Name: touch and heat sensors in cell membranes
Uploaded: 2023-04-30T10:16:02.000Z
Duration: 1 min 12 s
Channel: JoVE

Mechanically-gated ion channels are transmembrane proteins that open in response to various stimuli like pressure, touch, sound, and temperature.
Through these open channels, ions move down their electrochemical gradient depolarizing the membrane. This leads to the propagation of an action potential to the central nervous system to induce appropriate responses.
The most extensively studied PIEZO channels open in response to mechanical stress like touch and pressure. Interestingly, these channels respond not only to external stimuli but are also internal sensors for blood pressure regulation and breathing.
Another type, TRP ion channels, have a broad role in sensory perception. On touching a hot surface,&#160; TRPV1, a temperature-gated ion channel at the nerve ending, opens. Sodium and calcium ions pass through this open channel, changing the nerve fibers&#39; membrane potential. This generates an action potential that travels to the brain, triggering a painful and burning sensation.

mechanically-gated ion channels

Mechanically-gated Ion Channels

Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, compression, swelling, and shear stress can alter the conformation of the protein, opening a transmembrane channel that allows the passage of ions for signal transmission. In eukaryotes, mechanically-gated channels are distributed in several regions like the neurons, lungs, skin, bladder, and heart, where they play critical roles in numerous physiological and pathophysiological processes.
In 2021 the Nobel Prize in Physiology or Medicine was awarded to David Julius and Ardem Patapoutian for their discovery and advancement of the knowledge of mechanically-gated ion channels, TRP, and Piezo channels.
David Julius discovered the presence of transient receptor potential (TRP) channels are expressed in many cell types and tissues. Some members of this large family of proteins act like thermometers involved in hot and cold sensations. Like the TRPV1, it gets activated by several factors such as temperature higher than 43 &#8451;, allyl isothiocyanate found in wasabi and mustard, and capsaicin, the hot component of peppers. So when we eat something spicy, the intense heat generated causes sweating. This is because the channel gets activated by capsaicin, allowing sodium and calcium ions to flow through it into the cell. This triggers electrical activity that sends messages of spice sensation and pain to the brain.
Ardem Patapoutian worked on the Piezo channels, the novel class of mechanosensitive ion channels. He discovered that these channels are required for the perception of touch and proprioception. Abnormalities in the functioning of these channels can cause muscular and neuronal degeneration, cardiac myopathies, hypertension, and cancer. In certain cancers, the upregulation of Piezo channels allows calcium ions influx, thereby modulating key calcium-dependent signaling pathways associated with cancer progression.&#160;

Mechanically-gated ion channels are proteins found in eukaryotic and prokaryotic cell membranes that open in response to mechanical stress. Tension, ...

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JoVE Core

Cell Biology

Unit 1

Channels and the Electrical Properties of Membranes

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KEY TERMS AND CONCEPTS

touch and heat sensors in cell membranes

Mechanically-gated ion channels are membrane proteins that open when cells experience physical stress. Tension, compression, swelling, and shear stress can change the shape of the protein. That change opens a transmembrane pore and lets ions pass to help transmit signals.

In eukaryotes, these channels are found in several body regions, including neurons, lungs, skin, bladder, and heart. They support many normal physiological processes. They are also involved in disease when their function changes.

The 2021 Nobel Prize in Physiology or Medicine recognized David Julius and Ardem Patapoutian for discoveries that advanced knowledge of mechanically-gated ion channels, TRP channels, and Piezo channels. Julius studied transient receptor potential, or TRP, channels. These proteins are found in many cell types and tissues. Some TRP channels act like thermometers and help with hot and cold sensations.

TRPV1 is one TRP channel with several triggers. It responds to temperatures above 43 °C, allyl isothiocyanate found in wasabi and mustard, and capsaicin, the hot compound in peppers. When capsaicin activates the channel, sodium and calcium ions move into the cell. This starts electrical activity that carries spice and pain signals to the brain. The heat response also explains why spicy food can cause sweating.

Patapoutian studied Piezo channels, a new class of mechanosensitive ion channels. He showed that they are needed for touch and proprioception, which is the sense of body position. When Piezo channels do not work properly, muscular and neuronal degeneration, cardiac myopathies, hypertension, and cancer can occur. In some cancers, higher Piezo channel activity allows calcium ions to enter cells and affect calcium-dependent signaling pathways linked to cancer progression.

Touch and Heat Sensors in Cell Membranes

aquaporins

Aquaporins and Membrane Transport

Aquaporins are membrane proteins that move water across cell membranes. Some aquaporins, called aquaglyceroporins, also transport glycerol. A few aquaporins may also help move volatile substances such as carbon dioxide and ammonia. These channels are found in many different tissues. Water-selective aquaporins are important in the kidneys, exocrine glands, and central nervous system. Aquaporins that may act as gas channels are often highly expressed in red blood cells, epithelial cells, and...

non-gated ion channels

Leak Channels in Resting Membranes

Leak channels are ion channels that let charged ions move across the plasma membrane without a gate. These proteins help maintain membrane potential, which is essential for cell survival. They can move more than a thousand ions in milliseconds during a cellular event. Unlike gated ion channels, non-gated channels have no opening trigger. They are also called leakage or passive channels. Instead, they switch between open and closed states at an intrinsic rate, so ions keep “leaking” through...

ligand-gated ion channels

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Ligand-gated ion channels are membrane proteins that open when a chemical signal binds to them. They have a channel for ions to pass through and a ligand-binding site. When the ligand attaches, the channel opens and ions can move across the cell membrane. These channels are grouped into three subfamilies. The Cys-loop group includes nicotinic acetylcholine receptors, gamma-aminobutyric acid (GABA) receptors, glycine receptors, and 5-hydroxytryptamine receptors. The pore-loop group includes...

voltage-gated ion channels

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Voltage-gated ion channels control electrical signals in neurons, heart cells, and muscle cells. These transmembrane proteins open and close when the membrane potential changes. They sit in the cell membrane of electrically excitable cells and help ions move across it. Each channel includes a voltage-sensing domain that spans the lipid bilayer. Charged residues in this sensor shift when the membrane potential changes. That movement opens the channel and allows ions to pass through. Different...

Mechanically-gated ion channels are membrane proteins that open when cells experience physical stress. Tension, compression, swelling, and shear stress can change the shape of the protein. That change opens a transmembrane pore and lets ions pass to help transmit signals. In eukaryotes, these channels are found in several body regions, including neurons, lungs, skin, bladder, and heart. They support many normal physiological processes. They are also involved in disease when their function...

neuron structure

Neuron Signaling and Synapses

Neurons are the main cells of the nervous system that generate and pass along electrochemical signals. They communicate with one another mainly through neurotransmitters at special connections called synapses. Neurons can have different shapes, and those shapes often match their function. Most, however, share three main parts: a cell body, dendrites, and an axon. The cell body, or soma, contains the nucleus and the organelles needed for cell activity. Dendrites extend from the soma and usually...

resting membrane potential

How Neurons Keep a Negative Voltage

Neurons keep a negative voltage across their membrane when they are at rest. This membrane potential is the voltage difference between the inside and outside of a cell. In a resting neuron, it is usually around -70 millivolts, which means the inside is more negative than the outside and the cell is polarized. This negative charge depends on two main factors. The membrane is selectively permeable, so most ions and molecules cannot cross the lipid bilayer without help from ion channel proteins.

resting potential decay

Resting Membrane Potential Maintenance

The resting membrane potential stays near -70 mV in a neuron because the membrane allows ions to move in a selective way. At rest, the membrane is slightly permeable to sodium ions (Na+) and chloride ions (Cl-) and highly permeable to potassium ions (K+). Ion channels and pumps keep the concentration differences between the inside and outside of the cell in place. Potassium leak channels let K+ move out of the cell at rest. This outward movement makes the inside of the cell more negative. A...

action potential

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Nerve signals travel down axons as action potentials, which are electrochemical pulses that let neurons communicate. This signal moves to the axon terminals and triggers neurotransmitter release, passing information through the nervous system. An action potential is an all-or-none change in membrane potential that produces a fast spike in voltage. Neurons usually rest at about -70 millivolts. When they receive input from neurotransmitters or sensory stimuli, the membrane potential can become...

channel rhodopsins

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Channel rhodopsins are light-sensitive ion channels found in some organisms. They belong to the rhodopsin family, which also includes photoreceptors in bacteria, plants, and the vertebrate retina. These proteins use bound chromophores, such as retinal in rhodopsins and bilin in phytochromes, to respond to light. Rhodopsins are a group of cell surface proteins called G-protein coupled receptors. These proteins help move signals across biological membranes. Over evolution, the rhodopsin family...

patch clamp

Recording Ion Channel Currents with Patch Clamp

Patch clamp is a lab method used to record electrical currents across a cell membrane. It helps scientists study how ions move through channels in the membrane. These electrical signals are important for functions such as muscle contraction and nerve transmission. The method uses a glass micropipette filled with electrolyte solution. The pipette is sealed tightly to a small part of the cell membrane. This creates an electrically isolated patch, so ions moving through the channels flow into the...

electrical synapses

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chemical synapses

How Neurons Signal at Synapses

Chemical synapses let neurons pass signals to another neuron, a muscle cell, a gland cell, or a sensory cell. They use neurotransmitter molecules released from synaptic vesicles to carry the message. Because of that process, there is a short delay of about one millisecond between the arrival of the action potential and the opening of ion channels on the postsynaptic cell. Chemical synapses also send information in one direction only. A synaptic cleft separates the presynaptic and postsynaptic...

excitatory and inhibitory effects of neurotransmitters

excitatory-and-inhibitory-effects-of-neurotransmitters

How Neurotransmitters Trigger or Block Signals

Neurotransmitters can either trigger or block signals at a chemical synapse. When an action potential reaches the presynaptic axon terminal, it causes the neuron to release neurotransmitters into the synaptic cleft. The released molecule then binds to specific receptors on the postsynaptic cell membrane. A molecule is usually identified as a neurotransmitter when it is present in the presynaptic neuron, released in response to strong presynaptic depolarization, and matched with receptors on...

muscle contraction

How Muscles Receive Signals to Contract

Muscle contraction begins when a nerve signal reaches a skeletal muscle fiber. At the motor endplate, a motor neuron releases acetylcholine, a neurotransmitter that carries the signal to the muscle cell. Acetylcholine binds to receptors on the sarcolemma, the muscle cell membrane, and lets sodium ions enter the cell. This starts an action potential in the muscle fiber and helps pass electrical signals from the brain to the muscle. The signal must also be controlled so the muscle does not stay...

the role of ion channels in neuronal computation

the-role-of-ion-channels-in-neuronal-computation

How Ion Channels Shape Neuron Firing

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long-term potentiation

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long-term depression

Synaptic Weakening in Memory Circuits

Long-term depression, or LTD, is a form of synaptic weakening in the brain. It is one way synaptic plasticity, or changes in the strength of chemical synapses, can occur over time between presynaptic and postsynaptic neurons. LTD works opposite long-term potentiation, or LTP, which strengthens synapses. Together, LTD and LTP help support learning and memory. LTD also helps keep the brain flexible. If synapses stayed maximally strengthened for too long, the brain would become less efficient and...

key terms and concepts

Explore how mechanically-gated ion channels detect touch, heat, and chemicals like capsaicin, and learn why TRP and Piezo channels matter in health.

Touch and Heat Sensors in Cell Membranes | 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.

Touch and Heat Sensors in Cell Membranes

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