UNASSIGNED: Chronic intestinal pseudo-obstruction (CIPO) is a type of intestinal dysfunction with symptoms of intestinal blockage but without the actual mechanical obstruction. Currently, there are no drugs available to treat this disease. Herein, we report the characterization of the PrP-SCA7-92Q transgenic (Tg) line as a valuable CIPO mouse model and investigated the tolerability and efficacy of the 5-hydroxytryptamine type-4 receptor (5HT4R) agonist velusetrag as a promising pharmacological treatment for CIPO.
UNASSIGNED: To test the pharmacodynamics of velusetrag, 8-week-old SCA7 Tg mice, which express human mutated Ataxin-7 gene containing 92 CAG repeats under the mouse prion protein promoter, were treated for 5 weeks by oral route with velusetrag at 1 and 3 mg/kg doses or vehicle. Body weight was monitored throughout the treatment. After sacrifice, the small intestine and proximal colon were collected for whole-mount immunostaining. Untreated, age-matched, C57BL/6J mice were also used as controls in comparison with the other experimental groups.
UNASSIGNED: Analysis of SCA7 Tg mice showed tissue damage and alterations, mucosal abnormalities, and ulcers in the distal small intestine and proximal colon. Morphological changes were associated with significant neuronal loss, as shown by decreased staining of pan-neuronal markers, and with accumulation of ataxin-7-positive inclusions in cholinergic neurons. Administration of velusetrag reversed intestinal abnormalities, by normalizing tissue damage and re-establishing the normal level of glia/neuron\'s count in both the small and large intestines.
UNASSIGNED: We demonstrated that the PrP-SCA7-92Q Tg line, a model originally developed to mimic spinocerebellar ataxia, is suitable to study CIPO pathology and can be useful in establishing new therapeutic strategies, such as in the case of velusetrag. Our results suggest that velusetrag is a promising compound to treat patients affected by CIPO or intestinal dysmotility disease.

OBJECTIVE: Brain MRI abnormalities and increases in neurofilament light chain (NfL) have mostly been observed in cross-sectional studies before ataxia onset in polyglutamine spinocerebellar ataxias. Our study aimed to identify longitudinal changes in biological, clinical, and/or imaging biomarkers in spinocerebellar ataxia (SCA) 2 and SCA7 carriers over 1 year.
METHODS: We studied SCA2 and SCA7 carriers and controls (expansion-negative relatives) at the Paris Brain Institute. Inclusion criteria included Scale for the Assessment and Rating of Ataxia (SARA) scores between 0 and 15. Assessments at baseline, 6 months, and 12 months comprised neurologic, quality of life, orofacial motor, neuropsychological, and ophthalmologic examinations, along with gait and oculomotor recordings, brain MRI, CSF, and blood sampling. The primary outcome was the longitudinal change in these assessments over 1 year.
RESULTS: We included 15 SCA2 carriers, 15 SCA7 carriers, and 10 controls between May 2020 and April 2021. At baseline, the ages were similar (41 [37, 46] for SCA2, 38 [28.5, 39.8] for SCA7, and 39.5 [31, 54.5] for controls, p = 0.78), as well the sex (p = 0.61); SARA scores were low but different (4 [1.25, 6.5] in SCA2, 2 [0, 11.5] in SCA7, and 0 in controls, p < 0.01). Pons and medulla volumes were smaller in SCAs (p < 0.05) and cerebellum volume only in SCA2 (p = 0.01). Plasma NfL levels were higher in SCA participants (SCA2: 14.2 pg/mL [11.52, 15.89], SCA7: 15.53 [13.27, 23.23]) than in controls (4.88 [3.56, 6.17], p < 0.001). After 1-year follow-up, in SCA2, there was significant pons (-144 ± 60 mm3) and cerebellum (-1,508 ± 580 mm3) volume loss and a worsening of gait assessment; in SCA7, SARA score significantly increased (+1.3 ± 0.4) and outer retinal nuclear layer thickness decreased (-15.4 ± 1.6 μm); for both SCA groups, the orofacial motor assessment significantly worsened. For preataxic and early ataxic carriers, the strongest longitudinal deterioration on outcome measures was orofacial motility in SCA2 and retinal thickness in SCA7.
CONCLUSIONS: Despite the limitation of the small sample size, we detected annual changes in preataxic and early ataxic SCA individuals across brain MRI imaging, clinical scores, gait parameters, and retinal thickness. These parameters could serve as potential end points for future therapeutic trials in the preataxic phase.
UNASSIGNED: ClinicalTrials.gov NCT04288128.

Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder resulting from abnormal expansion of an uninterrupted polyglutamine (polyQ) repeat in its disease protein, ataxin-7 (ATXN7). ATXN7 is part of Spt-Ada-Gcn5 acetyltransferase (SAGA), an evolutionarily conserved transcriptional coactivation complex with critical roles in chromatin remodeling, cell signaling, neurodifferentiation, mitochondrial health and autophagy. SCA7 is dominantly inherited and characterized by genetic anticipation and high repeat-length instability. Patients with SCA7 experience progressive ataxia, atrophy, spasticity, and blindness. There is currently no cure for SCA7, and therapies are aimed at alleviating symptoms to increase quality of life. Here, we report novel Drosophila lines of SCA7 with polyQ repeats in wild-type and human disease patient range. We find that ATXN7 expression has age- and polyQ repeat length-dependent reduction in fruit fly survival and retinal instability, concomitant with increased ATXN7 protein aggregation. These new lines will provide important insight on disease progression that can be used in the future to identify therapeutic targets for SCA7 patients.

Polyglutamine (polyQ)-encoding CAG repeat expansions represent a common disease-causing mutation responsible for several dominant spinocerebellar ataxias (SCAs). PolyQ-expanded SCA proteins are toxic for cerebellar neurons, with Purkinje cells (PCs) being the most vulnerable. RNA interference (RNAi) reagents targeting transcripts with expanded CAG reduce the level of various mutant SCA proteins in an allele-selective manner in vitro and represent promising universal tools for treating multiple CAG/polyQ SCAs. However, it remains unclear whether the therapeutic targeting of CAG expansion can be achieved in vivo and if it can ameliorate cerebellar functions. Here, using a mouse model of SCA7 expressing a mutant Atxn7 allele with 140 CAGs, we examined the efficacy of short hairpin RNAs (shRNAs) targeting CAG repeats expressed from PHP.eB adeno-associated virus vectors (AAVs), which were introduced into the brain via intravascular injection. We demonstrated that shRNAs carrying various mismatches with the CAG target sequence reduced the level of polyQ-expanded ATXN7 in the cerebellum, albeit with varying degrees of allele selectivity and safety profile. An shRNA named A4 potently reduced the level of polyQ-expanded ATXN7, with no effect on normal ATXN7 levels and no adverse side effects. Furthermore, A4 shRNA treatment improved a range of motor and behavioral parameters 23 weeks after AAV injection and attenuated the disease burden of PCs by preventing the downregulation of several PC-type-specific genes. Our results show the feasibility of the selective targeting of CAG expansion in the cerebellum using a blood-brain barrier-permeable vector to attenuate the disease phenotype in an SCA mouse model. Our study represents a significant advancement in developing CAG-targeting strategies as a potential therapy for SCA7 and possibly other CAG/polyQ SCAs.

暂无摘要。

SpinoCerebellar Ataxia type 7 (SCA7) is an inherited disorder caused by CAG triplet repeats encoding polyglutamine expansion in the ATXN7 protein, which is part of the transcriptional coactivator complex SAGA. The mutation primarily causes neurodegeneration in the cerebellum and retina, as well as several forebrain structures. The SCA7140Q/5Q knock-in mouse model recapitulates key disease features, including loss of vision and motor performance. To characterize the temporal progression of brain degeneration of this model, we performed a longitudinal study spanning from early to late symptomatic stages using high-resolution magnetic resonance imaging (MRI) and in vivo 1H-magnetic resonance spectroscopy (1H-MRS). Compared to wild-type mouse littermates, MRI analysis of SCA7 mice shows progressive atrophy of defined brain structures, with the striatum, thalamus and cortex being the first and most severely affected. The volume loss of these structures coincided with increased motor impairments in SCA7 mice, suggesting an alteration of the sensory-motor network, as observed in SCA7 patients. MRI also reveals atrophy of the hippocampus and anterior commissure at mid-symptomatic stage and the midbrain and brain stem at late stage. 1H-MRS of hippocampus, a brain region previously shown to be dysfunctional in patients, reveals early and progressive metabolic alterations in SCA7 mice. Interestingly, abnormal glutamine accumulation precedes the hippocampal atrophy and the reduction in myo-inositol and total N-acetyl-aspartate concentrations, two markers of glial and neuronal damage, respectively. Together, our results indicate that non-cerebellar alterations and glial and neuronal metabolic impairments may play a crucial role in the development of SCA7 mouse pathology, particularly at early stages of the disease. Degenerative features of forebrain structures in SCA7 mice correspond to current observations made in patients. Our study thus provides potential biomarkers that could be used for the evaluation of future therapeutic trials using the SCA7140Q/5Q model.

Spinocerebellar ataxia type 7 (SCA7) is an autosomal-dominant inherited disease characterized by progressive ataxia and retinal degeneration. SCA7 belongs to a group of neurodegenerative diseases caused by an expanded CAG repeat in the disease-causing gene, resulting in aberrant polyglutamine (polyQ) protein synthesis. PolyQ ataxin-7 is prone to aggregate in intracellular inclusions, perturbing cellular processes leading to neuronal death in specific regions of the central nervous system (CNS). Currently, there is no treatment for SCA7; however, a promising approach successfully applied to other polyQ diseases involves the clearance of polyQ protein aggregates through pharmacological activation of autophagy. Nonetheless, the blood-brain barrier (BBB) poses a challenge for delivering drugs to the CNS, limiting treatment effectiveness. This study aimed to develop a polymeric nanocarrier system to deliver therapeutic agents across the BBB into the CNS. We prepared poly(lactic-co-glycolic acid) nanoparticles (NPs) modified with Poloxamer188 and loaded with rapamycin to enable NPs to activate autophagy. We demonstrated that these rapamycin-loaded NPs were successfully taken up by neuronal and glial cells, demonstrating high biocompatibility without adverse effects. Remarkably, rapamycin-loaded NPs effectively cleared mutant ataxin-7 aggregates in a SCA7 glial cell model, highlighting their potential as a therapeutic approach to fight SCA7 and other polyQ diseases.

BACKGROUND: We present the first two Polish families diagnosed with spinocerebellar ataxia type 7 (SCA7) and draw attention to cardiac involvement as a new potential manifestation of this disease.
METHODS: Two well-documented kindreds are presented.
RESULTS: The proband from Family 1 presented aged 54 years with vision worsening followed by progressive imbalance. Brain MRI demonstrated cerebellar atrophy. Genetic testing confirmed CAG repeat expansion (42/10) in ATXN7 gene. The proband from Family 2 developed imbalance at age 20, followed by progressive deterioration of vision. Brain MRI revealed cerebellar atrophy. Additionally, she developed chronic congestive heart failure and, at age 38, had cardiomyopathy with an ejection fraction of 20% and significant mitral and tricuspid regurgitation. Genetic analysis found abnormal CAG expansion in the ATXN7 (46/10).
CONCLUSIONS: Vision loss due to pigmentary retinal degeneration is the distinguishing feature of SCA7 and often the initial manifestation. Although SCA7 is one of the most common SCAs in Sweden, it has never been reported in neighbouring Poland. Until now, cardiac abnormalities have only been described in infantile-onset SCA7 with large CAG repeats. The observed cardiac involvement in Family 2 may be coincidental, albeit a new possible manifestation of SCA7 cannot be excluded.

Ataxin-7 maintains the integrity of Spt-Ada-Gcn5-Acetyltransferase (SAGA), an evolutionarily conserved coactivator in stimulating preinitiation complex (PIC) formation for transcription initiation, and thus, its upregulation or downregulation is associated with various diseases. However, it remains unknown how ataxin-7 is regulated that could provide new insights into disease pathogenesis and therapeutic interventions. Here, we show that ataxin-7\'s yeast homologue, Sgf73, undergoes ubiquitylation and proteasomal degradation. Impairment of such regulation increases Sgf73\'s abundance, which enhances recruitment of TATA box-binding protein (TBP) (that nucleates PIC formation) to the promoter but impairs transcription elongation. Further, decreased Sgf73 level reduces PIC formation and transcription. Thus, Sgf73 is fine-tuned by ubiquitin-proteasome system (UPS) in orchestrating transcription. Likewise, ataxin-7 undergoes ubiquitylation and proteasomal degradation, alteration of which changes ataxin-7\'s abundance that is associated with altered transcription and cellular pathologies/diseases. Collectively, our results unveil a novel UPS regulation of Sgf73/ataxin-7 for normal cellular health and implicate alteration of such regulation in diseases.

Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disease caused by a trinucleotide CAG repeat. SCA7 predominantly causes a loss of photoreceptors in the retina and Purkinje cells of the cerebellum. Severe infantile-onset SCA7 also causes renal and cardiac irregularities. Previous reports have shown that SCA7 results in increased susceptibility to DNA damage. Since DNA damage can lead to accumulation of senescent cells, we hypothesized that SCA7 causes an accumulation of senescent cells over the course of disease. A 140-CAG repeat SCA7 mouse model was evaluated for signs of disease-specific involvement in the kidney, heart, and cerebellum, tissues that are commonly affected in the infantile form. We found evidence of significant renal abnormality that coincided with an accumulation of senescent cells in the kidneys of SCA7140Q/5Q mice, based on histology findings in addition to RT-qPCR for the cell cycle inhibitors p16Ink4a and p21Cip1 and senescence-associated ß-galactosidase (SA-ßgal) staining, respectively. The Purkinje layer in the cerebellum of SCA7140Q/5Q mice also displayed SA-ßgal+ cells. These novel findings offer evidence that senescent cells accumulate in affected tissues and may possibly contribute to SCA7\'s specific phenotype.