Endocrine signalling and reproductive biology 1 + 2

Question 1

When were hormones identified?

Answer 1

1900s

Question 2

polytene chromosomes

Answer 2

large chromosomes from drosophila

chromosome puffs - chromatin opening

Question 3

nuclear receptor ligands

Answer 3

testosterone, oestradiol, cortisol, AT retinoid acid

Question 4

structure of ligands

Answer 4

aromatic rings - lipophilic

dissolve and get to the nucleus

Question 5

receptors

Answer 5

glucocorticoid, thyroid hormone, progesterone, oestrogen

Question 6

what do nuclear receptors promote?

Answer 6

transactivation

Question 7

what are steroid hormones based on?

Answer 7

CPPP nucleus - 17 carbons

cholesterol

Question 8

classes of steroid hormones (carbons)

Answer 8

18 - oestradiol
19 - testosterone
21 - progestrone, cortisol and aldosterone
27 - secosteroid, broken ring

Question 9

what groups can be added to make different hormones?

Answer 9

methyl, ketone, hydroxyl

Question 10

what does StAR do?

Answer 10

steroiodenic acute regulatory protein - regulate cholesterol transfer within mitochondria

Question 11

where does steroid hormone synthesis control happen?

Answer 11

mitochondria

Question 12

acute and chronic hormone control effects

Answer 12

acute - increase calcium and cAMP

stAR and synthetic enzymes

Question 13

catabolism of steroid hormones

Answer 13

can add hydrophilic groups to make it more water soluble

Question 14

what does thyroid secrete?

Answer 14

T3 and T4

Question 15

where does synthesis of throid hormone occur and what happens?

Answer 15

thyroid epithelia
protein suicide of thyroglobulin
catalysed by thyroperoxidase
make DIT and MIT

Question 16

explain synthesis of thyroid hormone

Answer 16

thyroglobulin and iodide
iodine and tyrosine = MIT and DIT
linked to form T3 and T4
thyroglobulin colloid
lysosome cleaves and release hormone

Question 17

how is thyroid hormone synthesis turned on or off?

Answer 17

deiodinases

Question 18

what receptors bind chaperones in cytoplasm?

Answer 18

aldosterone, oestrogen, progesterone, gluocorticoid

Question 19

class 3 receptors are present where? examples?

Answer 19

nucleus

thyroid hormone, retinoic acid and vitamin D

Question 20

3 main domains of nuclear receptors

Answer 20

DNA binding domain
ligand binding domain
Unique N terminal domain

Question 21

LBD

Answer 21

binds ligand

Question 22

what does the LBD form?

Answer 22

ligand binding pocket that restricts what may bind

Question 23

what may the LBD also be required for?

Answer 23

dimerisation
interaction with chaperones
interaction with co-regulators

Question 24

DBD - structure

Answer 24

8 cysteine residues
2 alpha helices perpendicular
2 zinc ions - recognition helix
C terminal extension

Question 25

CTE

Answer 25

mediates amino acid nucleotide interactions

Question 26

N terminal domain

Answer 26

variable | AF1 region

Question 27

AF1 region

Answer 27

important for ligand dependent transactivation

Question 28

hinge region

Answer 28

N terminal domain | flexible

Question 29

Hormone response element

Answer 29

positions nuclear receptors and complexes recruited by them close to gene to be transcribed

Question 30

what can sequence of HRE dictate?

Answer 30

whether receptor will activate or repress transcription of neighbouring promoter

Question 31

4 classes of nuclear receptor based on what?

Answer 31

interaction with HRE

Question 32

class 1 DNA binding sequence

Answer 32

AGAACA

Question 33

all other receptors DNA binding sequence

Answer 33

AGGTCA

Question 34

what repeat does class 1 HRE and receptors use?

Answer 34

inverted repeat separated by 3 nucleotides - IR3

Question 35

what will activate class 1 HRE?

Answer 35

AR, GR, MR, PR

Question 36

AR and class 1 HRE

Answer 36

also uses DR3 for specific control

Question 37

class 2 HRE nuclear receptors

Answer 37

IR3 of AGGTCA

Question 38

what uses class 2 HRE?

Answer 38

ER for specific control

Question 39

what do class 3 HRE nuclear receptors use?

Answer 39

direct repeat AGGTCA | 1 to 5 rule - number of nucleotides spacing repeat

Question 40

Class 4 HRE nuclear receptors

Answer 40

binds as monomers | NGF1B aaaAGGTCA

Question 41

2 halves of bipartite HRE

Answer 41

``` 1 = more like consensus site , recognised by DBD 2 = co-operative binding of second DBD to less conserved site ```

Question 42

3 parts of promoter

Answer 42

TATA box initiator element dowstream promoter element

Question 43

how is nuclear receptor activating transcription achieved?

Answer 43

RNA polymerase 2 machinery of basal promoter

Question 44

What is the PIC?

Answer 44

RNA polymerase 2, transcription factors eg TF2B

Question 45

how do nuclear receptors promote formation of stable PIC?

Answer 45

help PIC assemble by making direct contact with components of basal transcription machinery recruit co-activators, promote PIC assembly

Question 46

what is chromatin?

Answer 46

repeating array of DNA-protein structures called nucleosome, DNA wrapping around histone octamers

Question 47

what can change properties of nucleosome?

Answer 47

covalent modification of lysine, arginine, serine residues of histone N-terminals

Question 48

what are the steroid receptor co-activators?

Answer 48

SRC1,2,3

Question 49

what do SRC1,2,3 do?

Answer 49

bind NR and have histone deacetylase activity and promote association proteins recruit PIC

Question 50

short alpha-helical segment of SRC

Answer 50

NR box LXXLL - lysine separated interacts with hydrophobic groove on LBD when bound to agonist

Question 51

shutting of the system - how is it done?

Answer 51

chaperone protein eg p23 promote removal of NR and RNA pol 2 from DNA covalent modification of co-activators eg acetylation of SRC3

Question 52

SMRT/NCoR

Answer 52

2 nuclear receptor interaction domains with 2 amino acids repressor activity in N terminal region recruit histone deacetylases

Question 53

uses of anti-hormones

Answer 53

hormone dependent tumours eg breast and prostate

Question 54

bind inverse agonist

Answer 54

helix 12 shifts to N terminus of antagonist bound LBD | inhibit binding of co-activators and promote binding of co-repressor

Question 55

Negative response element

Answer 55

hormone bind | HDAC activity and repression