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Molecular neuropathology of the synapse in sheep with CLN5 Batten disease.

ABSTRACT: Synapses represent a major pathological target across a broad range of neurodegenerative conditions. Recent studies addressing molecular mechanisms regulating synaptic vulnerability and degeneration have relied heavily on invertebrate and mouse models. Whether similar molecular neuropathological changes underpin synaptic breakdown in large animal models and in human patients with neurodegenerative disease remains unclear. We therefore investigated whether molecular regulators of synaptic pathophysiology, previously identified in Drosophila and mouse models, are similarly present and modified in the brain of sheep with CLN5 Batten disease.Gross neuropathological analysis of CLN5 Batten disease sheep and controls was used alongside postmortem MRI imaging to identify affected brain regions. Synaptosome preparations were then generated and quantitative fluorescent Western blotting used to determine and compare levels of synaptic proteins.The cortex was particularly affected by regional neurodegeneration and synaptic loss in CLN5 sheep, whilst the cerebellum was relatively spared. Quantitative assessment of the protein content of synaptosome preparations revealed significant changes in levels of seven out of eight synaptic neurodegeneration proteins investigated in the motor cortex, but not cerebellum, of CLN5 sheep (α-synuclein, CSP-α, neurofascin, ROCK2, calretinin, SIRT2, and UBR4).Synaptic pathology is a robust correlate of region-specific neurodegeneration in the brain of CLN5 sheep, driven by molecular pathways similar to those reported in Drosophila and rodent models. Thus, large animal models, such as sheep, represent ideal translational systems to develop and test therapeutics aimed at delaying or halting synaptic pathology for a range of human neurodegenerative conditions.

SUBMITTER: Amorim IS

PROVIDER: S-EPMC4667763 | biostudies-other | 2015 Nov

REPOSITORIES: biostudies-other

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Project description:BACKGROUND:Neuronal ceroid lipofuscinoses type I and type II (NCL1 and NCL2) also known as Batten disease are the commonly observed neurodegenerative lysosomal storage disorder caused by mutations in the PPT1 and TPP1 genes respectively. Till date, nearly 76 mutations in PPT1 and approximately 140 mutations, including large deletion/duplications, in TPP1 genes have been reported in the literature. The present study includes 34 unrelated Indian patients (12 females and 22 males) having epilepsy, visual impairment, cerebral atrophy, and cerebellar atrophy. METHODS:The biochemical investigation involved measuring the palmitoyl protein thioesterase 1 and tripeptidy peptidase l enzyme activity from the leukocytes. Based on the biochemical analysis all patients were screened for variations in either PPT1 gene or TPP1 gene using bidirectional Sanger sequencing. In cases where Sanger sequencing results was uninformative Multiplex Ligation-dependent Probe Amplification technique was employed. The online tools performed the protein homology modeling and orthologous conservation of the novel variants. RESULTS:Out of 34 patients analyzed, the biochemical assay confirmed 12 patients with NCL1 and 22 patients with NCL2. Molecular analysis of PPT1 gene in NCL1 patients revealed three known mutations (p.Val181Met, p.Asn110Ser, and p.Trp186Ter) and four novel variants (p.Glu178Asnfs*13, p.Pro238Leu, p.Cys45Arg, and p.Val236Gly). In the case of NCL2 patients, the TPP1 gene analysis identified seven known mutations and eight novel variants. Overall these 15 variants comprised seven missense variants (p.Met345Leu, p.Arg339Trp, p.Arg339Gln, p.Arg206Cys, p.Asn286Ser, p.Arg152Ser, p.Tyr459Ser), four frameshift variants (p.Ser62Argfs*19, p.Ser153Profs*19, p.Phe230Serfs*28, p.Ile484Aspfs*7), three nonsense variants (p.Phe516*, p.Arg208*, p.Tyr157*) and one intronic variant (g.2023_2024insT). No large deletion/duplication was identified in three NCL1 patients where Sanger sequencing study was normal. CONCLUSION:The given study reports 34 patients with Batten disease. In addition, the study contributes four novel variants to the spectrum of PPT1 gene mutations and eight novel variants to the TPP1 gene mutation data. The novel pathogenic variant p.Pro238Leu occurred most commonly in the NCL1 cohort while the occurrence of a known pathogenic mutation p.Arg206Cys dominated in the NCL2 cohort. This study provides an insight into the molecular pathology of NCL1 and NCL2 disease for Indian origin patients.

Project description:The present review is focused on juvenile neuronal ceroid lipofuscinosis (JNCL; Batten disease) due to a mutation in CLN3. Functional vision impairment occurring around 5-6 years of age is the first symptom in more than 80% of patients. Approximately 2 years later (though sometimes simultaneously), obvious signs of cognitive impairment appear. Behavior problems can occur in advance, especially in boys. These include anxious and depressed mood, aggressive behavior, and hallucinations, and even psychotic symptoms. Following the teens, severe dementia is present, including loss of memory, attention, and general reasoning abilities, as well as loss of independent adaptive skills such as mobility, feeding, and communicating. Sleep abnormalities, such as settling problems, nocturnal awakenings, and nightmares, are reported in more than half of patients. The vast majority, if not all, patients develop seizures, starting at approximately 10 years of age. Generalized tonic-clonic seizure occurs as the only type of seizure in approximately half of patients, and in combination with partial seizures in a third of patients. There seems to be no difference in seizure severity according to sex or genotype, and there is great variation in seizure activity among patients. Soon after diagnosis, patients begin to have slight ataxic symptoms, and at adolescence extrapyramidal symptoms (rigidity, bradykinesia, slow steps with flexion in hips and knees) occur with increasing frequency. Chewing and swallowing difficulties emerge as well, and food intake is hampered in the late teens. Disabling periodically involuntary movements may occur as well. A progressive cardiac involvement with repolarization disturbances, ventricular hypertrophy, and sinus-node dysfunction, ultimately leading to severe bradycardia and/or other conduction abnormalities, starts in the mid-teens. Patients are usually bedridden at 20 years of age, and death usually occurs in the third decade of life.

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Molecular neuropathology of the synapse in sheep with CLN5 Batten disease.

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