Identification of Rac guanine nucleotide exchange factors promoting Lgl1 phosphorylation in glioblastoma
| Autor: | Alexander Gont, Danny Jomaa, Karen Jardine, Ian A. J. Lorimer, Sylvie J. Lavictoire, David P. Cook |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
LLGL1
Cellular differentiation Motility Hyperphosphorylation PREX1 cell motility Biochemistry GEF guanine nucleotide exchange factor Gene Knockout Techniques Glioma glioma Cell Line Tumor medicine PTEN Guanine Nucleotide Exchange Factors Humans T-Lymphoma Invasion and Metastasis-inducing Protein 1 Phosphorylation Molecular Biology Lgl1 Glycoproteins biology Chemistry glioblastoma Cell Biology medicine.disease Cell biology Neoplasm Proteins cell polarity biology.protein TIAM1 phosphatidylinositol signaling Guanine nucleotide exchange factor lethal giant larvae Research Article Signal Transduction |
| Zdroj: | The Journal of Biological Chemistry |
| ISSN: | 1083-351X 0021-9258 |
| Popis: | The protein Lgl1 is a key regulator of cell polarity. We previously showed that Lgl1 is inactivated by hyperphosphorylation in glioblastoma as a consequence of PTEN tumour suppressor loss and aberrant activation of the PI 3-kinase pathway; this contributes to glioblastoma pathogenesis both by promoting invasion and repressing glioblastoma cell differentiation. Lgl1 is phosphorylated by atypical protein kinase C that has been activated by binding to a complex of the scaffolding protein Par6 and active, GTP-bound Rac. The specific Rac guanine nucleotide exchange factors that generate active Rac to promote Lgl1 hyperphosphorylation in glioblastoma are unknown. We used CRISPR/Cas9 to knockout PREX1, a PI 3-kinase pathway-responsive Rac guanine nucleotide exchange factor, in patient-derived glioblastoma cells. Knockout cells had reduced Lgl1 phosphorylation, which was reversed by re-expressing PREX1. They also had reduced motility and an altered phenotype suggestive of partial neuronal differentiation; consistent with this, RNA-seq analyses identified sets of PREX1-regulated genes associated with cell motility and neuronal differentiation. PREX1 knockout in glioblastoma cells from a second patient did not affect Lgl1 phosphorylation. This was due to overexpression of a short isoform of the Rac guanine nucleotide exchange factor TIAM1; knockdown of TIAM1 in these PREX1 knockout cells reduced Lgl1 phosphorylation. These data show that PREX1 links aberrant PI 3-kinase signaling to Lgl1 phosphorylation in glioblastoma, but that TIAM1 is also to fill this role in a subset of patients. This redundancy between PREX1 and TIAM1 is only partial, as motility was impaired in PREX1 knockout cells from both patients. |
| Databáze: | OpenAIRE |
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