Effector-mediated ERM activation locally inhibits RhoA activity to shape the apical cell domain.
Ontology highlight
ABSTRACT:
SUBMITTER: Zaman R
PROVIDER: S-EPMC8185690 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:To identify novel proteins that control melanoma development and progression, we integrated high-throughput proteomics, mRNA and miRNAs datasets from isogenic primary (WM115) and metastatic (WM266-4) melanoma cell-lines. We focused on differentially expressed proteins that had non-differential mRNA levels and were putatively targeted by a high number of miRNAs. SNX18, a sub-family member of sorting-nexins that participates in endocytosis and autophagy was down-regulated by 6-fold in WM266-4, and predicted to be targeted by 17 miRNAs. Over-expression of SNX18 in several melanoma cell-lines significantly reduced migration rate, while silencing of SNX18 resulted in the opposite effect. Notably, progression tissue microarrays demonstrated a trend for SNX18 downregulation in early metastasis. Luciferase assays confirmed the direct regulation of SNX18 by multiple miRNAs. Indeed, over-expression of these miRNAs repressed endogenous SNX18 expression at the protein but not mRNA level. Further, protein but not mRNA expression levels correlated with better overall survival as determined in a cohort of 48 metastatic melanoma patients and in the TCGA database. Mechanistically, SNX18-mediated reduced migration coincided with RhoA activation and Cdc42 inactivation. Both play a role, as RhoA inhibitor and constitutively activated Cdc42 mutants abrogated this effect. Moreover, phosphorylation-defective SNX18 mutants (S233A,S233D) migrated faster, with S233A inactivating RhoA and activating Cdc42, while S233D activated both. The downstream phosphorylation of the p38>MAPKAPK2>HSP27 signaling pathway was concordant. Both mutants were more abundant in the plasma membrane. Taken together, phosphorylation of S233 is crucial for SNX18 activation, but de-phosphorylation dynamics, which may occur at the membrane, is required for functional effect. miRNA expression profile of primary (WM115) and metastatic (WM266-4) melanoma cell lines.
2021-09-17 | GSE120033 | GEO
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