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Autocrine signaling: cells respond to substances that they themselves release.

Autocrine signaling: cells respond to substances that they themselves release.

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Autocrine signaling: cells respond to substances that they themselves release.

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  1. Autocrine signaling: • cells respond to substances that they themselves release. • cultured cells often secrete growth factors that stimulate their own growth and proliferation. This type of signaling is particularly common in tumor cells, many of which overproduce and release growth factors that stimulate inappropriate, unregulated proliferation of themselves as well as adjacent nontumor cells; this process may lead to formation of tumor mass

  2. CELL TO CELL CONTACTS/ JUNCTIONS Invertebrates: junctions, for example septate junctions or the C. elegans apical junction. epithelial cells, barrier to solute diffusion through the intracellular space beneath the apical, lumenal surface of the intestinal cells

  3. MULTICELLULAR PLANTS PLASMODESMATA portions of the endoplasmic reticulum are trapped across the middle lamella in newly dividing plant cells eventually becoming (primary plasmodesmata). wall is not thickened further, and depressions or thin areas known as pits are formed Alternatively, plasmodesmata can be inserted into existing cell walls between non-dividing cells (secondary plasmodesmata)

  4. CHEMICAL SIGNALING • The series of steps involved signal transduction pathway

  5. CHEMICAL SIGNALING signal transduction involves: RECEPTION • Detection of the stimulus (in most cases a molecule secreted by another cell) TRANSDUCTION: Receptor ligand binding brings about a change in the receptor molecule (often a conformational change) which in turn activates a second molecule/ Secondary messengers to initiate the response which will often serve to amplify the signal for a greater response. RESPONSE: activate enzymatic activity, genetic transcription, movement of cytoskeletal components, or other cell activities.

  6. Signal transduction involves 1- STIMULI/ SIGNAL MOLECULE: lipids, phospholipids, amino acids, monoamines, proteins, glycoproteins, or gases. Hormones A: Steroid Hormones: androgens, estrogens, and progestogens B: Peptide Hormones and Growth Factors: insulin, glucagon, pituitary gland hormones, growth hormone, FSH, prolactin etc Neurotransmitters: molecules including acetylcholine, dopamine, epinephrine (adrenaline), serotonin, histamine, glutamate, glycine, and γ-aminobutyric acid (GABA). Eicosanoids: Lipids, in contrast to the steroid hormones, bind to cell surface receptors Cytokines: signaling molecules of the immune system

  7. Signal transduction involves 2-RECEPTION via RECEPTORS A: Plasma membrane receptors B: Intracellular

  8. Membrane Receptor Types Enzymatic Receptors, catalytic receptor • Channel Linked, Ionotropic Receptors • G Protein coupled Receptor – 7TM

  9. B: Intracellular • Examples are the class of • Nuclear receptors …..steroid hormones • Cytoplasm ……peptide hormones • IP3 receptor located on the endoplasmic reticulum….IP3 Nuclear receptors The steroid hormones Thyroid hormone

  10. Pathways initiated by receptors

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