Topic: Involvement of Vitamin D Receptor In Energy Metabolism: Regulation of Uncoupling Proteins Summary: Today, obesity is a rising epidemic that leads to serious health problems. Obesity can be defined as a medical condition in which excess fat has accumulated. To help understand this epidemic, Wong et. al researched the role of vitamin D in energy metabolism. They created vitamin D receptor-null mutant mice (VDR-null) and compared the metabolic phenotypes with those of wild type mice. On a high-fat diet, VDR-null mice had less body fat and lower plasma triglycerides and cholesterol than wild-type mice. To understand why plasma lipids were increased, Wong et. al looked at brown fat and found the expression of uncoupling proteins (UCPs) was higher in VDR-null mice. Upregulation of UCPs, which alters ATP production by separating oxidative phosphorylation from ATP production, suggests higher energy expenditure and could help explain the lower plasma lipid levels. This research shows vitamin D does play a role in energy metabolism and could be useful in creating new ways to minimize body fat. Now, we may better understand how it may be possible to increase energy expenditure, helping to reduce the prevalence and incidence of obesity.

1. Kari E. Wong, Frances L. Szeto, Wenshuo Zhang, Honggang Ye, Juan
Kong, Zhongyi Zhang, Xiao Jian Sun, and Yan Chun Li
22 January 2009
Presented by:
Cheryl Gregory
Linh Pho

2. Introduction
Materials & Methods
Results
◦ Graphs & Diagrams
Conclusion
Further Research

3. What is the definition of obesity?
◦ The Excess of Body Fat
What is the prevalence of obesity in
the United States?
◦ In 2008, the obesity prevalence
increased to 30%
What are the associated health
problems?
◦ Gangreen
◦ Type II Diabetes
◦ Cancer
◦ Cardiovascular Disease
◦ Hypertension
http://science.kukuchew.com/wp-
content/uploads/2009/02/obesity_surgery.jpg

4. Energy Metabolism: the use of fuels to create energy to be
used for work.
D-
Vitamin D-Receptor (VDR) knockout mice used to show
1alpha,25- D-
Vitamin D, 1alpha,25-dihydroxyvitamin D-3, involvement in
energy metabolism
VDR-null mice had decreased adiposity and lower plasma
lipid levels
VDR-null mice had increased Uncoupling Protein expression
UCPs separate the process of oxidative phosphorylation
from ATP production
Overall, VDR knockout mice had higher energy expenditure

5. Animal Treatment
◦ Created Vitamin D Receptor (VDR) knockout mice
◦ Placed the mice on two diets: High Fat & High Calcium
High Fat (HF)
Mice were place on HCa for 4 months, then switch to HF diet
Mice were weighed and monitored weekly
End, animals were killed: plasma and adipose tissue were
harvested
High Calcium (HCa)
To normalize the plasma calcium level
Used as a control

6. Assessed Plasma Parameters Using Test Kits
◦ Used to determine levels of:
Triglycerides
Cholesterol
Adipokine
Thyroid Stimulating Hormone

7. Observed the Histology
◦ Cultured White Adipose Tissue (WAT)
Storage depot of the body
Stores excess energy in triglyceride form
Releases signals indicating the body’s energy state
◦ Cultured Brown Adipose Tissue (BAT)
Regulates thermogenesis
Expresses uncoupling protein
Separate oxidative phosphorylation from ATP production
◦ Adipose tissues were:
Processed and Stained

8. Assayed Fatty Acid B-oxidation
◦ Isolated white adipose tissue from male mice
◦ Measure the B-oxidation using tritiated palmitate
Analyzed Northern Blot of total RNA
◦ Show the total cellular RNA extraction
Performed RT-PCR
◦ Strands of DNA extracted from the mice
◦ To analyze protein and hormone mRNA levels

9. Weight Difference
•VDR (-/-) mice weighed sig. less than WT on both high-Ca++ and
high-fat diet
•Gender difference: Male mice more protected against weight gain
MALE FEMALE
•VDR-null mice had a decrease in adiposity
•Lower # of adipocytes
•Smaller size

10. ADIPOSE DIFFERENCE C. White Adipose Tissue
•VDR-null mice on the high-fat
diet had smaller adipocytes & less
BAT
•The BAT accumulated fewer lipids
& had better cell morphology
•VDR-null had less adipose tiss. in
all fat depots
•More dramatic difference between
males
D. Brown Adipose Tissue

11. ENZYME LEVELS
MALE MICE ONLY
Fatty acid synthase higher in VDR-null mice on HCa diet but
diff. not as big on HF diet
Malonyl-CoA Dehydrogenase and Stearoyl CoA-Desaturase-1
were not significantly different
LPL lower in mutant mice on HF diet
PPAR-gamma higher in mutant mice on HCa diet

12. Fatty Acid Synthase
Lipoprotein Lipase
PPAR - Gamma

13. ADIPOKINE LEVELS
Leptin: lower in VDR-null mice on HCa diet and much lower in
HF diet
Adiponectin: On the HF diet, mRNA expression was reduced in
WT mice
Resistin: no difference between mice on HCa or HF

14. PLASMA LIPID LEVELS
Triglyceride
Female: No difference in plasma triglycerides, cholesterol,
free-fatty acids on both diets
Male: VDR-null mice had lower triglycerides and cholesterol
on both diets
(NOT DUE TO: food intake, increased physical activity,
decreased intestinal absorption, or increased thyroid
stimulating hormone levels)
Top Image: hubpages.com/hub/Triglycerides-can-kill
Cholesterol Bottom Image: www.3dchem.com/molecules.asp?ID=92

15. B-Oxidation
•Carnitine palmitolytransferase II (CPTII) protein is responsible for
transporting fatty acids into the mitochondrial matrix
• CPTII expression higher in the WAT of VDR-null mice
CPTII mRNA increased too
•Increased rate of B-oxidation in adipocytes helps explain increased level
of lipids in VDR-null mice
•Suggests more fatty acids are oxidized, which leads to higher basal
energy expenditure

16. UNCOUPLING PROTEINS
UCP expression in BAT was increased in VDR-null mice, the difference was
higher when mice where on the HF diet
The expression of the B-adrenergic receptor 3 was unchanged
B/c AdrB3 is known to directly regulate UCPs
Suggests Vit D directly regulates UCPs
Double Check: treated VDR-null and WT mice with 1,25(OH)2D3
As expected, found no effect on VDR-null cells
VDR transcript was missing in VDR-null mice Vit D directly targets fat

17. High Calcium Diet High Fat Diet

18. VDR-Knockout Phenotype:
◦ Lower fat mass & lower plasma lipid levels
Vit D-Receptor is involved in Energy
Metabolism
◦ VDR-null mice had higher energy expenditure as
shown by the indirect calorimetric measurement
Possible Mechanism for this involvement:
◦ Vit D directly downregulates UCP expression in BAT
This Alteration of E Metabolism explains:
◦ The lower adiposity and lower plasma lipid profile

19. Studies should look at VDR in other body tissues to
further understand its role in total body energy
metabolism.
Also, look at the difference btwn in vivo and in vitro
By better understanding total body energy
metabolism, we may be one step closer to helping
understand and treat obesity.
May eventually, lead to a way to alter energy
metabolism

20. hubpages.com/hub/Triglycerides-can-kill
http://science.kukuchew.com/wp-content/uploads/2009/02/obesity_surgery.jpg
http://ajpendo.physiology.org/cgi/content/full/296/4/E820
http://www.cdc.gov/obesity/data/trends.html
Wong, Kari. E. “Involvement of the vitamin D receptor in energy metabolism:
regulation of uncoupling proteins.” Division of Biological Sciences. Dept.
of Medicine Metabolism and Nutrition. Chicago, Illinois. 22 Jan. 2009
www.3dchem.com/molecules.asp?ID=92

21. Question & Answer