SKA2 regulated hyperactive secretory autophagy drives neuroinflammation-induced neurodegeneration

High levels of proinflammatory cytokines induce neurotoxicity and catalyze inflammation-driven neurodegeneration, but the specific release mechanisms from microglia remain elusive. Here we show that secretory autophagy (SA), a non-lytic modality of autophagy for secretion of vesicular cargo, regulates neuroinflammation-mediated neurodegeneration via SKA2 and FKBP5 signaling. SKA2 inhibits SA-dependent IL-1β release by counteracting FKBP5 function. Hippocampal Ska2 knockdown in male mice hyperactivates SA resulting in neuroinflammation, subsequent neurodegeneration and complete hippocampal atrophy within six weeks. The hyperactivation of SA increases IL-1β release, contributing to an inflammatory feed-forward vicious cycle including NLRP3-inflammasome activation and Gasdermin D-mediated neurotoxicity, which ultimately drives neurodegeneration. Results from protein expression and co-immunoprecipitation analyses of male and female postmortem human brains demonstrate that SA is hyperactivated in Alzheimer's disease. Overall, our findings suggest that SKA2-regulated, hyperactive SA facilitates neuroinflammation and is linked to Alzheimer's disease, providing mechanistic insight into the biology of neuroinflammation.

Effects of a video game intervention on symptoms, training motivation, and visuo-spatial memory in depression

Background

People with Major Depressive Disorder (MDD) often experience reduced affect, mood, and cognitive impairments such as memory problems. Although there are various treatments for MDD, many of them do not address the cognitive deficits associated with the disorder. Playing 3D video games has been found to improve cognitive functioning in healthy people, but it is not clear how they may affect depressed mood and motivation in people with MDD. The aim of this study was to investigate whether a six-week video game intervention leads to improvements in depressed mood, training motivation, and visuo-spatial (working) memory functions in patients with MDD.

Methods

A total of 46 clinically depressed individuals were randomly assigned to one of three groups: an experimental "3D video gaming" group (n = 14) which played a video game, an active control group (n = 16) which trained with a computer program "CogPack," and a treatment-as-usual group (n = 16) which received a standard clinical treatment including psychotherapy and/or pharmacotherapy. Participants performed a neuropsychological assessment, including self-report questionnaires asking for depressive symptoms, training motivation, and visuo-spatial (working) memory functions before and after the training intervention.

Results

Regarding depressive symptoms, a significant decrease in the proportion of participants who showed clinical levels of depressive symptoms as measured by the Beck Depression Inventory was only found in the 3D video gaming group. Additionally, mean motivational levels of performing the training were significantly higher in the 3D video gaming group when compared with the active control group. Moreover, whereas the 3D Video Gaming group only significantly improved on one visuo-spatial memory test, the active control group improved in all visuo-spatial memory functions. The 3D video gaming group did not perform significantly better than the CogPack group, and the TAU group.

Conclusion

Besides a standalone cognitive training, the current findings suggest that cognitive trainings using a video game have potential to increase subjective well-being, show higher levels of training motivation, and lead to improvements in visuo-spatial (working) memory functions in MDD. However, given the mixed and unblinded nature of this study, the results should be interpreted with caution. Further research with larger samples and follow-up measurements is needed.

[Attention deficit hyperactivity disorder and substance use in adulthood-Guideline-conform diagnostics and treatment]

Attention deficit hyperactivity disorder (ADHD) is the most frequent developmental disorder in childhood, adolescence and adulthood. Substance use disorders are a frequent comorbidity in ADHD. The many different forms and severities of these comorbidities necessitate individual strategies in the diagnostics and treatment. Principally, ADHD and addictive disorders should be treated together whenever possible. The more acute or severe the dependence disorder is, the less priority can be given to the topic of ADHD and the lower are the chances of carrying out valid diagnostics and simultaneous treatment at the beginning of the treatment of the addictive disorder. The less severe and acute the addictive disorder is, the quicker the diagnostics and, if necessary, treatment of ADHD can be initiated. In this continuing education article, the customary means for diagnostics and pharmacotherapy as well as the special features that must be considered with respect to comorbidities of both disorders are presented.

Hippo-released WWC1 facilitates AMPA receptor regulatory complexes for hippocampal learning

Learning and memory rely on changes in postsynaptic glutamergic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type receptor (AMPAR) number, spatial organization, and function. The Hippo pathway component WW and C2 domain-containing protein 1 (WWC1) regulates AMPAR surface expression and impacts on memory performance. However, synaptic binding partners of WWC1 and its hierarchical position in AMPAR complexes are largely unclear. Using cell-surface proteomics in hippocampal tissue of Wwc1-deficient mice and by generating a hippocampus-specific interactome, we show that WWC1 is a major regulatory platform in AMPAR signaling networks. Under basal conditions, the Hippo pathway members WWC1 and large tumor-suppressor kinase (LATS) are associated, which might prevent WWC1 effects on synaptic proteins. Reduction of WWC1/LATS binding through a point mutation at WWC1 elevates the abundance of WWC1 in AMPAR complexes and improves hippocampal-dependent learning and memory. Thus, uncoupling of WWC1 from the Hippo pathway to AMPAR-regulatory complexes provides an innovative strategy to enhance synaptic transmission.

Lower fractional anisotropy of the corticothalamic tract and increased response time variability in adult patients with ADHD

BACKGROUND

Intraindividual intertrial variability has been suggested as an endophenotype of attention-deficit/hyperactivity disorder (ADHD). It is usually evaluated as response time variability (RTV) in reaction time tasks, and RTV has emerged as a robust and stable feature of ADHD. Among attempts to elucidate the neurobiological underpinnings of RTV, it has been suggested that alterations in white matter microstructure may explain RTV.

METHODS

We used diffusion tensor imaging (DTI) in a group of 53 adults with ADHD and 50 healthy controls. We obtained RTV parameters from a simple reaction-time task, in which participants were asked to respond to the appearance of white crosses on a screen using button presses.

RESULTS

We observed significant between-group differences for the ex-Gaussian parameter τ, indicating that the mean of extremely slow responses was greater for adults with ADHD than controls. Fractional anisotropy (FA) derived from DTI was significantly different between groups in 2 clusters of the corticothalamic tract. In the ADHD group, relatively decreased FA values were significantly associated with the parameter τ, such that lower FA values in the corticothalamic tract predicted greater τ as an index of RTV. We did not observe this association in healthy controls.

LIMITATIONS

For comparison with previous studies, we used FA as a dependent variable of interest. However, although this metric is sensitive to white matter structural properties, there are ambiguities in its interpretation.

CONCLUSION

Even in a simple reaction-time task, RTV proved again to be a stable feature of ADHD. It was associated with altered white matter structural properties of the corticothalamic tract in adults with ADHD.

Sipa1l3/SPAR3 is targeted to postsynaptic specializations and interacts with the Fezzin ProSAPiP1/Lzts3

Rap GTPase-activating proteins (RapGAPs) are essential for synaptic function as they tightly regulate synaptic Rap signaling. Among the most abundant synaptic RapGAPs in brain are the Spine-associated RapGAPs (SPARs) Sipa1l1/SPAR and Sipa1l2/SPAR2, whereas nothing has been reported on Sipa1l3/SPAR3. In this study, we show that Sipa1l3/SPAR3 is conserved across species, has a distinct expression pattern in the developing rat brain and is localized at excitatory postsynapses. We further demonstrate that the Sipa1l3/SPAR3 C-terminus is required for postsynaptic targeting and represents an interaction module for Fezzins such as ProSAPiP1/Lzts3, a binding partner of the postsynaptic scaffold protein Shank3. Taken together, our data imply that Sipa1l3/SPAR3 is a hitherto unknown synaptic RapGAP, which is targeted to postsynaptic specializations and interacts with Fezzins. Spine-associated RapGAPs (SPARs) are essential modulators of synaptic signaling. Our study is the first to characterize the SPAR family member Sipa1l3/SPAR3 in neuronal tissue. We show that Sipa1l3/SPAR3 is conserved across species, has a distinct expression pattern in brain and is localized to excitatory postsynapses via its C-terminus, which represents an interaction module for other postsynaptic proteins including the Fezzin ProSAPiP1/Lzts3.