People
Current Lab Members
Dr. Sheng Luan, Principal Investigator email
Dr. Legong Li, Postgraduate Researcher email
Dr. Aigen Fu, Postdoc
email
Dr. Lubomir N. Sokolov, Postgraduate
Researcher
email
Dr. Jose R. Dominguez-Solis, Postdoc
email
Dr. Wenzhi Lan, Postdoc
email
Dr. Hye Sun
Cho, Postdoc email
Dr. Sung Chul Lee,
Postdoc email
Dr. Hong Li, Postdoc email
Lee
Chae, Graduate Student email
Leila Ross, Undergraduate Student
Stefanie, Undergraduate
Student
Former Lab Members
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Research
Projects
Signal Transduction and
Chloroplast Biology
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.
Current
Projects
Environmental
Sensing Using Ca2+
as a Ubiquitous Messenger
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.
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.
Environmental
Adaptation through Metabolic Regulation in the
Chloroplast
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.
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.
Recent Publications
For Abstracts, PDFs
[Please
Click Here]
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
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.
65:789-95.
Pandey,
G.K., Cheong, Y.H, Kim, K.-N., Grant, J.J., Li, L., Hung, W.,
D'Angelo, C., Weinl, S., Kudla, J., and Luan, S. (2004) The Calcium
Sensor Calcineurin B-Like 9 Modulates Abscisic Acid Sensitivity and
Biosynthesis in Arabidopsis Plant Cell. 16: 1912-1924.
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.
Gupta,
R., and Luan, S. (2003) Redox regulation of protein tyrosine
phosphatases and
MAP kinases in higher plants. Plant Physiol. 132,
1149-1152.
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.
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
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.
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.
Gupta,
R., He, Z., and Luan, S. (2002) Functional relationship of cytochrome
c6 and plastocyanin in Arabidopsis. Nature 417, 567-571.
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.
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.
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.
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.
Liu, K., and Luan, S. (2001) Internal Aluminum Block of
Plant Inward K+ Channels. Plant Cell 13, 1453-1465.
Kim, K.N., Cheong, Y.H., Gupta, R., and Luan, S. (2000)
Interaction Specificity of Arabidopsis Calcineurin B-Like Calcium
Sensors and Their Target Kinases. Plant Physiol. 124,
1844-1853.
Liu, K., Fu, H.H., Bei, Q., and Luan, S. (2000) Inward
Potassium Channel in Guard Cells As a Target for Polyamine Regulation
of Stomatal Movements. Plant Physiol. 124, 1315-1326.
Huang Y, Li H, Gupta R, Morris PC, Luan S, and Kieber JJ.
(2000) ATMPK4, an Arabidopsis
homolog of mitogen-activated protein kinase, is activated in vitro by
AtMEK1 through threonine phosphorylation. Plant Physiol.
122, 1301-1310.
Shi, J., Kim, K.N., Ritz, O.,
Albrechtb, U., Gupta, R., Harterc, K., Luan, S., and Kudlab, J. (1999)
Novel Protein Kinases Associated with Calcineurin B-like Calcium
Sensors in Arabidopsis. Plant Cell, 11, 2393-2406.
Kudla, J., Xu, Q., Harter, K.
Gruissem, W. and Luan, S. (1999) Genes for calcineurin B-like proteins
in Arabidopsis are
differentially regulated by stress signals. Proc. Natl. Acad.
Sci. USA 96, 4718-4723.[a
commentary on this article: Trewavas, A. (1999) How plants learn. PNAS
96, 4216-4218.]
Gupta, R., Huang, Y., Kieber, J.J. and
Luan, S. (1998) Identification of a dual- specificity protein
phosphatase that inactivates MAP kinase in Arabidopsis. Plant J.
16, 581-590.
Liu, K. and Luan, S. (1998)
Voltage-dependent K+ channels as targets for osmosensing in guard
cells. Plant Cell 10, 1957-1970.
Xu, Q., Liang, S., Kudla, J. and Luan,
S. (1998) Molecular characterization of a plant FKBP12 that does not
mediate action of FK506 and rapamycin. Plant J. 15,
511-520.
Fu, H. and Luan, S. (1998) AtKUP1: a
dual-affinity K+ transporter in Arabidopsis. Plant Cell
10, 63-73
Bei, Q. and Luan, S. (1998) Functional
expression and characterization of a plant K+ channel gene in a plant
cell model. Plant J. 13, 857-865.
Xu, Q., Fu, H., Gupta, R. and Luan, S.
(1998) Molecular characterization of a protein tyrosine phosphatase
encoded by a stress-responsive gene in Arabidopsis. Plant Cell
10, 849-857.
Luan, S., Kudla, J., Gruissem, W., and
Schreiber, S.L. (1996) Molecular characterization of a
FKBP-type immunophilin from higher plants. Proc. Natl. Acad.
Sci. USA. 93, 6964-6969.
Luan, S., and Schreiber, S.L. (1994)
pCyP B: a chloroplast-localized, heat shock-responsive cyclophilin from
fava
bean. Plant Cell 6, 885-892.
Luan, S., Albers, M.W., and Schreiber,
S.L. (1994) Light-regulated, tissue-specific immunophilins in a higher
plant. Proc. Natl. Acad. Sci. USA 91, 984-988.
Li, W., Luan, S., Schreiber, S.L. and
Assmann, S.M. (1994) Cyclic AMP Stimulates K+ channel Activity in
Mesophyll Cells of V. faba. Plant Physiol. 106, 963-970.
Li, W., Luan, S., Schreiber, S.L., and
Assmann, S.M. (1994) Evidence for protein phosphatase 1 and 2A
regulation of K+ channels in two types of leaf cells. Plant
Physiol. 106, 957-961.
Luan, S., Li, W., Rusnak, F., Assmann,
S.M. and Schreiber, S.L. (1993) Immunosuppressants implicate protein
phosphatase-regulation of K+ channels in guard cells. Proc.
Natl. Acad. Sci. USA 90, 2202-2206.
Liu, J., Albers, M.W., Wandless, T.J.,
Luan, S. Alberg, D., Belshaw, P., McIntosh, C., Klee, C.B., Cohen, P.
and Schreiber, S.L. (1992) Inhibition of T cell signaling by
immunophilin ligand complexes correlates with loss of calcineurin
phosphatase activity. Biochemistry 31, 3897-3901.
Luan, S. and Bogorad, L. (1992) A rice
gene promoter contains separate cis-acting elements for the expression
in dicot and monocot plants. Plant Cell 4, 971-981.
Luan, S. and Bogorad, L. (1989)
Nucleotide sequences of two genes encoding the light harvesting
chlorophyll a-b binding protein of rice. Nucleic Acids Res.
17, 2357-2358.
Reviews and Book Chapters
Luan, S. (2003) Protein phosphatases
in plants. Annu. Rev. Plant Biol. 54, 69-90.
Luan,S., Kudla, J., Gruissem, W.
(2002) Calmodulins and calcineurin B-like proteins: calcium sensors for
specific signal response coupling in plants.Plant Cell
14, 389-400.
Luan, S. (2002) Tyrosine
phosphorylation in plant cell signaling. Proc. Natl.
Acad. Sci. USA. 99, 11567-11569.
Luan, S. (2001) Signaling Drought in
Guard Cells. Plant Cell Environment 25, 229-237.
Luan, S., Gupta,
R., and Ting, T. (2001) Tyrosine phosphatases in higher plants. New
Phytol. 151, 155-164.
Luan, S. (1999)
Plant protein phosphatases. In "Plant Protein Phosphorylation"
Ed. M. Kreis and J.C. Walker. Academic Press (London, UK).
Luan, S. (1998)
Protein phosphatases and plant signaling
cascades. Trends Plant Sci. 3, 271-275.
Luan, S. (1998)
Immunophilins in animals and higher
plants. Bot. Bull. Acad. Sin. 39, 217-223.
Luan, S. (1998)
Protein phosphatases in higher plants. Acta Bot. Sin.
40, 883-889.
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