How organisms respond to light and how photosensory receptors mediate light responses are basic questions in biology. Our long-term goal is to find the molecular explanation of these questions, using the cryptochrome photoreceptor as a model system. Cryptochromes (CRY) are the blue/UV-A light receptors and/or core components of the circadian oscillator found in all evolutionary lineages including human. My laboratory focuses on the study of plant cryptochromes. In the previous funding periods, we discovered two major CRY2 signal transduction mechanisms: the CIB1 (Cryptochrome-Interacting bHLH 1)-based transcription- regulatory mechanism and SPA1/COP1 (Suppressor of Phytochrome A 1/Constitutive Photomorphogenesis 1)-based proteolysis-regulatory mechanism. More recently, we identified a CIB-interacting protein FOF1 (F-box of Flowering 1) responsible for the blue light-regulated degradation of CIB1;two new blue light-specific CRY2-interacting proteins: PRR5 (Pseudo Response Regulator 5) that is a core protein of the circadian clock, and a novel protein BIC1 (Blue- light Inhibitor of CRYs 1) that suppresses blue light-dependent phosphorylation, degradation, and activities of CRY1 and CRY2. Based on these discoveries and newly developed tools, we propose to study three key issues of light signal transduction: the photochemical mechanism underlying photoexcitation of the CRY photoreceptor, mechanisms governing the function and regulation of the CRY complexome, and the mechanism underlying a novel coding sequence (CDS)-dependent blue light regulation of CRY2 expression.

Public Health Relevance

How organisms respond to light and how photosensory receptors mediate light responses are some of the most basic questions in biology. Cryptochromes (CRY) are blue/UV-A light receptors found in bacteria, plants, and animals including human, but the molecular mechanisms of CRYs remain not well understood. We propose to test the working hypotheses resulting from previous studies and to investigate how light regulates gene expression and plant development.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM056265-17A1
Application #
8632891
Study Section
Cellular Signaling and Regulatory Systems Study Section (CSRS)
Program Officer
Maas, Stefan
Project Start
1997-08-01
Project End
2018-02-28
Budget Start
2014-03-01
Budget End
2015-02-28
Support Year
17
Fiscal Year
2014
Total Cost
$536,632
Indirect Cost
$180,567
Name
University of California Los Angeles
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Liu, Hongtao; Liu, Bin; Zhao, Chenxi et al. (2011) The action mechanisms of plant cryptochromes. Trends Plant Sci 16:684-91
Zuo, Zecheng; Liu, Hongtao; Liu, Bin et al. (2011) Blue light-dependent interaction of CRY2 with SPA1 regulates COP1 activity and floral initiation in Arabidopsis. Curr Biol 21:841-7