講師資料
Talks：
BASIC PENTACYSTIENEs, plant-specific GAGA-binding factors, constitute a regulatory gene network for tuning plant circadian clock
Name：
蔡皇龍(Huang-Lung Tsai)
Position：
Assistant Professor
Affiliation：
Institute of Molecular and Cellular Biology, National Taiwan University
Email：
Photo：
Research Interests：
Most of organisms on the earth evolve circadian clocks to control the oscillations of multiple physiological pathways in sync with the ~24-h period, upon the day-night cycles resulted from the earth rotation, such oscillations are called “circadian rhythms”. Besides the predictable day-night and seasonal cycles, plants are sessile in circumstances with numerous unpredictable transient changes during their growth and development. The rhythmicity of the “circadian clock” profoundly keeps plants on the track without over reacting to the random cues, therefore sustains propagating on an optimal season time. The circadian clock comprises genes tightly interlocked in regulatory feedback loops, in other words, clock related genes are directly or indirectly regulated by their downstream genes. Such regulatory feedback loops make genes peak at a specific time of the day and oscillate according to the external cues like light and temperature through the day-night cycles. In the model plant, Arabidopsis , LIGHT-REGULATED WD1 (LWD1) plays a role in the morning activation of circadian clock. The five WD repeats of LWD1 form a propeller structure and serve as a protein-protein interaction platform. In our previous study, we have revealed that LWDs form co-activator protein complexes with specific TCP members to directly activate the expression of morning gene CCA1 , thus, secure the normal operation of the circadian clock at dawn. However, expressions of several clock genes in the lwd1 lwd2 double mutant don't obey the interlocking gene circuits, e.g. genes and their repressors are down regulated simultaneously when lacking LWDs. This indicates that our knowledge of the circadian clock is not thorough. To investigate the regulatory mechanism of circadian clock, we will use LWD1 as bait to identify transcription factors with similar transcription trends through a plenty of transcriptomes. We will reveal the molecular mechanism of the circadian clock operation via the study of the LWD1 co-expressed transcription factors. Our study would unravel multifaceted connections between circadian clock and plant developmental processes.
Selected Publications：
1. Yi-Chen Lee, Pei-Ting Tsai, Xun-Xian Huang and Huang-Lung Tsai* (2022, May). Family members additively repress the ectopic expression of BASIC PENTACYSTEINE3 to prevent disorders in Arabidopsis circadian vegetative development. Frontiers in Plant Science, 13: 919946. (*corresponding author)
2. Neda Sanobar, Pin-Chun Lin, Zhao-Jun Pan, Ru-Ying Fang, Veny Tjita, Fang-Fang Chen, Hao-Ching Wang, Huang-Lung Tsai, Shu-Hsing Wu, Tang-Long Shen, Yan-Huey Chen and Shih-Shun Lin (2021, Sep). Investigating the Viral Suppressor HC-Pro Inhibiting Small RNA Methylation through Functional Comparison of HEN1 in Angiosperm and Bryophyte. Viruses, 13(9): 1837.
Abstract：
BASIC PENTACYSTEINE (BPC) family members are plant-specific GAGA-motif binding factors (GAFs) controlling multiple developmental processes of growth and propagation. BPCs recruit histone remodeling factors of repressive complexes involving in the transcriptional repression of downstream targets. Under day-night cycles, we found multiple BPC members are transcriptionally co-expressed with LIGHT-REGULATED WD1 (LWD1), which encodes a co-activator for the activation of central clock gene, CIRCADIAN CLOCK ASSOCIATED1 (CCA1). The co expression between BPCs and LWDs prompted us to investigate the role of BPCs in the circadian regulation. We revealed that BPC3, a member antagonized by the functional overlap of other BPCs in vegetative tissues aboveground, is ectopically expressed in the quadruple mutant of bpc1-1 bpc2 bpc4 bpc6. The ectopic BPC3 suppresses multiple clock genes including CCA1 in the mutant and the clock oscillation is therefore phase-delayed. Consequently, the expression peak of CONSTANS (CO) is delayed and the day-time CO level is insufficient to activate the expression of FLOWERING LOCUS T (FT). Intriguingly, even FT expression is obliterated, the mutant is still early-flowered due to that the ectopic BPC3 simultaneously suppresses the main floral repressor FLOWERING LOCUS C (FLC) of the autonomous pathway through direct binding to the FLC promoter. Taken together, our study reveals plant-specific GAFs tune the photoperiodic and autonomous floral promotion pathways concurrently to control the vegetative-to-reproductive transition.