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Wahlestedt Lab
Molecular and Integrative Neurosciences Department (MIND)
Research: Bioinformatics, Cell Biology, Genetics, Genomics, Molecular and Experimental Medicine, Molecular Biology, Neurobiology, Neuropharmacology, Neuroscience, Nucleic Acid Structure and Function
Diseases & Disorders: Aging, Alcoholism, Autism Spectrum Disorders; Fragile X Syndrome, Alzheimer's Disease, Anxiety Disorders, Depression, Diabetes, Drug Abuse and Addiction, Heart Disease, Metabolic Disorders, Obesity, Parkinson's Disease, Schizophrenia
Technologies: Computational Biology, High-Throughput Screening
Neuropeptide Y Y2 Receptor Modulators in Alcoholism
In 1986, we were the first to show that that there existed two kinds of neuropeptide Y (NPY) receptor populations on neurons, which we termed Y1 and Y2 receptors. Since then, there have been other NPY receptors discovered, including the Y4 and Y5 subtypes. The neuropeptide Y-Y2 receptor (Y2R) is a G protein coupled receptor found in many cell types throughout the body. The Y2R is thought to play a role in alcohol addiction and dependence. There are currently no good Y2R antagonists available to researchers to study the role of the Y2R in the alcohol dependence process. Therefore, we embarked on an ultra High Throughput Screening (uHTS) campaign to discover novel receptor modulators. After screening hundreds of thousands of compounds, we identified 5 ligands that antagonize the Y2R, but have no activity at the Y1R; these results are currently being peer-reviewed. We also began the process of improving these compounds in collaboration with Dr. Ed Roberts, a medicinal chemist at Scripps, La Jolla, Dr. Michael Cameron, a drug metabolism and pharmacokinetic expert at Scripps Florida, and Dr. Markus Heilig, the clinical director of the National Institutes of Alcohol Abuse and Alcoholism at the NIH. We hope to provide the scientific and medical communities with a highly potent and selective Y2R antagonist that can be used to discover the contribution of the Y2R to the alcohol dependence process and may even be useful as a therapeutic agent.
Natural Antisense Transcripts And Their Role In Neurological Disorders
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We recently identified a conserved noncoding antisense transcript for [?]-secretase-1 (BACE1), a critical enzyme in Alzheimer's disease pathophysiology (Faghihi et al., Nature Medicine, 14:723, 2008) [1]. We showed that the BACE1-antisense transcript (BACE1-AS) concordantly regulates BACE1 mRNA and subsequently BACE1 protein expression in vitro and in vivo. We clearly demonstrated that upon exposure to various cell stressors including amyloid-[?] 1-42 (A[?] 1-42) BACE1-AS becomes elevated, increasing BACE1 mRNA stability and generating additional A[?] 1-42 through a post-transcriptional feed-forward mechanism. Additionally, we verified that BACE1-AS concentrations were elevated in Alzheimer's disease subjects as well as in amyloid precursor protein (APP) transgenic mice, an Alzheimer's disease animal model. Our data revealed that BACE1 mRNA expression is under the control of a regulatory noncoding RNA that may drive Alzheimer's disease associated pathophysiology. We are currently trying to develop an optimized strategy for reduction of BACE1 protein levels. We will simultaneously target BACE1 and BACE1-AS by small interfering RNA (siRNA) to induce reduction of BACE1 protein. We anticipate that reduction of BACE1 protein will significantly alleviate Alzheimer's disease-related pathologies in the brain APP transgenic mice.
- Faghihi, M.A., et al., Expression of a noncoding RNA is elevated in Alzheimer's disease and drives rapid feed-forward regulation of beta-secretase. Nat Med, 2008. 14(7): p. 723-30.
In researching Alzheimer's Disease, the focus is to use the basics of cell biology of Neural Stem Cells to try to understand the mechanisms involved in neuronal differentiation and its possible implications in neurodegenerative pathologies. The discovery of neurogenic areas in the brain opens up the possibility for natural cell replacement after neuronal loss. Dr. Miguel Lopez Toledano was the first to publish on age-related changes in neurogenesis in an animal model of Alzheimer's disease. Now, it is widely believe that increased neurogenesis is linked to an excess of A-beta production and oligomeric aggregation. This finding makes the study of hippocampal neurogenesis in AD more appealing, as an increasingly important need for Alzheimer's disease research is the finding of biomarkers for early diagnosis. By extrapolating what happens in the animal models to humans, we expect increased neurogenesis in hippocampus before other clinical symptoms of AD develop. If we can elucidate the signaling pathways involved in A-beta-mediated neurogenesis, it could be possible to find a biomarker for early AD diagnosis and, also, a tool to slow down the pathology of AD related with neurogenesis. In order to do so, extensive studies of changes of signal pathways, gene expression and RNA profile have to be done in vitro and compared to the in vivo results with samples taken from the brain, blood and CSF. If we were able to relate any of these changes with A-beta-meditated neurogenesis we would have a clinical tool for an early diagnosis of AD as a part of the global contribution in the fight against Alzheimer's disease.
Schizophrenia affects approximately 1% of the population worldwide. This disorder has a 60-70% heritability rate, with phenotypic penetrance regulated by a complex gene-environment interaction. Genome-wide association (GWAS) analysis has been used to identify disease-associated loci, but has not led to the identification of causative genes. Family-based QTL mapping studies have successfully identified causative genetic mutations, but these mutations are present in only a small fraction of patients. The identification of quantitative trait genes has yet to result in either the identification of dysregulated genetic pathways common to a large proportion of the patient population or the production of novel drug therapies.
MicroRNAs (miRNA), small, endogenous non-coding RNAs of ~23 nucleotides in length, have been shown to regulate the transcription and translation of multiple RNA targets. Recent studies have suggested that microRNAs may be involved in complex disorders such as schizophrenia and autism. Our goal is to characterize the role that microRNAs, and their RNA targets, play in schizophrenia in order to identify novel therapeutic targets. Our approach combines genome-wide genotyping of human patient samples, gene expression analysis of RNA and miRNA from human brain samples, and behavioral analysis of mouse models of schizophrenia.
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