The ligands of translocator protein: design and biological properties

2020 ◽  
Vol 26 ◽  
Author(s):  
Grigory V. Mokrov ◽  
Olga A. Deeva ◽  
Tatiana A. Gudasheva
Keyword(s):  
Protein Design ◽  
Mitochondrial Membrane ◽  
Benzodiazepine Receptor ◽  
Biological Properties ◽  
Translocator Protein ◽  
Peripheral Benzodiazepine Receptor ◽  
Inner Mitochondrial Membrane ◽  
Limiting Stage

: In 2020, it is already 43 years since Braestrup and Squires discovered 18 kDa translocator protein (TSPO), known until 2006 as "peripheral benzodiazepine receptor". During this time the functions of this receptor which is located on the outer membrane of mitochondria were studied in detail. One of the key functions of TSPO is the transfer of cholesterol from the outer to the inner mitochondrial membrane, which is the limiting stage in the synthesis of neurosteroids. TSPO is also involved in the transport of porphyrins, mitochondrial respiration, the opening of mitochondrial pores, apoptosis and cell proliferation. This review presents current information on the structure of TSPO, the mechanism of its participation in neurosteroidogenesis, as well as endogenous and synthetic TSPO ligands. Particular emphasis is placed on the analysis of approaches to the design of synthetic ligands and their neuropsychotropic activity in vitro and in vivo. The presented review demonstrates the promise of constructing new neuropsychotropic drugs in the series of TSPO ligands.

scholarly journals Midazolam and Dexmedetomidine Affect Neuroglioma and Lung Carcinoma Cell Biology In Vitro and In Vivo

2018 ◽  
Vol 129 (5) ◽  
pp. 1000-1014 ◽  
Author(s):  
Chunyan Wang ◽  
Tanweer Datoo ◽  
Hailin Zhao ◽  
Lingzhi Wu ◽  
Akshay Date ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Proliferation ◽  
Lung Carcinoma ◽  
Mitochondrial Membrane ◽  
Benzodiazepine Receptor ◽  
Tumor Burden ◽  
Oxygen Species ◽  
Peripheral Benzodiazepine Receptor

AbstractEditor’s PerspectiveWhat We Already Know about This TopicWhat This Article Tells Us That Is NewBackgroundSeveral factors within the perioperative period may influence postoperative metastatic spread. Dexmedetomidine and midazolam are widely used general anesthetics during surgery. The authors assessed their effects on human lung carcinoma (A549) and neuroglioma (H4) cell lines in vitro and in vivo.MethodsCell proliferation and migration were measured after dexmedetomidine (0.001 to 10 nM) or midazolam (0.01 to 400 μM) treatment. Expression of cell cycle and apoptosis markers were assessed by immunofluorescence. Mitochondrial membrane potential and reactive oxygen species were measured by JC-1 staining and flow cytometry. Antagonists atipamezole and flumazenil were used to study anesthetic mechanisms of action. Tumor burden after anesthetic treatment was investigated with a mouse xenograft model of lung carcinoma.ResultsDexmedetomidine (1 nM) promoted cell proliferation (2.9-fold in A549 and 2-fold in H4 cells vs. vehicle, P < 0.0001; n = 6), migration (2.2-fold in A549 and 1.9-fold in H4 cells vs. vehicle, P < 0.0001; n = 6), and upregulated antiapoptotic proteins in vitro. In contrast, midazolam (400 μM) suppressed cancer cell migration (2.6-fold in A549 cells, P < 0.0001; n = 4), induced apoptosis via the intrinsic mitochondrial pathway, decreased mitochondrial membrane potential, and increased reactive oxygen species expression in vitro—effects partly attributable to peripheral benzodiazepine receptor activation. Furthermore, midazolam significantly reduced tumor burden in mice (1.7-fold vs. control; P < 0.05; n = 6 per group).ConclusionsMidazolam possesses antitumorigenic properties partly mediated by the peripheral benzodiazepine receptor, whereas dexmedetomidine promotes cancer cell survival through signaling via the α2-adrenoceptor in lung carcinoma and neuroglioma cells.

Peripheral Benzodiazepine Receptor Antisense Knockout Increases Tumorigenicity of MA-10 Leydig Cells in Vivo and in Vitro†

Biochemistry ◽  
2004 ◽  
Vol 43 (38) ◽  
pp. 12315-12321 ◽  
Author(s):  
Gary Weisinger ◽  
Ela Kelly-Hershkovitz ◽  
Leo Veenman ◽  
Ilana Spanier ◽  
Svetlana Leschiner ◽  
...  
Keyword(s):  
Leydig Cells ◽  
Benzodiazepine Receptor ◽  
Peripheral Benzodiazepine Receptor

Design, Synthesis and Anxiolytic Activity Evaluation of N-Acyltryptophanyl- Containing Dipeptides, Potential TSPO Ligands#

2019 ◽  
Vol 15 (4) ◽  
pp. 383-399 ◽  
Author(s):  
Tatiana A. Gudasheva ◽  
Olga A. Deeva ◽  
Grigory V. Mokrov ◽  
Alina S. Dyabina ◽  
Milada A. Yarkova ◽  
...  
Keyword(s):  
Open Field ◽  
Design Method ◽  
Anxiolytic Effect ◽  
Benzodiazepine Receptor ◽  
Anxiolytic Activity ◽  
Translocator Protein ◽  
In Vivo Studies ◽  
Inner Mitochondrial Membrane ◽  
New Compounds

Background:The 18 kDa translocator protein (TSPO), previously known as the peripheral- type benzodiazepine receptor, plays a key role for the synthesis of neurosteroids by promoting transport of cholesterol from the outer to the inner mitochondrial membrane, which is the ratelimiting step in neurosteroid biosynthesis. Neurosteroids interact with nonbenzodiazepine site of GABAa receptor causing an anxiolytic effect without the side effects.Methods:Using the original peptide drug-based design strategy, the first putative dipeptide ligand of the TSPO N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide (GD-23) was obtained. Molecular docking of GD-23 in the active pocket of the TSPO receptor using Glide software was carried out. The lead compounds GD-23 and its analogues were synthesized using activated succinimide esters coupling method. The anxiolytic activity of GD-23 and its analogues was investigated in vivo, using two validated behavioral tests, illuminated open field and elevated plus-maze.Results:he in vivo studies revealed that the following parameters are necessary for the manifestation of anxiolytic activity of new compounds: the L-configuration of tryptophan, the presence of an amide group at the C-terminus, the specific size of the N-acyl substituent at the Nterminus. Compound GD-23 (N-carbobenzoxy-L-tryptophanyl-L-isoleucine amide) demonstrated a high anxiolytic-like effect in the doses of 0.05–1.0 mg/kg i.p. comparable with that of diazepam. Compound GD-23 was also active in the open field test when was administered orally in the doses of 0.1-5.0 mg/kg. The involvement of TSPO receptor in the mechanism of anxiolytic-like activity of new compounds was proved by the antagonism of compound GD-23 with TSPO selective inhibitor PK11195 as well as with inhibitors of enzymes which are involved in the biosynthesis of neurosteroids, trilostane and finasteride.Conclusion:A series of N-acyl-tryptophanyl-containing dipeptides were designed and synthesized as 18 kDa translocator protein (TSPO) ligands. Using a drug-based peptide design method a series of the first dipeptide TSPO ligands have been designed and synthesized and their anxiolytic activity has been evaluated. In general, some of the compounds displayed a high level of anxiolytic efficacy comparable with that of diazepam. The involvement of TSPO receptor in the mechanism of anxiolytic activity of new compounds was proved using two methods. On this basis, the N-acyl-Ltryptophanyl- isoleucine amides could potentially be a novel class of TSPO ligands with anxiolytic activity.

107 DIFFERENCES IN THE INNER MITOCHONDRIAL MEMBRANE POTENTIAL BETWEEN NON-CULTURED AND CULTURED PORCINE EMBRYOS

2011 ◽  
Vol 23 (1) ◽  
pp. 159
Author(s):  
M. Romek ◽  
B. Gajda ◽  
M. Rolka ◽  
Z. Smorag
Keyword(s):  
Fatty Acids ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Developmental Competence ◽  
Critical Event ◽  
Inner Mitochondrial Membrane ◽  
Oxidation Rates

In comparison to in vivo derived pig embryos, in vitro culture conditions produce embryos with altered metabolic rates of carbohydrates and fatty acids (Romek M et al. 2010 Theriogenology 74, 265–276), which may compromise embryo viability. Because various energy substrates are metabolized via several aerobic pathways leading to generation of the inner mitochondrial membrane potential (ΔΨm), value of ΔΨm is a key indicator of embryo metabolic activity, closely related to oxygen consumption and cellular energy needs. Therefore, the aim of this study was to compare ΔΨm between non-cultured and cultured pig embryos during early development. The non-cultured embryos were obtained from 6-month-old gilts, whereas those derived in vitro were cultured from zygotes to the appropriate stage in North Carolina State University 23 (NCSU-23) medium supplemented with 4 mg mL–1 of bovine serum albumin. The ΔΨm measurements were carried out on both non-cultured and cultured 4 to 8 cell embryos, morulae, blastocysts and late blastocysts. For this, embryos were labelled with 0.5 μM Mito Tracker Orange CMTMRos (MtOR) for 30 min at 39°C and then with 0.5 μM Mito Tracker Deep Red (MtDR) for 30 min at 10°C. Using a LSM 510 Meta Zeiss confocal microscope, we measured the amounts of fluorescence (IMtOR and IMtDR) emitted from embryos and values of ΔΨm were estimated as the IMtOR/IMtDR ratios. The results were analysed by ANOVA and Tukey's test. From the zygote to morula stages, ΔΨm remained unchanged and did not differ between developmentally matched non-cultured and cultured embryos (P < 0.001). The value of ΔΨm increased significantly (P < 0.05) from 0.90 ± 0.26 arbitrary units (a.u.) for morulae to 3.92 ± 0.63 and 2.06 ± 0.38 a.u. for non-cultured and cultured early blastocysts, respectively. Whereas the mean value of ΔΨm was almost 2 times higher in non-cultured than in cultured early blastocysts, the mitochondrial membrane potential was statistically similar (P < 0.05) in the in vivo derived (2.10 ± 0.37 a.u.) compared to cultured (1.87 ± 0.30 a.u.) blastocysts. The lower ΔΨm in cultured early blastocysts may be explained by several-fold higher glucose concentration in NCSU-23 medium than in the oviductal fluid. It was reported that high levels of glucose decreases the Krebs cycle metabolism of pyruvate, glutamine, and glucose, and reduces oxidation rates of fatty acids in cultured pig embryos in comparison with in vivo counterparts. Hence, this impaired metabolism reflected by decreased ΔΨm may be responsible for insufficient energy production and reduced developmental competence of cultured early blastocysts. Therefore, because embryo-cavitation is a critical event in pig development, further effort should be focused on proper blastocyst culture. Research was partially supported by Grant NR 12 0036 06 from NCBiR, Poland.

PK11195, a Ligand of the Peripheral Benzodiazepine Receptor, Inhibits Myeloma Cell Growth In Vitro and Chemosensitizes Myeloma Cells In Vivo in SCID-hu Models of Human Multiple Myeloma.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3459-3459
Author(s):  
Richard A. Campbell ◽  
Eric Sanchez ◽  
Haiming Chen ◽  
Lauren Turker ◽  
Olivia Trac ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cell Growth ◽  
Tumor Growth ◽  
Single Agent ◽  
Benzodiazepine Receptor ◽  
Peripheral Benzodiazepine Receptor ◽  
Once Daily ◽  
Inhibition Of Tumor Growth

Abstract The peripheral benzodiazepine receptor (mPBR) appears to be a potential target to induce apoptosis in tumor cells. The expression of this receptor has been linked to a poor prognosis in cancer patients. PK11195 may represent a new, well-tolerated potent chemosensitizing agent that affects multiple resistance mechanisms within malignant cells. We have evaluated whether PK11195 inhibits multiple myeloma (MM) cell growth in vitro; and, furthermore, whether this drug can chemosensitize a melphalan resistant human MM tumor, LAGλ-1 (Campbell et al, International Journal of Oncology 2006), to arsenic trioxide (ATO) and melphalan using an in vivo SCID-hu model. The MM cell lines RPMI8226 and U266 were treated with varying concentrations of PK11195 (1 – 100 mM). After incubating with PK11195 for 24 hours, cell growth was measured by MTT assay. Those cells treated with PK11195 showed decreased proliferation at concentrations as low as 1 mM compared to the untreated cells. Next, we investigated the chemosensitizing effects of PK11195 using an in vivo model of human MM. To accomplish this, each immunodeficient (SCID) mouse was implanted with a 2.0 – 4.0 mm3 LAGλ-1 tumor fragment into the left superficial gluteal muscle. The tumors were allowed to grow for 14 days at which time human IgG levels were detectable in the mouse serum or when tumors became palpable (21 days) and mice were blindly assigned into treatment groups. PK11195 (10, 50 and 100 mg/kg) was administered via oral gavage once weekly when combined with melphalan and once daily five times per week when combined with ATO. Melphalan (3 mg/kg) was administered once weekly via intraperitoneal (i.p.) injection. ATO (1.25 mg/kg) was administered once daily five times per week via i.p. injection. Mice receiving the combination of PK11195 and melphalan (3 mg/kg) showed marked inhibition of tumor growth (PK11195 10 mg/kg, P = 0.03; PK11195 50 mg/kg, P = 0.02; PK11195 200 mg/kg, P < 0.01) compared to mice receiving no therapy. Animals treated with melphalan, as a single agent, did show minimal tumor growth inhibition and reduced paraprotein levels whereas mice treated with single agent PK11195 showed tumor growth similar to the control mice. Mice receiving the combination of PK11195 and low dose ATO (1.25 mg/kg) also showed inhibition of tumor growth (PK11195 200 mg/kg, P < 0.01) whereas treatment with either single agent PK11195 or ATO demonstrated growth similar to the control groups. Treatment with the highest dose of PK11195 (200 mg/kg) was not associated with any observed toxicity suggesting that high doses can be safely administered and are well tolerated. In this study, we showed PK11195 inhibits MM cell growth in vitro at very low concentrations and can chemosensitize drug resistant tumor cells in vivo at doses that have no observable toxicity. We are further evaluating PK11195 as a single agent and in combination therapy both in vitro and in vivo..

scholarly journals Current status and future perspectives: TSPO in steroid neuroendocrinology

2016 ◽  
Vol 231 (1) ◽  
pp. R1-R30 ◽  
Author(s):  
Vimal Selvaraj ◽  
Lan N Tu
Keyword(s):  
Therapeutic Target ◽  
De Novo ◽  
Benzodiazepine Receptor ◽  
Translocator Protein ◽  
Current Status ◽  
Hormone Production ◽  
Neuronal Disease ◽  
Negative Impacts

The mitochondrial translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor (PBR), has received significant attention both as a diagnostic biomarker and as a therapeutic target for different neuronal disease pathologies. Recently, its functional basis believed to be mediating mitochondrial cholesterol import for steroid hormone production has been refuted by studies examining both in vivo and in vitro genetic Tspo-deficient models. As a result, there now exists a fundamental gap in the understanding of TSPO function in the nervous system, and its putative pharmacology in neurosteroid production. In this review, we discuss several recent findings in steroidogenic cells that are in direct contradiction to previous studies, and necessitate a re-examination of the purported role for TSPO in de novo neurosteroid biosynthesis. We critically examine the pharmacological effects of different TSPO-binding drugs with particular focus on studies that measure neurosteroid levels. We highlight the basis of key misconceptions regarding TSPO that continue to pervade the literature, and the need for interpretation with caution to avoid negative impacts. We also summarize the emerging perspectives that point to new directions that need to be investigated for understanding the molecular function of TSPO, only after which the true potential of this therapeutic target in medicine may be realized.

scholarly journals Opa1 Prevents Apoptosis and Cisplatin-Induced Ototoxicity in Murine Cochleae

2021 ◽  
Vol 9 ◽  
Author(s):  
Tingting Dong ◽  
Xuejie Zhang ◽  
Yiqing Liu ◽  
Shan Xu ◽  
Haishuang Chang ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Death ◽  
Mitochondrial Membrane ◽  
Vital Role ◽  
Mitochondrial Morphology ◽  
Oxygen Species ◽  
Inner Mitochondrial Membrane ◽  
Cochlear Damage

Optic atrophy1 (OPA1) is crucial for inner mitochondrial membrane (IMM) fusion and essential for maintaining crista structure and mitochondrial morphology. Optic atrophy and hearing impairment are the most prevalent clinical features associated with mutations in the OPA1 gene, but the function of OPA1 in hearing is still unknown. In this study, we examined the ability of Opa1 to protect against cisplatin-induced cochlear cell death in vitro and in vivo. Our results revealed that knockdown of Opa1 affects mitochondrial function in HEI-OC1 and Neuro 2a cells, as evidenced by an elevated reactive oxygen species (ROS) level and reduced mitochondrial membrane potential. The dysfunctional mitochondria release cytochrome c, which triggers apoptosis. Opa1 expression was found to be significantly reduced after cell exposed to cisplatin in HEI-OC1 and Neuro 2a cells. Loss of Opa1 aggravated the apoptosis and mitochondrial dysfunction induced by cisplatin treatment, whereas overexpression of Opa1 alleviated cisplatin-induced cochlear cell death in vitro and in explant. Our results demonstrate that overexpression of Opa1 prevented cisplatin-induced ototoxicity, suggesting that Opa1 may play a vital role in ototoxicity and/or mitochondria-associated cochlear damage.

scholarly journals The mitochondrial Ca2+ uniporter MCU is required for normal glucose-stimulated insulin secretion in vitro and in vivo

2019 ◽  
Author(s):  
Elizabeth Haythorne ◽  
Eleni Georgiadou ◽  
Matthew T. Dickerson ◽  
Livia Lopez-Noriega ◽  
Timothy J. Pullen ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Β Cells ◽  
Β Cell ◽  
Compensatory Mechanisms ◽  
Glucose Stimulated Insulin Secretion

AbstractMitochondrial oxidative metabolism is central to glucose-stimulated insulin secretion (GSIS). Whether Ca2+ uptake into pancreatic β-cell mitochondria potentiates or antagonises this process is still a matter of debate. Although the mitochondrial importer (MCU) complex is thought to represent the main route for Ca2+ transport across the inner mitochondrial membrane, its role in β-cells has not previously been examined in vivo. Here, we inactivated the pore-forming subunit MCUa (MCU) selectively in the β-cell in mice using Ins1Cre-mediated recombination. Glucose-stimulated mitochondrial Ca2+ accumulation, ATP production and insulin secretion were strongly (p<0.05 and p<0.01) inhibited in MCU null animals (βMCU-KO) in vitro. Interestingly, cytosolic Ca2+ concentrations increased (p<0.001) whereas mitochondrial membrane depolarisation improved in βMCU-KO animals. Male βMCU-KO mice displayed impaired in vivo insulin secretion at 5 (p<0.001) but not 15 min. post intraperitoneal (IP) injection of glucose while the opposite phenomenon was observed following an oral gavage at 5 min. Unexpectedly, glucose tolerance was improved (p<0.05) in young βMCU-KO (<12 weeks), but not older animals. We conclude that MCU is crucial for mitochondrial Ca2+ uptake in pancreatic β-cells and is required for normal GSIS. The apparent compensatory mechanisms which maintain glucose tolerance in βMCU-KO mice remain to be established.

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