Upregulated Chaperone-Mediated Autophagy May Perform a Key Role in Reduced Cancer Incidence in Huntington's Disease.

Incidence of cancer is markedly reduced in patients with the hereditary neurodegenerative polyglutamine (polyQ) diseases. We have very poor knowledge of the underlying molecular mechanisms, but the expanded polyQ sequence is assumed to play a central role, because it is common to the respective disease related proteins. The inhibition seems to take place in all kinds of cells, because the lower cancer frequency applies to nearly all types of tumors and is not related with the characteristic pathological changes in specific brain tissues. Further, the cancer repressing mechanisms appear to be active early in life including in pre-symptomatic and early phase polyQ patients. Autophagy plays a central role in clearing proteins with expanded polyQ tracts, and autophagy modulation has been demonstrated and particularly investigated in Huntington's disease (HD). Macroautophagy may be dysfunctional due to defects in several steps of the process, whereas increased chaperone-mediated autophagy (CMA) has been shown in HD patients, cell and animal models. Recently, CMA is assumed to play a key role in prevention of cellular transformation of normal cells into cancer cells. Investigations of normal cells from HD and other polyQ carriers could therefore add further insight into the protective mechanisms of CMA in tumorigenesis, and be important for development of autophagy based strategies to prevent malignant processes leading to cancer and neurodegeneration.

Correction: Systematic cascade screening in the Danish Fabry Disease Centre: 20 years of a national single-centre experience.

[This corrects the article DOI: 10.1371/journal.pone.0277767.].

Systematic cascade screening in the Danish Fabry Disease Centre: 20 years of a national single-centre experience.

The lysosomal storage disorder Fabry disease is caused by deficient or absent activity of the GLA gene enzyme α-galactosidase A. In the present study we present the molecular and biochemical data of the Danish Fabry cohort and report 20 years' (2001-2020) experience in cascade genetic screening at the Danish National Fabry Disease Center. The Danish Fabry cohort consisted of 26 families, 18 index patients (9 males and 9 females, no available data for 8 index-patients) and 97 family members with a pathogenic GLA variant identified by cascade genetic testing (30 males and 67 females). Fourteen patients (5 males and 9 females; mean age of death 47.0 and 64.8 years respectively) died during follow-up. The completeness of the Fabry patient identification in the country has resulted in a cohort of balanced genotypes according to gender (twice number of females compared to males), indicating that the cohort was not biased by referral, and further resulted in earlier diagnosis of the disease by a lower age at diagnosis in family members compared to index-patients (mean age at diagnosis: index-patients 42.2 vs. family members 26.0 years). Six previously unreported disease-causing variants in the GLA gene were discovered. The nationwide screening and registration of Fabry disease families provide a unique possibility to establish a complete cohort of Fabry patients and to advance current knowledge of this inherited rare lysosomal storage disorder.

CCG•CGG interruptions in high-penetrance SCA8 families increase RAN translation and protein toxicity.

Spinocerebellar ataxia type 8 (SCA8), a dominantly inherited neurodegenerative disorder caused by a CTG•CAG expansion, is unusual because most individuals that carry the mutation do not develop ataxia. To understand the variable penetrance of SCA8, we studied the molecular differences between highly penetrant families and more common sporadic cases (82%) using a large cohort of SCA8 families (n = 77). We show that repeat expansion mutations from individuals with multiple affected family members have CCG•CGG interruptions at a higher frequency than sporadic SCA8 cases and that the number of CCG•CGG interruptions correlates with age at onset. At the molecular level, CCG•CGG interruptions increase RNA hairpin stability, and in cell culture experiments, increase p-eIF2α and polyAla and polySer RAN protein levels. Additionally, CCG•CGG interruptions, which encode arginine interruptions in the polyGln frame, increase toxicity of the resulting proteins. In summary, SCA8 CCG•CGG interruptions increase polyAla and polySer RAN protein levels, polyGln protein toxicity, and disease penetrance and provide novel insight into the molecular differences between SCA8 families with high vs. low disease penetrance.

Paroxysmal Cranial Dyskinesia and Nail-Patella Syndrome Caused by a Novel Variant in the LMX1B Gene.

BACKGROUND: In a Danish family, multiple individuals in five generations present with early-onset paroxysmal cranial dyskinesia, musculoskeletal abnormalities, and kidney dysfunction. OBJECTIVE: To demonstrate linkage and to identify the underlying genetic cause of disease. METHODS: Genome-wide single-nucleotide polymorphisms analysis, Sequence-Tagged-Site marker analyses, exome sequencing, and Sanger sequencing were performed. RESULTS: Linkage analyses identified a candidate locus on chromosome 9. Exome sequencing revealed a novel variant in LMX1B present in all affected individuals, logarithm of the odds (LOD) score of z = 6.54, predicted to be damaging. Nail-patella syndrome (NPS) is caused by pathogenic variants in LMX1B encoding a transcription factor essential to cytoskeletal and kidney growth and dopaminergic and serotonergic network development. NPS is characterized by abnormal musculoskeletal features and kidney dysfunction. Movement disorders have not previously been associated with NPS. CONCLUSIONS: Paroxysmal dyskinesia is a heretofore unrecognized feature of the NPS spectrum. The pathogenic mechanism might relate to aberrant dopaminergic circuits. © 2020 International Parkinson and Movement Disorder Society.

Ghrelin-mediated improvements in the metabolic phenotype in the R6/2 mouse model of Huntington's disease.

Huntington's disease (HD) is a heritable neurodegenerative disorder, characterised by metabolic disturbances, along with cognitive and psychiatric impairments. Targeting metabolic HD dysfunction via the maintenance of body weight and fat mass and restoration of peripheral energy metabolism can improve the progression of neurological symptoms. In this respect, we focused on the therapeutic potential of the orexigenic peptide hormone ghrelin, which plays an important role in promoting a positive energy balance. In the present study, we found a significant disruption of circadian metabolic regulation in a R6/2 mouse HD model in the late stage of disease. Daily circadian rhythms of activity, energy expenditure, respiratory exchange ratio and feeding were strongly attenuated in R6/2 mice. During the rest phase, R6/2 mice had a higher total activity, elevated energy expenditure and excessive water consumption compared to control mice. We also found that, in the late stage of disease, R6/2 mice had ghrelin axis deficiency as a result of low circulating ghrelin levels, in addition to down-regulation of the ghrelin receptor and several key signalling molecules in the hypothalamus, as well as a reduced responsiveness to exogenous peripheral ghrelin. We demonstrated that, in pre-symptomatic mice, responsiveness to ghrelin is preserved. Chronic ghrelin treatment efficiently increased lean body mass and decreased the energy expenditure and fat utilisation of R6/2 mice in the early stage of disease. In addition, ghrelin treatment was also effective in the normalisation of drinking behaviour and the rest activity of these mice. Ghrelin treatment could provide a novel therapeutic possibility for delaying disease progression; however, deficiency in ghrelin receptor expression could limit its therapeutic potential in the late stage of disease.

Perturbations in the p53/miR-34a/SIRT1 pathway in the R6/2 Huntington's disease model.

The three factors, p53, the microRNA-34 family and Sirtuin 1 (SIRT1), interact in a positive feedback loop involved in cell cycle progression, cellular senescence and apoptosis. Each factor in this triad has roles in metabolic regulation, maintenance of mitochondrial function, and regulation of brain-derived neurotrophic factor (BDNF). Thus, this regulatory network holds potential importance for the pathophysiology of Huntington's disease (HD), an inherited neurodegenerative disorder in which both mitochondrial dysfunction and impaired neurotrophic signalling are observed. We investigated expression of the three members of this regulatory triad in the R6/2 HD mouse model. Compared to wild-type littermates, we found decreased levels of miR-34a-5p, increased SIRT1 mRNA and protein levels, and increased levels of p53 protein in brain tissue from R6/2 mice. The upregulation of SIRT1 did not appear to lead to an increased activity of the enzyme, as based on measures of p53 acetylation. In other words, the observed changes did not reflect the known interactions between these factors, indicating a general perturbation of the p53, miR-34a and SIRT1 pathway in HD. This is the first study investigating the entire triad during disease progression in an HD model. Given the importance of these three factors alone and within the triad, our results indicate that outside factors are regulating - or dysregulating - this pathway in HD.

The D313Y variant in the GLA gene - no evidence of a pathogenic role in Fabry disease.

Fabry disease is an X- linked inherited lysosomal storage disease caused by mutations in the GLA gene encoding the lysosomal enzyme alpha-galactosidase A (α-Gal A). The possible pathological significance of the D313Y variant in the GLA gene has not been verified and it may be a Fabry variant. Our aim was to elucidate whether the presence of the D313Y variant influenced the α-Gal A activity or resulted in Fabry symptoms or Fabry organ involvement. In two Danish families the presence of the D313Y variant did not result in reduced α-Gal A activity or clinical Fabry manifestations in males, and the presence in Fabry females did not significantly enhance the phenotype of a known causative mutation in the GLA gene (G271S). Our findings indicate that the D313Y variant is not causative to nor enhancing Fabry disease phenotype. The D313Y variant in the GLA gene was not disease causative in 2 Danish families. Investigating male family members were crucial in excluding the Fabry phenotype, and thus very important for proper genetic counceling of all family members, as well as overdiagnosing a devastating genetic disease.

Induced pluripotent stem cell - derived neurons for the study of spinocerebellar ataxia type 3.

The neurodegenerative disease spinocerebellar ataxia type 3 (SCA3) is caused by a CAG-repeat expansion in the ATXN3 gene. In this study, induced pluripotent stem cell (iPSC) lines were established from two SCA3 patients. Dermal fibroblasts were reprogrammed using an integration-free method and the resulting SCA3 iPSCs were differentiated into neurons. These neuronal lines harbored the disease causing mutation, expressed comparable levels of several neuronal markers and responded to the neurotransmitters, glutamate/glycine, GABA and acetylcholine. Additionally, all neuronal cultures formed networks displaying synchronized spontaneous calcium oscillations within 28days of maturation, and expressed the mature neuronal markers NeuN and Synapsin 1 implying a relatively advanced state of maturity, although not comparable to that of the adult human brain. Interestingly, we were not able to recapitulate the glutamate-induced ataxin-3 aggregation shown in a previously published iPSC-derived SCA3 model. In conclusion, we have generated a panel of SCA3 patient iPSCs and a robust protocol to derive neurons of relatively advanced maturity, which could potentially be valuable for the study of SCA3 disease mechanisms.

Induced pluripotent stem cells (iPSCs) derived from a patient with frontotemporal dementia caused by a P301L mutation in microtubule-associated protein tau (MAPT).

Skin fibroblasts were obtained from a 57-year-old woman diagnosed with frontotemporal dementia. The disease is caused by a P301L mutation in microtubule-associated protein tau (MAPT). Induced pluripotent stem cells (iPSCs) were established by electroporation with episomal plasmids containing hOCT4, hSOX2, hKLF2, hL-MYC, hLIN-28 and shP53. iPSCs were free of genomically integrated reprogramming genes, contained the expected c.902C>T substitution in exon 10 of the MAPT gene, expressed the expected pluripotency markers, displayed in vitro differentiation potential to the three germ layers and had normal karyotype. The iPSC line may be useful for studying hereditary frontotemporal dementia and TAU pathology in vitro.

Induced pluripotent stem cells (iPSCs) derived from a patient with frontotemporal dementia caused by a R406W mutation in microtubule-associated protein tau (MAPT).

Skin fibroblasts were obtained from a 59-year-old woman diagnosed with frontotemporal dementia. The disease is caused by a R406W mutation in microtubule-associated protein tau (MAPT). Induced pluripotent stem cells (iPSCs) were established by electroporation with episomal plasmids containing hOCT4, hSOX2, hKLF2, hL-MYC, hLIN-28 and shP53. iPSCs were free of genomically integrated reprogramming genes, contained the expected c.1216C>T substitution in exon 13 of the MAPT gene, expressed the expected pluripotency markers, displayed in vitro differentiation potential to the three germ layers and had normal karyotype. The iPSC line may be useful for studying hereditary frontotemporal dementia and TAU pathology in vitro.

Induced pluripotent stem cells (iPSCs) derived from a pre-symptomatic carrier of a R406W mutation in microtubule-associated protein tau (MAPT) causing frontotemporal dementia.

Skin fibroblasts were obtained from a 28-year-old pre-symptomatic woman carrying a R406W mutation in microtubule-associated protein tau (MAPT), known to cause frontotemporal dementia. Induced pluripotent stem cell (iPSCs) were established by electroporation with episomal plasmids containing hOCT4, hSOX2, hKLF2, hL-MYC, hLIN-28 and shP53. iPSCs were free of genomically integrated reprogramming genes, contained the expected c.1216C>T substitution in exon 13 of the MAPT gene, expressed the expected pluripotency markers, displayed in vitro differentiation potential to the three germ layers and had normal karyotype. The iPSC line may be useful for studying hereditary frontotemporal dementia and TAU pathology in vitro.

Generation of spinocerebellar ataxia type 3 patient-derived induced pluripotent stem cell line SCA3.A11.

Spinocerebellar ataxia type 3 (SCA3) is a dominantly inherited neurodegenerative disease caused by a CAG-repeat expanding mutation in ATXN3. We generated induced pluripotent stem cells (iPSCs) from a SCA3 patient by electroporation of dermal fibroblasts with episomal plasmids encoding L-MYC, LIN28, SOX2, KLF4, OCT4 and short hairpin RNA targeting P53. The resulting iPSCs had normal karyotype, were free of genomically integrated episomal plasmids, expressed pluripotency markers, could differentiate into the three germ layers in vitro and retained the disease-causing ATXN3 mutation. This iPSC line could be useful for the investigation of SCA3 disease mechanisms.

Generation of spinocerebellar ataxia type 3 patient-derived induced pluripotent stem cell line SCA3.B11.

Spinocerebellar ataxia type 3 (SCA3) is a dominantly inherited neurodegenerative disease caused by an expansion of the CAG-repeat in ATXN3. In this study, induced pluripotent stem cells (iPSCs) were generated from SCA3 patient dermal fibroblasts by electroporation with episomal plasmids encoding L-MYC, LIN28, SOX2, KLF4, OCT4 and short hairpin RNA targeting P53. The resulting iPSCs had normal karyotype, were free of integrated episomal plasmids, expressed pluripotency markers, could differentiate into the three germ layers in vitro and retained the disease-causing ATXN3 mutation. Potentially, this iPSC line could be a useful tool for the investigation of SCA3 disease mechanisms.

Seasonal difference in brain serotonin transporter binding predicts symptom severity in patients with seasonal affective disorder.

Cross-sectional neuroimaging studies in non-depressed individuals have demonstrated an inverse relationship between daylight minutes and cerebral serotonin transporter; this relationship is modified by serotonin-transporter-linked polymorphic region short allele carrier status. We here present data from the first longitudinal investigation of seasonal serotonin transporter fluctuations in both patients with seasonal affective disorder and in healthy individuals. Eighty (11)C-DASB positron emission tomography scans were conducted to quantify cerebral serotonin transporter binding; 23 healthy controls with low seasonality scores and 17 patients diagnosed with seasonal affective disorder were scanned in both summer and winter to investigate differences in cerebral serotonin transporter binding across groups and across seasons. The two groups had similar cerebral serotonin transporter binding in the summer but in their symptomatic phase during winter, patients with seasonal affective disorder had higher serotonin transporter than the healthy control subjects (P = 0.01). Compared to the healthy controls, patients with seasonal affective disorder changed their serotonin transporter significantly less between summer and winter (P < 0.001). Further, the change in serotonin transporter was sex- (P = 0.02) and genotype- (P = 0.04) dependent. In the patients with seasonal affective disorder, the seasonal change in serotonin transporter binding was positively associated with change in depressive symptom severity, as indexed by Hamilton Rating Scale for Depression - Seasonal Affective Disorder version scores (P = 0.01). Our findings suggest that the development of depressive symptoms in winter is associated with a failure to downregulate serotonin transporter levels appropriately during exposure to the environmental stress of winter, especially in individuals with high predisposition to affective disorders.media-1vid110.1093/brain/aww043_video_abstractaww043_video_abstract.

Liver function in Huntington's disease assessed by blood biochemical analyses in a clinical setting.

Huntington's disease (HD) is a dominantly inherited, progressive neurological disorder caused by a CAG repeat elongation in the huntingtin gene. In addition to motor-, psychiatric- and cognitive dysfunction, peripheral disease manifestations in the form of metabolic changes and cellular dysfunction are seen. Blood levels of a wide range of hormones, metabolites and proteins have been analyzed in HD patients, identifying several changes associated with the disease. However, a comprehensive panel of liver function tests (LFT) has not been performed. We investigated a cohort of manifest and premanifest HD gene-expansion carriers and controls, using a clinically applied panel of LFTs. Here, we demonstrate that the level of alkaline phosphatase is increased in manifest HD gene-expansion carriers compared to premanifest HD gene-expansion carriers and correlate with increased disease severity indicated by the Unified Huntington's disease rating scale-Total Functional Capacity Score (UHDRS-TFC). For gamma-glutamyl transferase, elevated levels were more frequent in the manifest groups than in both the HD gene-expansion negative controls and premanifest HD gene-expansion carriers. Finally, the manifest HD gene-expansion carriers displayed moderate increases in total cholesterol and blood glucose relative to the premanifest HD gene-expansion carriers, as well as increased C-reactive protein relative to HD gene-expansion negative controls. Our results show that LFT values are elevated more frequently in manifest compared to premanifest HD gene-expansion carriers and controls. The majority of the manifest HD gene-expansion carriers receive medication, and it is possible that this can influence the liver function tests performed in this study.

Progressive Impairment of Lactate-based Gluconeogenesis in the Huntington's Disease Mouse Model R6/2.

Huntington's disease (HD) is a neurodegenerative illness, where selective neuronal loss in the brain caused by expression of mutant huntingtin protein leads to motor dysfunction and cognitive decline in addition to peripheral metabolic changes. In this study we confirm our previous observation of impairment of lactate-based hepatic gluconeogenesis in the transgenic HD mouse model R6/2 and determine that the defect manifests very early and progresses in severity with disease development, indicating a potential to explore this defect in a biomarker context. Moreover, R6/2 animals displayed lower blood glucose levels during prolonged fasting compared to wild type animals.

Reduced ceramide synthase 2 activity causes progressive myoclonic epilepsy.

OBJECTIVE: Ceramides are precursors of complex sphingolipids (SLs), which are important for normal functioning of both the developing and mature brain. Altered SL levels have been associated with many neurodegenerative disorders, including epilepsy, although few direct links have been identified between genes involved in SL metabolism and epilepsy. METHODS: We used quantitative real-time PCR, Western blotting, and enzymatic assays to determine the mRNA, protein, and activity levels of ceramide synthase 2 (CERS2) in fiibroblasts isolated from parental control subjects and from a patient diagnosed with progressive myoclonic epilepsy (PME). Mass spectrometry and fluorescence microscopy were used to examine the effects of reduced CERS2 activity on cellular lipid composition and plasma membrane functions. RESULTS: We identify a novel 27 kb heterozygous deletion including the CERS2 gene in a proband diagnosed with PME. Compared to parental controls, levels of CERS2 mRNA, protein, and activity were reduced by ˜50% in fibroblasts isolated from this proband, resulting in significantly reduced levels of ceramides and sphingomyelins containing the very long-chain fatty acids C24:0 and C26:0. The change in SL composition was also reflected in a reduction in cholera toxin B immunofluorescence, indicating that membrane composition and function are altered. INTERPRETATION: We propose that reduced levels of CERS2, and consequently diminished levels of ceramides and SLs containing very long-chain fatty acids, lead to development of PME.

Three-week bright-light intervention has dose-related effects on threat-related corticolimbic reactivity and functional coupling.

BACKGROUND: Bright-light intervention is reported to successfully treat depression, in particular seasonal affective disorder, but the neural pathways and molecular mechanisms mediating its effects are unclear. An amygdala-prefrontal cortex corticolimbic circuit regulates responses to salient environmental stimuli (e.g., threat) and may underlie these effects. Serotonin signaling modulates this circuit and is implicated in the pathophysiology of seasonal and other affective disorders. METHODS: We evaluated the effects of a bright-light intervention protocol on threat-related corticolimbic reactivity and functional coupling, assessed with an emotional faces functional magnetic resonance imaging paradigm at preintervention and postintervention. In a double-blind study conducted in the winter, 30 healthy male subjects received bright-light intervention (dose range between participants: .1-11.0 kilolux) for 30 minutes daily over a period of 3 weeks. Additionally, we considered serotonin transporter-linked polymorphic region (5-HTTLPR) genotype status as a model for differences in serotonin signaling and moderator of intervention effects. RESULTS: Bright-light dose significantly negatively affected threat-related amygdala and prefrontal reactivity in a dose-dependent manner. Conversely, amygdala-prefrontal and intraprefrontal functional coupling increased significantly in a dose-dependent manner. Genotype status significantly moderated bright-light intervention effects on intraprefrontal functional coupling. CONCLUSIONS: This is the first study to evaluate the effects of clinically relevant bright-light intervention on threat-related brain function. We show that amygdala-prefrontal reactivity and communication are significantly affected by bright-light intervention, an effect partly moderated by genotype. These novel findings support that this threat-related corticolimbic circuit is sensitive to light intervention and may mediate the therapeutic effects of bright-light intervention.

p53 increases caspase-6 expression and activation in muscle tissue expressing mutant huntingtin.

Activation of caspase-6 in the striatum of both presymptomatic and affected persons with Huntington's disease (HD) is an early event in the disease pathogenesis. However, little is known about the role of caspase-6 outside the central nervous system (CNS) and whether caspase activation might play a role in the peripheral phenotypes, such as muscle wasting observed in HD. We assessed skeletal muscle tissue from HD patients and well-characterized mouse models of HD. Cleavage of the caspase-6 specific substrate lamin A is significantly increased in skeletal muscle obtained from HD patients as well as in muscle tissues from two different HD mouse models. p53, a transcriptional activator of caspase-6, is upregulated in neuronal cells and tissues expressing mutant huntingtin. Activation of p53 leads to a dramatic increase in levels of caspase-6 mRNA, caspase-6 activity and cleavage of lamin A. Using mouse embryonic fibroblasts (MEFs) from YAC128 mice, we show that this increase in caspase-6 activity can be mitigated by pifithrin-α (pifα), an inhibitor of p53 transcriptional activity, but not through the inhibition of p53's mitochondrial pro-apoptotic function. Remarkably, the p53-mediated increase in caspase-6 expression and activation is exacerbated in cells and tissues of both neuronal and peripheral origin expressing mutant huntingtin (Htt). These findings suggest that the presence of the mutant Htt protein enhances p53 activity and lowers the apoptotic threshold, which activates caspase-6. Furthermore, these results suggest that this pathway is activated both within and outside the CNS in HD and may contribute to both loss of CNS neurons and muscle atrophy.