Joanna Chiu

Joanna Chiu, Ph.D. - Molecular Genetics of Animal Behavior

• B.A., Biology and Music, Mount Holyoke College
• Ph.D., Molecular Genetics, New York University

Departmental Affliliations: Department of Entomology, College of Agricultural and Environmental Sciences.

Graduate Group Affliliations: Entomology, Biochemistry, Molecular, Cellular and Developmental Biology.

Laboratory Research Interests: Molecular Genetics of Animal Behavior, Circadian Rhythm Biology, Posttranslational Regulation of Proteins.

Selected Publications:

• Chiu, J. C., H. W. Ko, and I. Edery (2011). NEMO/NLK phosphorylates PERIOD to initiate a time-delay phosphorylation circuit that sets circadian clock speed. Cell 145(3):357-370.
• Chiu, J. C., K. H. Low, D. H. Pike, E. Yildirim, and I. Edery (2010). Assaying locomotor activity to study circadian rhythms and sleep parameters in Drosophila. J Vis. Exp. 43. http://www.jove.com/index
• Ko, H. W., E. Y. Kim, J. C. Chiu, J. T. Vanselow, A. Kramer, and I. Edery (2010). A hierarchical phosphorylation cascade that regulates the timing of PERIOD nuclear entry reveals novel roles for proline-mediated kinases and GSK-3ß/SGG in circadian clocks. J. Neurosci. 30:12664-12675.
• Egan, M., E. K. Lee, J. C. Chiu, G. Coruzzi, and R. DeSalle (2009). Gene orthology assessment with OrthologID. Methods Mol. Biol. 537:23-38.
• Chiu, J. C., J. T. Vanselow, A. Kramer, and I. Edery (2008). The phospho-occupancy of an atypical SLIMB binding site on PERIOD that is phosphorylated by DOUBLETIME controls the pace of the clock. Genes. Dev. 22(13):1758-1772.
• Chiu, J. C., E. K. Lee, M. G. Egan, I. N. Sarkar, G. M. Coruzzi, and R. DeSalle (2006). OrthologID: Automation of genome scale ortholog identification within a parsimony framework. Bioinformatics 22(6):699-707.
• Chiu, J. C., E. Brenner, R. DeSalle, M. N. Nitabach, T. C. Holmes, and G. Coruzzi (2002). Phylogenetic and expression analysis of the glutamate-receptor-like gene family in Arabidopsis thaliana. Molecular Biology and Evolution 19(7):1066-1082.
• Lacombe, B., D. Becker, R. Hedrich , R. DeSalle, M. Hollmann, J. Kwak, J. I. Schroeder, N. Le Novere, G. N. Hong, E. P. Spalding, M. Tester, F. J. Turano, J. Chiu, and G. Coruzzi (2001). The identity of plant glutamate receptors. Science 292:1486-1487.
• Chiu, J., R. DeSalle, H. M. Lam, L. Meisel, and G. Coruzzi (1999). Molecular evolution of glutamate receptors: a primitive signaling mechanism that existed before plants and animals diverged. Molecular Biology and Evolution 16(6): 826-838.
• Lam, H. M., J. Chiu, M. H. Hsieh, L. Meisel, I. C. Oliveira, M. Shin, and G. Coruzzi (1998). Glutamate receptor genes in plants. Nature 396:125-126.

Lab Research

Research in my laboratory focuses on the regulation of circadian clock and its control over organismal physiology. Circadian clocks regulate molecular oscillations that manifest into physiological and behavioral rhythms. The self-sustained molecular oscillator can be synchronized to daily and seasonal environmental changes, thus allowing organisms to perform necessary tasks at biologically advantageous times of day. Analyses of mammalian and Drosophila transcriptomes using DNA microarrays identified a large number of clock-controlled genes that are involved in diverse physiological processes. Besides being indispensable for the control of daily activities in animals, such as the sleep-wake cycle, locomotor activity, hormone circulation and food intake, defects in circadian rhythms and clock genes have also been implicated in a wide range of human disorders, including chronic sleep orders, various forms of depression, metabolic syndromes, as well as susceptibility to cancer and drug and alcohol addiction.

Although circadian clock genes are not highly conserved across kingdoms (plant, animal, fungi, and bacteria), the regulation of circadian oscillators in all organisms studied to date appears to be variations on the same theme. In general, circadian pacemakers are comprised of a set of species and tissue-specific clock genes that are cell-autonomous and autoregulatory through a series of interconnected transcriptional-translational feedback loops. The circadian oscillator is capable of receiving input signals from external time cues, thereby synchronizing its activity to the environment; and can control cell and organismal physiology by regulating the rhythmic expression of downstream effectors in cell and tissue-specific manners. One feature of the oscillator that is inherent in its design is the rhythmic expression of a number of clock RNAs and daily oscillations in clock protein abundance. Despite the centrality of cycling clock mRNA expression, more recent studies have highlighted the importance of post-translational mechanisms, in particular phosphorylation, in regulating clock protein abundance. In addition, posttranslational modifications of clock proteins are believed to regulate their transcriptional activity, subcellular localization, and protein-protein interaction.

Using a combination of biochemical, molecular genetics, and proteomic approaches, we hope to understand the biochemical and cellular basis of clocks, and the mechanisms by which they regulate organismal physiology.