Altered fronto-striatal functions in the Gdi1-null mouse model of X-linked Intellectual Disability

ECM1-associated miR-1260b promotes osteogenic differentiation by targeting GDI1

Osteoporosis (OP) is a common disease among older adults. The promotion of osteoblast differentiation plays a crucial role in alleviating OP symptoms. Extracellular matrix protein 1 (ECM1) has been reported to be closely associated with osteogenic differentiation. In this study, we constructed U2OS cell lines with ECM1 knockdown and ECM1a overexpression based on knockdown, and identified the target miRNA (miR-1260b) by sequencing. Overexpression of miR-1260b promoted the osteogenic differentiation of U2OS and MG63 cells, as demonstrated by increased alkaline phosphatase (ALP) activity, matrix mineralization, and Runt-Related Transcription Factor 2 (RUNX2), Osteopontin (OPN), Collagen I (COL1A1), and Osteocalcin (OCN) protein expressions, whereas low expression of miR-1260b had the opposite effect. In addition, miR-1260b expression was decreased in OP patients than in non-OP patients. Next, we predicted the target gene of miRNA through TargetScan and miRDB and found that miR-1260b negatively regulated GDP dissociation inhibitor 1 (GDI1) by directly binding to its 3'-untranslated region. Subsequent experiments revealed that GDI1 overexpression decreased ALP activity and calcium deposit, reduced RUNX2, OPN, COL1A1, and OCN expression levels, and reversed the effects of miR-1260b on osteogenic differentiation. In conclusion, ECM1-related miR-1260b promotes osteogenic differentiation by targeting GDI1 in U2OS and MG63 cells. Thus, this study has significant implication for osteoporosis treatment.

Neural precursor cells tune striatal connectivity through the release of IGFBPL1

The adult brain retains over life endogenous neural stem/precursor cells (eNPCs) within the subventricular zone (SVZ). Whether or not these cells exert physiological functions is still unclear. In the present work, we provide evidence that SVZ-eNPCs tune structural, electrophysiological, and behavioural aspects of striatal function via secretion of insulin-like growth factor binding protein-like 1 (IGFBPL1). In mice, selective ablation of SVZ-eNPCs or selective abrogation of IGFBPL1 determined an impairment of striatal medium spiny neuron morphology, a higher failure rate in GABAergic transmission mediated by fast-spiking interneurons, and striatum-related behavioural dysfunctions. We also found IGFBPL1 expression in the human SVZ, foetal and induced-pluripotent stem cell-derived NPCs. Finally, we found a significant correlation between SVZ damage, reduction of striatum volume, and impairment of information processing speed in neurological patients. Our results highlight the physiological role of adult SVZ-eNPCs in supporting cognitive functions by regulating striatal neuronal activity.

Emerging roles of brain metabolism in cognitive impairment and neuropsychiatric disorders

Here we discuss the role of diverse environmental manipulations affecting cognition with special regard to psychiatric conditions. We present evidence supporting a direct causal correlation between the valence of the environmental stimulation and some psychopathological traits and how the environment influences brain structure and function with special regard to oxidative stress and mitochondrial activity. Increasing experimental evidence supports a role for mitochondrial dysfunctions in neuropsychiatric disorders. Brain mitochondria are considered crucial mediators of allostasis, that is the capability to adapt to stress via a complex interaction between the autonomic, metabolic, and immune systems to maintain cellular homeostasis. In this process, mitochondria act as highly dynamic integrators by sensing and transducing stressors into adaptation mechanisms via metabolic stress mediators, such as glucocorticoids and catecholamines. Alterations in cellular homeostasis induced by chronic stress are thought to predispose to disease by triggering the so-called "mitochondrial allostatic load". This process is characterized by functional and structural changes of the mitochondria, ultimately leading to oxidative stress, inflammation, mitochondrial DNA damage and apoptosis. In this review we discuss the role of diverse environmental manipulations to affect cognition with special regard to psychiatric conditions. How the environment influences brain structure and function, and the interactions between rearing conditions, oxidative stress and mitochondrial activity are fundamental questions that are still poorly understood. As will be discussed, increasing experimental evidence supports a role for mitochondrial dysfunctions in neuropsychiatric disorders. Brain mitochondria are considered crucial mediators of allostasis, that is the capability to adapt to stress via a complex interaction between the autonomic, metabolic, and immune systems to maintain cellular homeostasis. In this process, mitochondria act as highly dynamic integrators by sensing and transducing stressors into adaptation mechanisms via metabolic stress mediators, such as glucocorticoids and catecholamines. Alterations in cellular homeostasis induced by chronic stress are thought to predispose to disease by triggering the so-called "mitochondrial allostatic load". This process is characterized by functional and structural changes of the mitochondria, ultimately leading to oxidative stress, inflammation, mitochondrial DNA damage and apoptosis. The brain requires considerable mitochondrial reserve not only to sustain basal neuronal needs but a also to provide increasing energy demands during stress. Consistently with these high energetic requirements, it is reasonable to hypothesise that the brain is particularly vulnerable to mitochondrial defects. Thus, even subtle metabolic alterations might have a substantial impact on cognitive functions. Over the last decade, several experimental evidence supported the hypothesis that a suboptimal mitochondrial function, which could be of genetic origin or acquired following adverse life events, is a key vulnerability factor for stress-related psychopathologies. Chronic psychological stress is a major promoter of anxiety as well as of oxidative damage, as shown in several studies. Recent evidence from mouse models harbouring mutations in mitochondrial genes demonstrated the role of mitochondria in modulating the response to acute psychological stress. However, it has yet to be determined whether mitochondrial dysfunctions are the cause or the consequence of anxiety. In this review, we discuss how adverse psychosocial environments can impact mitochondrial bioenergetics at the molecular level and we gather evidence from several studies linking energy metabolism and stress resilience/vulnerability. Moreover, we review recent findings supporting that metabolic dysfunction can underlie deficits in complex social behaviours. As will be discussed, aberrations in mitochondrial functionality have been found in the nucleus accumbens of highly anxious mice and mediate low social competitiveness. In addition, alterations in sociability can be reversed by enhancing mitochondrial functions. Recent evidence also demonstrated that a specific mutation in mitochondrial DNA, previously linked to autism spectrum disorder, produces autistic endophenotypes in mice by altering respiration chain and reactive oxygen species (ROS) production. Finally, we discuss a "Negative Enrichment" model that can explain some of the psychopathological conditions relevant to humans. Evidence of a direct causal correlation of valence of environmental stimulation and psychopathological traits will be presented, and possible molecular mechanisms that focus on oxidative stress. Collectively, the findings described here have been achieved with a wide set of behavioural and cognitive tasks with translational validity. Thus, they will be useful for future work aimed to elucidate the fine metabolic alterations in psychopathologies and devise novel approaches targeting mitochondria to alleviate these conditions.

Not All Mice Are Created Equal: Interval Timing Accuracy and Scalar Timing in 129, Swiss-Webster, and C57BL/6 Mice

Many species, including humans, show both accurate timing − appropriate time estimation in the seconds to minutes range − and scalar timing − time estimation error varies linearly with estimated duration. Behavioral paradigms aimed at investigating interval timing are expected to evaluate these dissociable characteristics of timing. However, when evaluating interval timing in models of neuropsychiatric disease, researchers are confronted with a lack of adequate studies about the parent (background) strains, since accuracy and scalar timing have only been demonstrated for the C57BL/6 strain of mice (Buhusi, Aziz, Winslow, Carter, Swearingen, & Buhusi (2009) Behav. Neurosci., 123, 1102–1113). We used a peak-interval (PI) procedure with three intervals − a protocol in which other species, including humans, demonstrate accurate, scalar timing − to evaluate timing accuracy and scalar timing in three strains of mice frequently used in genetic and behavioral studies: 129, Swiss-Webster (SW), and C57BL/6. C57BL/6 mice showed accurate, scalar timing, while 129 and SW mice showed departures from accuracy and/or scalar timing. Results suggest that the genetic background/strain of the mouse is a critical variable for studies investigating interval timing in genetically engineered mice. Our study validates the PI procedure with multiple intervals as a proper technique, and the C57BL/6 strain as the most suitable genetic background to date for behavioral investigations of interval timing in genetically engineered mice modeling human disorders. In contrast, studies using mice in 129, SW, or mixed-background strains should be interpreted with caution, and thorough investigations of accuracy and scalar timing should be conducted before a less studied strain of mouse is considered for use in timing studies.

GDI2 is a novel diagnostic and prognostic biomarker in hepatocellular carcinoma

Background: GDP Dissociation inhibitor 2 (GDI2) gene has been correlated with some important biological processes in a variety of cancers, whereas the role of GDI2 in hepatocellular carcinoma (HCC) is ill-defined. We aimed to demonstrate the relationship between GDI2 and HCC based on The Cancer Genome Atlas (TCGA) data mining.

Methods: The expression of GDI2 was compared between cancer and normal tissues of 371 HCC patients collected from TCGA-LIHC, and verified in HCC cell lines. Gene set enrichment analysis (GSEA) was applied to annotate biological function of GDI2. Furthermore, Wilcoxon rank sum test, Logistics regression, as well as Cox regression and Kaplan-Meier survival analysis, were employed to evaluate the association of GDI2 expression with clinicopathological characteristics, and survival status of HCC patients, respectively.

Results: It showed that the expression of GDI2 was much higher in tumor tissues than in normal tissues (P < 0.001) of HCC patients. And the elevated expression of GDI2 was correlated with more aggressive HCC tumor status, including severe primary tumor extent, advanced pathological stage, serious histologic grade, and mutated TP53 status (P < 0.05). Moreover, high GDI2 expression was strongly associated with a poor survival rate (P < 0.001). Both enrichment and immune infiltration analyses implied that GDI2-associated signaling mainly involve lipid metabolism and extracellular matrix (ECM) constructing pathways related to tumor microenvironment (TME) (P < 0.05).

Conclusions: The elevated expression of GDI2 predicts poor prognosis in HCC patients, indicating that GDI2 could be applied as a predictive biomarker for diagnosis and prognosis of HCC.

Timing behavior in genetic murine models of neurological and psychiatric diseases

How timing behavior is altered in different neurodevelopmental and neurodegenerative disorders is a contemporary research question. Genetic murine models (GMM) that offer high construct validity also serve as useful tools to investigate this question. But the literature on timing behavior of different GMMs largely remains to be consolidated. The current paper addresses this gap by reviewing studies that have been conducted with GMMs of neurodevelopmental (e.g. ADHD, schizophrenia, autism spectrum disorder), neurodegenerative disorders (e.g., Alzheimer's disease, Huntington's disease) as well as circadian and other mutant lines. The review focuses on those studies that specifically utilized the peak interval procedure to improve the comparability of findings both within and between different disease models. The reviewed studies revealed timing deficits that are characteristic of different disorders. Specifically, Huntington's disease models had weaker temporal control over the termination of their anticipatory responses, Alzheimer's disease models had earlier timed responses, schizophrenia models had weaker temporal control, circadian mutants had shifted timed responses consistent with shifts in the circadian periods. The differences in timing behavior were less consistent for other conditions such as attention deficit and hyperactivity disorder and mutations related to intellectual disability. We discuss the implications of these findings for the neural basis of an internal stopwatch. Finally, we make methodological recommendations for future research for improving the comparability of the timing behavior across different murine models.

A proteomic signature for CNS adaptations to the valence of environmental stimulation

Environmental Enrichment leads to a significant improvement in long-term performance across a range of cognitive functions in mammals and it has been shown to produce an increased synaptic density and neurogenesis. Nevertheless it is still an open question as to whether some key aspects of spatial learning & memory and procedural learning might be embodied by different molecular pathways to those of social cognition. Associated with synaptic changes and potentially underlying conditions, the Ras-ERK pathway has been proposed to be the primary mediator of in vivo adaptations to environmental enrichment, acting via the downstream Ras-ERK signalling kinase MSK1 and the transcription factor CREB. Herein, we show that valence of environmental stimulation increased social competition and that this is associated with a specific proteomic signature in the frontal lobe but notably not in the hippocampus. Specifically, we show that altering the valence of environmental stimuli affected the level of social competition, with mice from negatively enriched environments winning significantly more encounters-even though mice from positive were bigger and should display dominance. This behavioural phenotype was accompanied by changes in the proteome of the fronto-ventral pole of the brain, with a differential increase in the relative abundance of proteins involved in the mitochondrial metabolic processes of the TCA cycle and respiratory processes. Investigation of this proteomic signature may pave the way for the elucidation of novel pathways underpinning the behavioural changes caused by negative enrichment and further out understanding of conditions whose core feature is increased social competition.

Enhancing cognition through pharmacological and environmental interventions: Examples from preclinical models of neurodevelopmental disorders

In this review we discuss the role of environmental and pharmacological treatments to enhance cognition with special regards to neurodevelopmental related disorders and aging. How the environment influences brain structure and function, and the interactions between rearing conditions and gene expression, are fundamental questions that are still poorly understood. We propose a model that can explain some of the discrepancies in findings for effects of environmental enrichment on outcome measures. Evidence of a direct causal correlation of nootropics and treatments that enhanced cognition also will be presented, and possible molecular mechanisms that include neurotrophin signaling and downstream pathways underlying these processes are discussed. Finally we review recent findings achieved with a wide set of behavioral and cognitive tasks that have translational validity to humans, and should be useful for future work on devising appropriate therapies. As will be discussed, the collective findings suggest that a combinational therapeutic approach of environmental enrichment and nootropics could be particularly successful for improving learning and memory in both developmental disorders and normal aging.

Golgipathies in Neurodevelopment: A New View of Old Defects

The Golgi apparatus (GA) is involved in a whole spectrum of activities, from lipid biosynthesis and membrane secretion to the posttranslational processing and trafficking of most proteins, the control of mitosis, cell polarity, migration and morphogenesis, and diverse processes such as apoptosis, autophagy, and the stress response. In keeping with its versatility, mutations in GA proteins lead to a number of different disorders, including syndromes with multisystem involvement. Intriguingly, however, > 40% of the GA-related genes known to be associated with disease affect the central or peripheral nervous system, highlighting the critical importance of the GA for neural function. We have previously proposed the term "Golgipathies" in relation to a group of disorders in which mutations in GA proteins or their molecular partners lead to consequences for brain development, in particular postnatal-onset microcephaly (POM), white-matter defects, and intellectual disability (ID). Here, taking into account the broader role of the GA in the nervous system, we refine and enlarge this emerging concept to include other disorders whose symptoms may be indicative of altered neurodevelopmental processes, from neurogenesis to neuronal migration and the secretory function critical for the maturation of postmitotic neurons and myelination.