Biomedical subjects

Shaoli Che

Publications and source records attributed to Shaoli Che.

10 recordsLinked to original sources

PubMed2006

Down regulation of trk but not p75NTR gene expression in single cholinergic basal forebrain neurons mark the progression of Alzheimer's disease.

Dysfunction of cholinergic basal forebrain (CBF) neurons of the nucleus basalis (NB) is a cardinal feature of Alzheimer's disease (AD) and correlates with cognitive decline. Survival of CBF neurons depends upon binding of nerve growth factor (NGF) with high-affinity (trkA) and low-affinity (p75(NTR)) neurotrophin receptors produced within CBF neurons. Since trkA and p75(NTR) protein levels are reduced within CBF neurons of people with mild cognitive impairment (MCI) and mild AD, trkA and/or p75(NTR) gene expression deficits may drive NB degeneration. Using single cell expression profiling methods coupled with custom-designed cDNA arrays and validation with real-time quantitative PCR (qPCR) and in situ hybridization, individual cholinergic NB neurons displayed a significant down regulation of trkA, trkB, and trkC expression during the progression of AD. An intermediate reduction was observed in MCI, with the greatest decrement in mild to moderate AD as compared to controls. Importantly, trk down regulation is associated with cognitive decline measured by the Global Cognitive Score (GCS) and the Mini-Mental State Examination (MMSE). In contrast, there is a lack of regulation of p75(NTR) expression. Thus, trk defects may be a molecular marker for the transition from no cognitive impairment (NCI) to MCI, and from MCI to frank AD.

Aged↗

PubMed2006

Galanin fiber hypertrophy within the cholinergic nucleus basalis during the progression of Alzheimer's disease.

Galanin (GAL)-containing fibers enlarge and hyperinnervate remaining cholinergic basal forebrain (CBF) neurons within the anterior nucleus basalis (NB) in late-stage Alzheimer's disease (AD). Whether GAL hypertrophy occurs in the CBF in the prodromal or early stages of AD remains unknown. The present study used GAL immunohistochemistry and an unbiased semiquantitative scoring method to evaluate GAL innervation in the anterior NB of subjects clinically diagnosed as having no cognitive impairment, mild cognitive impairment or early-stage (mild/moderate) AD. There was no difference in GAL fiber staining within the anterior NB across the three clinical groups examined. Furthermore, GAL fiber innervation was not correlated with the number of NB neurons expressing the nerve growth factor receptors p75(NTR) or TrkA or with cortical choline acetyltransferase activity in the same cases. Single-cell gene expression analysis demonstrated that cholinergic NB neurons express mRNA for the GAL receptors GALR1, GALR2 and GALR3, yet the levels of these mRNAs were unchanged across the three diagnostic groups. These observations indicate that GAL hypertrophy within the anterior NB subfield is a late-stage AD response, which may play a role in regulating the cholinergic tone of remaining basocortical projection neurons.

Aged↗

PubMed2006

Single cell gene expression profiling in Alzheimer's disease.

Development and implementation of microarray techniques to quantify expression levels of dozens to hundreds to thousands of transcripts simultaneously within select tissue samples from normal control subjects and neurodegenerative diseased brains has enabled scientists to create molecular fingerprints of vulnerable neuronal populations in Alzheimer's disease (AD) and related disorders. A goal is to sample gene expression from homogeneous cell types within a defined region without potential contamination by expression profiles of adjacent neuronal subpopulations and nonneuronal cells. The precise resolution afforded by single cell and population cell RNA analysis in combination with microarrays and real-time quantitative polymerase chain reaction (qPCR)-based analyses allows for relative gene expression level comparisons across cell types under different experimental conditions and disease progression. The ability to analyze single cells is an important distinction from global and regional assessments of mRNA expression and can be applied to optimally prepared tissues from animal models of neurodegeneration as well as postmortem human brain tissues. Gene expression analysis in postmortem AD brain regions including the hippocampal formation and neocortex reveals selectively vulnerable cell types share putative pathogenetic alterations in common classes of transcripts, for example, markers of glutamatergic neurotransmission, synaptic-related markers, protein phosphatases and kinases, and neurotrophins/neurotrophin receptors. Expression profiles of vulnerable regions and neurons may reveal important clues toward the understanding of the molecular pathogenesis of various neurological diseases and aid in identifying rational targets toward pharmacotherapeutic interventions for progressive, late-onset neurodegenerative disorders such as mild cognitive impairment (MCI) and AD.

Alzheimer Disease↗

PubMed2006

Neuronal gene expression profiling: uncovering the molecular biology of neurodegenerative disease.

The development of gene array techniques to quantify expression levels of dozens to thousands of genes simultaneously within selected tissue samples from control and diseased brain has enabled researchers to generate expression profiles of vulnerable neuronal populations in several neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, schizophrenia, multiple sclerosis, and Creutzfeld-Jakob disease. Intriguingly, gene expression analysis reveals that vulnerable brain regions in many of these diseases share putative pathogenetic alterations in common classes of genes, including decrements in synaptic transcript levels and increments in immune response transcripts. Thus, gene expression profiles of diseased neuronal populations may reveal mechanistic clues to the molecular pathogenesis underlying various neurological diseases and aid in identifying potential therapeutic targets. This chapter will review how regional and single cell gene array technologies have advanced our understanding of the genetics of human neurological disease.

Animals↗

PubMed2006

Shift in the ratio of three-repeat tau and four-repeat tau mRNAs in individual cholinergic basal forebrain neurons in mild cognitive impairment and Alzheimer's disease.

Molecular mechanisms underlying tauopathy remain undetermined. In the current study, single cell gene expression profiling was coupled with custom-designed cDNA array analysis to evaluate tau expression and other cytoskeletal elements within individual neuronal populations in patients with no cognitive impairment (NCI), mild cognitive impairment (MCI), and Alzheimer's disease (AD). Results revealed a shift in the ratio of three-repeat tau (3Rtau) to four-repeat tau (4Rtau) mRNAs within individual human cholinergic basal forebrain (CBF) neurons within nucleus basalis (NB) and CA1 hippocampal neurons during the progression of AD, but not during normal aging. A shift in 3Rtau to 4Rtau may precipitate a cascade of events in the selective vulnerability of neurons, ultimately leading to frank neurofibrillary tangle (NFT) formation in tauopathies including AD.

Acetylcholine↗

PubMed2005

Expression profile analysis within the human hippocampus: comparison of CA1 and CA3 pyramidal neurons.

The hippocampus contains several distinct cell types that are interconnected by a well-characterized series of synaptic circuits. To evaluate molecular and cellular signatures of individual cell types within the normal adult human hippocampal formation, expression profile analysis was performed on individual CA1 and CA3 pyramidal neurons using a novel single cell RNA amplification methodology coupled with custom-designed cDNA array analysis. Populations of CA1 and CA3 neurons were also compared with regional dissections of the hippocampus from the same tissue sections. Molecular fingerprint comparison of cresyl violet-stained CA1 and CA3 pyramidal neurons microaspirated from the hippocampus of normal control subjects indicated significant differences in relative expression levels for approximately 16% (20 of 125) genes evaluated on the custom-designed cDNA array platform. Significant differences were observed for several transcripts relevant to the structure and function of hippocampal neurons, including specific glutamate receptors, gamma-aminobutyric acid (GABA) A receptors, cytoskeletal elements, dopamine receptors, and immediate-early genes. Compared with the regional assessment of gene expression, both CA1 and CA3 neurons displayed a relative enrichment of classes of transcripts that included glutamate receptors, transporters, and interacting proteins, GABA receptors and transporters, synaptic-related markers, and catecholamine receptors and transporters. In contrast, the regional hippocampal dissection had an increased level of gene expression for cytoskeletal elements as well as glial-associated markers. Expression profile analysis illustrates the importance of evaluating individual cellular populations within a functional circuit and may help define elements that confer unique properties to individual populations of hippocampal neurons under normal and diseased conditions.

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PubMed2004

Single-cell gene expression analysis: implications for neurodegenerative and neuropsychiatric disorders.

Technical and experimental advances in microaspiration techniques, RNA amplification, quantitative real-time polymerase chain reaction (qPCR), and cDNA microarray analysis have led to an increase in the number of studies of single-cell gene expression. In particular, the central nervous system (CNS) is an ideal structure to apply single-cell gene expression paradigms. Unlike an organ that is composed of one principal cell type, the brain contains a constellation of neuronal and noneuronal populations of cells. A goal is to sample gene expression from similar cell types within a defined region without potential contamination by expression profiles of adjacent neuronal subpopulations and noneuronal cells. The unprecedented resolution afforded by single-cell RNA analysis in combination with cDNA microarrays and qPCR-based analyses allows for relative gene expression level comparisons across cell types under different experimental conditions and disease states. The ability to analyze single cells is an important distinction from global and regional assessments of mRNA expression and can be applied to optimally prepared tissues from animal models as well as postmortem human brain tissues. This focused review illustrates the potential power of single-cell gene expression studies within the CNS in relation to neurodegenerative and neuropsychiatric disorders such as Alzheimer's disease (AD) and schizophrenia, respectively.

Cell Physiological Phenomena↗

PubMed2004

Amplification of RNA transcripts using terminal continuation.

A new methodology has been developed to amplify RNA from minute amounts of starting material. Specifically, an efficient means of second-strand (ss) cDNA synthesis using a sequence-specific 'terminal continuation' (TC) method is demonstrated. An RNA synthesis promoter is attached to the 3' and/or 5' region of cDNA utilizing the TC mechanism. The orientation of amplified RNAs is 'antisense' or a novel 'sense' orientation. TC RNA amplification is utilized for many downstream applications including gene expression profiling, cDNA microarray analysis, and cDNA library/subtraction library construction. Synthesized sense TC-amplified RNA can also be used as a template for in vitro protein translations and downstream proteomic applications. The TC RNA amplification methodology offers high sensitivity, flexibility, and throughput capabilities. A likely mechanism is that the TC primer binds preferentially to GC-rich CpG islands flanking 5' regions of DNA that contain promoter sequences. Following TC RNA amplification, a large proportion of genes can be assessed quantitatively as evidenced by bioanalysis and cDNA microarray analysis in mouse and human postmortem brain tissues.

Animals↗

PubMed2004

Combined histochemical staining, RNA amplification, regional, and single cell cDNA analysis within the hippocampus.

The use of five histochemical stains (cresyl violet, thionin, hematoxylin & eosin, silver stain, and acridine orange) was evaluated in combination with an expression profiling paradigm that included regional and single cell analyses within the hippocampus of post-mortem human brains and adult mice. Adjacent serial sections of human and mouse hippocampus were labeled by histochemistry or neurofilament immunocytochemistry. These tissue sections were used as starting material for regional and single cell microdissection followed by a newly developed RNA amplification procedure (terminal continuation (TC) RNA amplification) and subsequent hybridization to custom-designed cDNA arrays. Results indicated equivalent levels of global hybridization signal intensity and relative expression levels for individual genes for hippocampi stained by cresyl violet, thionin, and hematoxylin & eosin, and neurofilament immunocytochemistry. Moreover, no significant differences existed between the Nissl stains and neurofilament immunocytochemistry for individual CA1 neurons obtained via laser capture microdissection. In contrast, a marked decrement was observed in adjacent hippocampal sections stained for silver stain and acridine orange, both at the level of the regional dissection and at the CA1 neuron population level. Observations made on the cDNA array platform were validated by real-time qPCR using primers directed against beta-actin and glyceraldehyde-3 phosphate dehydrogenase. Thus, this report demonstrated the utility of using specific Nissl stains, but not stains that bind RNA species directly, in both human and mouse brain tissues at the regional and cellular level for state-of-the-art molecular fingerprinting studies.

Aged↗

PubMed2002

RNA amplification in brain tissues.

Recent developments in gene array technologies, specifically cDNA microarray platforms, have made it easier to try to understand the constellation of gene alterations that occur within the CNS. Unlike an organ that is comprised of one principal cell type, the brain contains a multiplicity of both neuronal (e.g., pyramidal neurons, interneurons, and others) and noneuronal (e.g., astrocytes, microglia, oligodendrocytes, and others) populations of cells. An emerging goal of modern molecular neuroscience is to sample gene expression from similar cell types within a defined region without potential contamination by expression profiles of adjacent neuronal subtypes and noneuronal cells. At present, an optimal methodology to assess gene expression is to evaluate single cells, either identified physiologically in living preparations, or by immunocytochemical or histochemical procedures in fixed cells in vitro or in vivo. Unfortunately, the quantity of RNA harvested from a single cell is not sufficient for standard RNA extraction methods. Therefore, exponential polymerase-chain reaction (PCR) based analyses and linear RNA amplifications, including a newly developed terminal continuation (TC) RNA amplification methodology, have been used in combination with single cell microdissection procedures to enable the use of cDNA microarray analysis within individual populations of cells obtained from postmortem brain samples as well as the brains of animal models of neurodegeneration.

Aged↗