The Low-Affinity Binding of Second Generation Radiotracers Targeting TSPO is Associated with a Unique Allosteric Binding Site

0489560 - ÚOCHB 2019 RIV US eng J - Journal Article
Rojas, C. - Stathis, M. - Coughlin, J. M. - Pomper, M. - Slusher, Barbara S.
The Low-Affinity Binding of Second Generation Radiotracers Targeting TSPO is Associated with a Unique Allosteric Binding Site.
Journal of Neuroimmune Pharmacology. Roč. 13, č. 1 (2018), s. 1-5. ISSN 1557-1890. E-ISSN 1557-1904
Institutional support: RVO:61388963
Keywords : translocator protein 18KDa (TSPO) * allosteric modulation * residence time
OECD category: Organic chemistry
Impact factor: 3.870, year: 2018

[C-11]-PK11195 (PK11195) has been widely used with positron emission tomography (PET) to assess levels of the translocator protein 18 kDa (TSPO) as a marker of neuroinflammation. Recent ligands, such as [C-11]-PBR28 and [C-11]-DPA713, have improved signal-to-noise ratio and specificity for TSPO over PK11195. However, these second generation radiotracers exhibit binding differences due to a single polymorphism (rs6971) that leads to three genotypes: C/C, C/T and T/T associated with high, mixed and low binding affinities, respectively. Here we report that [H-3]-DPA-713 in the presence of cholesterol or PK11195 has an accelerated dissociation rate from TSPO in platelets isolated from individuals with the T/T genotype. This allosteric interaction was not observed in platelets isolated from individuals with the C/C or C/T genotype. The results provide a molecular rationale for low binding affinity of T/T TSPO and further support the exclusion of these subjects from PET imaging studies using second generation TSPO ligands.
Permanent Link: http://hdl.handle.net/11104/0283957