Rolle von SGK1 in der Salzempfindlichkeit von Blutdruck und der Glukoseaufnahme [Elektronische Ressource] : Studien in Knockoutmäusen = Role of SGK1 in salt sensitivity of blood pressure and peripheral glucose uptake/ vorgelegt von Krishna Murthy Boini

Krishna Murthy Boini

Sujets

• Gesundheit

Informations

• Publié par: eberhard_karls_universitat_tubingen
• Publié le: 01 janvier 2006
• Nombre de lectures: 32
• Langue: English
• Poids de l'ouvrage: 13 Mo

Extrait

Rolle von SGK1 in der Salzempfindlichkeit von
Blutdruck und der Glukoseaufnahme: Studien in
Knockoutmäusen

Role of SGK1 in Salt Sensitivity of Blood Pressure and
Peripheral Glucose Uptake: Studies in Knockout Mice


DISSERTATION

der Fakultät für Chemie und Pharmazie
der Eberhard-Karls-Universität Tübingen

zur Erlangung des Grades eines Doktors
der Naturwissenschaften

2006

vorgelegt von
Krishna Murthy Boini













Tag der mündlichen Prüfung 07.11.2006
Dekan Prof. Dr. L. Wesemann
1. Berichterstatter: Prof. Dr. F. Lang
2. Berichterstatter: Prof. Dr. P. Ruth
3. Berichterstatter: Prof. Dr. Ch. Korbmacher ACKNOWLEDGEMENTS


It is with immense pleasure, I record my humble gratitude to my research guide
Prof. Dr. Florian Lang for his expert guidance and critical review throughout the work. My
sincere and heart felt thanks for his abundant encouragement.
I am very grateful to Prof. Dr. Hartmut Osswald for his encouragement and timely
help during the progress of the work. I would like to thank Prof. Dr. Peter Ruth for giving
me an opportunity to present the dissertation at the Faculty of Pharmacy and Chemistry,
Eberhard Karls Universität Tübingen, Germany.
I am very thankful to my supervisors, colleagues and friends Dr. Dan Yang Huang,
Dr. Ferruh Artunc, Dr. Susanne Ullrich, Dr. Monica Palmada, Dr. Florian Grahammer,
Saisudha Koka, Jeyaganesh Rajamanikam, Diana Avram, Barbara Hartel, Tanja Loch, Lejla
Subasic for their timely help and encouragement.
I affectionately acknowledge the help and encouragement received from my friends
Dr. Srinivas Nammi, Dr. Srinivas Ghatta, Srinivasa Rao Gella, Uma Devi Palaparthi, Uma
Rani Chintakindi, Eswar Kumar Kilari, Ramesh Alluri, Govinda Rao Mutta, Goverdhan
Puchchakayala.
This task never completes without the mention of my beloved parents, sisters,
brother and brothers-in-law, who blessed me in every aspect of my career.











CONTENTS

ABBREVIATIONS ………………………………………………………………………...1

SUMMARY ……………………………………………………………………………...2

Zusammenfassung .................................................................................................................5

I. INRODUCTION …………………………………………………………………………8

1.1. Stimuli that cause SGK1 induction ……………………………………………………9
1.2. The SGK1 isoforms SGK2 and SGK3 ………………………………..………………10
1.3. Regulation of SGK1 by phosphorylation ……………………………………………..12
1.4. Tissue distribution of SGK1 isoforms …………………………………….………...14
+1.5. Role of SGK1 in aldosterone dependent Na reabsorption …………………………...15
+1.6. Role of SGK1 in Renal K secretion ………………………………………...…….….20
1.7. Serum and glucocorticoid inducible kinase 1 and blood pressure………..……………21

II. AIMS OF THE STUDIES…………………………………………………….……….26

II. 1. Study 1: Influence of SGK1 on renal function and systolic
blood pressure during high fat diet and high salt diet…………………......…..27
II. 2. Study 2: Role of SGK1 in the hypertensive effect of combined
treatment with dietary fructose and salt load ………………………………29
II. 3. Study 3: Role of SGK1 in the regulation of electrolyte metabolism
and blood pressure by the glucocorticoid dexamethasone…………………..31
II. 4. Study 4: Role of SGK1 in salt sensitivity of glucose tolerance and
peripheral glucose uptake ..…………………………………………………32

III. METHODS……………………………………………………………………………34

III. 1. Animals ………………………………………………………………………….…..34
III. 2.Glucose tolerance and insulin tolerance tests ………………………………………..35 III. 3. Blood pressure ………….… ………………………………………………………..35
III. 4. Metabolic cages ……………………………………………………………………..36
III. 5. Blood and urinary concentrations ……………………………………………….…..36
III. 6. In vivo glucose uptake ……………………………………………………………….37
III. 7. In vitro glucose uptake ………………………………………………………………37
III. 8. SGK1 protein abundance ……………………………………………………….…..37
III.9. SGK1 mRNA expression ………………………………………………………..…..39
III.10. In situ hybridisation ………………………………………………………………..39
III.11. In vivo clearance studies ……………………………………………………………40
III.12. Data analysis and statistics ………………………………………………………...41

IV. RESULTS …………………………………………………………………………..42

IV. 1. Study 1: Influence of SGK1 on renal function and systolic
blood pressure during high fat diet and high salt diet

IV. 1. 1 Body weight, plasma electrolytes and intake of food, fluid
and electrolytes …………………………………………………………………….42
IV. 1. 2 Plasma insulin and aldosterone concentrations ………………………………….…..44
IV. 1. 3 Hypoglycemic effect of insulin and glucose tolerance in mice
during high fat diet …………………………………………………………….…..45
IV. 1. 4 SGK1 protein abundance ..................................................................……………….47
IV. 1. 5 Plasma lipid concentrations ……………………………………………………...….48
IV. 1. 6 Systolic blood pressure. …………………………………………………………….50
IV. 1. 7 Urinary excretion ………………………………………………………………….51

IV. 2. Study 2: Role of SGK1 in the hypertensive effect of combined
treatment with dietary fructose and salt load

IV. 2. 1 Plasma glucose, insulin and aldosterone concentrations …………………………….53
+ + -IV. 2. 2 Packed cell volume, plasma Na , K and Cl concentrations………………………...53
IV. 2. 3 Fluid intake, urinary flow rate, creatinine clearance and
urinary excretion……………………………………………………………….…..56
IV. 2. 4 Systolic blood pressure ……………………………………………………………58 IV. 2. 5 SGK1 mRNA expression ……………………………………………………….…59
IV. 2. 6 In vivo insulin clearance ……………………………………………………….….61
IV. 3. Study 3: Role of SGK1 in the regulation of electrolyte metabolism
and blood pressure by the glucocorticoid dexamethasone

IV. 3. 1 Plasma glucose, aldosterone and chloride concentrations ……………………….….63
+ + 2+ 3- IV. 3. 2 Plasma Na , K , Ca and PO concentrations ……………………………………..63 4
IV. 3. 3 Fluid intake, urinary flow rate, creatinine clearance and urinary
protein excretion …………..…………………………………………………….….66
IV. 3. 4 Urinary electrolyte excretion …………………………………………………….….67
IV. 3. 5 Systolic blood pressure ………………………………………………………….…..71

IV. 4. Study 4: Role of SGK1 in salt sensitivity of glucose tolerance and
peripheral glucose uptake

IV. 4. 1 Glucose tolerance tests ……………………………………………………………...72
IV. 4. 2 Insulin tolerance tests ……………………………………………………………….72
IV. 4. 3 Glucose tolerance tests during mineralocorticoid excess ………………………...….75
IV. 4. 4 In vivo glucose uptake ………………………………………………………………75
IV. 4. 5 SGK1 protein abundance ……………………………………………………………76
IV. 4. 6 In vitro glucose uptake .................................................................………………...…..79

V. DISCUSSION ……………………………………………………………………….80
V. 1. Study 1: Influence of SGK1 on renal function and systolic
blood pressure during high fat diet and high salt diet …………………….…..80
V. 2. Study 2: Role of SGK1 in the hypertensive effect of combined
treatment with dietary fructose and salt load ………………………………83
IV. 3. Study 3: Role of SGK1 in the regulation of electrolyte metabolism
and blood pressure by the glucocorticoid dexamethasone …………………86
IV. 4. Study 4: Role of SGK1 in salt sensitivity of glucose tolerance and
peripheral glucose uptake ……….………………………………………...89

V. REFERENCES ………………………………………………………………………..92 VII. PUBLICATIONS AND ABSTRACTS DERIVED FROM THE
WORK FOR DOCTORAL THESIS ………………………………………….….114


VIII. LEBENSLAUF ...............………………………………………………………….116

ABBREVIATIONS

ASDN: Aldosterone sensitive distal nephron
B.W.: Body weight
CCD: Cortical collecting duct
Dexa: Dexamethasone
DOCA: Deoxycorticosterone acetate
EDTA: Ethylene diamine tetra acetate
ENaC: Epithelial sodium channel
F: Fructose
GFR: Glomerular filtration rate
H O : Hydrogen peroxide 2 2
HCl: Hydrochloric acid
HFD: High fat diet
I.P.: Intraperitoneal
Kg: Kilogram
KO: Knockout
MAP: Mean arterial pressure
MCD: Medullary collecting duct
Mg: Milligram
MgCl : Magnesium Chloride 2
MR: Mineralocorticoid receptor
NaCl: Sodium Chloride
PDK1: Phosphoinositide dependent kinase 1
PI-3K: Phosphatidylinositide-3-kinase
PKB: Protein kinase B
PPAR γ: Peroxisome proliferator activated receptor γ
ROMK: Renal outer