Impact of prenatal environmental stress on cortical development

Prenatal exposure of the developing brain to various types of environmental stress increases susceptibility to neuropsychiatric disorders such as autism, attention deficit hyperactivity disorder and schizophrenia. Given that even subtle perturbations by prenatal environmental stress in the cerebral cortex impair the cognitive and memory functions, this review focuses on underlying molecular mechanisms of pathological cortical development. We especially highlight recent works that utilized animal exposure models, human specimens or/and induced Pluripotent Stem (iPS) cells to demonstrate: 1. molecular mechanisms shared by various types of environmental stressors, 2. the mechanisms by which the affected extracortical tissues indirectly impact the cortical development and function, and 3. interaction between prenatal environmental stress and the genetic predisposition of neuropsychiatric disorders. Finally, we discuss current challenges for achieving a comprehensive understanding of the role of environmentally disturbed molecular expressions in cortical maldevelopment, knowledge of which may eventually facilitate discovery of interventions for prenatal environment-linked neuropsychiatric disorders

Proteome dynamics during postnatal mouse corpus callosum development.

Formation of cortical connections requires the precise coordination of numerous discrete phases. This is particularly significant with regard to the corpus callosum, whose development undergoes several dynamic stages including the crossing of axon projections, elimination of exuberant projections, and myelination of established tracts. To comprehensively characterize the molecular events in this dynamic process, we set to determine the distinct temporal expression of proteins regulating the formation of the corpus callosum and their respective developmental functions. Mass spectrometry-based proteomic profiling was performed on early postnatal mouse corpus callosi, for which limited evidence has been obtained previously, using stable isotope of labeled amino acids in mammals (SILAM). The analyzed corpus callosi had distinct proteomic profiles depending on age, indicating rapid progression of specific molecular events during this period. The proteomic profiles were then segregated into five separate clusters, each with distinct trajectories relevant to their intended developmental functions. Our analysis both confirms many previously-identified proteins in aspects of corpus callosum development, and identifies new candidates in understudied areas of development including callosal axon refinement. We present a valuable resource for identifying new proteins integral to corpus callosum development that will provide new insights into the development and diseases afflicting this structure

Heat shock factor 2 is a stress‐responsive mediator of neuronal migration defects in models of fetal alcohol syndrome

Fetal alcohol spectrum disorder (FASD) is a frequent cause of mental retardation. However, the molecular mechanisms underlying brain development defects induced by maternal alcohol consumption during pregnancy are unclear. We used normal andHsf2‐deficient mice and cell systems to uncover a pivotal role for heat shock factor 2 (HSF2) in radial neuronal migration defects in the cortex, a hallmark of fetal alcohol exposure. Upon fetal alcohol exposure, HSF2 is essential for the triggering of HSF1 activation, which is accompanied by distinctive post‐translational modifications, and HSF2 steers the formation of atypical alcohol‐specific HSF1–HSF2 heterocomplexes. This perturbs the in vivo binding of HSF2 to heat shock elements (HSEs) in genes that control neuronal migration in normal conditions, such as p35 or the MAPs(microtubule‐associated proteins, such as Dclk1 and Dcx), and alters their expression. In the absence of HSF2, migration defects as well as alterations in gene expression are reduced. Thus, HSF2, as a sensor for alcohol stress in the fetal brain, acts as a mediator of the neuronal migration defects associated with FASD

Anti-Tumor Effect against Human Cancer Xenografts by a Fully Human Monoclonal Antibody to a Variant 8-Epitope of CD44R1 Expressed on Cancer Stem Cells

BACKGROUND: CD44 is a major cellular receptor for hyaluronic acids. The stem structure of CD44 encoded by ten normal exons can be enlarged by ten variant exons (v1-v10) by alternative splicing. We have succeeded in preparing MV5 fully human IgM and its class-switched GV5 IgG monoclonal antibody (mAb) recognizing the extracellular domain of a CD44R1 isoform that contains the inserted region coded by variant (v8, v9 and v10) exons and is expressed on the surface of various human epithelial cancer cells. METHODS AND PRINCIPAL FINDINGS: We demonstrated the growth inhibition of human cancer xenografts by a GV5 IgG mAb reshaped from an MV5 IgM. The epitope recognized by MV5 and GV5 was identified to a v8-coding region by the analysis of mAb binding to various recombinant CD44 proteins by enzyme-linked immunosorbent assay. GV5 showed preferential reactivity against various malignant human cells versus normal human cells assessed by flow cytometry and immunohistological analysis. When ME180 human uterine cervix carcinoma cells were subcutaneously inoculated to athymic mice with GV5, significant inhibition of tumor formation was observed. Furthermore, intraperitoneal injections of GV5markedly inhibited the growth of visible established tumors from HSC-3 human larynx carcinoma cells that had been subcutaneously transplanted one week before the first treatment with GV5. From in vitro experiments, antibody-dependent cellular cytotoxicity and internalization of CD44R1 seemed to be possible mechanisms for in vivo anti-tumor activity by GV5. CONCLUSIONS: CD44R1 is an excellent molecular target for mAb therapy of cancer, possibly superior to molecules targeted by existing therapeutic mAb, such as Trastuzumab and Cetuximab recognizing human epidermal growth factor receptor family

Identifying cellular level epigenetic markers for the prediction of cognitive and learning deficits in a fetal alcohol spectrum disorders model

Background/Rationale: Although the physical manifestations of prenatal exposure to alcohol are often easy to identify, the more devastating effects on cognitive function and intellectual ability, however, are highly varied and thus difficult to predict. In order to aid physicians in early identification of potential deficits and the implementation of the appropriate therapies, we aim to identify biomarkers that are associated with infants who have an increased risk of Fetal Alcohol Spectrum Disorders (FASD), and of developing cognitive and learning disabilities later on in life. Methods: For FASD model, pregnant female mice received 4.0g/kg intraperitoneal EtOH or PBS injections at embryonic day (E) 12-14 with expected pup delivery at E18-20. Postnatal day 30 pups (n=10) subsequently underwent rotarod behavior tests over 2 days in order to quantify learning capabilities as measured by latency to fall over a period of 6 trials. One day following the completion of the rotarod test, cardiac puncture was performed for whole blood collection and buffy coat, containing peripheral mononuclear cells, was isolated using Ficoll-density gradient medium. T lymphocytes, B lymphocytes and monocyte populations were collected via fluorescence-activated cell sorting (FACS) and underwent RNA sequencing to identify variations in gene expression between the EtOH exposed and PBS groups. Results: Findings to date indicate that prenatal exposure to alcohol negatively impacts learning abilities where 44% of the EtOH-exposed group are classified as poor learners (learning index \u3c10) compared to 28% in the PBS-control group. RNA sequencing analysis of collected cellular populations is currently underway with the goal of identifying specific biomarkers that may be correlated to results encountered in our behavioral model. Conclusion: - The identification of potential biomarkers associated with cognitive and learning disabilities in our FASD mouse model may be useful in the development of future investigations that target markers specific to human patients with FASD

Roles of very long chain fatty acids in pathophysiology of FASD

Fetal alcohol spectrum disorders (FASD) are caused by prenatal alcohol exposure (PAE). These children suffer from life-long learning and intellectual disabilities, and other behavioral deficits. Our single cell RNA sequencing of cortical neurons from PAE mouse cortex showed the single cell variability in gene expressions. Among the differentially expressed genes, we found enhanced gene expressions in fatty acid synthesis and modification in a specific neuronal population. Among those genes, Elovl4 is known to be associated with intellectual disabilities. In the endoplasmic reticulum (ER), Elovl4 elongates fatty acids. Under normal conditions, elongated very long chain fatty acids (VLCFAs) in the ER are shuttled to the plasma membranes; however, the fate and function of VLCFAs synthesized by Elovl4 remain elusive. Fatty acids crucially regulate neuronal function and structure, and the disturbed fatty acid synthesis is linked to neurodevelopmental disorders such as autism and ADHD. Therefore, we hypothesized that the increase of Elovl4 in the cerebral cortex is involved in the pathophysiology of the FASD. To examine this hypothesis, we first measured the content of fatty acids in the cerebral cortex after ectopically express Elovl4. Compared to the control brain, Elovl4 overexpression shows the fatty acid profile similar to that of PAE. Second, to define the changes in neuronal membrane dynamics due to Elovl4 overexpression, the fluorescence recovery after photobleaching (FRAP) was performed in the somal and dendritic domains of transfected neurons. Notably, the Elovl4 alters the membrane dynamics only in dendritic domains. Lastly, the single pellet reaching task was assessed in the animals overexpressing Elovl4 in the cortex. Unexpectedly, Elovl4 overexpression causes excessive self-grooming behavior, indicating indirect effects of Elovl4 OE on anxiety or/and repetitive behavior due to the changes in other than cortical region. Altogether, these results suggest a potential contribution of Elovl4 overexpression in FASD-relevant neurobehavior problems, and thus the nutritional or pharmacological intervention focusing on fatty acids may be effective

Activation of the anterior cingulate cortex ameliorates anxiety in a preclinical model of fetal alcohol spectrum disorders

People with fetal alcohol spectrum disorders (FASD) are suffered from a wide range of interlinked cognitive and psychological problems. However, few therapeutic options are available for those patients due to limited dissection of its underlying etiology. Here we found that prenatal alcohol exposure (PAE) increases anxiety in mice due to a dysregulated functional connectivity between the anterior cingulate cortex (ACC) and basolateral amygdala (BLA). We also show that chemogenetic activation of excitatory neurons in the ACC reduced this anxiety behavior in the PAE mice. Interestingly, although the level of plasma corticosterone correlated with the increase in anxiety in the PAE, this level was not altered by chemogenetic activation of the ACC, suggesting that the functional connectivity between the ACC and the BLA does not alter the activity of the hypothalamic–pituitary–adrenal axis. Altogether, this study demonstrated that reduced excitation in the ACC is a cause of anxiety in the PAE mice, providing critical insights into the ACC–BLA neural circuit as a potential target for treating anxiety in FASD patients

Nonapoptotic caspases in neural development and in anesthesia-induced neurotoxicity

Apoptosis, classically initiated by caspase pathway activation, plays a prominent role during normal brain development as well as in neurodegeneration. The noncanonical, nonlethal arm of the caspase pathway is evolutionarily conserved and has also been implicated in both processes, yet is relatively understudied. Dysregulated pathway activation during critical periods of neurodevelopment due to environmental neurotoxins or exposure to compounds such as anesthetics can have detrimental consequences for brain maturation and long-term effects on behavior. In this review, we discuss key molecular characteristics and roles of the noncanonical caspase pathway and how its dysregulation may adversely affect brain development. We highlight both genetic and environmental factors that regulate apoptotic and sublethal caspase responses and discuss potential interventions that target the noncanonical caspase pathway for developmental brain injuries