Objective

Cockayne syndrome (CS) is a rare monogenic disorder in which patients display rapid deterioration mirroring aspects of ageing in certain tissues and organs, and including severe neurodegeneration. The disorder exhibits significant clinical heterogeneity, even between cases due to early protein truncations. CS is caused by mutations in either the CSA or CSB, genes encoding multifunctional proteins primarily known for their role in transcription-coupled nucleotide excision repair (TC-NER). However, similar mutations can also cause UV-sensitive syndrome (UVSS), a condition marked solely by photosensitivity, but lacking the progeria and neurodegeneration seen in CS. This discrepancy suggests that CS pathology involves functions of CSA/CSB beyond TC-NER, such as transcription regulation and chromatin remodeling. Differences in oxidative stress management and proteome stability between CS and UVSS further support TC-NER-independent pathogenic mechanisms. These altered pathways may also be relevant in normal ageing.

Methods

To study the neurodegenerative and neurodevelopmental aspects of CS and identify their causal mechanisms, our lab has developed whole-brain and dorsal forebrain neural organoid models, derived from CS and UVSS patient cells. Solely CS (and not UVSS)-derived organoids show defects in growth, differentiation and cytoarchitecture. To determine whether CS organoids exhibit a distinct transcriptomic landscape compared to healthy controls and UVSS, we analyzed both whole-brain and dorsal forebrain organoids derived from CS type-I (classic) and type-II (severe) as well as UVSS patients and healthy controls.

Results

RNA-seq data from these organoids reveals significant transcriptional differences among samples, enabling the identification of key genes and gene networks potentially involved in neurodevelopmental and neurodegenerative defects associated with CS. Functional validation of selected candidates is currently ongoing.

Conclusions

Based on a powerful patient-derived paradigm where impairment and loss of the same protein may or not lead to precocious ageing and neurodegeneration, and recapitulation of the severity of defects in neural organoid models, using transcriptomics analyses we dissect genes and pathways that are potentially responsible for progeroid-related degeneration.