Stress‐induced vesicular assemblies of dual leucine zipper kinase are signaling hubs involved in kinase activation and neurodegeneration

Abstract

Mitogen-activated protein kinases (MAPKs) drive key signaling cascades during neuronal survival and degeneration. The localization of kinases to specific subcellular compartments is a critical mechanism to locally control signaling activity and specificity upon stimulation. However, how MAPK signaling components tightly control their localization remains largely unknown. Here, we systematically analyzed the phosphorylation and membrane localization of all MAPKs expressed in dorsal root ganglia (DRG) neurons, under control and stress conditions. We found that MAP3K12/dual leucine zipper kinase (DLK) becomes phosphorylated and palmitoylated, and it is recruited to sphingomyelin-rich vesicles upon stress. Stress-induced DLK vesicle recruitment is essential for kinase activation; blocking DLK-membrane interaction inhibits downstream signaling, while DLK recruitment to ectopic subcellular structures is sufficient to induce kinase activation. We show that the localization of DLK to newly formed vesicles is essential for local signaling. Inhibition of membrane internalization blocks DLK activation and protects against neurodegeneration in DRG neurons. These data establish vesicular assemblies as dynamically regulated platforms for DLK signaling during neuronal stress responses.

Rab11 suppresses neuronal stress signaling by localizing Dual leucine zipper kinase to axon terminals for protein turnover

“…Thus, our study suggests that DLK axonal localization is not a prerequisite for DLK signaling, and that DLK retrograde pathway is a way employed by axonally expressed DLK. Consistent with this notion, a recent work demonstrated that DLK palmitoylation is not essential for DLK signaling but its main role is to bring DLK proteins to the intracellular membrane (Tortosa et al, 2022).…”

“…Unlike diffuse cytoplasmic expression pattern of palmitoylation-deficient DLK proteins in C. elegans and mammalian cells, we observed a discrete subcellular expression pattern of Wnd-C130S::GFP in C4da cell body (Figure 3E), which showed a strong colocalization with the somatic Golgi (Data not shown). A recent work from Tortosa et al suggested that it is membrane localization of DLK proteins, but not palmitoylation itself is essential for DLK signaling (Tortosa et al, 2022). Thus, we tested whether Wnd-C130S::GFP retains signaling capacity.…”

DLK-dependent axonal mitochondrial fission drives degeneration following axotomy

“…Based in its localization, DLK likely has many substrates and regulators, and these will be of great interest to uncover as well as the functions of these interactions. DLK is reported to associate with the plasma membrane, Rab3, Rab6, Rab7, Rab11, Golgi-derived, and LAMP1-positive vesicles 39,82 . Localization of DLK to mitochondria has also just recently been described in cultured mouse embryonic DRG neurons 82 , corroborating our observation of DLK-mitochondrial association.…”

“…DLK is reported to associate with the plasma membrane, Rab3, Rab6, Rab7, Rab11, Golgi-derived, and LAMP1-positive vesicles 39,82 . Localization of DLK to mitochondria has also just recently been described in cultured mouse embryonic DRG neurons 82 , corroborating our observation of DLK-mitochondrial association.…”

Novel determinants of NOTCH1 trafficking and signaling in breast epithelial cells

“…Intriguingly, Mg 2+ supplementation during osteogenesis appears to activate Notch1 signaling, a phenomenon reverted by TRPM7 inhibition [112]. In addition, the Caenorhabditis elegans homolog of MAP3K12 (also called DLK), a Ca 2+ activated MAP kinase involved in trafficking and signaling regulation that we identified [113, 114], has been shown to repress Notch signaling by activating autophagy in neurons [115]. Finally, we have the calmodulin-encoding CALM2.…”