Cell engineering method using fluorogenic oligonucleotide signaling probes and flow cytometry.

OBJECTIVE: Chromovert® Technology is presented as a new cell engineering technology to detect and purify living cells based on gene expression. METHODS: The technology utilizes fluorogenic oligonucleotide signaling probes and flow cytometry to detect and isolate individual living cells expressing one or more transfected or endogenously-expressed genes. RESULTS: Results for production of cell lines expressing a diversity of ion channel and membrane proteins are presented, including heteromultimeric epithelial sodium channel (αßγ-ENaC), sodium voltage-gated ion channel 1.7 (NaV1.7-αß1ß2), four unique γ-aminobutyric acid A (GABAA) receptor ion channel subunit combinations α1ß3γ2s, α2ß3γ2s, α3ß3γ2s and α5ß3γ2s, cystic fibrosis conductance regulator (CFTR), CFTR-Δ508 and two G-protein coupled receptors (GPCRs) without reliance on leader sequences and/or chaperones. In addition, three novel plasmid-encoded sequences used to introduce 3' untranslated RNA sequence tags in mRNA expression products and differentially-detectable fluorogenic probes directed to each are described. The tags and corresponding fluorogenic signaling probes streamline the process by enabling the multiplexed detection and isolation of cells expressing one or more genes without the need for gene-specific probes. CONCLUSIONS: Chromovert technology is provided as a research tool for use to enrich and isolate cells engineered to express one or more desired genes.

4-(2-Pyridyl)piperazine-1-benzimidazoles as potent TRPV1 antagonists.

A series of 4-(2-pyridyl)piperazine-1-benzimidazole analogues based on compound 1 was synthesized and evaluated for TRPV1 antagonist activity in capsaicin-induced (CAP) and pH5.5-induced (pH) FLIPR assays in a human TRPV1-expressing HEK293 cell line. Potent TRPV1 antagonists were identified through SAR studies. From these studies, several antagonists were found, with IC(50) values ranging from 32 nM to approximately 5000 nM. Among these, 11 [IC(50)=90 nM (CAP) and 104 nM (pH)] was further evaluated and found to be orally available in rats (F%=19.7).

Synthesis and evaluation of pyridazinylpiperazines as vanilloid receptor 1 antagonists.

A structurally biased chemical library of pyridazinylpiperazine analogs was prepared in an effort to improve the pharmaceutical and pharmacological profile of the lead compound N-(4-tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine-1(2H)-carboxamide (BCTC). The library was evaluated for VR1 antagonist activity in capsaicin-induced (CAP) and pH5.5-induced (pH) FLIPR assays in a human VR1-expressing HEK293 cell line. The most potent VR1 antagonists were found to have IC(50) values in the range of 9-200nM with improved pharmaceutical and pharmacological profiles versus the lead BCTC. These compounds represent possible second-generation BCTC analogs.

4-(2-pyridyl)piperazine-1-carboxamides: potent vanilloid receptor 1 antagonists.

A series of 4-(2-pyridyl)piperazine-1-carboxamide analogues based on the lead compound 1 was synthesized and evaluated for VR1 antagonist activity in capsaicin-induced (CAP) and pH (5.5)-induced (pH) FLIPR assays in a rat VR1-expressing HEK293 cell line. Potent VR1 antagonists were identified through SAR studies. From these studies, 18 was found to be very potent in the in vitro assay [IC(50)=4.8 nM (pH) and 35 nM (CAP)] and orally available in rat (F%=15.1).

N-(4-tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine -1(2H)-carbox-amide (BCTC), a novel, orally effective vanilloid receptor 1 antagonist with analgesic properties: I. in vitro characterization and pharmacokinetic properties.

Vanilloids such as capsaicin have algesic properties and seem to mediate their effects via activation of the vanilloid receptor 1 (VR1), a ligand-gated ion channel highly expressed on primary nociceptors. Although blockade of capsaicin-induced VR1 activation has been demonstrated in vitro and in vivo with the antagonist capsazepine, efficacy in rat models of chronic pain has not been observed with this compound. Here, we describe the in vitro pharmacology of a highly potent VR1 antagonist, N-(4-tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine-1(2H)-carbox-amide (BCTC). Similar to capsazepine, this compound inhibits capsaicin-induced activation of rat VR1 with an IC50 value of 35 nM. Interestingly however, BCTC also potently inhibits acid-induced activation of rat VR1 (IC50 value of 6.0 nM), whereas capsazepine is inactive. Similarly, in the rat skin-nerve preparation both BCTC and capsazepine block capsaicin-induced activation, whereas the response to acidification is inhibited by BCTC, but not by capsazepine. Specificity for VR1 was demonstrated against 63 other receptor, enzyme, transporter, and ion channel targets. BCTC was orally bioavailable in the rat, demonstrating a plasma half-life of approximately 1 h and significant penetration into the central nervous system. Thus, BCTC is a high potency, selective VR1 antagonist that, unlike capsazepine, has potent blocking effects on low pH-induced activation of rat VR1. These properties make it a more suitable candidate than capsazepine for testing the role played by VR1 in rat models of human disease.