An unambiguous assay for the cloned human sigma1 receptor reveals high affinity interactions with dopamine D4 receptor selective compounds and a distinct structure–affinity relationship for butyrophenones

Abstract

The ability of sigma 1 receptors to interact with a huge range of drug structural classes coupled with its wide distribution in the body has contributed to it being implicated as a possible therapeutic target for a broad array of disorders ranging from substance abuse to depression to Alzheimer's disease. Surprisingly, the reported affinity values for some sigma 1 receptor ligands vary more than 50-fold. The potential of the sigma 1 receptor as a pharmacotherapeutic target prompted us to develop an unambiguous assay system for measuring the affinity of ligands to the cloned human sigma 1 receptor. In the course of characterizing this system and determining the true affinity values for almost three dozen compounds, it was discovered that some dopamine D 4 receptor selective compounds bind sigma 1 receptors with high affinity. A systematic analysis of haloperidol-like compounds revealed a clear structure-affinity relationship amongst clinically relevant butyrophenones. The antidepressant fluvoxamine, the drug of abuse methamphetamine, and the neurosteroid progesterone were amongst the many ligands whose interactions with sigma 1 receptor were confirmed with our screening assay.

Activation of the sigma-1 receptor by haloperidol metabolites facilitates brain-derived neurotrophic factor secretion from human astroglia

“…The reference agonists 4-PPBP and (+)-SKF10047, but not the reference antagonist BD1063, facilitated BDNF secretion from astrocytic cells. In the case of (+)-SKF10047, a higher concentration (at the limit of its solubility in this assay) was needed to observe an agonist effect consistent with the relatively low affinity of this compound for the S1R (Lee et al, 2008). …”

“…Binding conditions were the same as described previously for the S1R (Lee et al, 2008): binding buffer (Tris 50 mM, pH = 8.1 at 37°C), ice-cold wash buffer (Tris 10 mM, pH = 8.1 at 0–2°C), and incubation time (3 hrs at 37°C) with shaking. Non-specific binding for the S1R and S2R was determined in the presence of 5 μM BD1063 and 15 μM haloperidol, respectively.…”

Genetic Polymorphisms in Sigma-1 Receptor and Apolipoprotein E Interact to Influence the Severity of Alzheimers Disease

“…Its regulation of lipid transport, similar to ApoE, is required for membrane repair and synaptic plasticity in nervous system [2,15]. SIGMAR1 agonists have been identified with therapeutic potential for depression in AD [16], along with other potential drugs for the treatment of AD by accelerating A clearance [17]. The polymorphism c.5A>C (rs1800866, resulting in an amino acid substitution Q2P) in the first exon is in complete linkage disequilibrium with certain polymorphisms in the promoter, and the haplotype TT-241-240P2 shows a 43% reduction in SIGMAR1 transcription activity compared to its pair GC-241-240Q2 [18].…”

Characterization of Ligand Binding to the σ1Receptor in a Human Tumor Cell Line (RPMI 8226) and Establishment of a Competitive Receptor Binding Assay

“…In 2008, a s 1 assay with the breast cancer cell line MCF-7 was described. 32 Its s 1 receptor expression was controversially discussed. 21,32 The native cell line was supposed not to have any endogenous s 1 receptors.…”

“…32 Its s 1 receptor expression was controversially discussed. 21,32 The native cell line was supposed not to have any endogenous s 1 receptors. Therefore it was stably transfected with the human s 1 receptor DNA and then employed as human s 1 receptor material in a s 1 assay.…”