Selective Inhibition of Collagen Prolyl 4-Hydroxylase in Human Cells

Abstract

Collagen is the most abundant protein in animals. Its overproduction is associated with fibrosis and cancer metastasis. The stability of collagen relies on post-translational modifications, the most prevalent being the hydroxylation of collagen strands by collagen prolyl 4-hydroxylases (CP4Hs). Catalysis by CP4Hs enlists an iron cofactor to convert proline residues to 4 hydroxyproline residues, which are essential for the conformational stability of mature collagen. Ethyl 3,4-dihydroxybenzoate (EDHB) is commonly used as a “P4H” inhibitor in cells, but suffers from low potency, poor selectivity, and off-target effects that cause iron deficiency. Dicarboxylates of 2,2′-bipyridine are among the most potent known CP4H inhibitors but suffer from a high affinity for free iron. A screen of biheteroaryl compounds revealed that replacing one pyridyl group with a thiazole moiety retains potency and enhances selectivity. A diester of 2 (5-carboxythiazol-2-yl)pyridine-5-carboxylic acid is bioavailable to human cells and inhibits collagen biosynthesis at concentrations that neither cause general toxicity nor disrupt iron homeostasis. These data anoint a potent and selective probe for CP4H and a potential lead for the development of a new class of antifibrotic and antimetastatic agents.

Targeting defective proteostasis in the collagenopathies

“…In tandem with biochemical studies, the development of improved compounds to target collagen chaperones, either alone or in the context of relevant complexes, is another key step for translating interactome and screeningbased findings into treatment options. There now are selective inhibitors for prolyl-4hydroxylase [33], Hsp47 [23], and protein disulfide isomerase A1 [34], all of which are involved in collagen biogenesis. Application of these tools to disease models, and the development of selective activating compounds for these and other chaperones, will help determine if modulating these proteostasis factors can favorably influence collagen folding and/or quality control outcomes.…”

Human Collagen Prolyl 4-Hydroxylase Is Activated by Ligands for Its Iron Center

“…20,21 These biheteroaryl dicarboxylates compete with α-ketoglutarate for binding to the active-site iron. To our surprise, we discovered two biheteroaryl monocarboxylates that activate CP4H.…”

Selective Inhibitors of a Human Prolyl Hydroxylase (OGFOD1) Involved in Ribosomal Decoding

“…Of the ∼60–70 human 2OG oxygenases, some are current medicinal chemistry targets, including enzymes involved in chromatin modification and lipid metabolism . Inhibition of the procollagen hydroxylases is under consideration as a target to limit the overproduction of collagen associated with certain cancers and fibrotic diseases . The PHDs are presently being targeted for the treatment of hypoxia‐related diseases, with inhibitors in late‐stage clinical trials for anaemia .…”

“…[5,16] Inhibition of the procollagen hydroxylasesi su nder consideration as a target to limit the overproduction of collagen associatedw ith certain cancers andf ibrotic diseases. [17] The PHDs are presently being targeted for the treatment of hypoxia-related diseases, with inhibitors in late-stage clinicalt rials for anaemia. [18] If OGFOD1i si ndeed involved in mRNA codon recognition, as suggested based on studies of yeast homologues, [8,13] smallmolecule-mediated inhibition of ribosomal hydroxylation could prove useful for the treatment of diseases such as muscular dystrophy that are caused by premature stop-codons through nonsense suppression.…”