Dgat1 detoxifies androgen receptor signaling to promote antitumor CD8+ T cell responses

The role of fatty acid (FA) oxidation 31 in T cell responses has been extensively studied, but whether FA esterification to triacylglycerol (TAG) regulates T cell exhaustion is unknown. Dgat1 catalyzes the rate-limiting step in TAGsynthesis. Here,we showthat deficiency in Dgat1 improvedmitochondrial metabolic fitness and expanded the pool of progenitors of CD8+ exhausted T (Tex) cells to sustain antitumor responses in femalemice. Inmalemice, however, Dgat1 deficiency synergized with androgen receptor (AR) signaling to cause FA peroxidation, endoplasmic reticulum (ER) stress, and Tex cell death. Deletion of Ar, overexpression of glutathione peroxidase 4 (Gpx4), or inhibition of ER stress-induced cell death rescued Dgat1-deficient CD8+ T cell survival and promoted antitumor responses in male mice. This study suggests that Dgat1 detoxifies AR signaling to protect against ER stress-induced cell death and maintain T cell stemness in males, and highlights sex-specific metabolic adaptations in the tumormicroenvironment. Overall design: Male and female C57BL/6N mice (6-8 weeks old) were subcutaneously inoculated with 3e5 B16-GP33 cells. On day 15 post-inoculation, P14 WT and Dgat1 KO mice were sacrificed, and splenocytes were isolated and cultured for 72 hours with GP33 peptide (10 ng/mL) and IL-2 (10 ng/mL). Activated splenocytes from KO and WT mice were mixed while maintaining equal numbers of CD8+ T cells in both groups. The mixture was intravenously injected into tumor-bearing mice. Four days later, mice were euthanized. TILs were enriched by gradient centrifugation, and WT and KO P14 donor cells were FACS-sorted.

脂肪酸（fatty acid, FA）氧化在T细胞应答中的作用已得到广泛研究，但脂肪酸酯化生成三酰甘油（triacylglycerol, TAG）是否调控T细胞耗竭尚不明确。二脂酰甘油酰基转移酶1（Dgat1）催化TAG合成的限速步骤。本研究发现，Dgat1缺失可改善雌性小鼠的线粒体代谢适配性，并扩增CD8+耗竭性T（Tex）细胞祖细胞库，以维持抗肿瘤应答。然而在雄性小鼠中，Dgat1缺失会与雄激素受体（androgen receptor, AR）信号通路协同作用，引发脂肪酸过氧化、内质网（endoplasmic reticulum, ER）应激以及Tex细胞死亡。敲除Ar基因、过表达谷胱甘肽过氧化物酶4（glutathione peroxidase 4, Gpx4）或抑制内质网应激诱导的细胞死亡，可挽救Dgat1缺失型CD8+ T细胞的存活，并促进雄性小鼠的抗肿瘤应答。本研究表明，Dgat1可通过拮抗AR信号通路以抵御内质网应激诱导的细胞死亡，并维持雄性小鼠的T细胞干性，同时凸显了肿瘤微环境中存在的性别特异性代谢适应性。实验设计：将6~8周龄的雄性与雌性C57BL/6N小鼠皮下接种3×10^5个B16-GP33细胞。接种后第15天，处死P14野生型（WT）与Dgat1基因敲除（KO）小鼠，分离脾细胞并使用GP33多肽（10 ng/mL）与IL-2（10 ng/mL）体外培养72小时。将KO组与WT组的活化脾细胞按CD8+ T细胞数量均等混合后，经静脉注射至荷瘤小鼠体内。4天后处死小鼠，通过密度梯度离心富集肿瘤浸润淋巴细胞（tumor-infiltrating lymphocytes, TILs），并经荧光激活细胞分选（FACS）分选出WT与KO型P14供体细胞。