CELL SIGNALLING
(cell signaling)
British vs. Amer. English
• Why does CELL SIGNALLING exist in nature? All cells receive and respond
to signals from their surroundings. Even the simplest bacteria sense and swim
toward high concentrations of nutrients, such as glucose or amino acids.
Many unicellular eukaryotes also respond to signaling molecules secreted by
other cells, allowing cell-cell communication. Mating between yeast cells, for
example, is signaled by peptides that are secreted by one cell and bind to
receptors on the surface of another. It is in multicellular organisms, however,
that cell-cell communication reaches its highest level of sophistication.
Whereas the cells of prokaryotes and unicellular eukaryotes are largely
autonomous, the behavior of each individual cell in multicellular plants and
animals must be carefully regulated to meet the needs of the organism as a
whole. This is accomplished by a variety of signaling molecules that are
secreted or expressed on the surface of one cell and bind to receptors
expressed by other cells, thereby integrating and coordinating the functions of
the many individual cells that make up organisms as complex as human
beings.
• The binding of most signaling molecules to their receptors initiates a series of
intracellular reactions that regulate all aspects of cell behavior, including
metabolism, movement, proliferation, survival, and differentiation.
Understanding the molecular mechanisms responsible for these pathways of
cell signaling has thus become a major area of active research (important for
cytostatic and other anti-cancer drug, regeneration, anti-apoptotic drug, …).
Rule 2
Rule 3
Learn the scheme!!!
1)
2)
3)
4)
5
5) …and very specific JUXTARINE cell-to-cell signaling
type of cell–cell or cell–extracellular matrix signaling in multicellular organisms that requires close contact. There are
three subtypes:
A B C
A = communicating junction links the intracellular compartments of two adjacent cells, allowing transit
of relatively small molecules.
B = membrane ligand (protein, oligosaccharide, lipid) and a membrane protein of two adjacent cells
interact.
C = ExtraCellular matrix (ECM) such as glycoprotein and a membrane protein interact
Additionally, in unicellular organisms such as bacteria, juxtacrine signaling means interactions by
membrane contact. Juxtacrine signaling has been observed for some growth factors, cytokine and
chemokine cellular signals, playing an important role in the immune response.
Mechanism of singaling
Overview – signal net
Most important signal molecules in clinical pharmacology and experimental
biology.
Please, learn
minimaly
5 hormones
and
5 local mediatores
And
2 neurotransmiter
(Name
Chemical nature
Action)
Signaling is important for
a) CELL CYCLE
b) APOPTOSIS
c) NON-apoptotic death
• (note: necrosis is very fast and unprogramed death,
where injury or toxic enviroment prevent apoptosis or another
non-apoptotic death, cell is lysed and solution is dangerous
for near cells in tissue)
a) Cell cycle
b) Apoptosis
apoptosis
- microscopical view to tissue
Example of apoptosis in rat heart (infarction of myocardium)
Apoptitc staining Control
• Figure 5C illustrates cleaved caspase-3 staining for apoptosis revealing the presence of intracytoplasmic positive
myofibers (small arrows) located in the interventricular septum; large arrow indicates an apoptotic body. Figure 5D
is a negative control of the same heart demonstrated in 5C. The small arrows demonstrate degenerating
myofibers; large arrows indicate apoptotic bodies.
(note: This proteolytic cascade, in which one caspase can activate other caspases, amplifies the apoptotic signaling
pathway and thus leads to rapid cell death )
apoptosis
Some advanced article for future study (not in exam)
(apoptosis is important curative factro in ancer, infarcted region, neurodageneratie d.)
Inhibiting the inhibitors: Targeting anti-apoptotic proteins in cancer and therapy resistance
Nir Shahar 1, Sarit Larisch 2
Abstract The cytotoxic effect of anti-cancer drugs relies on their ability to induce programmed
cell death known as apoptosis. Evading apoptosis is a common characteristic of cancer cells and it
is linked to both carcinogenesis and anticancer drug resistance.
Revisiting miRNA-21 as a Therapeutic Strategy for Myocardial Infarction:
A Systematic Review
V Sothivelr, MY Hasan, S Mohd Saffian… - Journal of …, 2022
Studies described thecardioprotective effects of miR-21 to reduce infarct size
by improving angiogenesis, antiapoptotic...
An overview of investigational antiapoptotic drugs with potential application
for the treatment of neurodegenerative disorders
A. Camins, F. Sureda, +4 authors M. Pallàs, 2010
c) NON-apoptotic death (learn minimaly 5 death-names and 5 initial signal molecule)
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