Saponin

Saponin (MP Biomedicals, USA) was dissolved in Tyrode’s solution with adequate ultrasonic agitation for 30 min. In addition, several experiments required the hearts to be perfused with Tyrode’s solution supplemented with various reagents including ryanodine (FUJIFILM Wako Pure Chemical Corporation, Japan), thapsigargin (FUJIFILM Wako Pure Chemical Corporation, Japan), MDL28170 (Sigma‒Aldrich, USA), 2,3-butanedione monoxime (BDM) (Nacalai Tesque, Japan) or carbonyl cyanide 4-trifluoromethoxy phenylhydrazone (FCCP) (Abcam, UK), for specific pharmacological interventions.

A total of 4 × 10⁵ cells were seeded on coverslips, which were placed in a 12-well plate for 24 h. The cells were treated with 20 nM paclitaxel or DMSO (control) for 24 h and then fixed in 4% paraformaldehyde PBS (Wako Pure Chemicals, Tokyo, Japan) for 20 min at 37 °C. After blocking with PBS containing 0.1% saponin (MP Biomedicals, Santa Ana, CA, USA) and 3% bovine serum albumin (BSA) for 30 min, the cells were incubated with primary antibodies for 1 h, followed by incubation with secondary donkey anti-rabbit IgG H&L, Alexa Fluor 405 (Abcam, Cambridge, UK, ab175651) or goat anti-mouse IgG (H+L), Alexa Fluor 647 (Thermo Fisher Scientific, Boston, MA, USA)-conjugated antibodies (diluted in PBS containing 0.1% saponin, 1:500) for 1 h; all reactions were carried out at room temperature. Coverslips were picked and mounted with DAPI-Fluormount-G^® (SouthernBiotech, Birmingham, AL, USA). Finally, the cells were observed under a Zeiss LSM 780 confocal microscope (Carl Zeiss MicroImaging GmbH, Jena, Germany). The dilutions used for the primary antibodies were as follows: GFAP (1:300; Bioss, Woburn, MA, USA, bs 0199R) and Ki67 (1:200) (Proteintech, Rosemont, IL, USA, 27309-1-AP). All primary antibodies were diluted in PBS containing 0.1% saponin and 3% BSA. The obtained images were analyzed using the ImageJ2 software (National Institute of Health, Bethesda, MD, USA).

BeauI and BeauIII were purified from the culture broth of the producing fungus Beauveria sp. FO-6979 according to our established methods (Supplementary Fig. 3)^{1 (link)}. Biotin-labeled beauveriolide (Biotin-Beau) was synthesized as reported previously (Supplementary Fig. 3)^{11 (link)}. [1-¹⁴C]Oleic acid (2.19 GBq/mmol) and [1-¹⁴C]oleoyl-CoA (1.85 GBq/mmol) were purchased from PerkinElmer Life and Analytical Sciences (Waltham, MA). 2.5% Trypsin and acrylamide-based streptavidin beads (Streptavidin UltraLink Resin) were purchased from Thermo Fisher Scientific (Waltham, MA). Triton X-100 was purchased from Sigma-Aldrich (St. Louis, MO). Digitonin were purchased from Wako Pure Chemical Industries (Tokyo, Japan). Saponin was purchased from MP Biomedicals (Santa Ana, CA). OptiPrep^TM was purchased from Axis-Shield (Luna Place, Scotland). An anti-rabbit IgG conjugated to horseradish peroxidase (HRP) was purchased from Medical & Biological Laboratories (Nagoya, Japan).