Name: cell signaling response speed and patterns
Uploaded: 2023-04-30T11:39:53.000Z
Duration: 1 min 22 s
Channel: JoVE

Signaling pathways translate extracellular and intracellular cues into diverse cellular responses. The output of a pathway may vary in its intensity and time of response, depending on the cell&#8217;s requirements.
Some signaling pathways generate a gradually increasing cellular response as the concentration of signaling molecules increases; the higher the concentration of signaling molecules, the stronger the cellular response.&#160;
On the other hand, some signaling pathways are activated like an on-off switch when the number of signaling molecules is above a certain threshold concentration.
Some cellular processes, such as neurotransmission, need a swift response within milliseconds after receiving a signal. Cells may achieve this with ion concentration changes and protein modifications, such as phosphorylation, that are easily reversible.
In contrast, certain processes, such as cell differentiation, require a prolonged response spanning hours or days. For instance, signaling pathways must continuously induce transcription and translation during embryonic development to regulate cell fate decisions.

diversity in cell signaling responses

Diversity in Cell Signaling Responses

The physiological function of a cell and cellular communication are outcomes of a range of extrinsic signals, intracellular signaling pathways, and cellular responses. No two cell types express the same repertoire of signaling components. Receptors are highly selective for their cognate ligands, but once activated, they can alter multiple cellular processes such as DNA transcription, protein synthesis, and metabolic activity.&#160;
Graded and Abrupt Responses 
Some signaling systems generate smoothly graded responses that vary proportionately with the signal concentration. For example, complexes made up of steroid hormone and its nuclear receptor bind to specific steroid hormone-responsive genes and cause increase or decrease in the mRNA production in proportion to the hormone concentration.
Some responses can also occur in an all-or-none (discontinuous) manner, where they are undetectable below the threshold concentration and reach a maximum level as soon as they cross the threshold. Such responses are irreversible. For example, at the neuromuscular junction, the activation of acetylcholine receptor-dependent ion channels causes Na+ influx into the muscle cells, depolarizing a part of the plasma membrane. The depolarization leads to the opening of the voltage-gated Na+ channels in the same membrane region, causing a higher influx of Na+ and further membrane depolarization. As additional Na+ channels open, the depolarization exceeds the threshold, and an action potential propagates to the entire muscle membrane.
Fast and Slow responses
Response timing is the time a cell takes to respond to an extracellular signal that varies significantly between different signaling systems. Certain cellular responses are highly rapid. For example, ion channels can open up to cause a change in the membrane potential within milliseconds of receiving the signal. Other responses, such as protein synthesis or metabolic alterations, can take several minutes. Some responses can also take hours and days, for example, cell division and programmed cell death.
The speed of any signaling response mainly depends on the nature of the intracellular signaling molecules involved in the response. For example, if proteins already present in the cell only need to be modified for activation/ deactivation (such as by phosphorylation or binding of GTP), then the response would occur rapidly. If changes in gene expression have to occur in response to a signal (such as during embryonic development), the response can take several minutes or hours. Responses that occur at a fast pace are transient and can be rapidly reversed. Whereas responses that occur at a slow pace mostly generate long-term or permanent cellular changes.

The physiological function of a cell and cellular communication are outcomes of a range of extrinsic signals, intracellular signaling pathways, and ...

Education

JoVE Core

Cell Biology

Unit 1

Principles of Cell Signaling

KEY TERMS AND CONCEPTS

cell signaling response speed and patterns

Cell signaling responses can differ in both pattern and speed. A cell’s function and communication depend on outside signals, internal signaling pathways, and the response that follows. Different cell types do not use the same set of signaling parts. Receptors are selective for their matching ligands, but once activated, they can affect DNA transcription, protein synthesis, and metabolism.

Some signaling systems produce graded responses. In a graded response, the cell output changes in proportion to the signal strength. Steroid hormone receptors are one example. Steroid hormone-receptor complexes bind to steroid hormone-responsive genes and increase or decrease mRNA production according to the hormone concentration.

Other responses are abrupt and act in an all-or-none way. These responses stay below detection until the signal reaches a threshold. Once that threshold is crossed, the response reaches its maximum level. In many cases, this kind of response is irreversible. At the neuromuscular junction, acetylcholine receptor-dependent ion channels let Na+ enter muscle cells. This depolarizes part of the plasma membrane. The depolarization opens nearby voltage-gated Na+ channels, which brings in even more Na+ and strengthens the change until an action potential spreads across the whole muscle membrane.

Cell signaling also varies in timing. Some responses happen within milliseconds, such as ion channels opening and changing membrane potential. Others take minutes, such as protein synthesis or changes in metabolism. Some responses take hours or days, including cell division and programmed cell death.

The speed of a response depends mainly on the intracellular signaling molecules involved. If the cell only needs to modify proteins that are already present, such as by phosphorylation or GTP binding, the response is rapid. If the signal must change gene expression, as in embryonic development, the response can take minutes or hours. Fast responses are usually transient and can be reversed quickly. Slow responses often create long-term or permanent changes in the cell.

Cell Signaling Response Speed and Patterns

cell-signaling-response-speed-and-patterns

overview of cell signaling

Cell Signaling Pathways and Responses

Cell signaling pathways help cells detect changes and respond to their environment. Cells also use signaling to communicate with other cells. Both unicellular and multicellular organisms rely on these signaling systems to share information. Cells often receive messages through receptor proteins on the cell membrane. Skin cells can respond to touch, and photoreceptors in the retina can detect light. Most cells respond to chemical signals such as hormones and neurotransmitters, and the same...

types of signaling molecules

Cell Signals That Travel Between Cells

Cell signals that travel between cells carry information in multicellular organisms. These signaling molecules can be small peptides, nucleotides, steroids, fatty acid derivatives, or dissolved gases such as nitric oxide. Some signals act near the cell that released them, while others move over long distances. Other signals stay on the cell surface and work only when cells make contact. Some signaling proteins need extra processing before they can act. Peptide and protein signals are made as...

types of receptors: cell surface receptors

types-of-receptors-cell-surface-receptors

Cell Surface Receptors and Signal Relay

Cell-surface receptors help cells detect signals outside the cell and relay them inward. They are also called transmembrane receptors because they sit in the cell membrane and span the plasma membrane. A ligand is the molecule that binds to the receptor, and it does not need to enter the cell to trigger a response. These receptors are membrane-anchored, integral proteins. They have three main parts. The extracellular domain binds the ligand outside the cell, the transmembrane domain passes...

types of receptors: internal receptors

Steroid Hormone Signaling with Intracellular Receptors

Steroid hormones and other small signaling molecules can enter the cell and bind intracellular receptors. These receptors are found in the cytoplasm or the nucleus. Because the ligands are hydrophobic, they can cross the plasma membrane, unlike many hydrophilic signals. When a ligand binds an intracellular receptor, the receptor changes shape and becomes active. The active receptor can work like a transcription factor. It binds to specific DNA sites and can increase or decrease the...

assembly of signaling complexes

Protein Docking in Cell Signaling

Protein docking helps cells build signaling complexes that pass messages inside the cell. These multiprotein complexes form through protein-protein interactions at the cytoplasmic side of transmembrane receptors. They can also include enzymatic and non-enzymatic proteins linked to the receptor. Together, they help activate and spread intracellular signals that control cell functions. Cell signaling often depends on interaction domains, which are protein parts that recognize specific binding...

interactions between signaling pathways

Cross-Talk in Cell Signaling Pathways

Cell signaling pathways often cross-talk with one another. This means one pathway can influence another instead of acting alone. Cells use these linked pathways to combine signals from the environment and respond in a controlled way. One common pattern is convergence. In convergence, two separate signaling pathways meet at the same functional unit. That unit may be a single protein or a protein complex. The final response can be different from, or stronger than, the response from either...

amplifying signals via second messengers

Cell-Surface Receptors and Second Messengers

Cell-surface receptors use second messengers to carry signals into the cell. Many receptor-binding ligands are hydrophilic, so they do not cross the cell membrane. Instead, they bind to receptors on the outside of the cell and pass the message to the cytoplasm. G protein-coupled receptors can activate the phosphoinositol pathway and the cAMP pathway. In the phosphoinositol pathway, the receptor activates phospholipase C. This enzyme splits phosphatidylinositol biphosphate, or PIP2, into two...

amplifying signals via enzymatic cascade

Turning Off Amplified Cell Signals

Cell signaling depends on both signal amplification and signal shutoff. When a ligand binds to a cell-surface receptor, the receptor changes shape inside the cell. That change can activate an enzyme function or let the receptor bind other molecules. In many signal transduction pathways, one ligand can trigger many downstream targets, so the signal is amplified. Proteins that pass the signal are often phosphorylated, which means a phosphate group is added at one or more sites. This modification...

Cell signaling responses can differ in both pattern and speed. A cell’s function and communication depend on outside signals, internal signaling pathways, and the response that follows. Different cell types do not use the same set of signaling parts. Receptors are selective for their matching ligands, but once activated, they can affect DNA transcription, protein synthesis, and metabolism. Some signaling systems produce graded responses. In a graded response, the cell output changes in...

cell signaling feedback loops

How Cells Balance Signal Strength

Cell signaling is controlled by feedback loops that connect a cell’s output back to its input. Positive feedback and negative feedback help keep signaling systems working in the right range. These loops are especially important when cells need to respond quickly and then adjust that response. Negative feedback loops act as output limiters in many signaling systems. After an input signal starts a response, the response rises quickly until it reaches a threshold. Beyond that point, the negative...

cell signaling in plants

Plant Receptor Kinases and Growth Signals

Plant receptor kinases help cells communicate and control growth, flowering, fruiting, and activity in roots, shoots, and leaves. These signals also help plants respond to changing environmental conditions. Plant signaling works differently from animal signaling, so the receptors used in plants are not the same as those commonly found in animals. Plants mainly use enzyme-linked receptors. In animals, the largest class of cell-surface receptors is the G-protein coupled receptor, or GPCR.

plant hormones

Plant Hormones and Growth Signals

Plant hormones are chemical signals that help control growth and development in plants. They allow different parts of a plant to communicate and respond to changes in the environment. The main plant hormones include auxin, gibberellins, cytokinins, abscisic acid, and ethylene. Each one has a different role, but they often work together to shape how a plant grows, matures, and reacts to stress. Auxin helps direct plant growth, while gibberellins support stem elongation and seed germination.

key terms and concepts

Explore how cells respond to signals with graded, all-or-none, fast, and slow responses. Learn examples from steroid hormones and neuromuscular signaling.

Cell Signaling Response Speed and Patterns | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Cell Signaling Response Speed and Patterns

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