RESUMEN
Kufs disease, an adult-onset neuronal ceroid lipofuscinosis, is challenging to diagnose and genetically heterogeneous. Mutations in CLN6 were recently identified in recessive Kufs disease presenting as progressive myoclonus epilepsy (Type A), whereas the molecular basis of cases presenting with dementia and motor features (Type B) is unknown. We performed genome-wide linkage mapping of two families with recessive Type B Kufs disease and identified a single region on chromosome 11 to which both families showed linkage. Exome sequencing of five samples from the two families identified homozygous and compound heterozygous missense mutations in CTSF within this linkage region. We subsequently sequenced CTSF in 22 unrelated individuals with suspected recessive Kufs disease, and identified an additional patient with compound heterozygous mutations. CTSF encodes cathepsin F, a lysosomal cysteine protease, dysfunction of which is a highly plausible candidate mechanism for a storage disorder like ceroid lipofuscinosis. In silico modeling suggested the missense mutations would alter protein structure and function. Moreover, re-examination of a previously published mouse knockout of Ctsf shows that it recapitulates the light and electron-microscopic pathological features of Kufs disease. Although CTSF mutations account for a minority of cases of type B Kufs, CTSF screening should be considered in cases with early-onset dementia and may avoid the need for invasive biopsies.
Asunto(s)
Catepsina F/genética , Mutación Missense , Lipofuscinosis Ceroideas Neuronales/genética , Adulto , Animales , Células del Asta Anterior/patología , Estudios de Casos y Controles , Catepsina F/metabolismo , Mapeo Cromosómico , Consanguinidad , Análisis Mutacional de ADN , Exoma , Femenino , Estudios de Asociación Genética , Humanos , Escala de Lod , Ratones , Ratones Noqueados , Persona de Mediana Edad , Modelos Moleculares , Lipofuscinosis Ceroideas Neuronales/enzimología , Lipofuscinosis Ceroideas Neuronales/patología , Linaje , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Análisis de Secuencia de ARNRESUMEN
Finnish variant LINCL (vLINCL(Fin)) is the result of mutations in the CLN5 gene. To gain insights into the pathological staging of this fatal pediatric disorder, we have undertaken a stereological analysis of the CNS of Cln5 deficient mice (Cln5-/-) at different stages of disease progression. Consistent with human vLINCL(Fin), these Cln5-/- mice displayed a relatively late onset regional atrophy and generalized cortical thinning and synaptic pathology, preceded by early and localized glial responses within the thalamocortical system. However, in marked contrast to other forms of NCL, neuron loss in Cln5-/- mice began in the cortex and only subsequently occurred within thalamic relay nuclei. Nevertheless, as in other NCL mouse models, this progressive thalamocortical neuron loss was still most pronounced within the visual system. These data provide unexpected evidence for a distinctive sequence of neuron loss in the thalamocortical system of Cln5-/- mice, diametrically opposed to that seen in other forms of NCL.
Asunto(s)
Corteza Cerebral/patología , Predisposición Genética a la Enfermedad/genética , Glicoproteínas de Membrana/genética , Degeneración Nerviosa/patología , Lipofuscinosis Ceroideas Neuronales/patología , Tálamo/patología , Edad de Inicio , Animales , Atrofia/genética , Atrofia/patología , Atrofia/fisiopatología , Corteza Cerebral/metabolismo , Corteza Cerebral/fisiopatología , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Finlandia , Proteínas de Membrana de los Lisosomas , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mutación/genética , Degeneración Nerviosa/genética , Degeneración Nerviosa/fisiopatología , Vías Nerviosas/metabolismo , Vías Nerviosas/patología , Vías Nerviosas/fisiopatología , Lipofuscinosis Ceroideas Neuronales/genética , Lipofuscinosis Ceroideas Neuronales/fisiopatología , Tálamo/metabolismo , Tálamo/fisiopatología , Vías Visuales/metabolismo , Vías Visuales/patología , Vías Visuales/fisiopatologíaRESUMEN
Cathepsin D (CTSD; EC 3.4.23.5) is a lysosomal aspartic protease, the deficiency of which causes early-onset and particularly aggressive forms of neuronal ceroid-lipofuscinosis in infants, sheep, and mice. Cathepsin D deficiencies are characterized by severe neurodegeneration, but the molecular mechanisms behind the neuronal death remain poorly understood. In this study, we have systematically mapped the distribution of neuropathologic changes in CTSD-deficient mouse brains by stereologic, immunologic, and electron microscopic methods. We report highly accentuated neuropathologic changes within the ventral posterior nucleus (ventral posteromedial [VPM]/ventral posterolateral [VPL]) of thalamus and in neuronal laminae IV and VI of the somatosensory cortex (S1BF), which receive and send information to the thalamic VPM/VPL. These changes included pronounced astrocytosis and microglial activation that begin in the VPM/VPL thalamic nucleus of CTSD-deficient mice and are associated with reduced neuronal number and redistribution of presynaptic markers. In addition, loss of synapses, axonal pathology, and aggregation of synaptophysin and synaptobrevin were observed in the VPM/VPL. These synaptic alterations are accompanied by changes in the amount of synaptophysin/synaptobrevin heterodimer, which regulates formation of the SNARE complex at the synapse. Taken together, these data reveal the somatosensory thalamocortical circuitry as a particular focus of pathologic changes and provide the first evidence for synaptic alterations at the molecular and ultrastructural levels in CTSD deficiency.
Asunto(s)
Catepsina D/deficiencia , Lipofuscinosis Ceroideas Neuronales/genética , Lipofuscinosis Ceroideas Neuronales/patología , Corteza Somatosensorial/patología , Sinapsis/fisiología , Tálamo/patología , Animales , Antígenos de Diferenciación/metabolismo , Atrofia/etiología , Encéfalo/patología , Muerte Celular , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/genética , Ratones , Ratones Endogámicos C57BL , Proteínas del Tejido Nervioso/metabolismo , Vías Nerviosas/patología , Lipofuscinosis Ceroideas Neuronales/complicaciones , Neuronas/metabolismo , Sinapsis/patología , Sinapsis/ultraestructuraRESUMEN
Batten disease, or juvenile neuronal ceroid lipofuscinosis (JNCL), results from mutations in the CLN3 gene. This disorder presents clinically around the age of 5 years with visual deficits progressing to include seizures, cognitive impairment, motor deterioration, hallucinations, and premature death by the third to fourth decade of life. The motor deficits include coordination and gait abnormalities, myoclonic jerks, inability to initiate movements, and spasticity. Previous work from our laboratory has identified an early reduction in catechol-O-methyltransferase (COMT), an enzyme responsible for the efficient degradation of dopamine. Alterations in the kinetics of dopamine metabolism could cause the accumulation of undegraded or unsequestered dopamine leading to the formation of toxic dopamine intermediates. We report an imbalance in the catabolism of dopamine in 3 month Cln3(-/-) mice persisting through 9 months of age that may be causal to oxidative damage within the striatum at 9 months of age. Combined with the previously reported inflammatory changes and loss of post-synaptic D1alpha receptors, this could facilitate cell loss in striatal projection regions and underlie a general locomotion deficit that becomes apparent at 12 months of age in Cln3(-/-) mice. This study provides evidence for early changes in the kinetics of COMT in the Cln3(-/-) mouse striatum, affecting the turnover of dopamine, likely leading to neuron loss and motor deficits. These data provide novel insights into the basis of motor deficits in JNCL and how alterations in dopamine catabolism may result in oxidative damage and localized neuronal loss in this disorder.
Asunto(s)
Cuerpo Estriado/metabolismo , Dopamina/metabolismo , Lipofuscinosis Ceroideas Neuronales/patología , Lipofuscinosis Ceroideas Neuronales/fisiopatología , Neuronas/patología , Sustancia Negra/patología , Factores de Edad , Análisis de Varianza , Animales , Conducta Animal/fisiología , Catecol O-Metiltransferasa/metabolismo , Muerte Celular/genética , Modelos Animales de Enfermedad , Regulación de la Expresión Génica/genética , Glicoproteínas de Membrana/deficiencia , Ratones , Ratones Noqueados , Modelos Biológicos , Chaperonas Moleculares , Actividad Motora/genética , Destreza Motora/fisiología , Lipofuscinosis Ceroideas Neuronales/genéticaRESUMEN
Patients and a mouse model of Batten disease, the juvenile form of neuronal ceroid lipofuscinosis (JNCL), raise autoantibodies against GAD65 and other brain-directed antigens. Here we investigate the adaptive component of the neuroimmune response. Cln3(-/-) mice have autoantibodies to GAD65 in their cerebrospinal fluid and elevated levels of brain bound immunoglobulin G (IgG). IgG deposition was found within human JNCL autopsy material, a feature that became more evident with increased age in Cln3(-/-) mice. The lymphocyte infiltration present in human and murine JNCL occurred late in disease progression, and was not capable of central/intrathecal IgG production. In contrast, we found evidence for an early systemic immune dysregulation in Cln3(-/-) mice. In addition evidence for a size-selective breach in the blood-brain barrier integrity in these mice suggests that systemically produced autoantibodies can access the JNCL central nervous system and contribute to a progressive inflammatory response.
Asunto(s)
Autoanticuerpos/líquido cefalorraquídeo , Encefalitis/inmunología , Glutamato Descarboxilasa/inmunología , Inmunoglobulina G/metabolismo , Isoenzimas/inmunología , Neuroinmunomodulación/inmunología , Lipofuscinosis Ceroideas Neuronales/inmunología , Animales , Barrera Hematoencefálica/inmunología , Barrera Hematoencefálica/fisiopatología , Encéfalo/inmunología , Encéfalo/patología , Encéfalo/fisiopatología , Encefalitis/metabolismo , Encefalitis/fisiopatología , Humanos , Activación de Linfocitos/inmunología , Linfocitos/inmunología , Linfocitos/patología , Masculino , Glicoproteínas de Membrana/genética , Ratones , Ratones Noqueados , Chaperonas Moleculares/genética , Lipofuscinosis Ceroideas Neuronales/líquido cefalorraquídeo , Lipofuscinosis Ceroideas Neuronales/fisiopatologíaRESUMEN
Juvenile neuronal ceroid lipofuscinosis (JNCL) is an autosomal recessive disorder of childhood caused by mutations in CLN3. Although visual deterioration is typically the first clinical sign to manifest in affected children, loss of Cln3 in a mouse model of JNCL does not recapitulate this retinal deterioration. This suggests that either the loss of CLN3 does not directly affect retinal cell survival or that nuclei involved in visual processing are affected prior to retinal degeneration. Having previously demonstrated that Cln3(-/-) mice have decreased optic nerve axonal density, we now demonstrate a decrease in nerve conduction. Examination of retino-recipient regions revealed a decreased number of neurons within the dorsal lateral geniculate nucleus (LGNd). We demonstrate decreased transport of amino acids from the retina to the LGN, suggesting an impediment in communication between the retina and projection nuclei. This study defines a novel path of degeneration within the LGNd, providing a mechanism for causation of JNCL visual deficits.