Cholesterol interaction sites on the transmembrane domain of the hedgehog signal transducer and Class F G protein-coupled receptor Smoothened

Abstract

Transduction of hedgehog signals across the plasma membrane is a key process during animal development. This is facilitated by the Class F G-protein-coupled-receptor (GPCR) Smoothened (SMO), a major drug target in the treatment of basal cell carcinomas. Recent studies have suggested that SMO is modulated via interactions of its transmembrane (TM) domain with cholesterol. Long time scale (>0.35 ms of simulation time) molecular dynamics simulations of SMO embedded in two different cholesterol containing lipid bilayers reveal direct interactions of cholesterol with the transmembrane domain at regions distinct from those observed in Class A GPCRs. In particular the extracellular tips of helices TM2 and TM3 form a well-defined cholesterol interaction site, robust to changes in membrane composition and in force field parameters. Potential of mean force calculations for cholesterol interactions yield a free energy landscape for cholesterol binding.Combined with analysis of equilibrium cholesterol occupancy these results reveal the existence of a dynamic 'greasy patch' interaction with the TM domain of SMO, which may be compared to previously identified lipid interaction sites on other membrane proteins. These predictions provide molecular level insights into cholesterol interactions with a biomedically relevant Class F GPCR, suggesting potential druggable sites.

The Glycosphingolipid GM3 Modulates Conformational Dynamics of the Glucagon Receptor

“…S3 ) compared with other lipid species. A locally high radial distribution of GM3 and PIP 2 has been observed previously for simulations of class A receptors ( 28 , 57 ), and PIP 2 binding has been seen during simulations of the class F GPCR Smoothened ( 58 ). Bound PIP 2 molecules have also been seen in a recent cryo-EM structure of neurotensin receptor 1 ( 16 ).…”

Data analysis of molecular dynamics simulation trajectories of β-sitosterol, sonidegib and cholesterol in smoothened protein with the CHARMM36 force field

“…The most favourable residues in SMO-CLR complex is TRP109 in the cysteine-rich domain (CRD) of smoothened which contributes the energy with less than −10 kJ/mol. This finding is consistent with a maximal well depth −10 kJ/mol at transmembrane 2/3e, which is the site of cholesterol-binding [8] . Residue TYR394 in SMO-SNG complex contributes to the highest binding energy towards sonidegib with the energy about −3 kJ/mol.…”

Protective effect of sonic hedgehog against oxidized low‑density lipoprotein‑induced endothelial apoptosis: Involvement of NF‑κB and Bcl‑2 signaling

“…Previous studies revealed that classical Shh pathway components are obviously decreased in the atherosclerotic vasculature (12) and anti-cd31 antibody labeling of Ecs produces Shh immunoreactivity that is not detected in carotid and femoral artery plaques (13). Recently, structural biology studies have focused on the modulated or interaction sites of cholesterol in hedgehog signaling, revealing a direct interaction between cholesterol and Smo, a critical component of the hedgehog signaling cascade, which suggests potential druggable sites (7,(26)(27)(28)(29). LdL is the main carrier of cholesterol, and ox-LdL plays an important role in atherogenesis (30).…”