Heterozygous variants in USP25 cause genetic generalized epilepsy.

USP25 encodes ubiquitin-specific proteases 25, a key member of deubiquitinating enzyme family and is involved in neural fate determination. Although abnormal expression in Down's syndrome was reported previously, the specific role of USP25 in human diseases has not been defined. In this study, we performed trio-based whole exome sequencing in a cohort of 319 cases (families) with generalized epilepsy of unknown etiology. Five heterozygous USP25 variants including two de novo and three co-segregated variants were determined in eight individuals affected by generalized seizures and/or febrile seizures from five unrelated families. The frequency of USP25 variants showed a significantly high aggregation in this cohort compared to the East Asian population and all populations in the gnomAD database. The mean onset ages of febrile and afebrile seizures were 10 months (infancy) and 11.8 years (juvenile), respectively. The patients achieved seizure freedom except one had occasional nocturnal seizures at the last follow-up. Two patients exhibited intellectual disability. Usp25 was ubiquitously expressed in mouse brain with two peaks on embryonic days (E14‒E16) and postnatal day 21, respectively. Similarly, USP25 expressed in fetus/early childhood stage with a second peak at approximately 12‒20 years old in human brain, consistent with the seizure onset age at infancy and juvenile in the patients. To investigate the functional impact of USP25 deficiency in vivo, we established Usp25 knock-out mice, which showed increased seizure susceptibility compared to wild-type mice in pentylenetetrazol-induced seizure test. To explore the impact of USP25 variants, we employed multiple functional detections. In HEK293T cells, the severe phenotype associated variant (p.Gln889Ter) led to a significant reduction of mRNA and protein expressions but formed a stable truncated dimers with increment of deubiquitinating enzyme activities and abnormal cellular aggregations, indicating a gain-of-function effect. The p.Gln889Ter and p.Leu1045del increased neuronal excitability in mice brain, with a higher firing ability in p.Gln889Ter. These functional impairments align with the severity of the observed phenotypes, suggesting a genotype-phenotype correlation. Hence, a moderate association between USP25 and epilepsy was noted, indicating USP25 is potentially a predisposing gene for epilepsy. Our results from Usp25 null mice and the patient-derived variants indicated that USP25 would play epileptogenic role via loss-of-function or gain-of-function effects. The truncated variant p.Gln889Ter would have profoundly different effect on epilepsy. Together, our results underscore the significance of USP25 heterozygous variants in epilepsy, thereby highlighting the critical role of USP25 in the brain.

Depressive- and anxiety-like phenotypes in young adult APPSwe/PS1dE9 transgenic mice with insensitivity to chronic mild stress.

Early Alzheimer's disease (AD) and depression share many symptoms, but the underlying mechanisms are not clear. Therefore, characterizing the shared and different biological changes between the two disorders will be helpful in making an early diagnosis and planning treatment. In the present study, 8-week-old APPSwe/PS1dE9 transgenic mice received chronic mild stress (CMS) for 8 weeks followed by a series of behavioral, biochemical and pathological analyses. APPSwe/PS1dE9 mice showed depressive- and anxiety-like behaviors, and reduced sociability, accompanied by high levels of soluble beta-amyloid, glial activation, neuroinflammation and brain derived neurotrophic factor signaling disturbance in the hippocampus. Notably, APPSwe/PS1dE9 mice exposure to CMS partially aggravated anxiety-like states rather than depressive-like responses and sociability deficits, with further elevated hippocampal interleukin-6 and tumor necrosis factor-α levels. These results demonstrated that young adult APPSwe/PS1dE9 have depressive- and anxiety-like phenotypes that were resistant to CMS compared to wild-type mice. This finding may help to understand the pathogenic mechanism of psychiatric symptoms associated with early AD.

[The study of adsorption of L-aspartic acid on silver sol by surface-enhanced Raman scattering].

The adsorption state and the characteristics of L-aspartic acid adsorbed on silver sol were studied by the Surface-Enhanced Raman Scattering (SERS) method. Strong Raman signals were detected in the experiments. The results suggested that L-aspartic acid adsorbed on the silver surfaces through carboxyl and nitrogen atoms since the signals were mainly due to the carboxyl and the nitrogen of the molecule of L-aspartic acid. The adsorption of carboxyl on the silver surfaces is chemical adsorption, which is based on the mechanism of charge-transfer, while the adsorption of nitrogen on the silver surfaces is physical type, which is due to the electromagnetic mechanism. The intensity of surface-enhanced Raman scattering of L-aspartic acid adsorbed on silver surface was also analyzed, and it was found that the intensity of surface-enhance Raman scattering will change with different concentrations of L-aspartic acid adsorbed on the silver surfaces. The intensity will reach the top value when the concentration of L-aspartic acid was 10(-3) mol x L(-1). When the concentration of L-aspartic acid decreased to 10(-4) mol x L(-1), the intensity of surface-enhanced Raman scattering became a little weaker than that with 10(-3) mol x L(-1). With further decrease in the concentration of L-aspartic acid, the intensity of surface-enhanced Raman scattering also decreased gradually. When the concentration of L-aspartic acid decreased to 10(-6) mol x L(-1), the intensity of surface-enhanced Raman scattering was very low. The above study will be helpful to the further study of peptide and other complex biological systems.

Aquaporin-4 mitigates retrograde degeneration of rubrospinal neurons by facilitating edema clearance and glial scar formation after spinal cord injury in mice.

Atrophy of upper motor neurons hampers axonal regeneration and functional recovery following spinal cord injury (SCI). Apart from the severity of primary injury, a series of secondary pathological damages including spinal cord edema and glial scar formation affect the fate of injured upper motor neurons. The aquaporin-4 (AQP4) water channel plays a critical role in water homeostasis and migration of astrocytes in the central nervous system, probably offering a new therapeutic target for protecting against upper motor neuron degeneration after SCI. To test this hypothesis, we examined the effect of AQP4 deficiency on atrophy of rubrospinal neurons after unilateral rubrospinal tract transection at the fourth cervical level in mice. AQP4 gene knockout (AQP4-/-) mice exhibited high extent of spinal cord edema at 72 h after lesion compared with wild-type littermates. AQP4-/- mice showed impairments in astrocyte migration toward the transected site with a greater lesion volume at 1 week after surgery and glial scar formation with a larger cyst volume at 6 weeks. More severe atrophy and loss of axotomized rubrospinal neurons as well as axonal degeneration in the rubrospinal tract rostral to the lesion were observed in AQP4-/- mice at 6 weeks after SCI. AQP4 expression was downregulated at the lesioned spinal segment at 3 days and 1 week after injury, but upregulated at 6 weeks. These results demonstrated that AQP4 not only mitigates spinal cord damage but also ameliorates retrograde degeneration of rubrospinal neurons by promoting edema clearance and glial scar formation after laceration SCI. This finding supports the notion that AQP4 may be a promising therapeutic target for SCI.

Calcium sensing receptor absence delays postnatal brain development via direct and indirect mechanisms.

Calcium sensing receptor (CaSR) is implicated in the establishment of neural connections and myelin formation. However, its contribution to brain development remains unclear. We addressed this issue by analyzing brain phenotype in postnatal CaSR null mice, a model of human neonatal severe hyperparathyroidism. One- and 2-week-old CaSR null mice exhibited decreased brain weight and size with a developmental delay in expression of proliferating cell nuclear antigen. Neuronal and glial differentiation markers, neuronal specific nuclear protein, glial fibrillary acidic protein, and myelin basic protein, were also decreased compared with age-matched wild-type littermates. Moreover, deletion of the parathyroid hormone gene that corrects hyperparathyroidism, hypercalcemia, hypophosphatemia, and whole-body growth retardation normalized brain cell proliferation, but not differentiation, in CaSR null mice. Cultured neural stem cells (NSCs) derived from the subventricular zones of CaSR null neonatal mice exhibited normal proliferation capacity but decreased differentiation capacity, compared with wild-type controls. These results demonstrate that direct effects of CaSR absence impair NSC differentiation, while secondary effects of parathyroid hormone-related endocrine abnormalities impair NSC proliferation, both of which contribute to delayed brain development in CaSR null newborn mice.

Aerobic exercise combined with antioxidative treatment does not counteract moderate- or mid-stage Alzheimer-like pathophysiology of APP/PS1 mice.

AIMS: The present study evaluated the combined treatment effects of aerobic exercise and antioxidative stress on moderate-stage Alzheimer's disease (AD). METHODS: Ten-month-old APP/PS1 mice were given antioxidative treatment with acetylcysteine, along with aerobic exercise for 6 weeks. Spatial learning and memory were tested using the Morris water maze, and ß-amyloid (Aß) plaque deposits in the forebrain were quantified by Thioflavin-S staining. Levels of soluble Aß1-42, ß-secretase enzyme, Ò¯-secretase enzyme, oxidative and antioxidant stress markers nitrotyrosine and peroxiredoxin-1, glial markers glial fibrillary acidic protein and ionized calcium-binding adaptor molecule 1, and synaptic protein synaptophysin in the hippocampus were all measured by western blotting and/or immunohistochemistry. RESULTS: APP/PS1 mice showed severe declines in spatial learning and memory compared with their wild-type littermates, which were not attenuated by aerobic exercise combined with antioxidative treatment. The pathologic analysis revealed that Aß deposition and production, oxidative stress, glial inflammation, and synaptic loss were not mitigated in the brain of exercised APP/PS1 mice, compared with the sedentary APP/PS1 animals. CONCLUSION: This study reveals that a combined treatment of aerobic exercise plus antioxidative stress does not counteract pathophysiology in the moderate- or mid-stages of AD.