Abstract
Mitogen-activated protein kinase phosphatase 1 (MKP-1) is a tyrosine phosphatase superfamily member that dephosphorylates and inactivates cardinal mitogen-activated protein kinase (MAPK) substrates, such as p38, c-Jun NH2-terminal kinase, and extracellular signal-regulated kinase. Although these MAPK substrates regulate many essential cellular processes associated with human diseases, few pharmacological inhibitors have been described. The lack of readily available selective MKP-1 inhibitors has severely limited interrogation of its biological role and was one rationale for using a recently described tricyclic pyrrole-2-carboxamide library in our screening efforts. In this report we demonstrate the pharmacological richness of the pyrrole carboxamide library by the finding that 10 of 172 members inhibited human MKP-1. Two of the pyrrole carboxamides, PSI2106 and MDF2085, were especially notable in vitro inhibitors of recombinant human MKP-1 enzyme activity with IC50 values of 8.0 ± 0.9 and 8.3 ± 0.8 μM, respectively. Both showed some selectivity for MKP-1 over the closely related phosphatases MKP-3, Cdc25B, VHR, and PTP1B. Computational examination of the surface properties near the catalytic site revealed that the phosphatases studied differ significantly in their electrostatic potential at the substrate binding site. The compounds inhibited MKP-1 reversibly but displayed mixed kinetics. Phosphatase inhibition was retained in the presence of physiologically relevant concentrations of glutathione. Molecular docking studies suggested that PSI2106 may interact with His229 and Phe299 on MKP-1. These results reveal the power of using a small focused library for identifying pharmacological probes.
Footnotes
-
This work was supported by National Institutes of Health Grants MH074411, GM067982, and CA052995 and by the Fiske Drug Discovery Fund.
-
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
-
doi:10.1124/jpet.107.122242.
-
ABBREVIATIONS: MAPK, mitogen-activated protein kinase; MKP-1, mitogen-activated protein kinase phosphatase-1; DSP, dual specificity phosphatase; Erk, extracellular signaling-related protein kinase; OMFP, 3-O-methylfluorescein phosphate; GSH, glutathione; NU-126, 2-((E))-2-(5-cyanobenzofuran-2-yl)vinyl)-1H-indole-6-carbonitrile.
- Received March 3, 2007.
- Accepted May 29, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|