Temporal changes in plasma membrane lipid content induce endocytosis to regulate developmental epithelial-to-mesenchymal transition

Abstract

Epithelial-to-mesenchymal transition (EMT) is a dramatic change in cellular physiology during development and metastasis which involves coordination between cell signaling, adhesion, and membrane protrusions. These processes all involve dynamic changes in the plasma membrane, yet how membrane lipid content regulates membrane function during developmental EMT remains incompletely understood. By screening for differential expression of lipid-modifying genes over the course of EMT in avian neural crest, we have identified the ceramide-producing enzyme neutral sphingomyelinase 2 (nSMase2) as a critical regulator of a developmental EMT. nSMase2 expression begins at the onset of EMT, and in vivo knockdown experiments demonstrate that nSMase2 is necessary for neural crest migration. Further, we find that nSMase2 promotes Wnt and BMP signaling, and is required to activate the mesenchymal gene expression program. Mechanistically, we show that nSMase2 is sufficient to induce endocytosis, and that inhibition of endocytosis mimics nSMase2 knockdown. Our results support a model in which nSMase2 is expressed at the onset of neural crest EMT to produce ceramide and induce membrane curvature, thus increasing endocytosis of Wnt and BMP signaling complexes and activating pro-migratory gene expression. These results highlight the critical role of plasma membrane lipid metabolism in regulating transcriptional changes during developmental EMT programs.

Transcriptomic Identification of Draxin-Responsive Targets During Cranial Neural Crest EMT

“…To better understand the molecular processes in which Draxin, and by extension canonical Wnt signaling, function during cranial neural crest EMT, we performed functional annotation for the dataset using the Database for Annotation, Visualization and Integrated Discovery (DAVID) ( Huang da et al, 2009a , b ). Consistent with established roles of canonical Wnt signaling and Draxin-mediated inhibition during cranial neural crest EMT, we observed enrichment of genes associated with transcriptional regulation, cell adhesion, and lipid synthesis, which we have recently shown is important for cell signaling during cranial neural crest EMT ( Piacentino et al, 2020 ). In addition, we found numerous genes associated with bone/cartilage formation (e.g., CYTL1 , ILK , NOV ), a critical function of cranial neural crest, and genes involved in ribosome biogenesis (e.g., NOP56 , PES1 , NOC2L ), which has implications for craniofacial development ( Ross and Zarbalis, 2014 ) ( Figure 3A ).…”

Influence of sphingomyelin metabolism during epithelial–mesenchymal transition associated with aging in the renal papilla

“…So, taking together these observations and our results, we can infer that during the aging process, the regulation of SM metabolism by nSMase may play a critical role in the EMT of CD cells of aged‐rats to generate renal fibrosis. Piacentino et al (2020) also demonstrated that at the beginning of the EMT, the conversion of SM into ceramide mediated by nSMase2 promotes membrane curvature. This facilitates the endocytosis of activated signaling complexes (Wnt and BMP) and leads to the activation of pro‐EMT transcriptional targets including Snail2, which promotes neural crest EMT and migration.…”

“…Consistent with our results, Hernandez‐Corbacho et al (2011) demonstrated that during aging, nSMase and ceramide synthase activities increase, and hexosylceramides and lactosylceramides accumulate in mouse kidney. Recently, Piacentino et al (2020) point to nSMase2 as a critical regulator of the EMT during neural development. So, taking together these observations and our results, we can infer that during the aging process, the regulation of SM metabolism by nSMase may play a critical role in the EMT of CD cells of aged‐rats to generate renal fibrosis.…”

Comparative membrane lipidomics of hepatocellular carcinoma cells reveals diacylglycerol and ceramide as key regulators of Wnt/β-catenin signaling and tumor growth

“…Importantly, Cer and DAG were among the “green” lipids, strongly suggesting that they moderate the cancer effect. The neutral sphingomyelinase 2 enzyme has been shown to induce production of Cer, a sphingolipid component of ordered membrane domains, which induces receptor clustering and plasma membrane curvature in the neural crest during development (52, 59). Subsequent endocytosis of Wnt and BMP signaling complexes was sufficient to activate epithelial-to-mesenchymal transition, suggesting a key role for Cer in regulating cell migration.…”