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Primary fibroblasts from CSP? mutation carriers recapitulate hallmarks of the adult onset neuronal ceroid lipofuscinosis.

ABSTRACT: Mutations in the co- chaperone protein, CSP?, cause an autosomal dominant, adult-neuronal ceroid lipofuscinosis (AD-ANCL). The current understanding of CSP? function exclusively at the synapse fails to explain the autophagy-lysosome pathway (ALP) dysfunction in cells from AD-ANCL patients. Here, we demonstrate unexpectedly that primary dermal fibroblasts from pre-symptomatic mutation carriers recapitulate in vitro features found in the brains of AD-ANCL patients including auto-fluorescent storage material (AFSM) accumulation, CSP? aggregates, increased levels of lysosomal proteins and lysosome enzyme activities. AFSM accumulation correlates with CSP? aggregation and both are susceptible to pharmacological modulation of ALP function. In addition, we demonstrate that endogenous CSP? is present in the lysosome-enriched fractions and co-localizes with lysosome markers in soma, neurites and synaptic boutons. Overexpression of CSP? wild-type (WT) decreases lysotracker signal, secreted lysosomal enzymes and SNAP23-mediated lysosome exocytosis. CSP? WT, mutant and aggregated CSP? are degraded mainly by the ALP but this disease-causing mutation exhibits a faster rate of degradation. Co-expression of both WT and mutant CSP? cause a block in the fusion of autophagosomes/lysosomes. Our data suggest that aggregation-dependent perturbation of ALP function is a relevant pathogenic mechanism for AD-ANCL and supports the use of AFSM or CSP? aggregation as biomarkers for drug screening purposes.

SUBMITTER: Benitez BA

PROVIDER: S-EPMC5524943 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Primary fibroblasts from CSPα mutation carriers recapitulate hallmarks of the adult onset neuronal ceroid lipofuscinosis.

Benitez Bruno A BA Sands Mark S MS

Scientific reports 20170724 1

Mutations in the co- chaperone protein, CSPα, cause an autosomal dominant, adult-neuronal ceroid lipofuscinosis (AD-ANCL). The current understanding of CSPα function exclusively at the synapse fails to explain the autophagy-lysosome pathway (ALP) dysfunction in cells from AD-ANCL patients. Here, we demonstrate unexpectedly that primary dermal fibroblasts from pre-symptomatic mutation carriers recapitulate in vitro features found in the brains of AD-ANCL patients including auto-fluorescent storag ...[more]

PMID: 28740222

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Project description:We performed whole-exome sequencing in two autopsy-confirmed cases and an elderly unaffected control from a multigenerational family with autosomal dominant neuronal ceroid lipofuscinosis (ANCL). A novel single-nucleotide variation (c.344T>G) in the DNAJC5 gene was identified. Mutational screening in an independent family with autosomal dominant ANCL found an in-frame single codon deletion (c.346_348 delCTC) resulting in a deletion of p.Leu116del. These variants fulfill all genetic criteria for disease-causing mutations: they are found in unrelated families with the same disease, exhibit complete segregation between the mutation and the disease, and are absent in healthy controls. In addition, the associated amino acid substitutions are located in evolutionarily highly conserved residues and are predicted to functionally affect the encoded protein (CSP?). The mutations are located in a cysteine-string domain, which is required for membrane targeting/binding, palmitoylation, and oligomerization of CSP?. We performed a comprehensive in silico analysis of the functional and structural impact of both mutations on CSP?. We found that these mutations dramatically decrease the affinity of CSP? for the membrane. We did not identify any significant effect on palmitoylation status of CSP?. However, a reduction of CSP? membrane affinity may change its palmitoylation and affect proper intracellular sorting. We confirm that CSP? has a strong intrinsic aggregation propensity; however, it is not modified by the mutations. A complementary disease-network analysis suggests a potential interaction with other NCLs genes/pathways. This is the first replication study of the identification of DNAJC5 as the disease-causing gene for autosomal dominant ANCL. The identification of the novel gene in ANCL will allow us to gain a better understanding of the pathological mechanism of ANCLs and constitutes a great advance toward the development of new molecular diagnostic tests and may lead to the development of potential therapies.

Dataset Information

Primary fibroblasts from CSP? mutation carriers recapitulate hallmarks of the adult onset neuronal ceroid lipofuscinosis.

Publications

Primary fibroblasts from CSPα mutation carriers recapitulate hallmarks of the adult onset neuronal ceroid lipofuscinosis.

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