USP38 Promotes TBK1 Degradation in an NLRP4-Dependent Manner

 这一段主要讲NLPR4的重要性

首先有一个事实依据

Since both NLRP4 and USP38 degraded TBK1 by a similar mechanism that promoted the K48-linked ubiquitination of TBK1 at Lys670    （就是USP38与TBK1作用效果类似）

然后提出猜想

NLRP4 and USP38 work together to regulate TBK1 stability.

之后用实验证明

        第一个实验  

we performed immunoprecipitation and immunoblot analysis in 293T cells expressing USP38, NLRP3, or NLRP4,

        第一个实验发现

USP38 interacted with NLRP4, but not with NLRP3 (Figure 6A).

        然后第二个实验验证交互的过程

To demonstrate the interaction between USP38 and NLRP4 in physiological conditions, we infected THP-1 cells or PBMCs with VSV-EGFP for the indicated time points,

          第二个实验发现

and we observed the enhanced interaction between USP38 and NLRP4 after viral infection (Figures 6B and 6C). In addition, we found that the PYD and NOD domains of NLRP4 interacted with USP38 (Figure 6D), whereas the N-terminal domain of USP38 was essential for binding to NLRP4 (Figure 6E).     

         同时

Further experiments showed that USP38 was co-localized with TBK1 and NLRP4 (Figure S5A).

          为了证实这些发现,又做了一些实验 (括号内为结论)

(1)we specifically knocked downNLRP4 and found that【 the interaction between USP38 and TBK1was markedly attenuated (Figure 6F).】

(2)we demonstrated that【 the dynamic interaction between USP38 and TBK1 was totally abrogated 】in NLRP4 small interfering RNA (siRNA)- treated THP-1 cells after viral infection (Figure 6G).

(3)【we also observed the reduced interaction between TBK1 and TRIP or DTX4】 when NLRP4 was knocked down (Figures S5B and S5C).

              结果显示

These results suggest that USP38, TRIP, and DTX4 may bind to TBK1 in an NLRP4-dependent manner.

             同时

Luciferase reporter assay further showed that the inhibition of ISRE-luc activity by USP38 could be completely relieved when NLRP4 was knocked down (Figures S5E and S5F).

综合以上所有

Taken together, these results suggest that NLRP4 is indispensable for the inhibitory function of USP38.  

。。。。貌似只有一个概念需要解释

siRNA是一类约21~25nt的RNA分子，由Dicer(RNAaseⅢ家族中对双链RNA具有特异性的酶)加工而成，通过完全互补配对的方式与目标mRNA结合，引起其降解，从而导致靶基因的的沉默。

然后，问题来了

Which phenomenon has proved that the NLPR4 is essential?