This document summarizes a lecture on the roles of muscle, white adipose tissue (WAT), and liver in metabolic flexibility. It discusses how these tissues function normally and how dysfunctions can lead to conditions like fatty liver disease. Specifically, it describes: 1) The normal functions of muscle, WAT, and liver related to metabolism and how dysfunctions can cause diseases. 2) Studies on non-alcoholic fatty liver disease (NAFLD) and how communication between WAT and liver is essential for lipid storage. 3) Research on the effects of high-protein diets on hepatic lipid accumulation and gene expression changes in the gut-liver axis. 4) How exercise increases heart rate

1. Lecture 3
From healthy to too much
The role of Muscle, WAT, Liver for metabolic flexibility
Michael Müller
Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University

2. Adipocytes at the crossroads of energy homeostasis

3. Liver functions related to nutrition
1. Bile formation
2. Gluconeogenesis
3. Glycogen-synthesis
4. Lipogenesis (new fat, TG)
5. VLDL formation
6. LDL uptake
7. Cholesterol synthesis
8. Bile acid synthesis (from cholesterol)

4. Liver

5. Hepatocyte

6. Liver dysfunctions /diseases
related to nutrition
1. Hepatic steatosis
(fatty liver)
2. Liver inflammation
3. NASH (non-
alcoholic
steatohepatitis)
4. Fibrosis
5. Cirrhosis
6. Cancer

7. Metabolic defects leading to the
development of hepatic steatosis

8. White (WAT)
Brown (BAT)
Adipose tissue

9. Adipose tissue

10. Adipocyte

11. WAT Functions related to Nutrition
1. Lipolysis
2. Lipogenesis (TG)
3. Maintaining triglyceride and free fatty acid levels
& determining insulin resistance
4. Protecting other organs from lipotoxicity

12. WAT dysfunctions related to nutrition
1. Overweight, Obesity, Metabolic
syndrome, Diabetes, CVD, Cancer….
2. Abdominal fat has a different metabolic
profile & being more prone to induce
insulin resistance.
3. Central obesity is a marker of impaired
glucose tolerance & is an independent
risk factor for cardiovascular disease

13. de Wit NJ, Afman LA, Mensink M, Müller M
Phenotyping the effect of diet on non-alcoholic
fatty liver disease J Hepatol 2012
.

14. Communication between liver and adipose
tissue essential for adequate lipid storage

17. Healthy (Homeostasis)

18. Unhealthy (Type 2 Diabetes)

19. Balance between insulin and glucagon
SREBP-1c
LXR
ChREBP
GR
FOXA2
CREB
PPARa
Fed state Fasted state
Glucose FFA

20. Metabolism & Inflammation

21. Liver, FAT & NASH/NAFLD
 Nonalcoholic Fatty Liver Diseases (NAFLD):
Liver component of Metabolic Syndrome
 Different stages in NAFLD progression:
 Molecular events involved in NASH pathogenesis:
 Role of PPARa (Endocrinology 2008 & Hepatology 2010)
 Role Kupffer cells (Hepatology 2010)
 Role of macrophages in lipid metabolism (JBC 2008; Cell Metabolism 2010)
hepatic steatosis steatohepatitis (NASH) & fibrosis cirrhosis

22. Interaction between WAT and liver tissue
essential for NASH/NAFLD in C57Bl/6 mice
Objective:
– Nonalcoholic fatty liver disease (NAFLD) is
strongly linked to obesity and diabetes,
suggesting an important role of adipose tissue
in the pathogenesis of NAFLD.
– Here we aimed to investigate the interaction
between adipose tissue and liver in NAFLD,
and identify potential early plasma markers
that predict NASH.

23. Experimental Design
• stratification
on body weight
• liver• plasma collection
multiple protein assays
RNA extraction: Affx microarrays
tissue collectionrun-in diet 20 weeks diet intervention
frozen sections: histological feat.
• ep. white adipose tissue
10% low
fat diet
(palm oil)
10 LFD
10 HFD
45% high
fat diet
(palm oil)
20 LFD
RNA extraction: real-time PCR
paraffin sections: histological feat.
lipid content
quality control &
data analysis
pipeline
Mouse
genome
430 2.0
0 2 4 8 12 16 20 weeks-3

24. High fat diet-induced obesity
0
5
10
15
20
25
0 2 4 8 12 16 20
weeks under diet intervention
BWgain(g)
*
*
*
**
* *
* *
LFL
LFH
HFL
HFH
**
*
***
Liver TG content
0
40
80
120
160
200
mgTG/gliver
ALTactivity(UI)
ALT plasma activity
RatioLW/BW(%)
Hepatomegaly
**
0
2
4
6
8
10
***
0
20
40
60
80
100
* *
LFL LFH HFL HFH

25. A subpopulation of mice fed HFD develops NASH

26. Immunohistochemical staining confirms enhanced liver
inflammation and early fibrosis in HFH mice
Macrophage CD68
Collagen
Stellate cell GFAP

27. Upregulation of inflammatory and fibrotic
gene expression in HFH responder mice

28. Adipose dysfunction in HFH mice

29. Change in adipose gene expression
indicate adipose tissue dysfunction

30. Plasma proteins as early predictive
biomarker for NASH in C57Bl/6 mice

31. Plasma proteins as early predictive
biomarker for NASH in C57Bl/6 mice
Multivariate analysis of association of protein
plasma concentrations with final liver
triglyceride content

32. Conclusions
• The data support the existence of a tight
relationship between adipose tissue
dysfunction and NASH pathogenesis.
• It points to several novel potential
predictive biomarkers for NASH.

33. Peripheral
blood
Protein turnover
Amino acid
metabolism
Glycogenogenesis
Glyconeogenesis
Glycolysis
Lipogenesis,
oxidation
GI-tract
Macronutrient
composition
of the diet
Liver
Gut peptides
Nutrients
Bacterial
derived
components
Influence of dietary protein on gene expression and
metabolic phenotype in the gut-liver axis

34. Objective
 Investigating the effect of a high protein diet on
hepatic lipid accumulation.
 Unravel mechanisms which are responsible for
the reduced liver fat.

35. Design & diets
1 week 12 weeks
Acute effect
of a high fat /
high protein diet
Long term diet effect
on the development
of liver steatosis
2 weeks
Run-in:
control diet
Experimental diets Carbohydrate (en%) Fat (en%) Protein (en%)
Two low fat diet – normal or high protein
LF-NP 75 10 15
LF-HP 40 10 50
Two high fat diet – normal or high protein
HF-NP 50 35 15
HF-HP 15 35 50

36. Body composition and food intake
Schwarz, J. et al., PLoS ONE 2012.

37. Hepatic steatosis
50 µm
Schwarz, J. et al., PLoS ONE 2012.

38. Fasting and postprandial plasma triglycerides
Schwarz, J. et al., PLoS ONE 2012.

39. Microarray analysis to study gene
expression

40. Enrichment map for HP vs. NP feeding
to identify biological functions
Schwarz, J. et al., PLoS ONE 2012.

41. Changes in liver amino acid metabolic pathways induced by
increasing dietary protein
Schwarz, J. et al., PLoS ONE 2012.

42. Skeletal muscle functions & disorders
• Force production =>
Movement
• Heat production
• Protein storage
• Glucose & lipid
homeostasis
• Myopathies (muscular
weakness)
• Atrophy
• Sarcopenia of aging
• Ectopic fat disposition
• Insulin resistance

43. Skeletal muscle

44. Myocyte

45. Interplay between adipokines and
myokines represent a yin–yang balance
Pedersen, B. K. & Febbraio, M. A. (2012) Muscles, exercise and obesity: skeletal muscle as a secretory organ
Nat. Rev. Endocrinol. doi:10.1038/nrendo.2012.49

46. Skeletal muscle is a secretory organ

47. Link of physical activity to protection
against premature mortality

48. The Molecular Basis of Adaptation to Exercise

49. Transcriptional Regulators of Metabolism and Adaptation in Skeletal Muscle

51. The timeline of the study (A) and set-up
of the endurance exercise bout (B)

52. Exercise increases heart rate and plasma levels
of FFA, insulin, cortisol and noradrenaline

53. Exercise mainly causes upregulation of gene expression
in both the exercising and non-exercising leg

54. Top 20 of most highly induced genes in
exercising and non-exercising leg

55. Induction of transcription factor
pathways by exercise

56. Nutrition, Metabolism & Genomics Group

57. Wageningen University
• Founded in 1918
• ~3000 employees
• ~7500 students
• ~220 PhD graduations per year