Adeno-Associated Virus-Mediated Rescue of the Cognitive Defects in a Mouse Model for Angelman Syndrome

Angelman syndrome (AS), a genetic disorder occurring in approximately one in every 15,000 births, is characterized by severe mental retardation, seizures, difficulty speaking and ataxia. The gene responsible for AS was discovered to be UBE3A and encodes for E6-AP, an ubiquitin ligase. A unique feature of this gene is that it undergoes maternal imprinting in a neuron-specific manner. In the majority of AS cases, there is a mutation or deletion in the maternally inherited UBE3A gene, although other cases are the result of uniparental disomy or mismethylation of the maternal gene. While most human disorders characterized by severe mental retardation involve abnormalities in brain structure, no gross anatomical changes are associated with AS. However, we have determined that abnormal calcium/calmodulin-dependent protein kinase II (CaMKII) regulation is seen in the maternal UBE3A deletion AS mouse model and is responsible for the major phenotypes. Specifically, there is an increased αCaMKII phosphorylation at the autophosphorylation sites Thr286 and Thr305/306, resulting in an overall decrease in CaMKII activity. CaMKII is not produced until after birth, indicating that the deficits associated with AS are not the result of developmental abnormalities. The present studies are focused on exploring the potential to rescue the learning and memory deficits in the adult AS mouse model through the use of an adeno-associated virus (AAV) vector to increase neuronal UBE3A expression. These studies show that increasing the levels of E6-AP in the brain using an exogenous vector can improve the cognitive deficits associated with AS. Specifically, the associative learning deficit was ameliorated in the treated AS mice compared to the control AS mice, indicating that therapeutic intervention may be possible in older AS patients

Defining Mild Cognitive Impairment: Impact of Varying Decision Criteria on Neuropsychological Diagnostic Frequencies and Correlates

To examine the impact of varying decision criteria on neuropsychological diagnostic frequencies and on their correlates. Descriptive and correlational study. Florida Alzheimer's Disease Research Center. A sample of 373 individuals with comprehensive baseline analyses participating in a longitudinal study of cognitive decline and early Alzheimer disease. Mild cognitive impairment (MCI) diagnoses were made on the basis of four sets of decision criteria created by crossing two approaches: varying the number of impaired test results required for a diagnosis within any domain (1 test versus 2) and varying the performance level required to determine impairment (1.5 or 2 standard deviations [SDs] below the normative mean) for any test. Under each criteria set, single-domain amnestic MCI was the most frequent MCI diagnosis. MCI global and subtype diagnosis frequencies were inversely related to the stringency of the criteria. The single test-1.5 SD criterion identified the largest number of cases as qualifying for an MCI diagnosis, and the two test-2.0 SD cutoff identified the fewest. Across all sets of criteria, the authors found significant positive associations between neuropsychological diagnoses and Clinical Dementia Rating score categories. Significant relationships between diagnoses and both apolipoprotein E (APOE) genotype and magnetic resonance imaging ratings of medial temporal atrophy (MTA) application were found only for the two test-1.5 SD and two test-2.0 SD cutoffs. MCI diagnosis frequencies are substantively affected by the stringency of the criteria, but the relative rankings of MCI subtype diagnoses are fairly consistent regardless of the stringency of the criteria. Significant associations of neuropsychological diagnoses with independent markers such as APOE genotype and MTA are only found with more stringent criteria, suggesting that a coherent network of associations reflecting cognitive decline occurs with more restrictive definitions for impairment

An open-label pilot trial of minocycline in children as a treatment for Angelman syndrome

Background: Minocycline, a member of the tetracycline family, has a low risk of adverse effects and an ability to improve behavioral performance in humans with cognitive disruption. We performed a single-arm open-label trial in which 25 children diagnosed with Angelman syndrome (AS) were administered minocycline to assess the safety and tolerability of minocycline in this patient population and determine the drug's effect on the cognitive and behavioral manifestations of the disorder. Methods: Participants, age 4-12 years old, were randomly selected from a pool of previously screened children for participation in this study. Each child received 3 milligrams of minocycline per kilogram of body weight per day for 8 weeks. Participants were assessed during 3 study visits: baseline, after 8-weeks of minocycline treatment and after an 8-week wash out period. The primary outcome measure was the Bayley Scales of Infant and Toddler Development 3rd Edition (BSID-III). Secondary outcome measures included the Clinical Global Impressions Scale (CGI), Vineland Adaptive Behavior Scales 2nd Edition (VABS-II), Preschool Language Scale 4th Edition (PLS-IV) and EEG scores. Observations were considered statistically significant if p < 0.05 using ANOVA and partial eta squared (η) was calculated to show effect size. Multiple comparisons testing between time points were carried out using Dunnett's post hoc testing. Results: Significant improvement in the mean raw scores of the BSID-III subdomains communication and fine motor ability as well as the subdomains auditory comprehension and total language ability of the PLS-IV when baseline scores were compared to scores after the washout period. Further, improvements were observed in the receptive communication subdomain of the VABS-II after treatment with minocycline. Finally, mean scores of the BSID-III self-direction subdomain and CGI scale score were significantly improved both after minocycline treatment and after the wash out period. Conclusion: The clinical and neuropsychological measures suggest minocycline was well tolerated and causes improvements in the adaptive behaviors of this sample of children with Angelman syndrome. While the optimal dosage and the effects of long-term use still need to be determined, these findings suggest further investigation into the effect minocycline has on patients with Angelman syndrome is warranted

Reelin Supplementation Recovers Sensorimotor Gating, Synaptic Plasticity and Associative Learning Deficits in the Heterozygous Reeler Mouse

The lipoprotein receptor ligand Reelin is important for the processes of normal synaptic plasticity, dendritic morphogenesis, and learning and memory. Heterozygous reeler mice (HRM) show many neuroanatomical, biochemical, and behavioral features that are associated with schizophrenia. HRM show subtle morphological defects including reductions in dendritic spine density, altered synaptic plasticity and behavioral deficits in associative learning and memory and pre-pulse inhibition. The present studies test the hypothesis that in vivo elevation of Reelin levels can rescue synaptic and behavioral phenotypes associated with HRM. We demonstrate that a single in vivo injection of Reelin increases GAD67 expression and alters dendritic spine morphology. In parallel we observed enhancement of hippocampal synaptic function and associative learning and memory. Reelin supplementation also increases pre-pulse inhibition. These results suggest that characteristics of HRM, similar to those observed in schizophrenia, are sensitive to Reelin levels and can be modified with Reelin supplementation in male and female adults

There were no changes in motor coordination, activity levels, or anxiety.

<p>(A) There was no change in latency to fall of the rotorod in either AS group. (B) Total distance travelled during the open field test revealed no significant difference between any of the treatment groups. (C) Time spent in the open arms of the elevated plus maze was used to determine general anxiety. (D) Time spent immobile in the elevated plus maze was not significantly different in any of the groups. Results shown represent the mean with standard error.</p

Increasing E6-AP in the AS mouse results in improvements in early phase LTP.

<p>(A) AS TR2-GFP mice have significant deficits in hippocampal synaptic plasticity. LTP was induced following 20 min of baseline recordings. (B) Immediately following TBS, acute hippocampal slices taken from AS TR2-GFP mice had significant deficits in the average PTP (average of first 5 min recordings of fEPSPs slopes). To compare late phase LTP, the last 5 min recordings of fEPSPs slopes were averaged, and there was no significant difference between any of the groups. (C) There were no significant differences between any of the groups in either PPF or (D) PTP, indicating that short term synaptic plasticity mechanisms are unaffected. Results shown represent the mean with standard error.</p

E6-AP protein levels were restored to wildtype levels in the TR2-UBE3A treated AS mice.

<p>(A) Representative coronal slices through the hippocampus from each group stained for E6-AP. (B) Quantitative analysis of the IHC revealed a significant increase in E6-AP expression in the WT and AS-TR2-UBE3A mice compared to the AS TR2-GFP group, while there was no significant change between the WT and AS TR2-UBE3A mice. Results shown represent the mean with standard error.</p