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1.  Slc25a12 disruption alters myelination and neurofilaments: A model for a hypomyelination syndrome and childhood neurodevelopmental disorders 
Biological psychiatry  2009;67(9):887-894.
Background
SLC25A12, a susceptibility gene for autism spectrum disorders (ASDs) that is mutated in a neurodevelopmental syndrome, encodes a mitochondrial aspartate/glutamate carrier (AGC1). AGC1 is an important component of the malate/aspartate shuttle, a crucial system supporting oxidative phosphorylation and ATP production.
Methods
We characterized mice with a disruption of the Slc25a12 gene, followed by confirmatory in vitro studies.
Results
Slc25a12-knockout mice, which showed no AGC1 by immunoblotting, were born normally but displayed delayed development and died around 3 weeks after birth. In P13-14 knockout brains, the brains were smaller with no obvious alteration in gross structure. However, we found a reduction in myelin basic protein (MBP)-positive fibers, consistent with a previous report. Furthermore, the neocortex of knockout mice contained abnormal neurofilamentous accumulations in neurons, suggesting defective axonal transport and/or neurodegeneration. Slice cultures prepared from knockout mice also showed a myelination defect, and reduction of Slc25a12 in rat primary oligodendrocytes led to a cellautonomous reduction in MBP expression. Myelin deficits in slice cultures from knockout mice could be reversed by administration of pyruvate, indicating that reduction in AGC1 activity leads to reduced production of aspartate/N-acetyl aspartate (NAA) and/or alterations in the NADH/NAD+ ratio, resulting in myelin defects.
Conclusions
Our data implicate AGC1 activity in myelination and in neuronal structure, and indicate that while loss of AGC1 leads to hypomyelination and neuronal changes, subtle alterations in AGC1 expression could affect brain development contributing to increased autism susceptibility.
doi:10.1016/j.biopsych.2009.08.042
PMCID: PMC4067545  PMID: 20015484
Malate/aspartate shuttle; mitochondria; N-acetyl aspartate (NAA); neuron-oligodendrocyte interactions; pyruvate
2.  The IRG Mouse: A Two-Color Fluorescent Reporter for Assessing Cre-Mediated Recombination and Imaging Complex Cellular Relationships In Situ 
Genesis (New York, N.y. : 2000)  2008;46(6):308-317.
Summary
The Cre-loxP system is widely used for making conditional alterations to the mouse genome. Cre-mediated recombination is frequently monitored using reporter lines in which Cre expression activates a reporter gene driven by a ubiquitous promoter. Given the distinct advantages of fluorescent reporters, we developed a transgenic reporter line, termed IRG, in which DsRed-Express, a red fluorescent protein (RFP) is expressed ubiquitously prior to Cre-mediated recombination and an enhanced green fluorescent protein (EGFP) following recombination. Besides their utility for monitoring Cre-mediated recombination, we show that in IRG mice red and green native fluorescence can be imaged simultaneously in thick tissue sections by confocal microscopy allowing for complex reconstructions to be created that are suitable for analysis of neuronal morphologies as well as neurovascular interactions in brain. IRG mice should provide a versatile tool for analyzing complex cellular relationships in both neural and nonneural tissues.†
doi:10.1002/dvg.20400
PMCID: PMC2928670  PMID: 18543298
Cre recombinase; loxP; conditional gene activation; DsRed-express; red fluorescent protein; enhanced green fluorescent protein; transgenic mice
3.  PERIPHERAL MYELIN PROTEIN-22 IS EXPRESSED IN CNS MYELIN 
Translational neuroscience  2010;1(4):282-285.
Myelin abnormalities exist in schizophrenia leading to the hypothesis that oligodendrocyte dysfunction plays a role in the pathophysiology of the disease. The expression of the mRNA for the peripheral myelin protein-22 (PMP-22) is decreased in schizophrenia and recent genetic evidence suggests a link between PMP-22 and schizophrenia. While PMP-22 mRNA is found in both rodent and human brain it has been generally thought that no protein expression occurs. Here we show that PMP-22 protein is present in myelin isolated from adult mouse and human brain. These results suggest that PMP-22 protein likely plays a role in the maintenance and function of central nervous system (CNS) myelin and provide an explanation for why altered PMP-22 expression may be pathophysiologically relevant in a CNS disorder such as schizophrenia.
doi:10.2478/v10134-010-0038-3
PMCID: PMC3093192  PMID: 21572910
Myelin; Peripheral myelin protein-22; Schizophrenia
4.  Pepsin Pretreatment Allows Collagen IV Immunostaining of Blood Vessels in Adult Mouse Brain 
Journal of neuroscience methods  2007;163(1):76-82.
While the brain vasculature can be imaged with many methods, immunohistochemistry has distinct advantages due to its simplicity and applicability to archival tissue. However, immunohistochemical staining of the murine brain vasculature in aldehyde fixed tissue has proven elusive and inconsistent using current protocols. Here we investigated whether antigen retrieval methods could improve vascular staining in the adult mouse brain. We found that pepsin digestion prior to immunostaining unmasked widespread collagen IV staining of the cerebrovasculature in the adult mouse brain. Pepsin treatment also unmasked widespread vascular staining with laminin, but only marginally improved isolectin B4 staining and did not enhance vascular staining with fibronectin, perlecan or CD146. Collagen IV immunoperoxidase staining was easily combined with cresyl violet counterstaining making it suitable for stereological analyses of both vascular and neuronal parameters in the same tissue section. This method should be widely applicable for labeling the brain vasculature of the mouse in aldehyde fixed tissue from both normal and pathological states.
doi:10.1016/j.jneumeth.2007.02.020
PMCID: PMC1931483  PMID: 17403541
adult; antigen retrieval; blood vessels; brain; collagen IV; immunohistochemistry; mouse; pepsin
5.  Selective Expression of Presenilin 1 in Neural Progenitor Cells Rescues the Cerebral Hemorrhages and Cortical Lamination Defects in Presenilin 1-Null Mutant Mice 
Development (Cambridge, England)  2005;132(17):3873-3883.
Summary
Mice with a null mutation of the presenilin 1 gene (Psen1-/-)die during late intrauterine life or shortly after birth and exhibit multiple CNS and non-CNS abnormalities, including cerebral hemorrhages and altered cortical development. The cellular and molecular basis for the developmental effects of Psen1 remain incompletely understood. Psen1 is expressed in neural progenitors in developing brain, as well as in postmitotic neurons. We crossed transgenic mice with either neuron-specific or neural progenitor-specific expression of Psen1 onto the Psen1-/- background. We show that neither neuron-specific nor neural progenitor-specific expression of Psen1 can rescue the embryonic lethality of the Psen1-/- embryo. Indeed neuron-specific expression rescued none of the abnormalities in Psen1-/- mice. However, Psen1 expression in neural progenitors rescued the cortical lamination defects, as well as the cerebral hemorrhages, and restored a normal vascular pattern in Psen1-/- embryos. Collectively, these studies demonstrate that Psen1 expression in neural progenitor cells is crucial for cortical development and reveal a novel role for neuroectodermal expression of Psen1 in development of the brain vasculature.
doi:10.1242/dev.01946
PMCID: PMC1698506  PMID: 16079160
Cortical development; CNS hemorrhages; Familial Alzheimer’s disease; Neural progenitor cells; Presenilin 1 (PS1, Psen1); Transgenic mice; Vascular development
6.  Presenilin transgenic mice as models of Alzheimer’s disease 
Brain structure & function  2009;214(0):127-143.
Mutations in presenilin-1 (PS1) and presenilin-2 (PS2) cause familial Alzheimer’s disease (FAD). Presenilins influence multiple molecular pathways and are best known for their role in the γ-secretase cleavage of type I transmembrane proteins including the amyloid precursor protein (APP). PS1 and PS2 FAD mutant transgenic mice have been generated using a variety of promoters. PS1-associated FAD mutations have also been knocked into the endogenous mouse gene. PS FAD mutant mice consistently show elevations of Aβ42 with little if any effect on Aβ40. When crossed with plaque forming APP FAD mutant lines, the PS1 FAD mutants cause earlier and more extensive plaque deposition. Although single transgenic PS1 or PS2 mice do not form plaques, they exhibit a number of pathological features including age-related neuronal and synaptic loss as well as vascular pathology. They also exhibit increased susceptibility to excitotoxic injury most likely on the basis of exaggerated calcium release from the endoplasmic reticulum. Electrophysiologically long-term potentiation in the hippocampus is increased in young PS1 FAD mutant mice but this effect appears to be lost with aging. In most studies neurogenesis in the adult hippocampus is also impaired by PS1 FAD mutants. Mice in which PS1 has been conditionally knocked out in adult forebrain on a PS2 null background (PS1/2 cDKO) develop a striking neurodegeneration that mimics AD neuropathology in being associated with neuronal and synaptic loss, astrogliosis and hyperphosphorylation of tau, although it is not accompanied by plaque deposits. The relevance of PS transgenic mice as models of AD is discussed.
doi:10.1007/s00429-009-0227-3
PMCID: PMC3527905  PMID: 19921519
Alzheimer’s disease; Familial Alzheimer’s disease; Hippocampal neurogenesis; Presenilin-1; Presenilin-2; Transgenic mice

Results 1-6 (6)