AMP-activated protein kinase (AMPK) is a principal metabolic regulator affecting growth and response to cellular stress. Comprised of catalytic and regulatory subunits, each present in multiple forms, AMPK is best described as a family of related enzymes. In recent years, AMPK has emerged as a desirable target for modulation of numerous diseases, yet clinical therapies remain elusive. Challenges result, in part, from an incomplete understanding of the structure and function of full-length heterotrimeric complexes. In this work, we provide the full-length structure of the widely expressed α1β1γ1 isoform of mammalian AMPK, along with detailed kinetic and biophysical characterization. We characterize binding of the broadly studied synthetic activator A769662 and its analogs. Our studies follow on the heels of the recent disclosure of the α2β1γ1 structure and provide insight into the distinct molecular mechanisms of AMPK regulation by AMP and A769662.

We report that 4-(3-(benzyloxy)phenyl)-2-ethylsulfinyl-6-(trifluoromethyl)pyrimidine (BETP), which behaves as a positive allosteric modulator at the glucagon-like peptide-1 receptor (GLP-1R), covalently modifies cysteines 347 and 438 in GLP-1R. C347, located in intracellular loop 3 of GLP-1R, is critical to the activity of BETP and a structurally distinct GLP-1R ago-allosteric modulator, N-(tert-butyl)-6,7-dichloro-3-(methylsulfonyl)quinoxalin-2-amine. We further show that substitution of cysteine for phenylalanine 345 in the glucagon receptor is sufficient to confer sensitivity to BETP.

The medicinal chemistry and preclinical biology of imidazopyridine-based inhibitors of diacylglycerol acyltransferase 2 (DGAT2) is described. A screening hit 1 with low lipophilic efficiency (LipE) was optimized through two key structural modifications: (1) identification of the pyrrolidine amide group for a significant LipE improvement, and (2) insertion of a sp(3)-hybridized carbon center in the core of the molecule for simultaneous improvement of N-glucuronidation metabolic liability and off-target pharmacology. The preclinical candidate 9 (PF-06424439) demonstrated excellent ADMET properties and decreased circulating and hepatic lipids when orally administered to dyslipidemic rodent models.

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Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that downregulates low-density lipoprotein (LDL) receptor (LDL-R) levels on the surface of hepatocytes, resulting in decreased clearance of LDL-cholesterol (LDL-C). Phenotypic screening of a small-molecule compound collection was used to identify an inhibitor of PCSK9 secretion, (R)-N-(isoquinolin-1-yl)-3-(4-methoxyphenyl)-N-(piperidin-3-yl)propanamide (R-IMPP), which was shown to stimulate uptake of LDL-C in hepatoma cells by increasing LDL-R levels, without altering levels of secreted transferrin. Systematic investigation of the mode of action revealed that R-IMPP did not decrease PCSK9 transcription or increase PCSK9 degradation, but instead caused transcript-dependent inhibition of PCSK9 translation. In support of this surprising mechanism of action, we found that R-IMPP was able to selectively bind to human, but not E. coli, ribosomes. This study opens a new avenue for the development of drugs that modulate the activity of target proteins by mechanisms involving inhibition of eukaryotic translation.