This document discusses biological crosstalk in signal transduction pathways, highlighting how components from different pathways can interact and influence each other, particularly through protein interactions. Examples include mechanisms of inhibition and activation within lymphocyte signaling and the role of salicylic acid, jasmonic acid, and ethylene in pathogen defense in plants. It also addresses cellular responses to environmental stresses such as drought and cold, focusing on transcription factors involved in cross-talk between these stress signals.

1. Course – PP– 603 – Signal Perceptions and Transductions
and Regulations of Physiological Processes (2+0)
Topic - Cross talk between signalling pathway
Department of Plant Physiology
Presented By -
Jyoti Prakash Sahoo
01ABT/PHD/17
Dept. of Agril.
Biotech.
OUAT, BBSR
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2.  Biological crosstalk refers to instances in which
one or more components of one signal transduction
pathway affects another.
 This can be achieved through a number of ways
with the most common form being crosstalk between
proteins of signaling cascades.
 In these signal transduction pathways, there are
often shared components that can interact with either
pathway.
 A more complex instance of crosstalk can be
observed with transmembrane crosstalk between the
extracellular matrix (ECM) and the cytoskeleton.
Cross talk Biology
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3. Crosstalk between signalling
pathways
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4. Crosstalk between signalling pathways -
Example
 Mechanism of cAMP/PKA inhibition of ERK activation (MAPK
pathway)
 cAMP activation of PKA activates Rap1 via Src
 Rap1 then phosphorylates Ras and inhibits signaling to Raf-1.
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5. Transmembrane crosstalk
 The matrix can play into other pathways inside the cell even
through just its physical state.
 Matrix immobilization inhibits the formation of fibrillar adhesions
and matrix reorganization.
 Likewise, players of other signaling pathways inside the cell can
affect the structure of the cytoskeleton and thereby the cell’s
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6. Crosstalk in lymphocyte activation
 Even without activation by a
ligand bound to the receptor
(R1), the MAPK pathway
normally shows basal activity
(at low levels). However, HePTP
counteracts this activity.
 Activation of the cAMP pathway by
binding of ligand to its appropriate
receptor (R2) leads to the activation of
cAMP-dependent protein kinase (PKA)
by adenylate cyclase (AC).
 This activated PKA then
phosphorylates HePTP at Ser23,
inhibiting its ability to bind to Erk and
subsequently inhibit the MAPK
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7. Salicylic acid (SA), Jasmonic acid (JA) and Ethylene
(ET) crosstalk against necrotrophic and biotrophic
pathogens
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8. A working model of the SA, JA and ET pathogen
defense pathways in Arabidopsis thaliana
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9. Cellular signal transduction pathways between the
initial drought-stress or cold-stress signal
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10. Molecular responses to dehydration and low
temperature based on stepwise gene expression
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11. The DREB1 and DREB2 transcription factors, key
components in cross-talk between cold and
drought signalling in Arabidopsis.
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12. Transcriptional regulation of stress-responsive
genes in response to osmotic stress
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Regulation of a cold-stress-responsive
transcriptome and freezing tolerance

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S. Mahajan, N. Tuteja / Archives of Biochemistry and Biophysics 444
Ion Homeostasis – Salinity
Tolerance

15. Pathways for reactive oxygen intermediate (ROI)
scavenging in plants for oxidative stress,
antioxidants and stress tolerance
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Pathways for ROS-scavenging in plant cell Mittler, 2002; Apel and
Superoxide dismutase (SOD)
Ascorbate peroxidase (APX)
Catalases (CAT)
Glutathione reductase (GR)
GSH(reduced
glutathione)
GSSG (oxidized
glutathione)
chloroplasts
chloroplast,
cytosol,
mitochondri
a, apoplast
and
peroxisome
s
peroxisomes

16. Differences in the steady-state levels of reactive
oxygen intermediates (ROI) during biotic stress
and abiotic stress.
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17. A suggested model for the activation of signal
transduction events during oxidative stress
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CDPK and MAPK Cascades In Stress
Crosstalking

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References

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