wk 4- Hormones (steroid and peptide) Flashcards
What is the biochemical mechanism responsible for transmitting extracellular signals across the plasma membrane and throughout the cell?
Signal transduction
What are examples of signal transduction?
Flux through metabolic pathways
Ion flow through plasma membrane
Cell mobility
Gene expression
Water soluble signalling molecules bins to what type of receptors?
Cell surface receptors
What receptors do lipophillic dervived from cholesterol bind to?
Intracellular receptors
What ligands mediate hormone signals by altering the expression for specific genes?
Cholesterol-derived
What are the multiple categories of steroid hormones?
Glucocorticoids
Mineralcorticoids
Androgens
Estrogens
Role of glucocorticoids
Regulation of glucose metabolism
Role of mineralcoticoids
Salt and water balances
Role of androgens
Regulate the development and maintenance of male characteristics in vertebrates (testosterone)
Role of estrogens
Development and regulation of female reproductive system (estradiol)
What are synthetic steroids
Agonists that mimic the biological response of the hormone
Type of steroids that bodybuilders use
Anabolic steroid (builds up muscles)
3 categories of hormones
Endocrine (steroids)
Paracrine (growth factor)
Autocrine
What type of cells do steroid hormones exit?
Endocrine cells
The cell-specific physiological responses controlled by intracellular/nuclear receptors is governed by what 3 parameters?
Cell specific expression of nuclear receptors
Localized bio-availability of ligands
Differential accessibility of target gene DNA sequences in chromatin nuclear receptor binding
Briefly describe the general mechanism of nuclear/intracellular receptor signalling
1) Binding of lipophillic first messengers to ligand binding domain
2) Ligand activated nuclear receptors bind directly or indirectly to hormone regulatory elements in DNA - alters transcription rates in chromatin structure
How to steroids receptors bind to inverted repeat DNA sequences?
Head-to-head homodimers (in pairs) - increases specificity meaning more contact
Where is the glucocorticoid receptor synthesized?
Adrenal gland
What term is also used for inverted repeat?
Palindromic
What are the 3 different modes of transcriptional regulation of the glucocorticoid-responsive promoters by glucocorticoid receptors?
Simple transactivation
Tethering
Synergism
What are simple and composote promoters?
Simple- Simple transactivation and Tethering
Composite- Synergism
What is simple transactivation?
The receptor binds directly to the responsive elements
What is Tethering?
The receptor binds to a transcriptional factor before binding to the responsive elements
What is Synergism?
A combination of the other two. The transcription factor may have an effect of the receptor binding to the responsive element. vice versa
How do glucocorticoid recepors regulate anti-inflammatory responses?
By down regulation the expression of pro-inflammatory proteins
What is the definition of hormones?
Any substance elaborated by one cell to regulate another cell. May be delivered by autocrine, paracrine or endocrine routes
True or false- Most hormones have effects on multiple targets in the body
True
What 3 classes are hormones grouped into based on their structure?
Steroid hormones
Amine-derived hormones
Peptide hormones
What hormones are hydrophilic and transported unbound in blood plasma?
Peptide hormones
Where are peptide hormones secreted from?
pituitary, parathyroid, heart, stomach, liver, kidneys
Where is mature insulin stored?
Secretory vesicles
How can different end hormones be made?
By cleaving a common precursor with a different enzyme
What are coactivators?
Proteins that acetylate histones
Where is the coregulatory protein binding site located?
On the surface of the GR ligand binding domain (hydrophobic pocket)
What is the difference between pharmaceutical glucocoticoids than that of physiologic steroids?
They have a higher binding affinity for the glucocoticoid receptor
