Recognizing limits of Z‐nucleic acid binding protein (ZBP1/DAI/DLM1) function

Abstract

Z‐nucleic acid binding protein (ZBP)1 (also known as DAI and DLM1) is a pathogen sensor activated by double‐strand character RNA to recruit receptor‐interacting protein (RIP) kinase via a RIP homotypic interaction motif. The activation of receptor‐interacting protein kinase (RIPK)3 and initiation of virus‐induced necroptosis were initially reported in a landmark publication Upton et al. (Cell Host Microbe 11: 290, 2012) employing the DNA virus murine cytomegalovirus (MCMV). M45‐encoded viral inhibitor of RIP activation prevents virus‐induced necroptosis. Additional virus‐encoded suppressors of necroptosis were then identified, including herpes simplex virus ICP6 and vaccinia virus E3L. Caspase‐8 suppressors encoded by these DNA viruses block apoptosis, unleashing necroptosis mediated through Z‐nucleic acid binding protein 1 (ZBP1) recruitment of RIPK3. These studies all utilized ZBP1‐deficient mice generated by the Akira Lab (Zbp1−/− AK) to bring the significance of virus‐induced necroptosis to light. C57BL/6 mice were chosen as controls based on the assumption that mutant mice were congenic; however, these mice were recently found to display an unexpected innate immune deficit, lacking C57BL/6‐specific NK1.1 and Ly49H natural killer cell subpopulations important in the early control of MCMV infection. Short nucleotide polymorphism analysis of Zbp1−/− AK breeders revealed a mixed genetic background (~ 71% C57BL/6 DNA and ~ 29% 129). Even though this level of 129 strain background does not alter ZBP1 cell‐autonomous function as a sensor and mediator of necroptosis, it confounds innate immune response characteristics. In the future, genetic background must be carefully controlled before implicating ZBP1 function in response characteristics that shape immunity, inflammation, metabolism, and pathogenesis.

Sensing of endogenous nucleic acids by ZBP1 induces keratinocyte necroptosis and skin inflammation

“…Casp1/11 −/− mice were purchased from The Jackson Laboratory (B6N.129S2-Casp1 tm1Flv /J). Ripk1 FL/FL , Mlkl FL/FL , and Zbp1 Zα1α2/Zα1α2 mice were generated in C57Bl/6 embryonic stem (ES) cells, Keratin-5-Cre transgenes were generated in C57Bl/6JxDBA/2J ES cells, and Ripk3 −/− , Casp1/11 −/− ( Kayagaki et al, 2015 ) and Zbp1 −/− ( Koehler et al, 2020 ) mice were generated in 129-derived ES cells. All lines were maintained in a C57Bl/6 background.…”

Die Another Way: Interplay between Influenza A Virus, Inflammation and Cell Death

“…Overall, the results suggest that a ZBP1-RIPK3-mediated cell death axis exists to limit viral replication in mice [23,85]. It is important to note that the widely used Zbp1 −/− mice generated in Shizou Akira's laboratory have been shown to be on a mixed-genetic C57BL/6 and 129 background, complicating in vivo studies that used C57BL/6 controls, rather than littermates [149]. However, in agreement with the hypersusceptibility observed in vivo, a lack of DAI/ZBP1 in murine LET1 cells resulted in increased PR8 replication in vitro [23].…”

Multiple Autonomous Cell Death Suppression Strategies Ensure Cytomegalovirus Fitness

“…For BMDM culture, this complete DMEM medium had a final 20% fetal bovine serum and 20% filtered L929-conditioned medium (as a source of macrophage colony-stimulating factor). Cells were harvested from C57BL/6 (referred to as WT), Ripk3 −/− Casp8 −/− , RIPK3 −/− , Ripk1 −/− Casp8 −/− Ripk3 −/− , Ripk1 K45A/K45A , Ripk3 K50A/K50A , Asc −/− , Aim2 −/− , Ifnar1 −/− , Ifngr −/− , and Gsdmd −/− [ 77 ], Zbp −/− [ 78 ], Bak −/− Bax fl/fl (also referred to as Bax tm2Sjk Bak1 tm1Thsn/J ) [ 38 ], Bid −/− , Bim −/− , Puma −/− , Bid −/− Bim −/− Puma −/− [ 79 ], Bax −/− Bak −/− [ 80 ], and Bok −/− [ 81 ] mice. BAX knockdown in Bak −/− Bax fl/fl BMDM cells was achieved by infection with lentivirus expressing Cre recombinase.…”

“…For BMDM culture, this complete DMEM medium had a final 20% fetal bovine serum and 20% filtered L929-conditioned medium (as a source of macrophage colony-stimulating factor). Cells were harvested from C57BL/6 (referred to as WT), Ripk3 [78], Bak −/− Bax fl/fl (also referred to as Bax tm2Sjk Bak1 tm1Thsn/J ) [38], [80], and Bok −/− [81] mice. BAX knockdown in Bak −/− Bax fl/fl BMDM cells was achieved by infection with lentivirus expressing Cre recombinase.…”