Neurogenic Potential of the 18-kDa Mitochondrial Translocator Protein (TSPO) in Pluripotent P19 Stem Cells.

Laura González-Blanco,Eduardo Antuña,Ignacio Vega-Naredo,Iván Menéndez-Valle,Gabriela Oliveira,Yaiza Potes,Ana Coto-Montes,Beatriz Caballero,Juan Carlos Bermejo-Millo

doi:10.3390/cells10102784

Laura González-Blanco, Eduardo Antuña + Show 7 more

Open Access

https://doi.org/10.3390/cells10102784

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Abstract

The 18-kDa translocator protein (TSPO) is a key mitochondrial target by which different TSPO ligands exert neuroprotective effects. We assayed the neurogenic potential of TSPO to induce the neuronal differentiation of pluripotent P19 stem cells in vitro. We studied changes in cell morphology, cell proliferation, cell death, the cell cycle, mitochondrial functionality, and the levels of pluripotency and neurogenesis of P19 stem cells treated with the TSPO ligand, PK 11195, in comparison to differentiation induced by retinoid acid (RA) and undifferentiated P19 stem cells. We observed that PK 11195 was able to activate the differentiation of P19 stem cells by promoting the development of embryoid bodies. PK 11195 also induced changes in the cell cycle, decreased cell proliferation, and activated cell death. Mitochondrial metabolism was also enhanced by PK 11195, thus increasing the levels of reactive oxygen species, Ca2+, and ATP as well as the mitochondrial membrane potential. Markers of pluripotency and neurogenesis were also altered during the cell differentiation process, as PK 11195 induced the differentiation of P19 stem cells with a high predisposition toward a neuronal linage, compared to cell differentiation induced by RA. Thus, we suggest a relevant neurogenic potential of TSPO along with broad therapeutic implications.

Highlights

The mitochondrial 18-kDa translocator protein (TSPO), which was first described as the peripheral benzodiazepine receptor, is primarily located in the mitochondrial outer membrane in different cell types and tissues
Undifferentiated P19 stem cells were seeded in plates at a density of 3 × 105 cells/cm2 and cultured under three experimental conditions for 4 days to induce cell differentiation: (a) undifferentiated P19 stem cells (SC); (b) P19 stem cells treated with a single dose of 1 μM Retinoic Acid (RA); and c) P19 stem cells treated with a single dose of the TSPO ligand PK 11195 at 50 μM (PK 11195), as described in previous studies [7]
Our present data reveal the expression of TSPO protein in association with a pluripotent state in P19 stem cells

Summary

Introduction

The mitochondrial 18-kDa translocator protein (TSPO), which was first described as the peripheral benzodiazepine receptor, is primarily located in the mitochondrial outer membrane in different cell types and tissues. TSPO expression is significantly increased in glial cells under neurodegeneration and inflammation conditions, including neurodegenerative pathologies such as Parkinson’s and Alzheimer’s diseases as well as after traumatic brain injury (TBI) [6]. Increased TSPO levels have been observed in blood from patients with TBI, which correlate with systemic and soluble proinflammatory parameters (e.g., IL-6, TNF-α, reactive C protein) as well as the level of neurological activity [9], it represents a valuable marker for monitoring the prognosis of brain injury. Damaged neurons show increased TSPO levels in those specific zones affected by brain injury [10], as well as under cell stress conditions in zones such as the brain cortex and hippocampus [11]

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