Stimulation of S14 mRNA and lipogenesis in brown fat by hypothyroidism, cold exposure, and cafeteria feeding: evidence supporting a general role for S14 in lipogenesis and lipogenesis in the maintenance of thermogenesis
In liver, thyroid hormone rapidly induces S14 mRNA, which encodes a small acidic protein. This sequence is abundantly expressed only in lipogenic tissues and is thought to have some function in fat metabolism. In the euthyroid rat, we measured 20-fold higher levels of S14 mRNA in interscapular brown adipose tissue than liver. Furthermore, whereas in liver or epididymal fat, hypothyroidism resulted in an 80% fall in S14 mRNA, in brown fat the level of this sequence increased a further 3-fold. In all three tissues, the expression of S14 mRNA correlated well with lipogenesis, as assessed by /sup 3/H/sub 2/O incorporation. Physiological activation of brown fat by chronic cold exposure or cafeteria feeding increased the concentration of S14 mRNA in this tissue and again this was accompanied by a greater rate of fatty acid synthesis. Overall, in liver and white and brown adipose tissue, S14 mRNA and lipogenesis were well correlated and strongly suggest a function of the S14 protein related to fat synthesis. These studies suggest that the S14 protein and lipogenesis may be important for thyroid hormone-induced and brown adipose tissue thermogenesis and that stimulation of these functions in hypothyroid brown fat is a consequence of decreased thyroid hormone-induced thermogenesis elsewhere.
- Research Organization:
- Univ. of Minnesota, Minneapolis, MN (United States)
- OSTI ID:
- 6409434
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 9
- Country of Publication:
- United States
- Language:
- English
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CARBOXYLIC ACIDS
BIOSYNTHESIS
LIPIDS
METABOLISM
MESSENGER-RNA
BIOLOGICAL FUNCTIONS
BIOLOGICAL LOCALIZATION
ADIPOSE TISSUE
BODY TEMPERATURE
DIET
HYPERTHYROIDISM
HYPOTHYROIDISM
LIVER
PROTEINS
RATS
RESPONSE MODIFYING FACTORS
THYROXINE
TRACER TECHNIQUES
TRITIUM COMPOUNDS
AMINO ACIDS
ANIMAL TISSUES
ANIMALS
BODY
CONNECTIVE TISSUE
DIGESTIVE SYSTEM
DISEASES
ENDOCRINE DISEASES
FUNCTIONS
GLANDS
HORMONES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PEPTIDE HORMONES
RNA
RODENTS
SYNTHESIS
THYROID HORMONES
TISSUES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques