Distinct Early Molecular Responses to Mutations Causing vLINCL and JNCL Presage ATP Synthase Subunit c Accumulation in Cerebellar Cells
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ABSTRACT: Variant late-infantile (vLINCL) and juvenile neuronal ceroid lipofuscinosis (JNCL) share clinical and pathological features, including lysosomal accumulation of mitochondrial ATP synthase subunit c, but the unrelated CLN6 and CLN3 genes may initiate disease via similar or distinct cellular processes. To gain insight into the NCL pathways, we established murine wild-type and vLINCL CbCln6nclf cerebellar cells and compared them to wild-type and JNCL CbCln3∆ex7/8 cerebellar cells. CbCln6nclf/nclf cells and CbCln3∆ex7/8/∆ex7/8 cells both displayed abnormally elongated mitochondria and reduced cellular ATP levels and, as cells aged to confluence, exhibited accumulation of subunit c protein in Lamp 1-positive organelles. However, at sub-confluence, endoplasmic reticulum PDI immunostain was decreased only in CbCln6nclf/nclf cells, while fluid-phase endocytosis and LysoTracker labeled vesicles were decreased in both CbCln6nclf/nclf and CbCln3∆ex7/8/∆ex7/8 cells, though only the latter cells exhibited abnormal vesicle subcellular distribution. Furthermore, unbiased gene expression analyses revealed only partial overlap in the cerebellar cell genes and pathways that were altered by the Cln3∆ex7/8 and Cln6nclf mutations. Thus, these data support the hypothesis that vLINCL and JNCL mutations trigger distinct processes that converge on a shared pathway, which is responsible for proper subunit c protein turnover and neuronal cell survival.
Project description:Variant late-infantile (vLINCL) and juvenile neuronal ceroid lipofuscinosis (JNCL) share clinical and pathological features, including lysosomal accumulation of mitochondrial ATP synthase subunit c, but the unrelated CLN6 and CLN3 genes may initiate disease via similar or distinct cellular processes. To gain insight into the NCL pathways, we established murine wild-type and vLINCL CbCln6nclf cerebellar cells and compared them to wild-type and JNCL CbCln3∆ex7/8 cerebellar cells. CbCln6nclf/nclf cells and CbCln3∆ex7/8/∆ex7/8 cells both displayed abnormally elongated mitochondria and reduced cellular ATP levels and, as cells aged to confluence, exhibited accumulation of subunit c protein in Lamp 1-positive organelles. However, at sub-confluence, endoplasmic reticulum PDI immunostain was decreased only in CbCln6nclf/nclf cells, while fluid-phase endocytosis and LysoTracker labeled vesicles were decreased in both CbCln6nclf/nclf and CbCln3∆ex7/8/∆ex7/8 cells, though only the latter cells exhibited abnormal vesicle subcellular distribution. Furthermore, unbiased gene expression analyses revealed only partial overlap in the cerebellar cell genes and pathways that were altered by the Cln3∆ex7/8 and Cln6nclf mutations. Thus, these data support the hypothesis that vLINCL and JNCL mutations trigger distinct processes that converge on a shared pathway, which is responsible for proper subunit c protein turnover and neuronal cell survival. Genotype comparison. 3 replicates each of CD1 wild-type cells, CD1 Cln3 mutant cells, C57BL6 wild-type cells, and C57BL6 Cln6 mutant cells.
Project description:CLN3 is a type II transmembrane protein localized in the late endosomal/lysosomal compartment. A deficiency of CLN3 leads to the development of a certain type of Neuronal Ceroid Lipofuscinosis, a neurodegenerative disorder of childhood caused by aggregation of undegraded material in the lysosomal compartment. Cultured, immortalized wild type and Cln3(Δex7/8) cerebellar granule cells were used in this project to determine the influence of Cln3 deficiency on the proteome of the lysosomal compartment. For this purpose, cells were labelled by stable amino acid labelling in cell culture and lysosomes were isolated by magnetic beads.
Project description:We developed an invitro model for Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) using isogenic CLN3 mutated human iPS cell lines and performed transcriptomic profiling of brain organoids derived from these lines to identify transcriptomic changes in the early developing brain model.
Project description:Mutations in the CLN3 gene lead to juvenile neuronal ceroid lipofuscinosis, a pediatric neurodegenerative disorder characterized by visual loss, epilepsy and psychomotor deterioration. Although most CLN3 patients carry the same 1 kb deletion in the CLN3 gene, their disease phenotype can be variable. The aims of this study were (1) to identify genes that are dysregulated in CLN3 disease regardless of the clinical course that could be useful as biomarkers, and (2) to find modifier genes that affect the progression rate of the disease. Genome-wide expression profiling was performed in 8 CLN3 patients, homozygous for the 1 kb deletion, with different disease progression and compared to seven age and gender matched controls.
Project description:Mutations in the CLN3 gene lead to juvenile neuronal ceroid lipofuscinosis, a pediatric neurodegenerative disorder characterized by visual loss, epilepsy and psychomotor deterioration. Although most CLN3 patients carry the same 1 kb deletion in the CLN3 gene, their disease phenotype can be variable. The aims of this study were (1) to identify genes that are dysregulated in CLN3 disease regardless of the clinical course that could be useful as biomarkers, and (2) to find modifier genes that affect the progression rate of the disease. Genome-wide expression profiling was performed in 8 CLN3 patients, homozygous for the 1 kb deletion, with different disease progression and compared to seven age and gender matched controls. Lymphocytes from eight patients diagnosed with CLN3 disease,all homozygous for the 1 kb deletion in the CLN3 gene and classified as having rapid (n = 2), average (n=4), and slow disease progression (n = 2), were used. These eight patients did not receive anticonvulsive medication. In addition, lymphocytes of seven age and gender matched controls were included in the study. Lymphocytes were prepared from fresh patient blood samples by Ficoll-gradient centrifugation (BiocollM-BM-., Biochrom AG, Berlin, Germany) according to the manufacturerM-bM-^@M-^Ys protocol and used for RNA isolation (RNeasyM-BM-. Micro Kit, Qiagen, Hilden, Germany).
Project description:Identification of differentially expressed genes in lecocytes of patients with autosomal dominat neronal ceroid lipofuscinosis (Kufs disease)
Project description:The lysosome has many cellular roles, including degrading and recycling macromolecules and signaling to the mTORC1 growth regulator. Lysosomal dysfunction occurs in various human diseases, including common neurodegenerative diseases as well as monogenic lysosomal storage disorders (LSDs). For most LSDs the causal genes have been identified, but in many cases the function of the implicated gene is unknown. Here, we develop the LysoTag mouse line for the tissue-specific isolation of intact lysosomes that are compatible with the multimodal profiling of their contents. We apply it to the study of CLN3, a lysosomal transmembrane protein of unclear function whose loss causes juvenile neuronal ceroid lipofuscinosis (Batten disease), a lethal neurodegenerative LSD. Untargeted metabolite profiling of lysosomes from the brains of mice lacking CLN3 revealed a massive accumulation of glycerophosphodiesters (GPDs), the end products of glycerophospholipid catabolism. GPDs also accumulate in the lysosomes of CLN3-deficient cultured cells and stable isotope tracing experiments show that CLN3 is required for their lysosomal egress. Loss of CLN3 also alters upstream glycerophospholipid catabolism in the lysosome. Our results suggest that CLN3 is a lysosomal effluxer of GPDs and reveal Batten disease as the first, to our knowledge, neurodegenerative LSD with a primary defect in glycerophospholipid metabolism.
Project description:Neuronal Ceroid Lipofuscinosis 6 (NCL6) is a neurodegenerative, lysosomal storage disease. It is caused by a deficiency of the transmembrane protein ceroid-lipofuscinosis neuronal protein 6 (CLN6) that resides in the endoplasmic reticulum. In this project the lysosomal proteome changes in NCL6 were investigated. Therefore, lysosomes were purifiedfrom liver tissue of CLN6 knock-out mice, the proteins were labeled by TMT and the CLN6 proteome was compared to wild type controls. Lysosome purification was obtained by either isolation of tritosomes or differential centrifugation generating 20,000 g pellets.
Project description:The Neuronal Ceroid Lipofuscinoses, one of the most common fatal neurodegenerative diseases of childhood, is caused by mutations of the CLN3 gene. Treatment regimens are symptomatic, highlighting the importance of disease-modifying drugs. Flupirtine confers neuroprotective effects in CLN3-deficient cells as well as in Cln3Δex7/8 mice. The purpose of the present study is to discern global expression programs embodying therapeutic targeting of CLN3 disease. Differential gene expression in the brains of 18-week-old Cln3Δex7/8 mice, a knock-in mouse model, was determined after daily oral supplementation of vehicle or flupirtine (30 mg/kg BW), for a period of 14 weeks, using GeneChip Mouse Genome 430 2.0 array platform from Affymetrix and quantitative real-time PCR. This manuscript sheds light on global expression programs that are associated with therapeutic treatment of CLN3 disease by flupirtine in male and female mice separately. Understanding the molecular effects of flupirtine treatment herein would pave the way for new personalized and sex-specific strategies for treatment of this debilitating genetic disease.