Faculty Bibliography
Searched for:
person:nixonr01 or ginsbs01 or levye01 or mathep01 or ohnom01 or raom01 or scharh01 or yangd02 or yuana01
Total Results:
1130
Elevation of GM2 ganglioside during ethanol-induced apoptotic neurodegeneration in the developing mouse brain
J. Neurochem. (2012) 121, 649-661. ABSTRACT: GM2 ganglioside in the brain increased during ethanol-induced acute apoptotic neurodegeneration in 7-day-old mice. A small but a significant increase observed 2 h after ethanol exposure was followed by a marked increase around 24 h. Subcellular fractionation of the brain 24 h after ethanol treatment indicated that GM2 increased in synaptic and non-synaptic mitochondrial fractions as well as in a lysosome-enriched fraction characteristic to the ethanol-exposed brain. Immunohistochemical staining of GM2 in the ethanol-treated brain showed strong punctate staining mainly in activated microglia, in which it partially overlapped with staining for LAMP1, a late endosomal/lysosomal marker. Also, there was weaker neuronal staining, which partially co-localized with complex IV, a mitochondrial marker, and was augmented in cleaved caspase 3-positive neurons. In contrast, the control brain showed only faint and diffuse GM2 staining in neurons. Incubation of isolated brain mitochondria with GM2 in vitro induced cytochrome c release in a manner similar to that of GD3 ganglioside. Because ethanol is known to trigger mitochondria-mediated apoptosis with cytochrome c release and caspase 3 activation in the 7-day-old mouse brain, the GM2 elevation in mitochondria may be relevant to neuroapoptosis. Subsequently, activated microglia accumulated GM2, indicating a close relationship between GM2 and ethanol-induced neurodegeneration.
PMCID:3325370
PMID: 22372857
ISSN: 0022-3042
CID: 166032
Identification of CSPalpha Clients Reveals a Role in Dynamin 1 Regulation
Cysteine string protein alpha (CSPalpha), a presynaptic cochaperone for Hsc70, is required for synapse maintenance. Deletion of CSPalpha leads to neuronal dysfunction, synapse loss, and neurodegeneration. We utilized unbiased, systematic proteomics to identify putative CSPalpha protein clients. We found 22 such proteins whose levels are selectively decreased in CSPalpha knockout synapses. Of these putative CSPalpha protein clients, two directly bind to the CSPalpha chaperone complex and are bona fide clients. They are the t-SNARE SNAP-25 and the GTPase dynamin 1, which are necessary for synaptic vesicle fusion and fission, respectively. Using hippocampal cultures, we show that CSPalpha regulates the stability of client proteins and synaptic vesicle number. Our analysis of CSPalpha-dynamin 1 interactions reveals unexpectedly that CSPalpha regulates the polymerization of dynamin 1. CSPalpha, therefore, participates in synaptic vesicle endocytosis and may facilitate exo- and endocytic coupling. These findings advance the understanding of how synapses are functionally and structurally maintained.
PMCID:3328141
PMID: 22500636
ISSN: 0896-6273
CID: 166686
Guidelines for the use and interpretation of assays for monitoring autophagy [Guideline]
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
PMCID:3404883
PMID: 22966490
ISSN: 1554-8627
CID: 181862
Role of vaccine-induced V2 antibodies in protection from HIV infection of recipients in the RV144 clinical vaccine trial [Meeting Abstract]
Objective: Determine the role of V2 antibodies (Abs) in protecting vaccinees from HIV infection after immunization with ALVAC/HIV and clade E and B recombinant gp120 (RV144 vaccine regimen). ELISA reactivity to a V1V2-gp70 fusion protein and a cyclic V2 peptide was assessed using coded plasma specimens from RV144 participants. Results showed that Ab responses were divided into tertiles (low, medium and high). Vaccinees with a high level of Abs to V1V2-gp70 had a lower rate of HIV infection than did those with a low level of Abs. Multivariate logistic regression analysis showed an estimated 71% reduction in the infecton rate for vaccinees with high vs. vaccinees with low Ab responses to V1V2-gp70 (p=0.02). Similarly, compared to the entire placebo group that was HIV- at 26 weeks, the estimated Vaccine Efficacy (VE) was 3% (p=0.91) for subjects with a low V1V2 Ab response, while the estimated VE was 58% (p=0.02) for vaccinees with high V1V2 Abs. The Abs measured by this assay appear to be specific for V2 because no V1 Abs were detected, and epitope mapping data suggest that the epitope recognized by vaccinees' Abs target the midloop region of V2. There was no statistically significant correlation between infection rate and Abs reactive with a cyclic V2 peptide containing the entire V2 loop of the clade E A244 strain. In the primary case control analysis the Ab response to V1V2-gp70 was statistically significantly inversely correlated with infection. While secondary analyses suggest that other immunologic responses (including Abs to other epitopes and cellular responses) may also play a role in protection, the data most strongly support the hypothesis that V2 Abs are important for protection
EMBASE:71184757
ISSN: 1525-4135
CID: 602642
Caloric restriction up-regulates hippocampal CA1 neuroprotective gene expression and reduces amyloid burden in an alzheimer's disease mouse model [Meeting Abstract]
OBJECTIVES/SPECIFIC AIMS: Th ere is no successful treatment or preventative measure for Alzheimer's disease (AD), a disorder characterized by altered amyloidbeta precursor (APP) processing, amyloid-beta (Abeta) aggregation, cell-type specific vulnerability, and cognitive deficits. Caloric restriction (CR) is a noninvasive dietary intervention that may prevent AD pathology. Previous studies have documented CRinduced AD pathology prevention through regional, low-resolution analysis. Th e effects of CR in selectively vulnerable hippocampal CA1 pyramidal neurons have not been demonstrated. METHODS/STUDY POPULATION: Th rough laser capture microdissection (LCM) and microarray analysis, we will investigate gene expression profiles of CA1 neurons isolated during pathology onset and later progression (5 and 15 mos.) from Tg2576 AD mice and nontransgenic littermates maintained on a 30% CR regimen versus ad libitum (AL) feeding. Abeta burden and APP metabolism are assessed as indicators of pathology and for correlation with high-throughput gene expression changes. RESULTS/ANTICIPATED RESULTS: We have identified CR-induced decreases in transcripts implicated in autophagy, synaptic transmission, transcription, and metabolism, as well as CR-specific increases in several kinase and phosphatase transcripts and qualitative reduction in Abeta peptides in CR-Tg2576 mice. We expect further characterization to support the hypothesis that CR induces increased neuronal efficiency, up-regulation of neuroprotective pathways, and decreased Abeta deposition in aged AL-Tg2576 mice. DISCUSSION/SIGNIFICANCE OF IMPACT: Alterations identified by these experiments may serve as targets in the development of therapeutic interventions. Additionally, this work may serve as the basis for further studies of CR-based dietary regimens as an AD pathology prevention option
EMBASE:70804110
ISSN: 1752-8054
CID: 463352
Alzheimer's disease and epilepsy: insight from animal models
Alzheimer's disease (AD) and epilepsy are separated in the medical community, but seizures occur in some patients with AD, and AD is a risk factor for epilepsy. Furthermore, memory impairment is common in patients with epilepsy. The relationship between AD and epilepsy remains an important question because ideas for therapeutic approaches could be shared between AD and epilepsy research laboratories if AD and epilepsy were related. Here we focus on one of the many types of epilepsy, temporal lobe epilepsy (TLE), because patients with TLE often exhibit memory impairment, depression and other comorbidities that occur in AD. Moreover, the seizures that occur in patients with AD may be nonconvulsive, which occur in patients with TLE. Here we first compare neuropathology in TLE and AD with an emphasis on the hippocampus, which is central to both AD and TLE research. Then we compare animal models of AD pathology with animal models of TLE. Although many aspects of the comparisons are still controversial, there is one conclusion that we suggest is clear: some animal models of TLE could be used to help address questions in AD research, and some animal models of AD pathology are bona fide animal models of epilepsy.
PMCID:3378058
PMID: 22723738
ISSN: 1479-6708
CID: 1875012
Reduced Hippocampal Brain-Derived Neurotrophic Factor (BDNF) in Neonatal Rats after Prenatal Exposure to Propylthiouracil (PTU)
Thyroid hormone is critical for central nervous system development. Fetal hypothyroidism leads to reduced cognitive performance in offspring as well as other effects on neural development in both humans and experimental animals. The nature of these impairments suggests that thyroid hormone may exert its effects via dysregulation of the neurotrophin brain-derived neurotrophic factor (BDNF), which is critical to normal development of the central nervous system and has been implicated in neurodevelopmental disorders. The only evidence of BDNF dysregulation in early development, however, comes from experimental models in which severe prenatal hypothyroidism occurred. By contrast, milder prenatal hypothyroidism has been shown to alter BDNF levels and BDNF-dependent functions only much later in life. We hypothesized that mild experimental prenatal hypothyroidism might lead to dysregulation of BDNF in the early postnatal period. BDNF levels were measured by ELISA at 3 or 7 d after birth in different regions of the brains of rats exposed to propylthiouracil (PTU) in the drinking water. The dose of PTU that was used induced mild maternal thyroid hormone insufficiency. Pups, but not the parents, exhibited alterations in tissue BDNF levels. Hippocampal BDNF levels were reduced at both d 3 and 7, but no significant reductions were observed in either the cerebellum or brain stem. Unexpectedly, more males than females were born to PTU-treated dams, suggesting an effect of PTU on sex determination. These results support the hypothesis that reduced hippocampal BDNF levels during early development may contribute to the adverse neurodevelopmental effects of mild thyroid hormone insufficiency during pregnancy.
PMCID:3384077
PMID: 22253429
ISSN: 0013-7227
CID: 160240
Rac1b increases with progressive tau pathology within cholinergic nucleus basalis neurons in Alzheimer's disease
Cholinergic basal forebrain (CBF) nucleus basalis (NB) neurons display neurofibrillary tangles (NFTs) during Alzheimer's disease (AD) progression, yet the mechanisms underlying this selective vulnerability are currently unclear. Rac1, a member of the Rho family of GTPases, may interact with the proapoptotic pan-neurotrophin receptor p75(NTR) to induce neuronal cytoskeletal abnormalities in AD NB neurons. Herein, we examined the expression of Rac1b, a constitutively active splice variant of Rac1, in NB cholinergic neurons during AD progression. CBF tissues harvested from people who died with a clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment, or AD were immunolabeled for both p75(NTR) and Rac1b. Rac1b appeared as cytoplasmic diffuse granules, loosely aggregated filaments, or compact spheres in p75(NTR)-positive NB neurons. Although Rac1b colocalized with tau cytoskeletal markers, the percentage of p75(NTR)-immunoreactive neurons expressing Rac1b was significantly increased only in AD compared with both mild cognitive impairment and NCI. Furthermore, single-cell gene expression profiling with custom-designed microarrays showed down-regulation of caveolin 2, GNB4, and lipase A in AD Rac1b-positive/p75(NTR)-labeled NB neurons compared with Rac1b-negative/p75(NTR)-positive perikarya in NCI. These proteins are involved in Rac1 pathway/cell cycle progression and lipid metabolism. These data suggest that Rac1b expression acts as a modulator or transducer of various signaling pathways that lead to NFT formation and membrane dysfunction in a subgroup of CBF NB neurons in AD.
PMCID:3349868
PMID: 22142809
ISSN: 0002-9440
CID: 157687
Microarray analysis of CA1 pyramidal neurons in a mouse model of tauopathy reveals progressive synaptic dysfunction
The hTau mouse model of tauopathy was utilized to assess gene expression changes in vulnerable hippocampal CA1 neurons. CA1 pyramidal neurons were microaspirated via laser capture microdissection followed by RNA amplification in combination with custom-designed microarray analysis and qPCR validation in hTau mice and nontransgenic (ntg) littermates aged 11-14months. Statistical analysis revealed ~8% of all the genes on the array platform were dysregulated, with notable downregulation of several synaptic-related markers including synaptophysin (Syp), synaptojanin, and synaptobrevin, among others. Downregulation was also observed for select glutamate receptors (GluRs), Psd-95, TrkB, and several protein phosphatase subunits. In contrast, upregulation of tau isoforms and a calpain subunit were found. Microarray assessment of synaptic-related markers in a separate cohort of hTau mice at 7-8months of age indicated only a few alterations compared to the 11-14month cohort, suggesting progressive synaptic dysfunction occurs as tau accumulates in CA1 pyramidal neurons. An assessment of SYP and PSD-95 expression was performed in the hippocampal CA1 sector of hTau and ntg mice via confocal laser scanning microscopy along with hippocampal immunoblot analysis for protein-based validation of selected microarray observations. Results indicate significant decreases in SYP-immunoreactive and PSD-95-immunoreactive puncta as well as downregulation of SYP-immunoreactive and PSD-95-immunoreactive band intensity in hTau mice compared to age-matched ntg littermates. In summary, the high prevalence of downregulation of synaptic-related genes indicates that the moderately aged hTau mouse may be a model of tau-induced synaptodegeneration, and has profound effects on how we perceive progressive tau pathology affecting synaptic transmission in AD
PMCID:3259262
PMID: 22079237
ISSN: 1095-953x
CID: 149951
Expression profiling in neuropsychiatric disorders: Emphasis on glutamate receptors in bipolar disorder
Functional genomics and proteomics approaches are being employed to evaluate gene and encoded protein expression changes with the tacit goal to find novel targets for drug discovery. Genome-wide association studies (GWAS) have attempted to identify valid candidate genes through single nucleotide polymorphism (SNP) analysis. Furthermore, microarray analysis of gene expression in brain regions and discrete cell populations has enabled the simultaneous quantitative assessment of relevant genes. The ability to associate gene expression changes with neuropsychiatric disorders, including bipolar disorder (BP), and their response to therapeutic drugs provides a novel means for pharmacotherapeutic interventions. This review summarizes gene and pathway targets that have been identified in GWAS studies and expression profiling of human postmortem brain in BP, with an emphasis on glutamate receptors (GluRs). Although functional genomic assessment of BP is in its infancy, results to date point towards a dysregulation of GluRs that bear some similarity to schizophrenia (SZ), although the pattern is complex, and likely to be more complementary than overlapping. The importance of single population expression profiling of specific neurons and intrinsic circuits is emphasized, as this approach provides informative gene expression profile data that may be underappreciated in regional studies with admixed neuronal and non-neuronal cell types
PMCID:3253885
PMID: 22005598
ISSN: 1873-5177
CID: 149796
