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Why Cell Signaling?
Cell signaling affects:• Development• Tissue Repair • Immunity • Movement • Diseases
• Complex system of communication
• Affects a cell’s ability to respond to its environment
What Happens When Cells Miscommunicate??Diabetes Rheumatoid Arthritis Cancer
Multiple Sclerosis LupusAsthma
How Do Cells Send Signals?
1. Contact Dependent
2. Autocrine3. Paracrine4. Synaptic 5. Endocrine
There are five different types of signaling pathways:
Why does such a variety of signaling
pathways exist?
Three Stages to Extracellular Signaling1. Ligand Binding
– Ligand binding to receptor induces conformational change
2. Transduction– Amplification and spreading of
signal down specific pathways in cell
3. Cellular Response– Cell response to signal – May result in any of the following:
i. Gene transcriptionii. Cell proliferation/divisioniii. Cell survival
Extracellular Signaling in a Nutshell
The signaling cell produces a particular type of signal molecule that is detected by the target cell. The target cells possess receptor proteins that recognize and respond specifically to the signal molecule.
Seem Simple? Think Again
How many different signaling molecules exist?• HUNDREDS
How do you think this effects a signals ability to be transduced? • Each cell responds selectively to a mixture of signals
– Disregards some– Reacts to others
What complications can arise?• One signal, binding to one type of receptor protein, can cause a variety of effects in the
target cell• Cells have an assortment of different receptors, making them sensitive to many signals
Cellular Suicide?
What do you think happens in the absence of signals?• In most cases, cells kill themselves.
Strengthening and Maintaining a Signal
Recall Synaptic Signaling Pathway
How can we alter/strengthen a signal?• Neuroplasticity – ability to reorganize neural
pathways based on new experiences
4 Stages to Neuroplasticity
1. Induction – Neuron realizes input needs to be changed
2. Selectivity – Type of change is based on input parameters (gain
or loss)
3. Expression – Synaptic efficiency is changed
4. Maintenance– Change is maintained over long period of time