A diverse array of organisms including prokaryotic and eukaryotic microbes, plants, and animals display daily rhythms in physiology, metabolism and/or behavior. These rhythms are not passively driven by environmental cycles of light and temperature, but are actively controlled by endogenous circadian clocks that are set by environmental cycles, keep time in the absence of environmental cues, and activate overt physiological, metabolic and behavioral rhythms at the appropriate time of day. This remarkable conservation of circadian clock function through evolution suggests that maintaining synchrony with the environment is of fundamental importance. Our understanding of the circadian clock is particularly important for human health and well-being. The clearest examples of circadian clock dysfunction are those that result in abnormal sleep-wake cycles, but clock disturbances are also associated with other ailments including epilepsy, cerebrovascular disease, depression, and seasonal affective disorder. The realization that disorders of the sleep-wake cycle such as Familial Advanced Sleep Phase Syndrome can result from alterations in clock gene function underscores the clinical importance of understanding the molecular organization of the circadian system.
Work in my laboratory focuses on defining the molecular mechanisms that drive circadian clock function in the fruit fly, Drosophila melanogaster. We previously found that the core timekeeping mechanism is based on core and interlocked transcriptional feedback loops. Our studies currently focus on (1) defining post-translational regulatory mechanisms that operate in the core loop to set the 24 hour period, (2) determining whether interlocked loops are important for circadian timekeeping and/or output, (3) understanding how circadian oscillator cells are determined during development, and (4) defining mechanisms that control rhythms in olfactory and gustatory physiology and behavior.
- Howard Hughes Medical Institute - (Chevy Chase, Maryland, United States), Postdoctoral Training 1991
- Ph.D. in Genetics, Indiana University Bloomington - (Bloomington, Indiana, United States) 1987
- B.S. in Biology, Southern Methodist University - (Dallas, Texas, United States) 1982
- Liu, T., Mahesh, G., Houl, J. H., & Hardin, P. E. (2015). Circadian Activators Are Expressed Days before They Initiate Clock Function in Late Pacemaker Neurons from Drosophila. The Journal of Neuroscience. 35(22), 8662-8671.
- Menet, J. S., & Hardin, P. E. (2014). Circadian Clocks: The Tissue Is the Issue. Current biology : CB. 24(1), R25-R27.
- Glossop, N., Gummadova, J. O., Ghangrekar, I., Hardin, P. E., & Coutts, G. A. (2014). Effects of TWIN-OF-EYELESS on Clock Gene Expression and Central-Pacemaker Neuron Development in Drosophila. JOURNAL OF BIOLOGICAL RHYTHMS. 29(3), 151-166.
- Lee, E., Jeong, E. H., Jeong, H., Yildirim, E., Vanselow, J. T., Ng, F., ... Kim, E. Y. (2014). Phosphorylation of a Central Clock Transcription Factor Is Required for Thermal but Not Photic Entrainment. PLoS Genet. 10(8), e1004545-e1004545.
- Mahesh, G., Jeong, E., Ng, F. S., Liu, Y., Gunawardhana, K., Houl, J. H., ... Hardin, P. E. (2014). Phosphorylation of the Transcription Activator CLOCK Regulates Progression through a similar to 24-h Feedback Loop to Influence the Circadian Period in Drosophila. JOURNAL OF BIOLOGICAL CHEMISTRY. 289(28), 19681-19693.
- Wangjie, Y. u., & Hardin, P. E. (2013). An RNAi screen of protein kinase genes identifies novel components of the circadian oscillator in Drosophila. JOURNAL OF PHYSIOLOGICAL SCIENCES. 63, S111-S111.
- Benito, J., Zheng, H., Ng, F. S., & Hardin, P. E. (2007). Transcriptional feedback loop regulation, function, and ontogeny in Drosophila. Symposia on Quantitative Biology. 72(1), 437-444.
- Ng, F. S., Houl, J. H., Francis, C., Callaerts, P., & Hardin, P. E. (2006). CLOCK expression and regulation during development in Drosophila. Journal of Neurogenetics. 20(3-4), 189-189.
- Zwiebel, L. J., Hardin, P. E., Hall, J. C., & Rosbash, M. (1991). Circadian oscillations in protein and mRNA levels of the period gene of Drosophila melanogaster.. Biochem Soc Trans. 19(2), 533-537.
- Moores Professorship conferred by University of Houston - (Houston, Texas, United States) 2004
- Gunawardhana, Kushan Lakshitha (2018-05). Characterization of Vrille Function in the Drosophila Circadian Clock. (Doctoral Dissertation)
- Liu, Tianxin (2017-08). Circadian Clock Development and Initiation in Drosophila melanogaster. (Doctoral Dissertation)
- Caster, Courtney Marie (2017-08). Investigating the Evolution of the Molecular Clock Mechanism Using the Housefly, Musca domestica. (Master's Thesis)
- Zhou, Jian (2017-08). Characterizing the Function of Clockwork Orange in the Circadian Feedback Loops in Drosophila melanogaster. (Doctoral Dissertation)
- Agrawal, Parul (2016-08). Characterizing Novel Circadian Clock Functions for Drosophila Phosphatases and Non-clock Functions for Circadian Photoreceptors. (Doctoral Dissertation)