出版社：American Society for Biochemistry and Molecular Biology
摘要：Lipoprotein lipase (LPL) supplies brown adipose tissue with fatty acids for nonshivering thermogenesis. In brown adipose tissue of the Djungarian hamster we studied i) the molecular mechanisms involved in cold-induced stimulation of LPL activity, ii) the adrenergic control of LPL expression, and iii) compared LPL expression in brown and white adipose tissue. i) After 8 h cold exposure we detected a 2-fold increase in LPL activity and protein level in brown adipose tissue, whereas LPL mRNA level remained unchanged. A cold-induced increase (1.5-fold) in LPL activity was observed in brown adipose tissue of hamsters treated with actinomycin D prior to 4 h cold exposure, whereas cycloheximide treatment completely abolished LPL stimulation. Thus, these data suggest that during the initial phase ( 24 h) cold exposure provides some evidence that the active fraction of the enzyme pool in brown adipose tissue is increased in response to cold. ii) Surgical denervation and noradrenaline treatment revealed a complex role of the sympathetic innervation in the control of LPL expression in brown adipose tissue. Denervation decreased LPL mRNA level, but increased LPL activity. Noradrenaline treatment stimulated LPL activity to a similar extent as cold exposure. However, cold-induced stimulation of LPL activity was not impaired by denervation. iii) Cold exposure significantly elevated LPL mRNA content of inguinal white adipose tissue, although LPL activity was not affected. Posttranscriptional mechanisms appear to be involved in the tissue specific control of LPL expression.
