Sheng Luan

Professor
Ph.D.  Cellular and Developmental Biology    Harvard University, 1991
  

451A Koshland Hall
Berkeley, California 94720
sluan@berkeley.edu
office: 510-642-6306   lab: 510-643-1725   fax:  510-642-4995

Web site         Recent publications      People

Our goal is to understand the molecular mechanism underlying plant response and adaptation to its environment. Because higher plants can not “walk away” from their environment, they have evolved elaborate mechanisms to integrate their outside world into the program of their life cycle control. When environmental conditions change, plants rapidly perceive those changes and respond by physiological and developmental changes that would help themselves adapt to the “new” environment. We are interested in revealing the molecular networks that connect the environmental input to the intracellular responses in plants. The understanding of biochemical pathways that allow plants to adapt to constantly changing environment is also among our primary research goals.

Upon environmental changes, a plant cell has a number of rapid responses. One of these is fluctuation of cellular Ca2+ that is often required for the further downstream responses and is thus referred to as a “second messenger”. A critical question regarding calcium signaling is how a simple cation serves as a messenger for so many different signals leading to distinct responses. The key step is signal “sensing”, i.e., the calcium signal is sensed by proteins functioning as Ca2+ sensors. These sensors bind Ca2+ and change their conformation/function. We have recently uncovered a family of novel Ca2+ sensors (CBLs) from Arabidopsis. The CBL-type Ca2+ sensors function by interacting with and regulating a family of protein kinases (CIPKs) in a number of signaling pathways. At least 10 members of CBLs interact with 25 CIPKs, forming a large number of molecular complexes that interpret the calcium signals in plant cells. The functional specificity, synergism, and antagonism among various CBLs and CIPKs constitute a complex signaling network for cellular regulation and crosstalk.

CBL-CIPK in nutrient sensing: Plants are growing in a nutrient-poor environment especially after a long history of farming. Agricultural production is heavily relying on the application of chemical fertilizers, opposing a serious economic and environmental problem worldwide. One solution would be to breed crops that can tolerate low-nutrient soils without the need of fertilizers. Recent work in Luan laboratory identified a CBL-CIPK signaling pathway that regulates the activity of a voltage-gated potassium channels involved in K-uptake in plant roots. Manipulation of CBL-CIPK network can therefore enhance the growth of plants under low-K soils, impacting agriculture and environment. (See Li et al., 2006 to get started on this subject).

CBL-CIPK in stress and ABA responses:Several CBL-CIPK pathways have been identified that function in plant responses to environmental stress conditions including salt, drought, and cold. CBL-CIPK network is also involved in the response to plant hormones such as ABA that regulates stress responses. The crosstalk and interaction among the CBLs and CIPKs form a complex signaling network that links environmental responses to biochemical processes in plant cells. (See Cheong et al., 2003 and Pandey et al., 2004 to get started on this subject).

After environmental signals are perceived and interpreted by signaling pathways, plant cells respond to the signals by biochemical and physiological changes downstream of the signaling process. Many of the biochemical changes in plants involve metabolic processes in the chloroplasts that serve as a critical “factory” for plant productivity. The best known photosynthetic process include both light harvesting by the photosystems and carbon fixation. As the most important metabolic process, photosynthetic activity and its regulated are connected to all environmental changes. Although the basic biochemical pathways are largely known, the regulatory pathways that link the environmental signals to the light and dark reactions are poorly understood. Luan laboratory focus on the mechanisms underlying regulation of photosynthetic activity by environmental signals.

Light reaction and bio-energy conversion: We are interested in the mechanism of assembly and maintenance of the photosystems that harvest light energy and convert it into the chemical forms. Our recent studies have discovered a family of protein foldases and chaperones (called immunophilins) in the chloroplast that function in the assembly and maintenance of photosynthetic electron transport complexes. Because maintaining the function of photosynthetic complexes is one of the limiting factors in photosynthetic activity, our findings on the immunophilins in the chloroplast will provide information for enhancing light energy conversion by plants.(See Lima et al., 2006 to get started on this subject).

Dark Reaction and Biomass: The output of photosynthetic carbon fixation is transitory starch in the chloroplast. The starch biosynthesis and degradation is under tight control by environmental factors such as light-dark cycle and stress conditions. Although regulation of glycogen (starch) metabolism is well understood in animal cells, our understanding of metabolic regulation of starch accumulation is still in its infancy. Recent research in Luan laboratory identified a protein phosphatase (DSP4) that plays a central role in regulating starch accumulation in Arabidopsis chloroplasts, providing a strong evidence that protein phosphorylation is involved in starch regulation. In addition, the DSP4 activity is regulated by redox states that are controlled by light-dark transition. Therefore DSP4 may provide a molecular link between diurnal cycle and starch accumulation. As starch is one of the most abundant plant-derived polymers, its sheer biomass and ease of production make it a critical source for biofuel production. Understanding the regulatory mechanism for starch accumulation in plants will directly impact the biomass production and biofuel industry.(See Sokolov et al., 2006 to get started on this subject).

Dominguez-Solis JR, He Z, Lima A, Ting J, Buchanan BB, Luan S. (2008) A cyclophilin links redox and light signals to cysteine biosynthesis and stress responses in chloroplasts. Proc Natl Acad Sci U S A. 105(42):16386-91. Epub 2008 Oct 9. Abstract

Li L, Liu K, Hu Y, Li D, Luan S. (2008) Single mutations convert an outward K+ channel into an inward K+ channel. Proc Natl Acad Sci U S A. 105(8):2871-6. Epub 2008 Feb 19. Abstract

Chen X, Lin WH, Wang Y, Luan S, Xue HW. (2008) An inositol polyphosphate 5-phosphatase functions in PHOTOTROPIN1 signaling in Arabidopis by altering cytosolic Ca2+. Plant Cell 20(2):353-66. Epub 2008 Feb 5. Abstract

Le-Gong Li, Lubomir N. Sokolov, Yong-Hua Yang, Dong-Ping Li, Julie Ting, Girdhar K. Pandy, and Sheng Luan (2008) A Mitochondrial Magnesium Transporter Functions in Arabidopsis Pollen Development. Mol Plant 1: 675 - 685.

Girdhar K. Pandey, John J. Grant, Yong Hwa Cheong, Beom-Gi Kim, Le Gong Li, and Sheng Luan (2008) Calcineurin-B-Like Protein CBL9 Interacts with Target Kinase CIPK3 in the Regulation of ABA Response in Seed Germination. Mol Plant 1: 238 - 248.

Li H, He Z, Lu G, Lee SC, Alonso J, Ecker JR, Luan, S. (2007) A WD40 Domain Cyclophilin Interacts with Histone H3 and Functions in Gene Repression and Organogenesis in Arabidopsis. Plant Cell. 19, 2403-2416.

Pandey GK, Cheong YH, Kim BG, Grant JJ, Li L, Luan, S. (2007) CIPK9: a calcium sensor-interacting protein kinase required for low-potassium tolerance in Arabidopsis. Cell Res. 17, 411-421. Abstract

Fu A, He Z, Cho HS, Lima A, Buchanan BB, Luan S. (2007) A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana. Proc Natl Acad Sci U S A. 104, 15947-15952. Abstract

Cheong YH, Pandey GK, Grant JJ, Batistic O, Li L, Kim BG, Lee SC, Kudla J, Luan S. (2007) Two calcineurin B-like calcium sensors, interacting with protein kinase CIPK23, regulate leaf transpiration and root potassium uptake in Arabidopsis. Plant J. 52, 223-239. Abstract

Lee SC, Lan WZ, Kim BG, Li L, Cheong YH, Pandey GK, Lu G, Buchanan BB, Luan S. (2007) A protein phosphorylation/dephosphorylation network regulates a plant potassium channel. Proc Natl Acad Sci U S A. 104, 15959-15964. Abstract

Liu, K., Li, L., Luan, S. (2006) Intracellular potassium sensing of SKOR, a shaker-type K-channel from Arabidopsis. Plant J. 46, 260-268.

Sokolov, L., Allery, A., Buchanan, B.B., and Luan, S. (2006) A redox-regulated chloroplast protein phosphatase binds to starch diurnally and functions in its accumulation. Proc. Natl. Acad. Sci. USA. 103, 9732-9737.

Li, L., Kim, B., Cheong, Y., Pandey, G., and Luan, S. (2006) A calcium signaling pathway regulates a potassium channel for low-potassium response in Arabidopsis. Proc. Natl. Acad. Sci. USA. 103:12625-30.

Gopalan G, He Z, Battaile KP, Luan S, Swaminathan K. (2006) Structural comparison of oxidized and reduced FKBP13 from Arabidopsis thaliana. Proteins 65:789-95.

Lima A, Lima S, Wong JH, Phillips RS, Buchanan BB, Luan S. (2006) A redox-active FKBP-type immunophilin functions in accumulation of the photosystem II supercomplex in Arabidopsis thaliana. Proc Natl Acad Sci U S A. 103:12631-6.

D'Angelo C, Weinl S, Batistic O, Pandey GK, Cheong YH, Schultke S, Albrecht V, Ehlert B, Schulz B, Harter K, Luan S, Bock R, Kudla J. (2006) Alternative complex formation of the Ca(2+)-regulated protein kinase CIPK1 controls abscisic acid-dependent and independent stress responses in Arabidopsis. Plant J. 2006 Nov 8; [Epub ahead of print]

Ren ZH, Gao JP, Li LG, Cai XL, Huang W, Chao DY, Zhu MZ, Wang ZY, Luan S*, Lin HX*. (2005) A rice quantitative trait locus for salt tolerance encodes a sodium transporter. Nature Genetics 37, 1141-1146. (News and Views on page 1029-1030, *corresponding author).

Liu K, Li L, Luan S. (2005) An essential function of phosphatidylinositol phosphates in activation of plant shaker-type K+ channels. Plant J. 42, 433-443.

Girdhar K. Pandey, John Grant, Yong-Hwa Cheong, Beom Gi Kim, Legong Li, and Sheng Luan (2005) ABR1, an AP2-Domain Transcription Factor That Functions as a Repressor of ABA Response in Arabidopsis. Plant Physiol. 139, 1185-1193.

Ok SH, Jeong HJ, Bae JM, Shin JS, Luan S, Kim KN. (2005) Novel CIPK1-associated proteins in Arabidopsis contain an evolutionarily conserved C-terminal region that mediates nuclear localization. Plant Physiol. 139, 138-150.

Romano P, Gray J, Horton P, Luan S. (2005) Plant immunophilins: functional versatility beyond protein maturation. (Tanksley Review) New Phytol. 166, 753-69.

Buchanan BB, Luan S. (2005) Redox regulation in the chloroplast thylakoid lumen: a new frontier in photosynthesis research. J Exp Bot. 56, 1439-1447.

Gopalan G, He Z, Balmer Y, Romano P, Gupta R, Heroux A, Buchanan BB, Swaminathan K, Luan S. (2004) Structural analysis uncovers a role for redox in regulating FKBP13, an immunophilin of the chloroplast thylakoid lumen. Proc Natl Acad Sci U S A. 101, 13945-50.

Romano, P., He, Z., and Luan, S. (2004) Introducing immunophilins: from organ transplantation to plant biology. Plant Physiol. 134, 1241-1243.

He, Z. and Luan, S. (2004) Immunophilins and parvulins: superfamily of peptidyl prolyl isomerases in Arabidopsis. Plant Physiol. 134, 1248-1267.

Pandey, G., Cheong, Y., Kim, N., Luan, S. (2004) Calcium sensor calcineurin B-like 9 modulates sensitivityand biosynthesis of ABA in Arabidopsis. Plant Cell 16, 1912-1924.

Kim, K., Cheong, Y., Grant, J., Pandey, G., and Luan, S. (2003) CIPK3, a calcium sensor-associated protein kinase that regulates abscisic acid and cold signal transduction in Arabidopsis. Plant Cell 15, 411-423.

Luan, S. (2003) Protein phosphatases in plants. Annu. Rev. Plant Biol. 54, 69-90.

Hrabak, E., Chan, C., Gribskov, M., Harper, J.F., Choi, J., Halford, N., Kudla, J., Luan S., et al., and Harmon, A.C. (2003) The Arabidopsis CDPK-SnRK Superfamily of Protein Kinases. Plant Physiol. 132: 666-680. [Abstract | PDF]

Gupta, R., and Luan, S. (2003) Redox regulation of protein tyrosine phosphatases and MAP kinases in higher plants. Plant Physiol. 132, 1149-1152.[Full Text | PDF]

Kim, K., Cheong, Y., Grant, J., Pandey, G., and Luan, S. (2003) CIPK3, a calcium sensor-associated protein kinase that regulates abscisic acid and cold signal transduction in Arabidopsis. Plant Cell 15, 411-423. [Abstract | PDF]

Cheong, Y., Kim, K., Pandey, G.K., Gupta, R., Grant, J., and Luan, S. (2003) CBL1, a Calcium Sensor That Differentially Regulates Salt, Drought, and Cold Responses in Arabidopsis. Plant Cell 15, 1833-1845. [Abstract | PDF]

Gupta, R., Mould, R., and Luan, S. (2002) A chloroplast FKBP interact and regulates the accumulation of Rieske subunit of cytochrome b/f complex in photosynthetic electron transport. Proc. Natl. Acad. Sci. USA 99, 15806-15811. [Abstract | PDF]

Gupta, R., Ting, T., Sokolov, L., Johnson, S.J., and Luan, S. (2002) AtPTEN1, a tumor suppressor homologue essential for pollen development in Arabidopsis. Plant Cell 14, 2495--2507. [Abstract | PDF]

Gupta, R., He, Z., and Luan, S. (2002) Functional relationship of cytochrome c6 and plastocyanin in Arabidopsis. Nature 417, 567-571. [Abstract | PDF]

Chen W, Provart NJ, Glazebrook J, Katagiri F, Chang H, Eulgem T, Mauch F, Luan S, et al. and Zhu T. (2002). Expression Profile Matrix of Arabidopsis Transcription Factor Genes Suggests Their Putative Functions in Response to Environmental Stresses. Plant Cell 14, 559-574. [Abstract | PDF | Supplemental data]

Cheong, Y., Chang, H.-S., Gupta, R., Wang, X., Zhu, T., and Luan, S. (2002) Transcriptional profiling reveals novel interaction between wounding, pathogen, abiotic stress, and hormonal responses in Arabidopsis. Plant Physiol. 129, 661-677. [Abstract | PDF | Supplemental data]

Li L, He Z, Pandey GK, Tsuchiya T, and Luan S. (2002) Functional cloning and characterization of a plant efflux carrier for multidrug and heavy metal detoxification. J Biol Chem. 277, 5360-5368.[Abstract | PDF]

Li L, Tutone AF, Drummond RS, Gardner RC, and Luan S. (2001) A novel family of magnesium transport genes in Arabidopsis. Plant Cell 13, 2761-2775. [Abstract | PDF]

Liu, K., and Luan, S. (2001) Internal Aluminum Block of Plant Inward K+ Channels. Plant Cell 13, 1453-1465.[PDF]