Tulipalin A

2-Methylenebutyrolactone (Tulipalin A, MBL, α-methylene-γ-butyrolactone), also known as α-methylene-γ-butyrolactone (MBL) (Tulipalin A), belongs to the class of sesquiterpene lactone family and is considered as cyclic analog of most common vinyl monomer methyl methacrylate (MMA).

After exposure of Jurkat T cells to 2-Methylenebutyrolactone (Tulipalin A , TUPA) for 72 h, a dose dependent toxicity is detected. Concentrations higher than 20 μM lead to a significant reduction of viable cells. Compared to vehicle-treated control cells, concentrations of 47.6 and 26.8 μM decrease the cell viability significantly by 50% (IC50) and 10% (IC10), respectively. In contrast, THP-1 cells are less sensitive toward TUPA. Concentrations >41 μM lead to a significant reduction of viable cells. IC10 is calculated with 50 μM, whereas a concentration of 83 μM is necessary to decrease the cell viability to 50% (IC50). In Jurkat T cells, four proteins responsible for the de novo purine synthesis, namely phosphoribosylformylglycinamidine synthase (PFAS), GMP synthase (GMPS), and ribosephosphate pyrophosphokinases 1 and 2 (PRPS1/2) are increased through TUPA treatment. Glutamine is also increased after TUPA treatment. In addition to the proteins belonging to the purine synthesis pathway, the abundances of proteins for DNA synthesis and repair (XRCC5, XRCC6, MCM3, MCM6, MCM7, TRA1) are also increased/induced during the treatment. While in THP-1 cells, no indication for higher purine synthesis induced by TUPA in subtoxic concentrations is discovered. TUPA induces the expression of proteins in Jurkat T cells responsible for cell stress, drug response, and protein folding: HYOU1, PDIA3, and DNAJB11. Additionally, the treatment with TUPA leads to the induction of three heat shock proteins (HSP90AA1, HSP90AB1, and HSP90B1) and three proteins belonging to the TRiC complex (CCT3,6,8) that are also responsible for proper protein folding. Treatment with TUPA leads to the induction of ROS that have adverse effects on Jurkat T cells and evokes slight cell stress responses in THP-1 cells. TUPA has influence on proteins in Jurkat T cells that contribute to different immune-specific, especially immunostimulating, reactions as allergic contact dermatitis. In THP-1 cells, no proteins regarding immune-specific reactions are up- or downregulated due to TUPA treatment[1].

[1] Zwicker P, et al. Proteomics. 2016, 16(23):2997-3008.