Carnitine palmitoyltransferase I (CPT-I)

In H9c2 cells, etomoxir facilitates the distinct metabolic channeling of fatty acid and glycerol precursors into cardiolipin[2]. Although etomoxir reduces the incorporation of [1-14C]palmitic acid or [1-14C]oleic acid into cardiolipin, it has no effect on the activity of the enzymes involved in the biosynthesis and remodeling of cardiolipin[2]. Cardiolipin's incorporation of [1,3-3H]glycerol is increased by etomoxir. The process involves a 33% rise in glycerol kinase activity, which causes an increase in glycerol flux via the cardiolipin biosynthesis de novo pathway [2].

Etomoxir suppresses the reduction of BMSCs-differentiated osteoblasts and significantly inhibits the decrease of bone mineral density (BMD) and bone breaking strength in mice fed high fat (HF) and db/db diets[3]. In mice fed HF and db/db, etopoxir inhibits the increase in mitochondrial ROS generation in osteoblasts and mice[3]. The in vivo partial inhibition of carnitine palmitoyltransferase-I (CPT-I) caused by etomoxir does not change the rates of cardiac long-chain fatty acid uptake and oxidation[4].

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This study evaluated the association between free fatty acid (FFA), ROS generation, mitochondrial dysfunction and bone mineral density (BMD) in type 2 diabetic patients and investigated the molecular mechanism. db/db and high fat (HF)-fed mice were treated by Etomoxir, an inhibitor of CPT1, MitoQ, and PFT-α, an inhibitor of P53. Bone metabolic factors were assessed and BMSCs were isolated and induced to osteogenic differentiation. FFA, lipid peroxidation and mtDNA copy number were correlated with BMD in T2DM patients. Etomoxir, MitoQ and PFT-α significantly inhibited the decrease of BMD and bone breaking strength in db/db and HF-fed mice and suppressed the reduction of BMSCs-differentiated osteoblasts. Etomoxir and MitoQ, but not PFT-α, inhibited the increase of mitochondrial ROS generation in db/db and HF-fed mice and osteoblasts. In addition, Etomoxir, MitoQ and PFT-α significantly inhibited mitochondrial dysfunction in osteoblasts. Moreover, mitochondrial apoptosis was activated in osteoblasts derived from db/db and HF-fed mice, which was inhibited by Etomoxir, MitoQ and PFT-α. Furthermore, mitochondrial accumulation of P53 recruited Bax and initiated molecular events of apoptotic events. These results demonstrated that fatty acid oxidation resulted in ROS generation, activating P53/Bax-mediated mitochondrial apoptosis, leading to reduction of osteogenic differentiation and bone loss in T2DM.[3]

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Although CPT-I (carnitine palmitoyltransferase-I) is generally regarded to present a major rate-controlling site in mitochondrial beta-oxidation, it is incompletely understood whether CPT-I is rate-limiting in the overall LCFA (long-chain fatty acid) flux in the heart. Another important site of regulation of the LCFA flux in the heart is trans-sarcolemmal LCFA transport facilitated by CD36 and FABPpm (plasma membrane fatty acid-binding protein). Therefore, we explored to what extent a chronic pharmacological blockade of the LCFA flux at the level of mitochondrial entry of LCFA-CoA would affect sarcolemmal LCFA uptake. Rats were injected daily with saline or etomoxir, a specific CPT-I inhibitor, for 8 days at 20 mg/kg of body mass. Etomoxir-treated rats displayed a 44% reduced cardiac CPT-I activity. Sarcolemmal contents of CD36 and FABPpm, as well as the LCFA transport capacity, were not altered in the hearts of etomoxir-treated versus control rats. Furthermore, rates of LCFA uptake and oxidation, and glucose uptake by cardiac myocytes from etomoxir-treated rats were not different from control rats, neither under basal nor under acutely induced maximal metabolic demands. Finally, hearts from etomoxir-treated rats did not display triacylglycerol accumulation. Therefore CPT-I appears not to present a major rate-controlling site in total cardiac LCFA flux. It is likely that sarcolemmal LCFA entry rather than mitochondrial LCFA-CoA entry is a promising target for normalizing LCFA flux in cardiac metabolic diseases[4].

shRNA-GFP lentiviral plasmid construction and infection[1] The puromycin resistance gene in 5 individual shRNA lentiviral plasmids against CPT1A was replaced with GFP cDNA using standard molecular biology techniques. Briefly, a 1.4 kb GFP cDNA insert was subcloned from the lentiviral PELPS-GFP plasmid into KpnΙ and BamHΙ sites in the pLKO.1 shRNA plasmid. The efficacy of each individual lentiviral plasmid was determined by immunoblot analysis. Lentiviral infections were performed as described36. Lymphocytes expressing shRNA against CPT1A were compared with the corresponding control plasmid that we also engineered to express GFP instead of puromycin resistance. The control plasmid encoded a scrambled shRNA sequence from the human β-actin gene. The efficiency of lentiviral infection ranged from 60–90% across experiments. In assessments of cell proliferation, enumeration was performed using bead-based counting methods following gating on GFP + cells. The titers for scramble-GFP and shRNA-CPT1A-GFP viral supernatants were 9.45e6 and 7.34e6 TU/ml, respectively.[1]

Male Lewis rats, weighing 150–200 g, were used in the present study. Animals were kept on a 12 h:12 h light/dark cycle and fed a Purina Chow diet and water ad libitum. The rats were divided into two groups: (1) control and (2) etomoxir. Etomoxir (20 mg/kg of body weight) was dissolved in 0.9% (w/v) NaCl and administered intraperitoneally for 8 days. Control rats received saline. The last injection was given 24 h before the experiment. Ethical approval for all experimental procedures was obtained from the Experimental Animal Committee of the Maastricht University, and the study conforms to the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No. 85–23, revised 1996). Animals were anaesthetized with an intraperitoneal injection of a nembutal and heparin (3:1) mixture. Subsequently, the heart was removed for LCFA uptake studies and for analyses of transporter protein contents. [4]

[1]. The CPT1a inhibitor, etomoxir induces severe oxidative stress at commonly used concentrations.Sci Rep. 2018 Apr 19;8(1):6289.

[2]. Etomoxir mediates differential metabolic channeling of fatty acid and glycerol precursors into cardiolipin in H9c2 cells.J Lipid Res. 2003 Feb;44(2):415-23.

[3]. FFA-ROS-P53-mediated mitochondrial apoptosis contributes to reduction of osteoblastogenesis and bone mass in type 2 diabetes mellitus.Sci Rep. 2015 Jul 31;5:12724.

[4]. Etomoxir-induced partial carnitine palmitoyltransferase-I (CPT-I) inhibition in vivo does not alter cardiac long-chain fatty acid uptake and oxidation rates.Biochem J. 2009 Apr 15;419(2):447-55.

C17H23CLO4

326.81512

326.128

C, 62.48; H, 7.09; Cl, 10.85; O, 19.58

828934-40-3

828934-41-4 (sodium) 82258-36-4 (racemate) 828934-40-3 (S-isomer) 124083-20-1; 828934-41-4 (sodium)

60765

White to off-white solid powder

4.001

0

4

11

22

342

1

CCOC(=O)C1(CO1)CCCCCCOC2=CC=C(C=C2)Cl

DZLOHEOHWICNIL-KRWDZBQOSA-N

InChI=1S/C17H23ClO4/c1-2-20-16(19)17(13-22-17)11-5-3-4-6-12-21-15-9-7-14(18)8-10-15/h7-10H,2-6,11-13H2,1H3/t17-/m0/s1

(S)-2-[6-(4-Chlorophenoxy)hexyl]oxiranecarboxylic Acid, Ethyl Ester

S-(-)-Etomoxir; B 807-54; B807-54; B-807-54; B 80754; B80754; B-80754

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)