Glycine targets NINJ1-mediated plasma membrane rupture to provide cytoprotection

Abstract

First recognized 35 years ago, glycine is known to protect cells against plasma membrane rupture from diverse types of tissue injury. This robust and widely observed effect has been speculated to target a late downstream process common to multiple modes of tissue injury. The molecular target of glycine cytoprotection, however, remains entirely elusive. We hypothesized that glycine targets ninjurin-1 (NINJ1), a newly identified executioner of plasma membrane rupture in pyroptosis, necrosis, and post-apoptotic cell death. NINJ1 is thought to cluster within the plasma membrane to cause cell rupture. Here, we first demonstrate that NINJ1 knockout functionally and morphologically phenocopies glycine cytoprotection in mouse and human macrophages stimulated to undergo lytic cell death. Next, we show that glycine treatment prevents NINJ1 clustering thereby preserving cellular integrity. By identifying NINJ1 as a glycine target, our data help resolve a long-standing mechanism of glycine cytoprotection. This new understanding will inform the development of cell preservation strategies to counter pathologic lytic cell death pathways. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/471765v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@b9c3d9org.highwire.dtl.DTLVardef@1e903f0org.highwire.dtl.DTLVardef@1018498org.highwire.dtl.DTLVardef@a819b9_HPS_FORMAT_FIGEXP M_FIG C_FIG SummaryGlycine is known to protect cells against plasma membrane rupture from diverse types of tissue injury by an unknown mechanism. The authors demonstrate that NINJ1, a newly identified executioner of plasma membrane rupture across lytic cell death pathways, is a glycine target and resolve a longstanding mechanism of glycine cytoprotection.