Chapter 4 Extracellular signals: Hormones, cytokines and growth factors

Objectives Understand the general role of Hormones, Cytokines, Growth Factors and Neurotransmitters Learn the abbreviations for the general molecules in each class Know one example of a function for each group of signals

Hormones Small water soluble molecules – Cannot cross plasma membrane – Must target cellular receptor – Examples Histamine Epinephrine

Hormones Peptide Hormones – Water soluble – Stored in vacuoles – Pro-peptides – Examples Insulin Glucagon LH (luteinizing hormone) FSH (follicle stimulating hormone)

Hormones Lipophilic molecules (extracellular) – Still need a receptor – Prostaglandins Synthesized from arachidonic acid – Usually have to do with inflammation

Hormones Lipophilic molecules (intracellular) – Receptors are on the inside of the cell – Steroid hormones – Examples Testosterone Progesterone Thyroxine

Hormones Plant hormones (for Joe!!) – All extracellular signals – Auxin Young leaves and seeds Very diverse effects – Cytokinins Developing seeds – Gibberellins Young shoots and seeds Flowering and germination – Abscisic acid Roots and mature leaves Stromal closure – Ethylene Gas Fruit ripening

Cytokines Very large family of peptides Range in size from kDa Name of GroupExamplesNotes InterferonsIFN- α IFN- β IFN- γ Viral infection response InterleukinsIL-1 to IL-35 Some with more than one isoform Cell growth and differentiation Tumor necrosis factors TNF α TNF β TGF β Inflammatory response ChemokinesMIP-1 α NAP-2 RANTES Leukocyte location signals Colony stimulating factors M-CSF G-CSF GM-CSF Development of bone marrow

Cytokines Interleukins – 37 family members – IL-x – Many different sizes – Many different receptors – Many different functions Immune response and maturation Can activate themselves or nearby cells

Cytokines Interferons – Type I IFN- α, INF- β, IFN-Ω – Type II INF-γ – Anti-tumor properties? Tumor necrosis factors – TNF-α and TNF-β Works closely with IFN and causes necrosis of tumors (hence the name!!)

Growth Factors Platelet-derived growth factors (PDGF) – Induces cell migration & proliferation Fibrosis and arteriosclerosis Epidermal growth factor (EGF) – Various functions Fibroblast growth factor (FGF) – Cell proliferation, migration and motility Proto-oncogenes?

Neurotransmitters Stored in vesicles, released upon Ca 2+ stimulation Small Molecules – Acetylcholine, GABA, dopamine, γ-aminobutyric acid – Glycine, glutamate, ATP and adenosine Neuropeptides – Substance P, Endorphin, vasopressin