Lee Sooncheol, Hoyt Stephanie, Wu Xiaoyun, Garvie Colin, McGaunn Joseph, Shekhar Mrinal, Tötzl Marcus, Rees Matthew G, Cherniack Andrew D, Meyerson Matthew, Greulich Heidi
Cancer Program, Broad Institute, Cambridge, MA, USA.
Dana-Farber Cancer Institute, Boston, MA, USA.
Nat Chem Biol. 2023 Mar;19(3):301-310. doi: 10.1038/s41589-022-01170-9. Epub 2022 Oct 27.
Velcrin compounds kill cancer cells expressing high levels of phosphodiesterase 3A (PDE3A) and Schlafen family member 12 (SLFN12) by inducing complex formation between these two proteins, but the mechanism of cancer cell killing by the PDE3A-SLFN12 complex is not fully understood. Here, we report that the physiological substrate of SLFN12 RNase is tRNA(TAA). SLFN12 selectively digests tRNA(TAA), and velcrin treatment promotes the cleavage of tRNA(TAA) by inducing PDE3A-SLFN12 complex formation in vitro. We found that distinct sequences in the variable loop and acceptor stem of tRNA(TAA) are required for substrate digestion. Velcrin treatment of sensitive cells results in downregulation of tRNA(TAA), ribosome pausing at Leu-TTA codons and global inhibition of protein synthesis. Velcrin-induced cleavage of tRNA(TAA) by SLFN12 and the concomitant global inhibition of protein synthesis thus define a new mechanism of apoptosis initiation.
维克林化合物通过诱导磷酸二酯酶3A（PDE3A）和施拉芬家族成员12（SLFN12）这两种蛋白质之间形成复合物来杀死高表达这两种蛋白的癌细胞，但PDE3A - SLFN12复合物杀死癌细胞的机制尚未完全明确。在此，我们报告SLFN12核糖核酸酶的生理底物是tRNA（TAA）。SLFN12选择性地消化tRNA（TAA），并且维克林处理通过在体外诱导PDE3A - SLFN12复合物形成来促进tRNA（TAA）的切割。我们发现tRNA（TAA）可变环和接受茎中的不同序列是底物消化所必需的。用维克林处理敏感细胞会导致tRNA（TAA）下调、核糖体在Leu - TTA密码子处停顿以及蛋白质合成的整体抑制。因此，维克林诱导的SLFN12对tRNA（TAA）的切割以及随之而来的蛋白质合成整体抑制定义了一种新的细胞凋亡起始机制。
