β2-Adrenoceptor agonists in the regulation of mitochondrial biogenesis

Abstract

The stimulation of mitochondrial biogenesis (MB) via cell surface G-protein coupled receptors is a promising strategy for cell repair and regeneration. Here we report the specificity and chemical rationale of a panel of β2-adrenoceptor agonists with regards to MB. Using primary cultures of renal cells, a diverse panel of β2-adrenoceptor agonists elicited three distinct phenotypes: full MB, partial MB, and non-MB. Full MB compounds had efficacy in the low nanomolar range and represent two chemical scaffolds containing three distinct chemical clusters. Interestingly, the MB phenotype did not correlate with reported receptor affinity or chemical similarity. Chemical clusters were then subjected to pharmacophore modeling creating two models with unique and distinct features, consisting of five conserved amongst full MB compounds were identified. The two discrete pharmacophore models were coalesced into a consensus pharmacophore with four unique features elucidating the spatial and chemical characteristics required to stimulate MB.

Keywords: Adrenoceptor; Biogenesis; Chemical similarity; Clustering; Mitochondria; Pharmacophore; Renal.

Figure 1

Generalized chemotype of MB stimulating β₂-AR agonists and similar compounds.

Figure 2

Representative β₂-AR agonists and similar compounds induce concentration-responsive increases in FCCP-uncoupled OCR after 24 h. Values indicate a percent of fold change relative to DMSO controls. Data is represented a mean ± s.e.m., N=4.

Figure 3

Chemical clustering, pK_d and MB activity of β₂-AR agonists and similar compounds. MAACS keyed chemical fingerprints were used to cluster compounds based on molecular similarity as measured by Tanimoto Coefficient. Three major clusters were identified and numbered within the chemogram. The MB heat map indicates full (red), partial (yellow), and inactive (green) biogenic compounds as determined by RPTC OCR. The pK_d heat map indicates the reported affinity for each ligand to the β₂-AR with high affinity (red), intermediate (yellow), and low affinity (green). The chemogram was rendered using Dendroscope.

Figure 4

Pharmacophore modeling of phenethylamines. A. Cluster 1/2: procaterol, formoterol and fenoterol. B. Pharmacophore overlay of cluster 1 pharmacophore with cluster 2 pharmacophore. Procaterol, formoterol and fenoterol were flexibly aligned to superimposed chemical features. C. Cluster 3: nisoxetine and tomoxetine. D. Pharmacophore model based on alignment of cluster 3. Nisoxetine and tomoxetine were flexibly aligned to superimposed chemical features. E and F. Pharmacophore overlay of cluster 1/2 pharmacophore with cluster 3 pharmacophore. E. Overlay of 5 compounds with features from cluster 1/2 and cluster 3 pharmacophore models. F. Consensus features derived from both cluster models with consensus features labeled in black and MB specific features in brown. The connectivity path of the phenethylamine core is depicted as a black line. F1 and F8 are aromatic, F2 and F9 are proton donors, F3, F5, and F6 are hydrophobic, F4 and F7 are proton acceptors.