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Uncoupling Protein-2 and -3 Messenger Ribonucleic Acids in Adipose Tissue and Skeletal Muscle of Healthy Males: Variability, Factors Affecting Expression, and Relation to Measures of Metabolic Rate*
- Source :
- The Journal of Clinical Endocrinology & Metabolism. 85:1975-1983
- Publication Year :
- 2000
- Publisher :
- The Endocrine Society, 2000.
-
Abstract
- Mitochondrial uncoupling protein-2 and -3 (UCP2 and UCP3) may be involved in the modulation of resting metabolic rate and energy balance. To investigate their variability, the influence of this on the variability of energy expenditure, and potential regulatory factors of the expression of the corresponding genes, we measured their messenger ribonucleic acids (mRNAs) in muscle and white adipose tissue of lean, healthy men and correlated the abundance of these mRNAs (attomoles per microg total RNA) with measures of resting metabolic rate, hormone levels (thyroid hormones, insulin, glucagon, leptin, and catecholamines), and fuels potentially involved in energy balance regulation. We also investigated whether the thiazolidinedione, troglitazone, stimulates UCP2 and UCP3 mRNA levels to follow up on the observation that this antidiabetic drug increases the levels of expression in cultured cells. We found UCP2 and UCP3 mRNA levels to be highly variable and poorly correlated with measures of energy expenditure and with most factors affecting energy balance. Only nocturnal urinary norepinephrine excretion could explain a significant fraction of the variability in both UCP2 and UCP3 expression in muscle, but not adipose tissue. Thyroid hormone and norepinephrine excretion were found to contribute to the variability of resting metabolic rate, but this could not be explained by an effect on UCP mRNAs. Troglitazone affected neither the expression of UCPs nor the hormones or the measures of metabolic rate investigated. In conclusion, our results show that the expression of UCP2 and UCP3 genes is quite variable in healthy males and that this variability does not explain that in resting energy expenditure, and suggest that sympathetic activity is an important potential regulator of the expression of these proteins in skeletal muscle. However, the data do not support the concept that regulation of the expression of these genes is the most important level of control of UCP3 and UCP2 functions, and other levels of control have to be invoked.
- Subjects :
- Adult
Leptin
Male
medicine.medical_specialty
Hydrocortisone
Transcription, Genetic
Endocrinology, Diabetes and Metabolism
Clinical Biochemistry
Thyrotropin
Adipose tissue
White adipose tissue
Biology
Biochemistry
Ion Channels
Mitochondrial Proteins
Norepinephrine
Endocrinology
Reference Values
Internal medicine
medicine
Humans
Insulin
Uncoupling Protein 3
Uncoupling protein
Uncoupling Protein 2
RNA, Messenger
Muscle, Skeletal
UCP3
Uncoupling Agents
Biochemistry (medical)
Membrane Transport Proteins
Proteins
Glucagon
Hormones
Thyroxine
Adipose Tissue
Basal metabolic rate
Triiodothyronine
Basal Metabolism
Carrier Proteins
Thermogenesis
Hormone
Subjects
Details
- ISSN :
- 19457197 and 0021972X
- Volume :
- 85
- Database :
- OpenAIRE
- Journal :
- The Journal of Clinical Endocrinology & Metabolism
- Accession number :
- edsair.doi.dedup.....17624e7f3a11b0177ed39b7ee36842b4