MG-132

20S proteasome:100 nM (cell free)|Calpain:1.2 μM (cell free)

MG132 (0.1 mg/kg/day) was intraperitoneally injected to rats with abdominal aortic banding (AAB) for 8 weeks. Results showed that treatment with MG132 significantly attenuated left ventricular (LV) myocyte area, LV weight/body weight, and lung weight/body weight ratios, decreased LV diastolic diameter and wall thickness and increased fractional shortening in AAB rats. AAB induced the phosphorylation of ERK1/2, JNK1, and p38 in cardiac myocytes. The elevated phosphorylation levels of ERK1/2 and JNK1 in AAB rats were significantly reversed by MG132 treatment [4]. MG132 significantly inhibited IκBα degradation thus preventing NFκB activation in vitro. MG132 preserved muscle and myofiber cross-sectional area by downregulating the muscle-specific ubiquitin ligases atrogin-1/MAFbx and MuRF-1 mRNA in vivo. This effect resulted in a diminished rehabilitation period [5].

The IC50 of MG-132 for the alkali-denatured casein-degrading activity of m-calpain was around 1.2 μM. The IC50 for the ZLLL MCA-degrading activity of 20S proteasome by MG-132 was 100 nM [1]. It also inhibits proteasomal chymotrypsin-like peptidase activity (IC50: 24.2 nM) [2]. Dose-dependent inhibition of cell growth was observed in HeLa cells with an IC50 of approximately 5 μM MG132 for 24 h. The treatment with MG132 induced S, G2-M or non-specific phase arrests of the cell cycle dose-dependently. Treatment with MG132 induced apoptosis in a dose-dependent manner, as evidenced by sub-G1 cells and annexin V staining cells [3].

DMSO:90 mg/mL (189.23 mM),Ethanol:47.5 mg/mL (100 mM),H2O:Insoluble

The effect of MG132 on HeLa cell growth was determined by trypan blue exclusion cell counting or measuring MTT dye absorbance of living cells as previously described. In brief, cells (5x10^5 cells per well) were seeded in 24-well plates for cell counting, and cells (5x10^4 cells per well) were seeded in 96-well microtiter plates for the MTT assay. After exposure to indicated amounts of MG132 for 24 h, cells in 24-well plates or 96-well plates were collected with trypsin digestion for trypan blue exclusion cell counting or were used for the MTT assay. Twenty microliters of MTT solution (2 mg/ml in PBS) was added to each well of 96-well plates. The plates were again incubated for 4 h at 37?C. MTT solution in the medium was aspirated off and 200 μl of DMSO was added to each well to solubilize the formazan crystals formed in viable cells. Optical density was measured at 570 nm using a microplate reader. Each plate contained multiple wells at a given experimental condition and multiple control wells. This procedure was replicated for 2-4 plates per condition [3].

Male Sprague–Dawley rats (8 weeks old, 180 – 230 g) were used to establish a pressure-overload model as described previously. All animals were separated into four groups (10 rats per group): (i) vehicle-treated sham group; (ii) MG132-treated sham group; (iii) vehicle-treated abdominal aortic banding (AAB) group; and (iv) MG132-treated AAB group. Under intraperitoneal pentobarbital (50 mg/kg) anesthesia, AAB was created using a 5-0 suture tied twice around the abdominal aorta in which. a 21-gauge needle was inserted. The needle was then retracted yielding a 70 – 80% constriction with an outer aortic diameter of 0.8 mm. In the sham surgery rats, the same surgery was performed as described above except the aorta was constricted. At Day 3 after the surgery, MG132-treated rats were intraperitoneally injected with 0.1 mg/kg/day of MG132 for 8 weeks. All control animals were injected with a corresponding volume of vehicle only (0.1% DMSO) [4]. Sixteen-week-old male CD1 mice were used for all our experiments. Thirty minutes before the immobilization procedure, 0.1 mg/kg of buprenorphine was administrated IP. The mice were then anesthetized using isoflurane. The right hindlimb was immobilized as previously described. Briefly, the hindlimb was immobilized 7 days by stapling the foot exploiting normal dorso-tibial flexion using an Autosuture Royal 35W skin stapler. One tine was inserted close to the toe at the plantar portion of the foot while the other was inserted in the distal portion of the gastrocnemius. The other hindlimb was used as a control. During the immobilization period, the mice were injected subcutaneously with MG132 (7.5 mg/kg/dose) or vehicle (DMSO) twice daily. DMSO containing or not MG132 was diluted in sterile pure corn oil (1:100, injected volume 150 μL). After 7 days, the tibialis anterior (TA) muscles of immobilized and non-i