berthold endocrine experiment remove- replacement-injection
DESCRIPTION
Berthold Endocrine Experiment Remove- replacement-injection. Objectives. 1. Chemical classes of hormones 2. Biosynthesis of a particular hormone 3.Transport of the hormones 4.Recognition & signaling of the hormone 5.Functions of the hormones . 6.Degradation of the hormone. - PowerPoint PPT PresentationTRANSCRIPT
Berthold Endocrine Experiment
Remove- replacement-injection
1. Chemical classes of hormones
2. Biosynthesis of a particular hormone
3.Transport of the hormones
4.Recognition & signaling of the hormone
5.Functions of the hormones.
6.Degradation of the hormone.
Objectives
Endocrine Methods• Remove-replacement-injection• Purification and cloning• Synthesis and production of hormone• Test biological activity with pure hormones• Development of antibodies• Localization by immunocytochemistry• Establish assays (RIA)• Microarray,deep sequencing, proteomics• Knock-out/Knock down/mutants
Hormone Types/Functions
Three structural divisions:
1) Amines--H2O sol. (small--AA) catecholamines and thyroid hormones
2) Steroids--lipid sol. cyclic hydrocarbon derivatives from cholesterol
3) Peptide/protein -- H2O sol. largest, complex
Amines
• Hormones derived from tyrosine and tryptophan.
• Include hormones secreted by adrenal medulla, thyroid, and pineal glands.
Thyroid Hormones
• Tyrosine derivatives bound together.
• Contain 4 iodine atoms (T4).
• Contain 3 iodine atoms (T3).
• Small, non-polar molecules.– Soluble in plasma
membranes.
Steroids• Lipids derived from
cholesterol.• Are lipophilic
hormones.– Testosterone– Estradiol– Cortisol– Progesterone
Peptides/Proteins
• Chains of amino acids (< 100 amino acids in length).– ADH – Insulin
• Long polypeptides (>100) bound to one or more carbohydrate groups.– FSH– LH
Biosynthesis of Peptides and Protein Hormones
DNA (The gene)
RNA (Primary transcript)
mRNA
Pre-(Pro)-hormone
Pro-hormone
Hormone
RNA processing
translation
Proteolysis via signal peptide cleavage
Proteolysis via second modificationGlycosylationphosphorylation
5’ 3’Proopiomelanocortin (POMC) gene
5’ 3’ mRNA
1 2 3 4 5 6 7N C
Signal peptide
-MSH
ACTH
-MSH CLIP
-lipotropin
4 6 7
6 8
-lipotropin -endorphin
-MSH enkephalin
Products in corticotrophic cell of the anterior pituitary
Products in the intermdeiary gland
Classification of chemical communication systems
1) Autocrine--secretion that affects the same cell which the secretion originated
Ex: Adrenergic nerve endings
2) Paracrine--secretion that affects neighboring cells
Ex: Inflammatory response
3) Endocrine--a secretion of a chemical substance that is released into the blood and affects a distant target
4) Exocrine--secretion of a substance that is released onto surface of animal--including internal structures
Exocrine Glands/tissues:
--possess ducts
--salivary glands, intestinal epithelium, secretory cells in stomach, and secretory cells of the liver and pancreas
Endocrine Glands/tissues:
--lack a definite duct
--Adrenal gland, GI tract, heart, kidney, ovary, pancreas, thyroid, pituitary, placenta, testes, and thymus
Fig. 7-8, p.265
Hypothalamus
Connecting stalk(infundibulum)
Hypothalamus
Opticchiasm
Posteriorlobe ofpituitary
Anteriorpituitary
(b)
(a)Posteriorpituitary
Anteriorlobe ofpituitary
Bone
Anterior and posterior pituitary glands.
• Also called the neurohypophysis.
• Formed by down growth of the brain during fetal development.
• Is in contact with the infundibulum.
• Nerve fibers extend through the infundibulum.
Posterior Pituitary
• Master gland (also called adenohypophysis).• Derived from a pouch of epithelial tissue
that migrates upward from the mouth.• Consists of 2 parts:• Pars distalis: anterior pituitary.• Pars tuberalis: thin extension in contact with
the infundibulum.
Anterior Pituitary
Hypothalamic Control of Posterior Pituitary
• Hypothalamus produces:– ADH: supraoptic nuclei.
– Oxytocin: paraventricular nuclei.
• Hormones transported along the hypothalamo-hypophyseal tract.
• Stored in posterior pituitary.
• Release controlled by neuroendocrine reflexes.
Posterior Pituitary(neurohypophysis)--releases
neurohormones
1) antidiuretic hormone (vasopressin)
2) oxcytocin
Larhammar et al, Ann. N.Y. Acad. Sci. 1163: 201–208 (2009)
• Hormonal control rather than neural.
• Hypothalamus synthesizes releasing hormones and inhibiting hormones.
• Hormones are transported to axon endings of median eminence.– Delivers blood and hormones to anterior
pituitary via portal system.
Hypothalamic Control of the Anterior Pituitary
Hypothalamic Control of the Anterior Pituitary
• Hormones secreted into the hypothalamo-hypophyseal portal system regulate the secretions of the anterior pituitary.
• Anterior pituitary and hypothalamic secretions are controlled by the target organs they regulate.
• Negative feedback inhibition by target gland hormones.
Feedback Control of the Anterior Pituitary
Feedback Control of the Anterior Pituitary
• Negative feedback at 2 levels:– The target gland hormone can act on the
hypothalamus and inhibit releasing hormones.– The target gland hormone can act on the
anterior pituitary and inhibit response to the releasing hormone.
Fig. 7-11, p.269
Fig. 7-12, p.270
Water vs. Lipid
Water soluble Lipid soluble
hydrophilic hydrophobic
external (2nd mess.) internal
external receptors cytoplasmic rec.
short half-life long half-life
intermediary resp. Long-term resp.
protein activation gene activation
Mechanisms of Hormone Action
• Hormones of same chemical class have similar mechanisms of action.– Location of cellular receptor proteins.
• Target cell must have specific receptors for that hormone (specificity).
• Hormones bind to receptors with high bond strength (affinity).
• Low capacity of receptors (saturation).
Hormones That Bind to Nuclear Receptor Proteins
• Lipophilic steroid and thyroid hormones bound to plasma carrier proteins.
• Hormones dissociate from carrier proteins to pass through lipid component of the target cell membrane.
• Receptors for the lipophilic hormones are known as nuclear hormone receptors.
Nuclear Hormone Receptors• Function within cell to activate genetic
transcription.• mRNA directs synthesis of specific enzyme
proteins that change metabolism.• Receptor must be activated by binding to hormone
before binding to specific region of DNA called HRE (hormone responsive element).– Located adjacent to gene that will be transcribed.
Mechanisms of Steroid Hormone Action
• Steroid receptors located in cytoplasm.
• Bind to steroid hormone.
• Translocates to nucleus.
• DNA-binding domain binds to specific HRE of the DNA.
• Dimerization occurs.
• Stimulates transcription.
Mechanism of Thyroid Hormone Action
• Receptor proteins located in nucleus.
• T3 binds to ligand-binding domain.
• DNA-binding domain can then bind to the half-site of the HRE.
• Other half-site is vitamin A derivative 9-cis-retinoic acid.
• Two partners can bind to the DNA to activate HRE.
Hormones That Use 2nd Messengers
• Cannot pass through plasma membrane.• Catecholamines, polypeptides, and
glycoproteins bind to receptor proteins on the target cell membrane.
• Actions are mediated by 2nd messengers (signal-transduction mechanisms).– Extracellular hormones are transduced into
intracellular second messengers.
Hormones That Use 2nd Messengers
2nd messenger systems:• Adenylate cyclase• Phospholipase C• Tyrosine kinase• NO• various kinases
• Hormone binds to receptor protein.
• Dissociation of a subunit of G-protein.
• G-protein binds and activates adenylate cyclase.
• ATP cAMP + PPi
• cAMP attaches to inhibitory subunit of protein kinase.
Adenylate Cyclase-cAMP
• Activates protein kinase.• Phosphorylates enzymes within the cell to produce
hormone’s effects.• Modulates activity of enzymes present in the cell.• Alters metabolism of the cell.• cAMP inactivated by phosphodiesterase.
– Hydrolyzes cAMP to inactive fragments.
Adenylate Cyclase-cAMP
CatecholaminesACTHFSHLHTSHGlucagonPTHCalcitonin
• Binding of epinephrine to alpha-adrenergic receptor activates a G-protein, (phospholipase C).
• Phospholipase C splits phospholipid into inositol triphosphate (IP3) and diacylglycerol (DAG).
• Both derivatives serve as second messengers.
Phospholipase-C-Ca++
• IP3 diffuses through cytoplasm to ER.
• Binding of IP3 to receptor protein in ER causes Ca++ channels to open.
• Ca++ diffuses into the cytoplasm.• Ca++ binds to calmodulin.• Calmodulin activates specific protein kinase enzymes.• Alters the metabolism of the cell, producing the
hormone’s effects.
Phospholipase-C-Ca++
CatecholaminesTRHLHRHOxytocinADH
1)By release of Ca2+ from intracellular Calcium storages
2)By influx of Calcium from cell exterior Ca2+ channel
Two ways to increase cytosol free Ca 2+
• Receptor protein on cell membrane is tyrosine kinase.• Insulin receptor consists of 2 units that dimerize when
they bind with insulin.• Insulin binds to ligand–binding site, activating
enzymatic site.• Autophosphorylation occurs, increasing tyrosine kinase.• Activates signaling molecules, altering the metabolism
of the cell.
Tyrosine Kinase
PRL
Stat
GH/PRL signaling mechanism
PI3K Src
P
D2D1
Box1
YYYY
P
P
D2D1
Box1
YYYY
P
PP
PRL
JAK2JAK2
Stat 1
P
Stat 3
Stat 5
P
Extra-cellular
Intra-cellular
Fyn MAPK
BiologicalResponse
AKT ? AKT ERK
PRLR alpha
PRL
PRLPRL
PRL
PRL
Circulation
Kinase
Signal Molecule
Known
Not Sure
Legend
OVERVIEW
Physiological Effects of Hormones
1.Reproduction (Gonads)
2.Stress & Steroids (Adrenal)
3.Metabolism (Pancreas and Thyroid)
4.Electrolyte/Water Balance
Gonads and Placenta• Gonads (testes and ovaries):
– Secrete sex hormones.• Testosterone.
• Estradiol.
• Progesterone.
• Placenta:– Secretes large amounts of estrogen and progesterone.
Sertoli cells: synthesis androgen-binding protein and inhibin.
Leydig cells: produce and secrete testosterone
Testosterone: key hormone for produce sperm, develop male sex characters, protein synthesis and general growth
ss
Cell type
Ploidy/Chromosomes #N Process
Time of completion
Oogonium diploid/46 2NOocytogenesis (mitosis) third trimester
primary Oocyte diploid/46 4N
Meiosis I (Folliculogenesis)
Dictyate in prophase I until ovulation
secondary Oocyte haploid/23 2N Meiosis II
Halted in metaphase II until fertilization
Ovum haploid/23 1N
1. hypothalamic GnRH control of FSH / LH release,
2. ovarian follicular development to ovulation and subsequent corpus luteum formation
3. the feedback control of FSH / LH secretion by ovarian hormones.
•the corpus luteum regresses,
•there is a rapid fall in the secretion of oestrogen and progesterone,
•the endometrium undergoes shrinkage due to extracellular fluid loss,
•the spiral arteries constrict,
•the endometrial blood flow decreases with cell death and destruction of blood vessels `
Adrenal Glands
• Paired organs that cap the kidneys.• Each gland consists of an outer cortex and inner
medulla.• Adrenal medulla:
– Derived from embryonic neural crest ectoderm (sympathetic ganglia).
– Synthesizes and secretes:• Catecholamines (mainly epinephrine but some
norepinephrine).
Adrenal Medulla
• Innervated by sympathetic nerve fibers.– Increase respiratory rate. – Increase heart rate, cardiac output; and
vasoconstrict blood vessels, thus increasing venous return.
– Stimulate glycogenolysis.– Stimulate lipolysis.
Adrenal Glands
• Adrenal cortex:– Does not receive neural innervation.– Must be stimulated hormonally.– Consists of 3 zones:
• Zona glomerulosa: – Aldosterone: regulate Na+ and K+ balance.
• Zona fasciculata: – Cortisol: regulate glucose metabolism.
• Zona reticularis:– Androstenedione and DHEA: supplement sex steroids.
Pancreas• Endocrine portion consists of islets of Langerhans.• Alpha cells secrete glucagon.
– Stimulus is decrease in plasma glucose concentrations.– Stimulates lipolysis.
• Beta cells secrete insulin.– Stimulus is increase in plasma glucose concentrations.– Promotes entry of glucose into cells.
Regulating Blood Glucose
Two major hormones:
1) insulin
2) glucagon
Origin: cells, cells-- islet of Langerhans
Control: BG high--insulin, BG low--glucagon
Diabetes MellitusTwo types:
1) Type I (IDDM)
--severe, insulin dependant, juvenile onset,
--loss of beta cell mass
2) Type II (NIDDM)
--less severe, non-insulin-dependant, adult onset, more common
--defective insulin receptors
untreatedfat metabolism(ketones) ketoacidosis ketoacidosis
Thyroid Hormones• Thyroid gland located just below the larynx.
• Thyroid is the largest of the pure endocrine glands.
• Follicular cells secrete thyroxine.
• Parafollicular cells secrete calcitonin.
Production of Thyroid Hormones
• I- (iodide) actively transported into the follicle and secreted into the colloid.
• Oxidized to (Io) iodine.• Iodine attached to tyrosine.
– Attachment of 1 iodine produces monoiodotyrosine (MIT).
– Attachment of 2 iodines produces diiodotyrosine (DIT).
• MIT and DIT or 2 DIT molecules coupled.
Production of Thyroid Hormones
• T3 and T4 produced.
• TSH stimulates pinocytosis into the follicular cell.– Enzymes hydrolyze to T3 and T4 from
thyroglobulin.
• Attached to thyroid-binding protein and released into blood.
T3 Effects • Stimulates cellular respiration by:
– Production of uncoupling proteins.– Stimulate active transport Na+/ K+ pumps.– Lower cellular [ATP].
• Increases metabolic heat.• Increases metabolic rate.
– Stimulates increased consumption of glucose, fatty acids and other molecules.
Hormonal Regulation: H2O, Electrolytes
Major organs: kidney, intestine, and bone
Antidiuretic hormone (ADH): also vasopressin, regulates H2O turnover in kidney
-- premeability of H2O in duct ( urine)
Aldosterone: Na+ reabsorption, blood osmolarity
Atrial natriuretic peptide (ANP): Na+ , ( urine)