Genome-wide studies have suggested that NRF1 regulates transcription of ~5-6% of human genes, including nuclear genes encoding mitochondrial products. My thesis focus is in neural systems in which NRF1 is a master regulator.
Prader-Willi syndrome (PWS) results from genetic loss of function of an imprinted domain in human chromosome 15q11.2. I confirmed NRF1 regulation of ~83% of PWS-region genes using chromatin immunoprecipitation (ChIP). Further studies focused on evolution of this region. Uniquely in marsupials, SNRPN and the ancestral SNRPB gene are adjacent each with an intronic snoRNA paralog. Based on molecular phylogenetics, a model is proposed for origin of each PWS snoRNA from a single ancestral snoRNA. Thus, most extant eutherian PWS genes originated by stepwise duplication and divergence over the past ~180 million years.
Circadian rhythms regulate organismal physiology in a 24 hour day-night cycle. Functional NRF1 binding sites in promoters/enhancers were found for ~56% of circadian regulatory genes using bioinformatics, ChIP, NRF1 siRNA assays, and luciferase reporter constructs having significantly reduced transcriptional activity on mutation of NRF1 sites. Further, co-immunoprecipitation showed that NRF1 and the phosphorylated, active form of CLOCK interact in a molecular complex. In serum-induced NIH3T3 cells with circadian oscillations of Dbp and Nr1d1 mRNA, Nrf1 mRNA and protein levels show ultradian oscillations. Hence, NRF1 regulates numerous circadian regulatory genes and interacts with CLOCK, suggesting multiple roles in circadian biology.
Additional studies included finding that NRF1 regulates ~45% known hereditary spastic paraplegia (HSP) genes, that NRF1 activates its own transcription, and that the number of NRF1 sites determine the degree of transcriptional activation.
In summary, NRF1 is a master regulator in PWS, circadian rhythms, and HSP. Identification of NRF1 target genes and mechanisms will lead to an understanding of the evolution, functions, disease processes, and therapeutic targets within gene regulatory networks involving NRF1. Circadian rhythms are disrupted by travel, shift-work, and in illness, including infection, psychiatric and sleep disorders, obesity, diabetes, and cancer. Consequently, understanding body clocks will provide insights into the pathogenesis of these disorders and potentially lead to improved treatment and prevention options, which will have enormous public health impact.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-07252011-180258 |
| Date | 23 September 2011 |
| Creators | Zhu, Wan |
| Contributors | Robert E. Ferrell, Robert D. Nicholls, Eleanor Feingold, Susanne M. Gollin |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-07252011-180258/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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