Class 2: Steroid Hormones

Question 1

Classes of reproductive steroid hormones

Answer 1

Androgens: I.e Testosterone → spermatogenesis
Estrogens: I.e Estradiol (Estrogen) → Menstrual cycle
Progestins: I.e Progesterone (“Pro-gestation” hormone) → Menstrual cycle

Question 2

Gametogenesis

Answer 2

process of making gametes (steroids regulate gametogenesis)

Question 3

Steroidogenesis

Answer 3

Process of making steroid hormones

Question 4

Prohormone

Answer 4

a hormone intermediate specifically pregnenolone created from cholesterol in the mitochondrion. It then moves to the ER and is converted to its final form (progesterone, testosterone, estrogen). It then passes out of the cell via diffusion, often attached to carrier proteins.

Question 5

Receptor

Answer 5

“receiver” as in the molecule that receives the signal, usually a protein with a binding site for a specific/particular molecule, called its ligand.
      	Androgen Receptor (AR): binds testosterone/ other androgens
      	Estrogen Receptor (ER): Binds estrogen
      	Progesterone receptor (PR): binds progesterone/ other progestins

Question 6

Ligand

Answer 6

A molecule that binds to a specific site on another molecule, the substance that binds to the receptor. Hormones, protein anchored on another cell. Any substance (e.g. hormone, drug, functional group, etc.) that binds specifically and reversibly to another chemical entity to form a larger complex.

Question 7

Properties of Steroid Hormone Receptors

Answer 7

1. Proteins located inside target cells
2. Ligand-dependent transcription factors
3. Steroid hormones affect cells by changing gene expression, through the transcription factor activity of their receptors

Question 8

Transcription

Answer 8

(RNA synthesis from nucleotides) DNA is copied to make RNA

Question 9

Transcription factors

Answer 9

Proteins that facilitate specialized transcription that act in response to specific signals. (a transcription factor (sometimes called a sequence-specific DNA-binding factor) is a protein that binds to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to mRNA)

Question 10

Translation:

Answer 10

(protein synthesis from amino acids)RNA provides the instructions to the cell’s protein synthetic machinery to translate the needed proteins.

Question 11

Differential gene expression

Answer 11

Expressing only certain genes in certain cell types. Ie: Only certain cells have job of steroidogenesis. Regulated by several factors including transcription factors and epigenetics. (and whether a gene is capable of being transcribed to make RNA or is “silenced”)

Question 12

Promoter region

Answer 12

regulatory region that controls if/when a gene (DNA) gets transcribed into RNA (region where transcription factors act)

Question 13

Coding region:

Answer 13

contains the actual instruction to encode the gene product

Question 14

Endocrinology

Answer 14

The study of hormones, their receptors, and the intracellular signaling pathways they stimulate.

Question 15

Hormone

Answer 15

Chemical messengers secreted into the blood or sometimes other extracellular fluid by a cell that affect the functioning of other cells.

Question 16

Target cell

Answer 16

Responds to a hormone because it has the specific receptor for that hormone.

Question 17

Endocrine:

Answer 17

Through the blood stream to the target cell.

Question 18

Paracrine

Answer 18

local action, hormone from diffusing to neighboring target cells.

Question 19

Autocrine

Answer 19

Acts on the same cell (“Auto”=self)

Question 20

Agonist

Answer 20

molecules that bind to a hormone’s receptor and induce the post-receptor events that lead to a biological effect.

Question 21

Agonistic or Antagonistic interaction

Answer 21

various chemicals can participate in steroid hormone receptor-mediated processes (pharma or enviro), most advanced drugs are agonistic in some tissue & antagonistic in others.

Question 22

SERM

Answer 22

Selective estrogen receptor modulator, “selective” estrogenic activity in some tissues, anti- estrogenic in others (can be agonistic or antagonistic)

Question 23

SARM, SPRM

Answer 23

Selective androgen/progesterone receptor modulators are also being developed (can be agonistic or antagonistic)

Question 24

Transcription factor

Answer 24

A protein that binds to a specific DNA sequence controlling the transcription of RNA from DNA. In this class we talked about it as part of a protein complex (the whole Androgen/ Estrogen/Progesterone Receptor) with the DNA binding domain, ligand binding domaine & other “variable” factors.

Question 25

Hormone response element (HRE)

Answer 25

a short sequence of DNA within the promoter of a gene that is able to bind a specific hormone receptor complex and therefore regulate transcription.

Question 26

Hypothalamic-Pituitary-Gonadal (HPG) axis

Answer 26

Regulating the gonads. Start in they HypothalamusàGnRphàPituitary GlandàGonadotropins (FSH & LH) –> Gonads –> Gametes & Steroid Hormones

Question 27

5 a -reductase

Answer 27

Convert Testosterone into the more potent DHT (dihydrotestosterone). Inhibition results in decreased production of DHT, increased levels of Testosterone, and possible increase in estradiol. Gynecomastia is a possible side effect of this inhibition. Inhibitor drugs are used in BPH, prostate CA, and male pattern baldness, and HRT for transgendered women (male to female).

Question 28

Aromatase (also called estrogen sythetase or estrogen sythase)

Answer 28

an enzyme responsible for a key step in biosynthesis of estrogens. Transforms testosterone to estrodiol. (steroid users will take antiaromatases to prevent gynecomastia)