Abstract

The LKB1/STRAD/MO25 complex (LSMK) has been identified as the major upstream kinase for AMP-activated protein kinase (AMPK). PKA phosphorylates LKB1 at the Ser428 residue in humans and Ser431 residue in mice. We investigated PKA as an upstream kinase for LSMK. LKB1 that had been incubated with PKA prior to incubation with AMPK experienced up to a 51% increase in AMPK Kinase activity compared to LKB1 alone (p < 0.05). When blocked with a PKA Inhibitor, the kinase effect of PKA on LKB1 was eliminated. Rat epitrochlearis muscle tissue incubated with epinephrine experienced no increase in AMPK activity compared with controls indicating that epinephrine does not cause AMPK activity in this type of tissue. In conclusion, phosphorylation by PKA can increase the AMPKK activity of LKB1-STRAD-MO25 in vitro. Because LKB1 has been found to be constitutively active, it is postulated that phosphorylation by PKA may act to enhance LKB1-AMPK interaction and thus achieve its effect.

Degree

College and Department

Life Sciences; Physiology and Developmental Biology

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