Regulation of co‐ and post‐translational myristoylation of proteins during apoptosis: interplay ofN‐myristoyltransferases and caspases

Abstract

Myristoylation occurs cotranslationally on nascent proteins and post-translationally during apoptosis after caspase cleavages expose cryptic myristoylation sites. We demonstrate a drastic change in the myristoylated protein proteome in apoptotic cells, likely as more substrates are revealed by caspases. We show for the first time that both N-myristoyltransferases (NMTs) 1 and 2 are cleaved during apoptosis and that the caspase-3- or -8-mediated cleavage of NMT1 at Asp-72 precedes the cleavage of NMT2 by caspase-3 mainly at Asp-25. The cleavage of NMTs did not significantly affect their activity in apoptotic cells until the 8 h time point. However, the cleavage of the predominantly membrane bound NMT1 (64%) removed a polybasic domain stretch and led to a cytosolic relocalization (>55%), whereas predominantly cytosolic NMT2 (62%) relocalized to membranes when cleaved (>80%) after the removal of a negatively charged domain. The interplay between caspases and NMTs during apoptosis is of particular interest since caspases may not only control the rates of substrate production but also their myristoylation rate by regulating the location and perhaps the specificity of NMTs. Since apoptosis is often suppressed in cancer, the reduced caspase activity seen in cancer cells might also explain the higher NMT levels observed in many cancers.

MicroRNA-99 Family Members Suppress Homeobox A1 Expression in Epithelial Cells

“…Among these genes, mTOR, CTDSPL and SMARCA5 have been previously identified and experimentally confirmed as functional targets for miR-99 family members [5], [7], [11], [34], [35]. HOXA1 is a known oncogene [36]–[40], and NMT1 also plays a role in regulating tumor cell proliferation and apoptosis [41], [42]. TMEM30A plays a major role in cell polarity control and microtubule regulation, and is also involved in cell migration [43].…”

Conformational Transition of Membrane-Associated Terminally Acylated HIV-1 Nef

“…Lipid modification serves to target many proteins to specific membranes or submembrane locations. Hundreds of proteins are known to be modified with covalently bound lipid groups, the most common of which are fatty acids, isoprenoids, and glycosylphosphatidylinositol anchors (Farazi et al, 2001; Jeromin et al, 2004; Perinpanayagan et al, 2013; Resh, 2006; Steinhauer and Treisman, 2009). Many of these proteins are involved in signaling, and require membrane association to signal efficiently.…”

“…Despite the obvious importance of acylated proteins in biology (e.g., kinases and phosphatases (Kim et al, 2009; Resh, 2006; Schlessinger, 2000), G proteins (Resh, 2006), GPCRs (Resh, 2006), morphogens (Steinhauer and Treisman, 2009), neuronal calcium sensors (Jeromin et al, 2004), pro- and anti-apoptotic proteins (Perinpanayagan et al, 2013)), standard approaches for studying their structure at membranes are neither adequate nor appropriate. In addition, understanding signaling mechanisms involving these proteins at the molecular level and developing pharmaceutical interventions has been limited by the absence of structural detail for these proteins in the membrane-bound state.…”

Recent Advances in The Discovery of N‐Myristoyltransferase Inhibitors

“…[12] NMT is constituted by a saddle-shaped b sheet motif flanked by a helices, displaying pseudo-twofold symmetry with regions corresponding to the N-and C-terminal portions of NMT. [17] Perinpanayagam et al [18] reported NMT-1 to be a substrate of caspases-3 and -8, whereas NMT-2 is a caspase-3 substrate only. [13] NMT is a member of the GNAT superfamily of proteins, which was first identified in Saccharomyces cerevisiae by Towler, Glaser, and colleagues via the N-terminal sequence (Gly-Asn-Ala-Ala-Ala-Ala-Arg-Arg) of the catalytic subunit of cAMP-dependent protein kinase.…”

“…NMT-1 was reported to be present in four distinct isoforms, ranging from 49 to 68 kDa, whereas only a single NMT-2 isoform (65 kDa) was found. [17] Perinpanayagam et al [18] reported NMT-1 to be a substrate of caspases-3 and -8, whereas NMT-2 is a caspase-3 substrate only. Meanwhile, the cleavage sites located at the N termini of both NMTs was identified as well.…”