OCT. 2022

CELL-CELL COMMUNICATION De Torres, Jillian Rose

Cell-to-Cell Communication

Cell communication is the ability of a cell to transmit a message, receive and process it between the cell and itself. communication requiring contact between cells In cell communication, both animal and plant cells have cell junctions allowing the molecules to pass readily between adjacent cells without passing the plasma membrane.

types and/or methods that is used in cell-cell communication

Local Signaling it is used by cells wherein cells communicate over relatively short distances

Long-Distance Signaling type of signal that travels around the body and reach far-away targets such as hormones

In most cases of cell communication, animal cell may communicate via local receptors. However, cell depends its response on whether the cell has specific receptor intended to that kind of signal. Some of the example of local regulator under local signaling is (a) PARACRINE SIGNALING, and; (b) SYNAPTIC SIGNALING

for this process to happen the cell should be in direct contact

Cell-surface Molecules

occur in animal cells, it is when the molecules pass on adjacent cells that interact with each other resulting in a signal passing between cells

Types of Signaling (over short/nearby distance) Cell-Cell Recognition - includes; (a) Membrane bound cell surface, (b) Glycoproteins, and; (c) Glycolipids Paracrine signaling. A secreting cell acts on nearby target cells by discharging molecules of a loca regulator into the extracellular fluid l .

A nerve cell Synaptic signaling. r molecules tte release neurotransmi ing the target lat mu sti e, ps na sy a o int cell.

Local Regulators - type of signaling that only work over a short distance (ex. growth factors)

PARACRINE SIGNALING

lONG-DISTANCE SIGNALING

- paracrine signaling only acted on nearby cells - its principle is only one cell secretes or releases molecules that act on nearby cell ("target cell")

- one example of regulators in long-distance signaling is hormone - hormones are used by plant and animals hence Endocrine signaling

One example of paracrine signaling is the growth factors. ENDOCRINE SIGNALING

SYNAPTIC SIGNALING

- it is a specialized cells that releases or

- it is specialized type of local signaling - occurs in animals' nervous system

secretes hormones wherein it travels through the circulatory system to other

- the nerve cell secretes/releases

body parts to act on target cells at a

neurotransmitter molecules into a

body-length distance

synapse, stimulating the "target" cell, such as muscle or another nerve cell

Stages of Cell Signaling Three stages or process of receiving signal suggested by Sutherland 1. 2. 3.

Signal reception Signal transduction Cell response

Step 2: Transduction - converts the signal into - a form that can bring specific cellular response (ex., receptor activates the protein that activates another molecules)

Step 3: Response - the signaling leads toregulation and transcription or cytoplasmic activities - cell's response sometimes reffered to as the "output response"

Step 1: Reception - a cell detects a signaling molecule from the outside of the cell - only when it binds into the protein on the cell surface creates signal

Receptors in Plasma Membrane Type 1 G-Protein Coupled Receptor - it is the largest family of cell-surface receptors - the G-protein acts as an "on/off" switch

Type 2 Receptor Tyrosine Kinases

° several types of cancer occur if the RTKs is abnormally function °

- a type of membrane receptor that attach from phosphate to tyroaines - multiple signals of transduction pathways can occur in this type of receptor at all once

Type 3 Ligand-Gated Ion Channel Receptors - this type of receptor acts a gate when the receptors changes its shape - when ligand is bind into the receptor, the gate allows only a specific ions (Na+/Ca2+) to enter through a channel Ligand-Gated Ion Channel Activation

signaling molecules binds to allow specific ions into cell

INTERCELLULAR RECEPTORS: Hormones

- it can act as trabscription factor (steroid and thyroid hormones in animals) - found in the cytosol or nucleus of target cells

Hormone Activation - the function of hormone and receptor bond is to initiate synthesis of specific genes

Signal Transduction Pathways - the receptor activates another protein that leads to another activation of molecules and so on. - every signal is transduced in each step resulting to change the shape into the protein Protein kinases

- transfer phosphates from ATP to protein >> phosphorylation Protein Phosphatases

- process of removing phosphate >> dephosphorylation

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First messenger - extracellular signaling molecules such as hormones or neurotransmitters that bind to cell-surface receptors and activate intracellular signaling pathways

second messenger - non-protein intracellular signaling molecules that relay extracellular signals received at receptors to target molecules within the cytosol

Common second messengers include calcium, cyclic AMP, inositol trisphosphate (IP3), and diacylglycerol (DAG)

Cyclic adenosine monophosphate - it is used for intracellular signal transduction in many different organisms, conveying the cAMPdependent pathway - ATP is made into cAMP considered as one of its common biological reaction

Calcium Ions Signaling - essential for the regulation of a diverse set of crucial functions within the human body (ex. cell death, gene transcription, muscle contraction, fertilization)

Calcium and Inositol trisphosphate - calcium is released into the cytosol, activating various calcium-regulated intracellular signals.

Response: Nuclear and Cytoplasmic Nuclear response: activation of a gene by growth factor - Signaling molecule (growth factor), triggers a phosphorylation cascade - Once phosphorylated, the last kinase in the sequence enters the nucleus and activates a gene-regulating protein, a transcription factor.

- A signal transduction pathway leads to the regulation of one or more cellular activities. - The response at the end of the pathway may occur in the nucleus of the cell or in the cytoplasm

Fine -Tuning of the Response 1. Amplication of the Signal, and Response 2. Specificity of the Response 3. Overall effiency of Response 4. Termination of the Signal Amplication of Signal

Termination of the Signal this is the last step in fine-tuning response - occurs when an enzyme called phosphodiesterase converts cAMP into AMP

Signaling efficiency

Scaffolding proteins

- it help relay the message between the cell membrane and nucleus faster (docking site)

OVERALL SIGNALING IN CELL COMMUNICATION (REVIEW OF SIGNAL)

Specificity of the Response