Exp Clin Endocrinol Diabetes 2018; 126(02): 77-84
DOI: 10.1055/s-0043-103282
Article
© Georg Thieme Verlag KG Stuttgart · New York

In vitro Effects of the Specific Mitochondrial TSPO Ligand Ro5 4864 in Cultured Human Osteoblasts

Nahum Rosenberg
1   The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, POB 9649, Bat Galim, Haifa, Israel
,
Orit Rosenberg
1   The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, POB 9649, Bat Galim, Haifa, Israel
,
Abraham Weizman
2   Research Unit, Geha Mental Health Center and the Laboratory of Biological Psychiatry, Felsenstein Medical Research Center, Sackler Faculty of Medicine, Tel Aviv University, Tel
,
Leo Veenman
3   Department of Neuroscience, The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, POB 9649, Bat Galim, Haifa, Israel
,
Moshe Gavish
3   Department of Neuroscience, The Ruth and Bruce Rappaport Faculty of Medicine, Technion – Israel Institute of Technology, POB 9649, Bat Galim, Haifa, Israel
› Author Affiliations
Further Information

Publication History

received 03 September 2016
revised 24 December 2016

accepted 06 February 2017

Publication Date:
27 September 2017 (online)

Abstract

The 18 kDa mitochondrial translocator protein (TSPO) ligands (10 µM), e. g., protoporphyrin IX, PK 11195 and FGIN-1-27, have different effects on metabolism and protein expression in human osteoblasts. In this study, we investigated the archetypical TSPO specific ligand Ro5-4864 (10 µM) effect in primary osteoblasts in culture aiming to further understand the TSPO role in these mature metabolically active cells.

We found that following exposure to Ro5-4864, cellular [18F]-FDG incorporation and ATP content were reduced by 48% (p<0.001) and 44% (p<0.001), respectively. The mitochondrial membrane potential (ΔΨm) increased by 50% (p<0.01), mRNA synthesis of TSPO and voltage dependent anion channel (VDAC1) decreased both by 70%, the TSPO and VDAC1 protein expression decreased by 80% and 68%, respectively (p<0.001). Ro5 4864 caused a decrease in the proportion of cells in the G1 phase (by 20%, p<0.05), shifting the cell cycle to the S and G2/M phases. Furthermore, 63% decrease in hexokinase 2 protein expression (p<0.001) was found. However, we found no significant effects on hexokinase 2 mRNA expression (by RT-PCR). We also did not see significant changes in mitochondrial mass (MitoTracker Green assay), apoptosis rate (TUNEL assay), overall cell death (LDH assay), cellular proliferation (BrdU assay), cell maturation (cellular alkaline phosphatase assay), and the number of cells in the culture.

Therefore, an overall effect of Ro5-4864 exhorts is via pathways related to the mitochondrial activity, which is only partly like PK 11195, but not to the other TSPO ligands.