 2024) and primary mitochondrial diseases are frequently associated with refractory epilepsy (Zsurka et Kunz 2015).

We aim at understanding mitochondria role in the pathophysiology of TSC and to investigate their potential as targets for drug-resistant epilepsy treatment (Zhang et al. 2025). We constituted a cohort that includes over 60 individuals, stratified by type of epilepsy, age and sex, including 20% of unaffected controls. Upon collection, skin biopsies are directly transferred to the dedicated cell culture laboratory for the generation of fibroblast cell lines. To characterize mitochondrial defects in TSC affected individuals with either drug-responding or refractory epilepsy, we are performing transcriptomic analysis and mitochondrial functional studies on skin-derived fibroblasts. By integrating these data, we aim at investigating mRNA-specific signature of refractory vs drug responding epilepsy and identifying new mitochondria-specific targeted therapies to improve epilepsy management.

Summary of the M2 project

mTORC1 regulates cell growth by promoting anabolic processes including mRNA translation, ribosome biogenesis, protein and lipid synthesis and inhibits autophagy. Moreover, it regulates mitochondrial mass and functions by coordinating multiple levels of gene expression. Loss of function of TSC complex lead to constitutive activation of mTORC1, inducing metabolic reprogramming involving mitochondria and often correlating with hypertrophic phenotypes. In this context, the objective of this M2 project will be to i) investigate alteration in cellular size and cellular morphology and ii) characterize mitochondrial network in human-skin derived fibroblasts from different groups (controls, TSC with drug-sensitive epilepsy and TSC with refractory epilepsy). During the internship the student will cultivate fibroblasts and perform immunochemical analysis (CellMask, phalloidin, TOMM20). Samples will be analyzed using epifluorescence and confocal microscopy to allow characterization and quantification of cellular phenotypes. The detailed analysis of these parameters might have profound consequences on the understanding of mitochondrial implication in the TSC disease.  

Methods and techniques:

• Cell culture (L2 biosafety level)
• Immunochemistry
• Epifluorescence and confocal microscopy
• Quantitative image analysis and post-acquisition image processing

Étudiant(e) en biologie cellulaire, biologie moléculaire, génétique ou neurosciences, motivé(e), rigoureux(se) et responsable. Le/la candidat(e) participera à un projet de recherche sur la sclérose tubéreuse de Bourneville, mené conjointement entre le service de Génétique et l’équipe MitoLab. Une expérience en culture cellulaire et en techniques de biologie moléculaire est souhaitée. Un intérêt pour la recherche translationnelle et le travail en équipe sera particulièrement apprécié.