Regulation of sensorimotor gating via Disc1/Huntingtin-mediated Bdnf transport in the cortico-striatal circuit

Schizophrenia-like phenotypes and long-term synaptic plasticity impairment in GluN2A-transgenic mice

While N-methyl-d-aspartate receptor (NMDAR) hypofunction has been suggested as a hallmark of schizophrenia, the role of subunit-specific dysregulation such as GluN2A overexpression remains poorly understood. The present study comprehensively investigated the impact of GluN2A overexpression on behavioral phenotypes, cognitive functions, and synaptic plasticity in transgenic mice with forebrain-specific overexpression of the GluN2A subunit (GluN2A-TG). Behavioral assessments revealed schizophrenia-like phenotypes, including prolonged stereotypic movement duration, impaired sensorimotor gating, reduced social interaction, and diminished nest-building activity in GluN2A-TG mice. Consistently, GluN2A-TG mice exhibited not only deficits in spatial working memory and olfactory working memory but also impaired associative learning. In addition, both long-term potentiation and long-term depression were significantly attenuated in the prefrontal cortex (PFC) of GluN2A-TG mice. Furthermore, electrophysiological analysis of NMDAR-mediated excitatory postsynaptic currents in PFC neurons revealed altered kinetics characterized by a faster decay time and significantly increased amplitude in GluN2A-TG mice. Collectively, these findings suggest that GluN2A overexpression may induce schizophrenia-like phenotypes via impairing NMDAR-dependent long-term synaptic plasticity in the PFC, likely due to altered NMDAR subunit composition leading to disrupted calcium signaling dynamics. These results provide critical insights into the pathological role of GluN2A in schizophrenia.

The Huntingtin Transport Complex

A dynamic network of scaffolding molecules, adaptor proteins, and motor proteins work together to orchestrate the movement of proteins, mRNA, and vesicular cargoes. Defects in intracellular transport can often lead to neurodegeneration. Huntingtin (HTT) is a ubiquitously expressed scaffolding protein with a multitude of cellular roles, including regulating the transport of various organelles. HTT is remarkable in its ability to regulate the transport of a wide range of cargoes, including BDNF vesicles, APP vesicles, early endosomes, autophagosomes, lysosomes, and mitochondria. This interaction network allows huntingtin to control microtubule-based transport by kinesin and dynein, as well as actin-based transport by myosin VI. By forming complexes with multiple motor adaptors, huntingtin regulates a variety of cargoes and guides cargoes through the different stages of biosynthesis, signaling, and degradation. Accordingly, pathogenic polyglutamine expansions seen in Huntington's Disease (HD) dysregulate huntingtin transport complexes, resulting in defects in transport and neurodegeneration.

Transcriptome Alterations Caused by Social Defeat Stress of Various Durations in Mice and Its Relevance to Depression and Posttraumatic Stress Disorder in Humans: A Meta-Analysis

The research on molecular causes of stress-associated psychopathologies is becoming highly important because the number of people with depression, generalized anxiety disorder and posttraumatic stress disorders (PTSDs) is steadily increasing every year. Investigation of molecular mechanisms in animal models opens up broad prospects for researchers, but relevant molecular signatures can differ significantly between patients and animal models. In our work, we for the first time carried out a meta-analysis of transcriptome changes in the prefrontal cortex of C57BL/6 mice after 10 and 30 days of social defeat stress (SDS). We then examined possible correlations of these alterations with transcriptome changes found in post-mortem samples from patients with depression or PTSD. Although transcriptional signatures of human psychiatric disorders and SDS did not overlap substantially, our results allowed us to identify the most reproducible changes seen after SDS of various durations. In addition, we were able to identify the genes involved in susceptibility to SDS after 10 days of stress. Taken together, these data help us to elucidate the molecular changes induced by SDS depending on its duration as well as their relevance to the alterations found in depression or PTSD in humans.