Calpeptin

d-Pantethine, imipramine, GW4869, calpeptin, Y-27632, imatinib mesylate, sulfisoxazole, bisindolymaleimide I, indomethacin, NSC23766, clopidogrel, glibenclamide, Chloramidine, amiloride, and U0126 were purchased from Selleckchem (Selleckchem, Houston, TX, USA). Manumycin A and cytochalasin D were purchased from Sigma-Aldrich (Sigma-Aldrich, St. Luis, MO, USA). All compounds (purity > 97%) were dissolved in dimethyl sulfoxide (DMSO; Sigma-Aldrich, St. Luis, MO, USA), at a concentration of 50 mM, before use.

The male C57BL/6 mice (8 weeks old) were purchased from Guangzhou Medical University. Procedures were approved by the Institutional Animal Care and Use Committee of Guangzhou Medical University (No. SYXK2016-0168). Eight week old mice were injected with 50mg/kg streptozotocin (STZ, Sigma) to induce diabetes for 5 consecutive days. The mice were randomly divided into four groups and were intraperitoneally injected PBS or calpeptin (calpain inhibitor) (30 mg/kg/day) diluted in DMSO in PBS every other day. The mice in the AgomiR group were administered with Agomir-223 200 μl at a concentration of 20 mM via tail vein injection. The calpeptin ware purchased from the SelleckChemicals Co, while the AgomiRs and miRNA mimic from Shanghai GenePharma Co.

SH-SY5Y neuroblastoma cells were cultured in Dulbecco's modified eagle's medium (DMEM, Gibco) containing 10% fetal calf serum (Gibco, Brazil) and grown in a CO₂ incubator maintained at atmospheric oxygen levels and 5% CO₂. Dissolved MPP⁺ (Sigma Aldrich) in phosphate buffered saline (PBS) to a storage concentration of 125 mM. Resveratrol (Sigma) was prepared in dissolved dimethyl sulfoxide (DMSO) at a stock of 25 mM. EX-527, SRT1720, CHX, MG-132, Calpeptin, Z-VAD, and Bobcat339 (Selleckchem) stocks were dissolved in DMSO at the concentrations of 10 mM,10 mM, 1 mg/ml, 10 mM, 10 mM, 50 mM, and 3 mM, respectively. They were both stored at −20°C. Resveratrol, EX-527, and SRT1720 were pretreated cells 12 h before specific administration.
TET2 knockdown by lentiviral delivery of a short hairpin RNA (shRNA) was achieved via lentiviruses expressing the green fluorescent protein (GFP) and shRNA-TET2. shRNA-TET2 containing human shTET2a and shTET2b. Sequences for human shTET2a and shTET2b were (5′-GGGTAAGCCAAGAAAGAAA-3′) and (5′-AAACAAAGAGCAAGAGATT-3′), respectively.