EXPRESSION OF A DOMINANT-NEGATIVE MUTANT HUMAN INSULIN-RECEPTOR IN THE MUSCLE OF TRANSGENIC MICE

To examine the in vivo effects of a kinase-deficient mutant human insu lin receptor, we used the muscle creatine kinase promoter to express a putative dominant-negative receptor: Ala(1134) --> Thr (Moller, D. E. , Yokota, A., White, M. F., Pazianos, A G., and Flier, J. S. (1990) J. Biol. Chem. 265, 14979-14985) in transgenic mice, Two lines were gene rated, where receptor expression was restricted to striated muscle and was increased by 5-12-fold in skeletal muscle. Transgenic gluteal mus cle insulin receptor kinase activity was reduced by approximate to 80% after maximal in vivo insulin stimulation. Glycogen content in this m uscle was reduced by 45% in transgenic mice. Insulin levels were appro ximate to 2-fold higher, and glucose concentrations were 12% higher in transgenics fed ad libitum. Transgenic mice exhibited reduced in vivo sensitivity to low dose (0.1 milliunits/g) intravenous insulin. In is olated soleus muscles from transgenics, where mutant receptors were ex pressed at lower levels, insulin-stimulated receptor kinase activity w as reduced by 42%, but insulin-stimulated 2-deoxyglucose uptake was un affected. These results indicate that (i) overexpression of a kinase-d eficient human insulin receptor in muscle causes dominant-negative eff ects at the level of receptor kinase activation, (ii) impairment of in sulin-stimulated muscle receptor tyrosine kinase activity can cause de creased insulin sensitivity in vivo, (iii) kinase-defective receptor m utants may be used to create novel animal models of tissue-specific in sulin resistance.