Prokinetic actions of luminally acting 5-HT4 receptor agonists.

BACKGROUND: 5-HT4 receptor (5-HT4 R) agonists exert prokinetic actions in the GI tract, but non-selective actions and potential for stimulation of non-target 5-HT4 Rs have limited their use. Since 5-HT4 Rs are expressed in the colonic epithelium and their stimulation accelerates colonic propulsion in vitro, we tested whether luminally acting 5-HT4 R agonists promote intestinal motility. METHODS: Non-absorbed 5-HT4 R agonists, based on prucalopride and naronapride, were assessed for potency at the 5-HT4 R in vitro, and for tissue and serum distribution in vivo in mice. In vivo assessment of prokinetic potential included whole gut transit, colonic motility, fecal output, and fecal water content. Colonic motility was also studied ex vivo in mice treated in vivo. Immunofluorescence was used to evaluate receptor distribution in human intestinal mucosa. KEY RESULTS: Pharmacological screening demonstrated selectivity and potency of test agonists for 5-HT4 R. Bioavailability studies showed negligible serum detection. Gavage of agonists caused faster whole gut transit and colonic motility, increased fecal output, and elevated fecal water content. Prokinetic actions were blocked by a 5-HT4 R antagonist and were not detected in 5-HT4 R knockout mice. Agonist administration promoted motility in models of constipation. Evaluation of motility patterns ex vivo revealed enhanced contractility in the middle and distal colon. Immunoreactivity for 5-HT4 R is present in the epithelial layer of the human small and large intestines. CONCLUSIONS AND INFERENCES: These findings demonstrated that stimulation of epithelial 5-HT4 Rs can potentiate propulsive motility and support the concept that mucosal 5-HT4 Rs could represent a safe and effective therapeutic target for the treatment of constipation.

Structure-Based Design of ASK1 Inhibitors as Potential Agents for Heart Failure.

Apoptosis signal-regulating kinase 1 (ASK1/MAP3K) is a mitogen-activated protein kinase family member shown to contribute to acute ischemia/reperfusion injury. Using structure-based drug design, deconstruction, and reoptimization of a known ASK1 inhibitor, a lead compound was identified. This compound displayed robust MAP3K pathway inhibition and reduction of infarct size in an isolated perfused heart model of cardiac injury.

Correction to "Structure-Based Design of ASK1 Inhibitors as Potential Agents for Heart Failure".

[This corrects the article DOI: 10.1021/acsmedchemlett.6b00481.].

Rational design of vitamin D3 analogues which selectively restore activity to a vitamin D receptor mutant associated with rickets.

[formula: see text] Vitamin D3-resistant rickets (VDRR) is associated with mutations to the Vitamin D receptor (VDR) which effect ligand-dependent transactivation. Some VDRR associated mutants directly disrupt ligand binding. Using the reported VDR-1,25-dihydroxy vitamin D3 (1,25(OH)2D3) cocrystal structure, three 1,25(OH)2D3 analogues were designed to uniquely complement the rickets associated mutant VDR(Arg274-->Leu). The three analogues were 17 to 286 times more potent than 1,25(OH)2D3 with the mutant in cell-based assays and did not substantially activate cellular calcium influx.

Structure-based design of selective agonists for a rickets-associated mutant of the vitamin d receptor.

The nuclear and steroid hormone receptors function as ligand-dependent transcriptional regulators of diverse sets of genes associated with development and homeostasis. Mutations to the vitamin D receptor (VDR), a member of the nuclear and steroid hormone receptor family, have been linked to human vitamin D-resistant rickets (hVDRR) and result in high serum 1,25(OH)(2)D(3) concentrations and severe bone underdevelopment. Several hVDRR-associated mutants have been localized to the ligand binding domain of VDR and cause a reduction in or loss of ligand binding and ligand-dependent transactivation function. The missense mutation Arg274 --> Leu causes a >1000-fold reduction in 1,25(OH)(2)D(3) responsiveness and is, therefore, no longer regulated by physiological concentrations of the hormone. In this study, computer-aided molecular design was used to generate a focused library of nonsteroidal analogues of the VDR agonist LG190155 that were uniquely designed to complement the Arg274 --> Leu associated with hVDRR. Half of the designed analogues exhibit substantial activity in the hVDRR-associated mutant, whereas none of the structurally similar control compounds exhibited significant activity. The seven most active designed analogues were more than 16 to 526 times more potent than 1,25(OH)(2)D(3) in the mutant receptor (EC(50) = 3.3-121 nM). Significantly, the analogues are selective for the nuclear VDR and did not stimulate cellular calcium influx, which is associated with activation of the membrane-associated vitamin D receptor.