Stress granules (SGs) are membrane-less ribonucleoprotein condensates that form in response to various stress stimuli via phase separation. SGs act as a protective mechanism to cope with acute stress, but persistent SGs have cytotoxic effects that are associated with several age-related diseases. Here, we demonstrate that the testis-specific protein, MAGE-B2, increases cellular stress tolerance by suppressing SG formation through translational inhibition of the key SG nucleator G3BP. MAGE-B2 reduces G3BP protein levels below the critical concentration for phase separation and suppresses SG initiation. Knockout of the MAGE-B2 mouse ortholog or overexpression of G3BP1 confers hypersensitivity of the male germline to heat stress in vivo. Thus, MAGE-B2 provides cytoprotection to maintain mammalian spermatogenesis, a highly thermosensitive process that must be preserved throughout reproductive life. These results demonstrate a mechanism that allows for tissue-specific resistance against stress and could aid in the development of male fertility therapies.

应激颗粒（SGs​​）是无膜核糖核蛋白缩合物，可通过相分离响应各种应激刺激而形成。SGs是应付急性应激的保护机制，但是持续性SGs具有与几种与年龄有关的疾病有关的细胞毒性作用。在这里，我们证明了睾丸特异性蛋白MAGE-B2通过对关键SG成核剂G3BP的翻译抑制来抑制SG的形成，从而增加了细胞对压力的耐受性。MAGE-B2可将G3BP蛋白水平降低至相分离的临界浓度以下，并抑制SG引发。MAGE-B2小鼠直系同源基因的敲除或G3BP1的过表达赋予雄性种系对体内热应激的超敏性。因此，MAGE-B2提供了细胞保护作用，以维持哺乳动物的精子发生，这是一个高度热敏的过程，必须在整个生殖生命中保存下来。这些结果证明了一种机制，该机制允许组织对压力的特异性抗性，并有助于男性生殖疗法的发展。