Biology subjects

Chear, S.

Publications and source records attributed to Chear, S..

2 recordsLinked to original sources

bioRxiv2024

Genetic and cellular basis of impaired phagocytosis and photoreceptor degeneration in CLN3 disease.

PurposeCLN3 Batten disease (also known as Juvenile Neuronal Ceroid Lipofuscinosis; JNCL) is a lysosomal storage disorder that typically initiates with retinal degeneration but is followed by seizure onset, motor decline and premature death. Patient-derived CLN3 disease iPSC-RPE cells show defective phagocytosis of photoreceptor outer segments (POSs). Because modifier genes are implicated in CLN3 disease, our goal here was to investigate a direct link between CLN3 mutation and POS phagocytosis defect. MethodsIsogenic control and CLN3 mutant stem cell lines were generated by CRISPR-Cas9{-}mediated biallelic deletion of exons 7 and 8. A transgenic CLN3{Delta}7-8/{Delta}7-8 (CLN3) Yucatan miniswine was also used to study the impact of CLN3{Delta}7-8/{Delta}7-8 mutation on POS phagocytosis. POS phagocytosis by cultured RPE cells was analyzed by Western blotting and immunohistochemistry. Electroretinogram, optical coherence tomography and histological analysis of CLN3{Delta}7/8 and wild-type miniswine eyes were carried out at 6-, 36-, or 48-month age. ResultsCLN3{Delta}7-8/{Delta}7-8 RPE (CLN3 RPE) displayed reduced POS binding and consequently decreased uptake of POS compared to isogenic control RPE cells. Furthermore, wild-type miniswine RPE cells phagocytosed CLN3{Delta}7-8/{Delta}7-8 POS less efficiently than wild-type POS. Consistent with decreased POS phagocytosis, lipofuscin/autofluorescence was decreased in CLN3 miniswine RPE at 36 months-of-age and was followed by almost complete loss of photoreceptors at 48 months of age. ConclusionsCLN3{Delta}7-8/{Delta}7-8 mutation (that affects up to 85% patients) affects both RPE and POSs and leads to photoreceptor cell loss in CLN3 disease. Furthermore, both primary RPE dysfunction and mutant POS independently contribute to impaired POS phagocytosis in CLN3 disease.

cell biology↗

bioRxiv2022

Lysosomal alterations and decreased electrophysiological activity in CLN3 disease (966 bp deletion, E295K) patient-derived cortical neurons

CLN3 disease is a lysosomal storage disorder associated with fatal neurodegeneration that is caused by mutations in CLN3. Most individuals with CLN3 disease carry at least one allele with a 966 bp deletion in CLN3 which results in the deletion of exons 7 and 8. There is a need for more physiologically relevant human cell-based CLN3 disease models to better understand the cellular changes during the disease process. Using CRISPR/Cas9, we corrected the 966 bp deletion mutation in human induced pluripotent stem cells (iPSCs) of a compound heterozygous patient (CLN3 {Delta} 966 bp and E295K). The isogenic deletion-corrected and unedited CLN3 patient iPSCs were used for disease modeling. iPSC-derived neurons carrying this particular CLN3 mutation (CLN3 neurons) had lower functional activity as recorded using microelectrode arrays for most of the culture period. Proteomics analysis showed downregulation of proteins related to axon guidance and endocytosis at day in vitro (DIV) 14 and 42 in CLN3 neurons. This was accompanied by an increase in lysosomal-related proteins in CLN3 neurons. Western blot analysis revealed hyperglycosylation of the lysosomal marker, Lysosome Associated Membrane Protein 1 (LAMP1) in CLN3 neurons at DIV 14, 28 and 42, which was not apparent in control neurons. Ultrastructural analysis of CLN3 neurons showed numerous membrane-bound vacuoles containing diverse types of storage material, ranging from curvilinear deposits, multilamellar structures to osmiophilic deposits. Our findings suggest alterations in lysosomal function and neurodevelopment involving axon guidance and synaptic transmission in CLN3-deficient neuronal derivatives, which could be potential targets for therapy.

neuroscience↗