Cell Signaling

 

Cell Signaling is a process by which Cells communicate with each other or within the Cell to perform various physiological activities and functions. Cell Signaling is also known as Cellular Signaling. The Cell Signaling process is vital for the proper functioning of prokaryotic and eukaryotic Cells. Cell Signaling involves three steps from receiving of Signal to termination of Signal including Signal, receptor, and effector.

Signals can be chemical and physical, Physical Signals like electric current, pressure, and temperature while chemical Signals include insulin, sodium, potassium, hormones, etc. In this article we will learn about, types of Signals, receptors, taxonomic range, etc.

Define Cell Signaling

Cell Signaling is the mechanism by which Cells interact with one another or with other Cells inside the Cell to carry out different physiological tasks.

What is Cell Signaling?

Cell Signaling is the mechanism by which Cells interact with one another or with other Cells inside the Cell to carry out different physiological tasks. Cellular Signaling is another name for Cell Signaling. Prokaryotic and eukaryotic Cells require the cell Signaling mechanism to operate properly.

Stages of Cell Signaling

Cell Signaling usually consists of the following important stages:

1. Receptors: Specific molecules binds on the specific receptors present on the surface of the Cell.
2. Transduction: After binding of Signaling molecule, it leads to the phosphorylation, activation or several cascades.
3. Amplification: Throughout the Signaling route, the signal is frequently amplified at several stages to ensure a strong cellular response.
4. Integration: Cells are able to react correctly to complicated stimuli by integrating many impulses from diverse routes.
5. Cell response: Cell Signaling response lead to alteration in expression of gene, Cell metabolism, Cell growth etc.
6. Termination: After Signals has been performed and termination needed to be done by removing Signaling molecules.

Taxonomic Range

Cell Signalling is a basic feature of cellular coordination and communication that is present in a large variety of living things.

1. Bacteria: Quorum sensing is a perfect example for it, which help bacteria to make biofims.
2. Archeae: Archeae also to Cell Signaling like bacteria to communicate with each other.
3. Protists: These are unicellular organism which deployed Cell Signaling to communicate, differentiation and locomotoion.
4. Fungi: Cell Signaling has a variety of roles in the mating, filamentation, and stress response of yeasts and other fungi.
5. Plants: Plants also performs Cell Signaling in response to biotic and abiotic stresses.
6. Animals: Cell Signaling is highly developed in multicellular organisms and is essential for functions such as immune response, nervous system function, hormone control, and embryonic development.
7. Humans: Human Cell Signalling is well understood to be essential for preserving homeostasis, controlling organ functions, and reacting to environmental cues.

Types of Cell Signaling

There are various types of Cell Signaling depending upon the type of Signaling molecule, distance of Signaling, and mechanism of Cell Signaling. Here is the types of Signaling;

1. Autocrine Signaling: When Cells produces Signaling molecules like cytokines which binds to own Cell receptor such as cancer Cells that result in cellular response.
2. Paracrine Signaling: It involves the release of paracrine factors or Signaling molecule into the extracellular fluid causes stimulation of nearby Cells. For examples release of local immune response, neurotransmitters and retinoic acids.
3. Endocrine Signaling: Endocrine Signaling involves endocrine glands which releases hormones that travel to the target Cell. For example insuline from pancreas gland.
4. Juxtacrine Signaling: It is a Cell to Cell Signaling in which Signaling molecule released from one Cell interact with adjacent Cell receptor such as in notch Signaling.
5. Intracrine Signaling: This type of Signaling occur within the Cell such in the case of steroid hormone that can cross transmembrane and reaches to required cellular compartment.
6. Contact dependent Signaling: In contact-dependent Signalling, as in juxtacrine signaling, there is direct physical contact between the Cells, and Signaling molecules that are attached to the membranes of one Cell interact with receptors on the other. For example T Cell activation by APC.
7. Synaptic Signaling: It occur between neuron through synaptic junction in the case of neurotransmitters.
8. Redox Signaling: Electrons are transferred both inside and between Cells during redox Signaling, which affects how cells react. For example ROS can act as a Signaling molecules for proliferation.

Receptors of Cell Signaling

The process of Cell Signaling is the interaction of Signaling molecules, or ligands, with certain receptors either within or on the surface of target Cells. Receptors are molecules, either proteins or other, that attach to Signaling molecules and start a cascade of events that results in a response from the Cell.

Cell Surface Receptors

1. G- Protein Coupled Receptors (GPCR): GPCRs are the class of Cell surface receptors that activate G proteins, which are intracellular signalling proteins, to send messages inside the Cell.
2. Receptor Tyrosine Kinases (RTKs): Receptors on the Cell surface with intrinsic kinase activity are known as RTKs. Tyrosine residues become phosphorylated and subsequent Signaling cascades are started when a ligand binds to the kinase domain.
3. Ion Channel Receptors: These membrane proteins, known as integral receptors, open or close ion channels in response to ligand binding, allowing ions to cross the Cell membrane.

Intacellular Signaling

1. Nuclear Receptors: Nuclear receptors are transcription factors that are located inside Cells and control the expression of genes in response to ligand binding.
2. Cytoplasmic Receptors: Certain transduction-inducing receptors reside in the cytoplasm and do not penetrate the nucleus.Fo example MAP kinase pathway.

Enzyme linked Receptors

1. Receptor Guanylyl Cyclases: These receptors function as both enzymes and ligand-binding agents. They function as a secondary messenger by catalysing the transformation of GTP into cyclic GMP upon ligand interaction.
2. Histidine Kinase Receptors: Signal transduction systems consisting of two components include histidine kinases. On histidine residues, they phosphorylate themselves, and subsequently they transmit the phosphoryl group to destinations downstream.

Pattern Recognition Receptors

1. Toll Like Receptors (TLLRs): They set off immunological reactions by identifying certain molecular patterns linked to infections.

Other Receptors

1. Adhesion Receptors: Interactions between Cells and the extracellular matrix are mediated by these receptors. Adhesion receptors include, for example, integrins.
2. Cytokine Receptors: Cytokines, crucial Signaling molecules in immune responses and other processes, operate through these receptors to modulate their effects.

Functions of Cell Signaling

There are various function in which Cell Signaling is involved in both prokaryotic and eukaryotic Cells, which are;

1. Communications between Cells: Through cell Signaling, Cells in tissues and organs may coordinate their activity with one another.
2. Development and differentiation of Cells: In order for Cells to specialize into distinct Cell types throughout development a process known as differentiation signaling pathways are essential. The development of tissues and organs depends on this mechanism.
3. Immune defense: The immune system relies heavily on Signaling to enable Cells to identify and react to invaders.
4. Cell Growth: Signaling routes control the Cell cycle, which affects the division and development of Cells that in turn help in Cell repair.
5. Metabolism: Apoptosis, a prearranged and regulated type of Cell death, is governed by Signaling pathways.