The DNA sensor cGAS catalyzes the production of the cyclic dinucleotide cGAMP, resulting in type I interferon responses. We addressed the functionality of cGAS-mediated DNA sensing in human and murine T cells. Activated primary CD4⁺ T cells expressed cGAS and responded to plasmid DNA by upregulation of ISGs and release of bioactive interferon. In mouse T cells, cGAS KO ablated sensing of plasmid DNA, and TREX1 KO enabled cells to sense short immunostimulatory DNA. Expression of IFIT1 and MX2 was downregulated and upregulated in cGAS KO and TREX1 KO T cell lines, respectively, compared to parental cells. Despite their intact cGAS sensing pathway, human CD4⁺ T cells failed to mount a reverse transcriptase (RT) inhibitor-sensitive immune response following HIV-1 infection. In contrast, infection of human T cells with HSV-1 that is functionally deficient for the cGAS antagonist pUL41 (HSV-1ΔUL41N) resulted in a cGAS-dependent type I interferon response. In accordance with our results in primary CD4⁺ T cells, plasmid challenge or HSV-1ΔUL41N inoculation of T cell lines provoked an entirely cGAS-dependent type I interferon response, including IRF3 phosphorylation and expression of ISGs. In contrast, no RT-dependent interferon response was detected following transduction of T cell lines with VSV-G-pseudotyped lentiviral or gammaretroviral particles. Together, T cells are capable to raise a cGAS-dependent cell-intrinsic response to both plasmid DNA challenge or inoculation with HSV-1ΔUL41N. However, HIV-1 infection does not appear to trigger cGAS-mediated sensing of viral DNA in T cells, possibly by revealing viral DNA of insufficient quantity, length, and/or accessibility to cGAS.

DNA 传感器 cGAS 催化环状二核苷酸 cGAMP 的产生，从而产生 I 型干扰素反应。我们研究了人类和鼠 T 细胞中 cGAS 介导的 DNA 传感的功能。激活的原代CD4 ⁺ T细胞表达cGAS，并通过上调ISG和释放生物活性干扰素来对质粒DNA做出反应。在小鼠 T 细胞中，cGAS KO 消除了质粒 DNA 的感知，而 TREX1 KO 使细胞能够感知短的免疫刺激性 DNA。与亲代细胞相比，cGAS KO 和 TREX1 KO T 细胞系中IFIT1和MX2的表达分别下调和上调。尽管人类 CD4 ⁺ T 细胞具有完整的 cGAS 传感通路，但在 HIV-1 感染后未能产生逆转录酶 (RT) 抑制剂敏感的免疫反应。相比之下，cGAS 拮抗剂 pUL41 (HSV-1Δ UL41 N) 功能缺陷的 HSV-1 感染人类 T 细胞会导致 cGAS 依赖性 I 型干扰素反应。根据我们在原代 CD4 ⁺ T 细胞中的结果，T 细胞系的质粒攻击或 HSV-1Δ UL41 N 接种引发了完全依赖 cGAS 的 I 型干扰素反应，包括 IRF3 磷酸化和 ISG 表达。相反，用VSV-G假型慢病毒或γ逆转录病毒颗粒转导T细胞系后，没有检测到RT依赖性干扰素反应。总之，T 细胞能够对质粒 DNA 攻击或 HSV-1Δ UL41 N 接种产生 cGAS 依赖性细胞内在反应。 然而，HIV-1 感染似乎不会触发 T 细胞中 cGAS 介导的病毒 DNA 感知，这可能是通过揭示病毒 DNA 的数量、长度和/或 cGAS 的可及性不足来实现的。