6/07/11
Cholesterol The Road to Oestradiol Oestradiol
Paul Bischof PhD
Steroids Peptides
Molecular weight = 300 Generally > 1000 Liposoluble !Hydrosoluble Circulate bound to !Circulate free proteines Diffuse into cells ! Remain outside the cells! Intracellular receptors ! Membrane receptors ! !
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Synthesis of cholesterol Mevalonate C 6 ! CH O 3 O H2C-CH2-C-CH2-C H3C C X 3! O- - OH OH O CH Acetate! 3 CO2
H2C=C-CH2-CH2-O-PP Isopentenyl pyrophosphate C 5 !
CH CH3 CH3 CH3 3
H C-C=CH-CH - 3 2 H2C-C=CH-CH2 - H2C-CH=C-CH2 - H2C-CH=C-CH3 2! 2! Cholesterol C 27 ! Squalene C 30 !
HO
Lipoproteines transport cholesterol (LDL, HDL, VLDL).
Phospholipides Neutral Lipids Proteines Cholesterol Esters Cholesterol!
HO
HO
22nm!
HO HO
HO
HO
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Penetration of cholesterol
LDL! into cells (endocytose)
LDL receptors! Endocytotic vesicles!
Cell membrane!
Fusion of vesicles ! and formation of! an endosome!
Free Cholesterol!
Fusion with the lysosome!
Certain cells produce steroides
MITOCHONDRIA! ENDOPLASMIC RETICULUM! Pregnenolone!
Cholest. Pregnenolone! Acetate! Progesterone Cholesterol! Androstenedione!
Testosterone!
Oestradiol!
CELL MEMBRANE!
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The 4 Classes of Steroids
Cholane C27 C24 Loss of C25 to C27!
Pregnane C27 C21 Loss of C22 to C27! Androstane C19 C21
Loss of C20, C21! Oestrane C19 C18 Loss of C19!
Steroidogenesis (1) Pituitary Hormones (LH, ACTH...)
Cholesterol! C27 HO
20-22 Desmolase
Pregnenolone! =O P450SCC C21 HO
Mitochondria
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Steroidogenesis (2)
Cholesterol HO
20-22 Desmolase
=O =O
3ß ol dehydro- Pregnenolone genase Progesterone HO O
Steroidogenesis (3)
Cholesterol HO 20-22 Desmolase
=O =O Pregnenolone 3ß ol dehydro- genase Progesterone HO O 17OH 17OH hydroxy- hydroxy- lase lase
=O =O 17OHPregnenolone OH OH 3ß ol dehydro- genase 17 OH Progesterone HO O
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Steroidogenesis (4)
Cholesterol
HO
20-22 Desmolase
=O =O Pregnenolone 3ß ol dehydro- Progesterone genase HO O 17OH 17OH hydroxy- hydroxy- lase lase CH 2 OH =O CH 2 OH =O =O =O OH OH OH HO 3ß ol dehydro- OH genase 21 hydroxylase 11 hydroxylase HO O O O 17OHPregnenolone 17 OH Progesterone 11 Deoxycortisol Cortisol
Steroidogenesis (5)
Cholesterol HO 20-22 Desmolase =O Progesterone =O Pregnenolone 3ß ol dehydro- genase HO O 17OH 17OH hydroxy- hydroxy- lase lase
CH OH 2 Cortisol CH 2OH =O 17 OHProgesterone =O 11 Deoxycortisol 17OHPregnenolone OH =O =O OH HO 3ß ol dehydro- genase 21 hydroxylase 11 hydroxylase HO O O O 17-20 17-20 Desmolase Desmolase
O O Androstenedione Dehydroepiandrosterone (DHEA) 3ß ol dehydro- genase HO O
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Steroidogenesis (6)
Cholesterol HO 20-22 Desmolase =O Progesterone =O pregnenolone 3ß ol dehydro- genase HO O 17OH 17OH hydroxy- hydroxy- lase lase
CH OH 2 Cortisol CH 2OH =O 17 OHProgesterone =O 11 Deoxycortisol 17OHPregnenolone =O =O HO 3ß ol dehydro- genase 21 hydroxylase 11 hydroxylase HO O O O 17-20 17-20 Desmolase Desmolase O O Androstenedione Dehydroepiandrosterone (DHEA) 3ß ol dehydro- genase HO O
17 OH keto 17 OH keto reductase reductase OH! OH! Testosterone Androstenediol 3ß ol dehydro- genase HO O
Steroidogenesis (7) Cholesterol HO 20-22 Desmolase =O Progesterone =O pregnenolone 3ß ol dehydro- genase HO O 17OH 17OH hydroxy- hydroxy- lase lase
CH OH 2 Cortisol CH 2OH =O 17 OHProgesterone =O 11 Deoxycortisol 17OHPregnenolone =O =O HO 3ß ol dehydro- genase 21 hydroxylase 11 hydroxylase HO O O O 17-20 17-20 Desmolase Desmolase
O Androstenedione O Oestrone O Dehydroepiandrosterone ( DHEA) 3ß ol dehydro- Aromatase genase HO O HO
17 OH keto 17 OH keto 17 OH keto reductase reductase reductase Testosterone Oestradiol Androstenediol 3ß ol dehydro- Aromatase genase HO HO O
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Cholesterol Steroidogenesis (summary) HO 20-22 Desmolase =O Progesterone =O pregnenolone 3ß ol dehydro- genase HO O 17OH 17OH hydroxy- hydroxy- lase lase
CH OH 2 Cortisol CH 2OH =O 17 OHProgesterone =O 11 Deoxycortisol 17OHPregnenolone =O =O HO 3ß ol dehydro- genase 21 hydroxylase 11 hydroxylase HO O O O 17-20 17-20 Desmolase Desmolase
O Androstenedione O Oestrone O Dehydroepiandrosterone ( DHEA) 3ß ol dehydro- Aromatase genase HO O HO
17 OH keto 17 OH keto 17 OH keto reductase reductase reductase Testosterone Oestradiol Androstenediol 3ß ol dehydro- Aromatase genase HO O HO 5 4
HO O
The Steroidogenic Flux
8 6/07/11
2 3 1 1 Adrenal Cholesterol 2 Testicle HO Desmolase =O Progesterone =O 3 Ovary pregnenolone 3ß ol dehydro- genase HO O 17OH 17OH hydroxy- hydroxy- lase lase
CH 2OH CH 2OH =O 17 OHProgesterone 11 Deoxycortisol Cortisol =O =O =O 17OHPregnenolone HO 3ß ol dehydro- genase 21 hydroxylase 11 hydroxylase HO O O O 17-20 17-20 Desmolase Desmolase
O Androstenedione O Oestrone O Dehydroepiandrosterone ( DHEA) 3ß ol dehydro- Aromatase genase O HO HO
17 OH keto 17 OH keto 17 OH keto reductase reductase reductase Testosterone Oestradiol Androstenediol 3ß ol dehydro- Aromatase genase HO O HO
Regulation of Steroidogenesis
9 6/07/11
Food! Ovarian LH Acetate! steroidogenesis Cholesterol HO Desmolase =O Progesterone =O pregnenolone 3ß ol dehydro- genase HO O 17OH 17OH hydroxy- hydroxy- lase lase FSH
=O 17 OHProgesterone =O 17OHPregnenolone 3ß ol dehydro- genase HO O 17-20 17-20 Desmolase Desmolase
O Androstenedione O Oestrone O Dehydroepiandrosterone ( DHEA) 3ß ol dehydro- Aromatase genase O HO HO
17 OH céto 17 OH keto 17 OH keto reductase reductase reductase Testosterone Oestradiol Androstenediol 3ß ol dehydro- Aromatase genase HO O HO
Steroidogenesis of the foeto-placental unit (1)
The particularities:
10 6/07/11
Steroidogenesis hCG of the foeto-placental unit (summary)
Acetate Acetate 17OH Adrenals! hydroxy- Cholesterol lase HO Desmolase Pregnenolone =O Progesterone =O =O LDL! 17OHPregnenolone! 3ß ol dehydro- Sulphate! genase O SO HO O 3 17OH 17OH hydroxy- 17-20 hydroxy- Desmolase lase lase 3ß ol dehydro- Adrenals! genase O Dehydroepiandrosterone! O Sulphate!( DHEA-S) Androstenedione O Oestrone O O SO HO 3 Dehydroepiandrosterone (DHEA) Aromatase O HO 3ß ol dehydro- genase 17 OH keto 17 OH keto reductase reductase 16 hydroxylase! Liver! Testosterone Oestradiol Aromatase HO O O Urine! Oestriol OH OH OH OH O SO 16 OH DHEA-S! 3 Aromatase HO HO
Steroid Transporters
CBG CH 3 SHBG C=O
O! HO
Sex Hormone Binding Globulin Corticosteroid Binding Globulin
Testosterone > Dihydrotesto.> Oestradiol Progestérone = Cortisol
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Steroid Receptors (1)
HO HSP-90 ! Rec
HO Target cell!
HO
HO
HO HO Rec
HO HSP-90 ! Rec
HO
HO Dimerisation!
Blood! HO Biological effect
The steroid-receptor complex is a transcription facor
=O!
Rec Gene Transcription O! RNA polym
Zn++ fingers!
5’ PRE TATA 3’ ex1 ex2 ex3 int 1 int 1
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Excretion of Steroids
O O Oestradiol Oestrone Sulphate !
Oestrone HO HO O O 16 alpha Hydroxylase S Oestriol Other Metabolites HO O
HO Sulphates Urine Glucuronides Bile Feces
-OH =O -OH
Progesterone HO Pregnanediol O COOH H O O H OH Other Metabolites Liver OH Pregnanediol Glucuronide OH Synthetic steroids used in oral contraceptives Have no hepatic metabolism. They thus have a longer half-life.
Steroid Receptors (2)
HO
NH2 HO
COOH
Zn++ Zn++
Regulatory Domain: «Hinge» Steroid binding Domain Regulates transcription DNA binding domain: domain Regulates trans- cription
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The difficulty of measuring steroids (1)
The difficulty of measuring steroids (2)
Progesterone =O 17 OH Progesterone =O OH
O O
It is difficult to discriminate between two steroids because they might differ! only by one function.!
14 6/07/11
Invention of hormonal measurements
Solomon Berson & Rosalyn Yallow Nobel prize in Medecine 1977
Quantification of steroids (1)
The RIA (Radio-immunoassay)
=O =O
O * O * * =O =O
O * O =O =O =O
O O * O * =O =O
O O * Conc of Progesterone!
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Quantification of steroids (2)
The IRMA (Immuno radiometric assay)
=O =O * * O O
HO *
=O =O
O O
Conc of Progesterone!
Follicular Phase Luteal Phase Early Late Mi d Late 60! LH UI/L! 50! Early 40! 30! 20! 10!
FSH UI/L! 12! 10! 8! 6! 4! 2!
Oestradiol pg/ml! 500! 400! 300! 200! 100!
Progestérone pg/ml!
10000! 5000! 0!
16 6/07/11
Conclusions
1.Steroids are hydrophobic molecules that circulate bound to proteins. 2.Cholesterol is the precursor of all steroids. It is synthesised from acetate. 3.There are two principal synthesis pathways, the delta 4 and delta 5. 4.The type of steroid produced by a gland depends on its repertoire of steroidogenic enzymes. 5.Steroid target cells have intra-cellular receptors. 6.Steroids are sulphated or glucuronised before excretion.
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