14-3-3 proteins promote synaptic localization of N-methyl d-aspartate receptors (NMDARs) in mouse hippocampal and cortical neurons.

One of the core pathogenic mechanisms for schizophrenia is believed to be dysfunction in glutamatergic synaptic transmissions, particularly hypofunction of N-methyl d-aspartate receptors (NMDARs). Previously we showed that 14-3-3 functional knockout mice exhibit schizophrenia-associated behaviors accompanied by reduced synaptic NMDARs in forebrain excitatory neurons. To investigate how 14-3-3 proteins regulate synaptic localization of NMDARs, here we examined changes in levels of synaptic NMDARs upon 14-3-3 inhibition in primary neurons. Expression of 14-3-3 protein inhibitor (difopein) in primary glutamatergic cortical and hippocampal neurons resulted in lower number of synaptic puncta containing NMDARs, including the GluN1, GluN2A, or GluN2B subunits. In heterologous cells, 14-3-3 proteins enhanced surface expression of these NMDAR subunits. Furthermore, we identified that 14-3-3ζ and ε isoforms interact with NMDARs via binding to GluN2A and GluN2B subunits. Taken together, our results demonstrate that 14-3-3 proteins play a critical role in NMDAR synaptic trafficking by promoting surface delivery of NMDAR subunits GluN1, GluN2A, and GluN2B. As NMDAR hypofunctionality is known to act as a convergence point for progression of symptoms of schizophrenia, further studies on these signaling pathways may help understand how dysfunction of 14-3-3 proteins can cause NMDAR hypofunctionality and lead to schizophrenia-associated behaviors.

A changing history: When is it a red flag for child abuse?

BACKGROUND AND OBJECTIVE: While a changing history is frequently cited as a red flag for child abuse, no data support which changes are significant, nor the degree to which concern should be increased. We sought to measure the impact of changing caregiver histories on expert assessments of abuse likelihood. METHODS: We used a vignette survey to measure the impact of a changing history on child abuse expert assessments of abuse likelihood and willingness to undertake testing and protective interventions. By randomly varying the presence and magnitude of history changes, we determined their impact on perceived abuse likelihood. RESULTS: Of 494 invited participants, 267 (54 %) completed the survey. The presence of historical changes significantly affected experts' level of concern for abuse and willingness to test or report abuse, though to variable degrees. For example, while a minor change in the timing of an injury did not significantly increase willingness to perform a skeletal survey (OR: 1.5, 95 % CI: 0.8-2.9), a major change in the timing of an injury did (OR: 2.0, 95 % CI: 1.1-3.6). In addition, a change from having no initial history of trauma to then giving a history of accidental trauma significantly lowered the mean estimate of abuse likelihood and triggered significantly less reports to child protective services (OR: 0.02, 95 % CI: 0.003-0.2). CONCLUSION: For abuse experts, some history changes are more concerning than others, with major changes in history, and an initial denial of trauma having the largest impact. Future research regarding changing histories should consider details of the change, rather than treating all changes equally.

Behavioral and Neuroanatomical Consequences of Cell-Type Specific Loss of Dopamine D2 Receptors in the Mouse Cerebral Cortex.

Developmental dysregulation of dopamine D2 receptors (D2Rs) alters neuronal migration, differentiation, and behavior and contributes to the psychopathology of neurological and psychiatric disorders. The current study is aimed at identifying how cell-specific loss of D2Rs in the cerebral cortex may impact neurobehavioral and cellular development, in order to better understand the roles of this receptor in cortical circuit formation and brain disorders. We deleted D2R from developing cortical GABAergic interneurons (Nkx2.1-Cre) or from developing telencephalic glutamatergic neurons (Emx1-Cre). Conditional knockouts (cKO) from both lines, Drd2 fl/fl, Nkx2.1-Cre + (referred to as GABA-D2R-cKO mice) or Drd2 fl/fl, Emx1-Cre + (referred to as Glu-D2R-cKO mice), exhibited no differences in simple tests of anxiety-related or depression-related behaviors, or spatial or nonspatial working memory. Both GABA-D2R-cKO and Glu-D2R-cKO mice also had normal basal locomotor activity, but GABA-D2R-cKO mice expressed blunted locomotor responses to the psychotomimetic drug MK-801. GABA-D2R-cKO mice exhibited improved motor coordination on a rotarod whereas Glu-D2R-cKO mice were normal. GABA-D2R-cKO mice also exhibited spatial learning deficits without changes in reversal learning on a Barnes maze. At the cellular level, we observed an increase in PV+ cells in the frontal cortex of GABA-D2R-cKO mice and no noticeable changes in Glu-D2R-cKO mice. These data point toward unique and distinct roles for D2Rs within excitatory and inhibitory neurons in the regulation of behavior and interneuron development, and suggest that location-biased D2R pharmacology may be clinically advantageous to achieve higher efficacy and help avoid unwanted effects.

Alix and Syntenin-1 direct amyloid precursor protein trafficking into extracellular vesicles.

BACKGROUND: Endosomal trafficking and amyloidogenic cleavage of amyloid precursor protein (APP) is believed to play a role in the neurodegeneration observed in Alzheimer's disease (AD). Recent evidence has suggested that packaging and secretion of APP and its amyloidogenic cleaved products into small extracellular vesicles (EVs) may facilitate uptake of these neurotoxic factors during disease progression. However, the molecular mechanisms underlying trafficking of APP into EVs are poorly understood. RESULTS: In this study, the mechanism and impact of APP trafficking into extracellular vesicles (EVs) were assessed by a series of inducible gene knockdowns. We demonstrate that vesicle-associated proteins Alix and Syntenin-1 are essential for proper subcellular localization and efficient EV secretion of APP via an endosomal sorting complexes required for transport (ESCRT)-independent pathway. The neurotoxic C-terminal fragment (CTFß) of APP is similarly secreted in association with small vesicles. These mechanisms are conserved in terminally differentiated neuron-like cells. Furthermore, knockdown of Alix and Syntenin-1 alters the subcellular localization of APP, sequestering the precursor protein to endoplasmic reticulum and endolysosomal compartments, respectively. Finally, transfer of small EVs containing mutant APP confers an increase in reactive oxygen species production and neurotoxicity to human induced pluripotent stem cell-derived cortical neurons and naïve primary neurons, an effect that is ameliorated by Alix and Syntenin-1 depletion. CONCLUSIONS: Altogether these findings elucidate a novel mechanism for understanding the intracellular trafficking of APP and CTFß into secreted extracellular vesicles, and the resultant potential impact on neurotoxicity in the context of Alzheimer's disease amyloidopathy.

Classic metaphyseal lesion of distal tibia following footling breech delivery.

Classic metaphyseal lesions associated with childbirth are rare. We report a distal tibial metaphyseal fracture following a difficult breech delivery. Classic metaphyseal fractures are considered highly specific injuries associated with non-accidental trauma. This case depicts a classic metaphyseal lesion sustained during footling breech extraction in an urgent delivery. The traction and torque placed on the distal extremities during this difficult delivery suggest a potential mechanism for this injury.

Synthesis of highly substituted adamantanones from bicyclo[3.3.1]nonanes.

Trifluoromethanesulfonic acid and other electrophiles promote formation of the adamantanone core from the readily accessible 1,5-dimethyl-3,7-dimethylenebicyclo[3.3.1]nonan-9-one 2. Because adamantyl cation 3 can be trapped by a range of nucleophiles, including aromatic and heteroaromatic rings, alcohol, nitriles, and halides, access to a wide variety of functionality at the newly formed tertiary position is provided.

Palladium hydride promoted stereoselective isomerization of unactivated di(exo)methylenes to endocyclic dienes.

The exomethylenes of 2,6-disubstituted bicyclo[3.3.1]nonan-9-ones 2 are readily isomerized over a palladium catalyst under an atmosphere of hydrogen to predominantly form the isomer 3 with C2 symmetry with very little formation of the analogous product with C(s) symmetry. A hydrogen source is essential to effect the rearrangement.