Optimization and Mechanistic Investigations of Novel Allosteric Activators of PKG1α

Activation of PKG1α is a compelling strategy for
the treatment
of cardiovascular diseases. As the main effector of cyclic guanosine
monophosphate (cGMP), activation of PKG1α induces smooth muscle
relaxation in blood vessels, lowers pulmonary blood pressure, prevents
platelet aggregation, and protects against cardiac stress. The development
of activators has been mostly limited to cGMP mimetics and synthetic
peptides. Described herein is the optimization of a piperidine series
of small molecules to yield activators that demonstrate in
vitro phosphorylation of vasodilator-stimulated phosphoprotein
as well as antiproliferative effects in human pulmonary arterial smooth
muscle cells. Hydrogen/deuterium exchange mass spectrometry experiments
with the small molecule activators revealed a mechanism of action
consistent with cGMP-induced activation, and an X-ray co-crystal structure
with a construct encompassing the regulatory domains illustrated a
binding mode in an allosteric pocket proximal to the low-affinity
cyclic nucleotide-binding domain.