RESUMEN
Tissue inhibitor of metalloproteinase 3 (TIMP-3) is an important regulator of extracellular matrix (ECM) turnover. TIMP-3 binds to sulfated ECM glycosaminoglycans or is endocytosed by cells via low-density lipoprotein receptor-related protein 1 (LRP-1). Here, we report that heparan sulfate (HS) and chondroitin sulfate E (CSE) selectively regulate postsecretory trafficking of TIMP-3 by inhibiting its binding to LRP-1. HS and CSE also increased TIMP-3 affinity for glycan-binding metalloproteinases, such as adamalysin-like metalloproteinase with thrombospondin motifs 5 (ADAMTS-5), by reducing the dissociation rate constants. The sulfation pattern was crucial for these activities because monosulfated or truncated heparin had a reduced ability to bind to TIMP-3 and increase its affinity for ADAMTS-5. Therefore, sulfation of ECM glycans regulates the levels and inhibitory activity of TIMP-3 and modulates ECM turnover, and small mimicries of sulfated glycans may protect the tissue from the excess destruction seen in diseases such as osteoarthritis, cancer, and atherosclerosis.
Asunto(s)
Sulfatos de Condroitina/metabolismo , Heparitina Sulfato/metabolismo , Inhibidor Tisular de Metaloproteinasa-3/metabolismo , Proteínas ADAM/química , Proteínas ADAM/metabolismo , Animales , Cartílago Articular/metabolismo , Sulfatos de Condroitina/química , Endocitosis , Matriz Extracelular/metabolismo , Proteoglicanos de Heparán Sulfato/metabolismo , Heparitina Sulfato/química , Humanos , Cinética , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad/química , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismo , Ratones , Unión Proteica , Inhibidor Tisular de Metaloproteinasa-3/antagonistas & inhibidores , Inhibidor Tisular de Metaloproteinasa-3/genéticaRESUMEN
The posttranslational modification of chromatin through acetylation at selected histone lysine residues is governed by histone acetyltransferases (HATs) and histone deacetylases (HDACs). The significance of this subset of the epigenetic code is interrogated and interpreted by an acetyllysine-specific protein-protein interaction with bromodomain reader modules. Selective inhibition of the bromo and extra C-terminal domain (BET) family of bromodomains with a small molecule is feasible, and this may represent an opportunity for disease intervention through the recently disclosed antiproliferative and anti-inflammatory properties of such inhibitors. Herein, we describe the discovery and structure-activity relationship (SAR) of a novel, small-molecule chemical probe for BET family inhibition that was identified through the application of structure-based fragment assessment and optimization techniques. This has yielded a potent, selective compound with cell-based activity (PFI-1) that may further add to the understanding of BET family function within the bromodomains.
