2-1-16-Steroid Biosynthesis (Theisen) Flashcards Preview

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Flashcards in 2-1-16-Steroid Biosynthesis (Theisen) Deck (48):
1

List examples of Glucocorticoids

Cortisol
Cortisone
Corticosterone

All synthesized in adrenal glands --> distributed to large # of tissues and organs --> increases BP and Na uptake in kidneys --> mediates response to stress by increasing protein catabolism and gluconeogenesis and reducing inflammation

2

List examples of Mineralocorticoids

Aldosterone and 11-deoxycorticosterone

Synthesized in adrenal glands --> distributed to kidney tubules, colon, and parotid gland --> increases Na/H2O retention, K excretion, and BP

3

List examples of Estrogens

Estradiol and Estrone

Synthesized in ovaries (major), placenta, and adipose tissue --> distributed to primary and secondary repro organs --> mediates feminization, estrous cycle, and inhibits testosterone synthesis

4

List the types of Lypophilic signaling molecules

Steroid hormones: Progesterone, estradiol, testosterone, cortisol, aldosterone, Vit D (not really a steroid)

Thyroid hormone: Thyroxine

Retinoids: Retinol, retinoic acid

5

Identify the receptor location and type for Lypophilic signaling molecules

Found in the cytoplasm and nucleus

Family of DNA-binding transcriptional factors

6

List the general steps in Lipophilic molecule signaling beginning with the signaling molecule (ligand) diffusing across the cell membrane

Lipophilic ligand diffuses across cell membrane --> ligand binds ligand receptor in cytosol --> ligand-receptor complex travels to the nucleus --> Transcription --> Translation --> Cell response

7

___ hormones regulate cell growth and differentiation into specific cell types, the bodys response to stress, and metabolism of nutrients

Steroid

8

Steroid receptors are ___ factors

Transcription --> bind to the signaling hormone and to DNA, most of which have a domain that can interact in transcriptional complexes to initiate/repress gene expression

9

Steroid hormones are synthesized from cholesterol in the ___ of the adrenal cortex, ovaries, and testes. These tissues obtain cholesterol from circulating ___, from de novo synthesis from Acetyl CoA, or from cholesterol esters stored in cytoplasmic lipid droplets

Smooth ER

LDL

10

The synthesis of steroid hormones begins with the rate-limiting step catalyzed by ____, an enzyme that incorporates a carbonyl group on the D ring of cholesterol and cleaves off a 6-carbon piece of its side chain (between C20 and C22) to form pregnenolone

Desmolase (Catalyzes Cholesterol ------> Prenenolone)

11

The conversion of cholesterol to prenenolone requires this enzyme ___ and can be stimulated by upregulated levels of ____

Desmolase

ACTH

12

Aldosterone can be synthesized from progesterone in the ___

Adrenal cortex --> ZONA GLOMERULOSA

13

Cortisol can be synthesized from progesterone in the _____

Adrenal cortex (zona fasciculata)

14

Estradiol can be synthesized from progesterone from ___

Testosterone in the ovaries

Minor amt synthesized in adrenal cortex

15

Testosterone can be synthesized from progesterone in the __

Testes (Dihydrotestosterone is more potent)

Minor amount in adrenal cortex

16

___ acts as a modulator of neurotransmitter signaling in the brain without being converted to other steroids. It effects the NMDA glutamate receptor (memory and learning)

Pregnenolone (an alcohol)

17

Pregnenolone must be converted to progesterone for synthesis of other proestrogens via these enzymes:

17-alpha-hydroxylase and 3-beta-hydroxysteroid dehydrogenase

18

___ is a P-450 family-monooxigenase that is essential for production of pregnenolone.

Desmolase

19

Desmolase is only found in these tissues:

Tissues that produce steroid hormones --> Gonads and adrenal cortex

20

Desmolase expression and activity is stimulated by ____

Peptide hormones:
ACTH
LH
FSH

21

The synthesis of Estrone from Androstenedione is catalyzed by this enzyme ___ and upregulation of ___ in the ovaries

Aromatase

FSH

22

___ defect leads to salt wasting (hyponatremia) and hypotension due to decreased production of aldosterone and hypoglycemia due to decreased production of cortisol.

In females, this deficiency causes virilism due to increased flow of intermediates into adrenal androgens

21-hydroxylase

23

A rare deficiency of ___ causes a loss of cortisol as well as sex steroids. However, the decrease in cortisol is compensated for by increased production of corticosterone

17-alpha-hydroxylase

24

Defects in ___ cause hypertension due to accumulation of 11-deoxycorticosterone, which has mineralocorticoid activity

11-beta-hydroxylase

25

___ is produced in a tissue-specific manner from progesterone in the adrenal cortex (zona glomerulosa), promotes retention of Na and H2O in kidneys as well as excretion of H and K.

Aldosterone

26

Reduced levels of aldosterone can lead to ___

Excessive levels of aldosterone can lead to ___

Loss of too much salt

Conn Syndrome-Increased blood volume, hypertension

27

____ is produced from progesterone in the adrenal cortex (zona fasciculata) and has anti-inflammatory and autoimmune properties. It stimulates the breakdown of muscle, gluconeogenesis, and glycogen synthesis.

Cortisol (glucocorticoid)

28

Elevated cortisol levels are associated with ___, a condition marked by accumulation of fat on the face and trunk

Cushing Syndrome--> can be caused by increased cortisol production due to pituitary or adrenal tumors or chronic administration of corticosteroids

29

Glucocorticoids such as cortisol cause immunosuppression by inhibiting both the cell and humoral IR. They induce the production of i-kBa inhibitory protein, which helps sequester the transcription factor ___ in inactive cytoplasmic complexes.

NF-kB

30

___ is necessary for synthesis of IL-2 (T cell proliferation)

NF-kB

31

The metabolism of Cortisol ---> Cortisone is done through the action of this enzyme:

11-B-hydroxysteroid dehydrogenase

32

Cortisol has an affinity for ___ receptors and are 100x more concentrated than mineralocorticoids

___ has a much lower affinity for mineralocorticoid receptors

Mineralocorticoid

Cortisone

33

Natural licorice root contains isoflavones, which are inhibitors of ___

11-beta-hydroxysteroid dehydrogenase

Consumption of real licorice can lead to HTN due to salt retention

34

The adrogenic potency of testosterone is amplified by its conversion to dihydrotestosterone mediated by the enzyme ____

5-alpha-reductase

35

___ has a much higher affinity than testosterone for the androgen receptor

DHT

36

___ is an inhibitor of 5-alpha-reductase which prevents potentiation of testosterone

Finasteride

Used to treat benign prostatic hyperplasia. Has also been used to treat male pattern baldness, which is caused by the action of DHT in the scalp

37

The effects of Vitamin D are attributed to its active form known as ____

Calcitriol (1,25-dihydroxycholecalciferol)

Technically, not classified as a steroid

38

___ is the inactive form of Vitamin D and produced in skin from the photochemical cleavage of the B ring of 7-dehydrocholesterol (via UV irradiation in skin)

Cholecalciferol (Vitamin D3)

39

In the intestine, Cholecalciferol is synthesized from ___

Ergocalciferol (D2)

40

Once in the liver, Cholecalciferol (D3) is converted to 25-hydroxycholecalciferol by the enzyme ___

25-hydroxylase

41

In the proximal tubule of the kidneys, 25-hydroxycholecalciferol is converted to 1,25-dihydroxycholecalciferol (calcitriol) by this enzyme ____

1-alpha-hydroxylase

42

The action of 1-alpha-hydroxylase in conversion of 25-hydroxycholecalciferol to calcitriol in the PCT of the kidneys is stimulated by ___ and inhibited by ___

Stimulates--> PTH, low [PO4]

Inhibits --> Calcitriol

43

Calitriol stimulates intestinal cells to ____, stimulates reabsorption of ___ in kidneys, and ____ resorption in bone

Ca and PO4 absorption-intestinal cells

Ca-kidneys

Ca-bone

44

List an example of a Progestin

Progesterone --> synthesized in adrenal glands, ovaries, and testis --> distributed to uterus --> mediates implantation (nidation) and maintenance of pregnancy

45

___ supports gestation (pregnancy) and embryogenesis and is also involved in the maintenance of the menstrual cycle

Progesterone

46

A decrease in ___ levels precedes menstruation, labor, and lactation

Progesterone

47

___ is a glycosylated globulin that belongs to the serine protease inhibitor (SERPIN) family of proteins and is involved in the transport and release of the majority (80-90%) of plasma glucocorticoid hormones and also progesterone

Corticosteroid-Binding Globulin (CBG)

48

Sex steroids such as testosterone, dihydrotestosterone, and estradiol are transported by the homodimeric glycoprotein ___

Sex steroid hormone binding globulin (SHBG)

Both CBG and SHBG are made mostly in the liver