Plectin plays a role in the migration and volume regulation of astrocytes: a potential biomarker of glioblastoma

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Authors

ZUGEC Maja FURLANI Borut CASTANON Maria J RITUPER Bostjan FISCHER Irmgard BROGGI Giuseppe CALTABIANO Rosario BARBAGALLO Giuseppe M V MICHELINO Di Rosa TIBULLO Daniele PARENTI Rosalba VICARIO Nunzio SIMCIC Sasa POZO DEVOTO Victorio Martin STOKIN Gorazd B WICHE Gerhard JORGACEVSKI Jernej ZOREC Robert POTOKAR Maja

Year of publication 2024
Type Article in Periodical
Magazine / Source Journal of Biomedical Science
MU Faculty or unit

Faculty of Medicine

Citation
Web https://jbiomedsci.biomedcentral.com/articles/10.1186/s12929-024-01002-z
Doi http://dx.doi.org/10.1186/s12929-024-01002-z
Keywords Astrocyte; Glioblastoma; Plectin; Aquaporin 4; Intermediate filaments; Cytoskeleton; Edema; Cell volume; Cell migration
Description BackgroundThe expression of aquaporin 4 (AQP4) and intermediate filament (IF) proteins is altered in malignant glioblastoma (GBM), yet the expression of the major IF-based cytolinker, plectin (PLEC), and its contribution to GBM migration and invasiveness, are unknown. Here, we assessed the contribution of plectin in affecting the distribution of plasmalemmal AQP4 aggregates, migratory properties, and regulation of cell volume in astrocytes.MethodsIn human GBM, the expression of glial fibrillary acidic protein (GFAP), AQP4 and PLEC transcripts was analyzed using publicly available datasets, and the colocalization of PLEC with AQP4 and with GFAP was determined by immunohistochemistry. We performed experiments on wild-type and plectin-deficient primary and immortalized mouse astrocytes, human astrocytes and permanent cell lines (U-251 MG and T98G) derived from a human malignant GBM. The expression of plectin isoforms in mouse astrocytes was assessed by quantitative real-time PCR. Transfection, immunolabeling and confocal microscopy were used to assess plectin-induced alterations in the distribution of the cytoskeleton, the influence of plectin and its isoforms on the abundance and size of plasmalemmal AQP4 aggregates, and the presence of plectin at the plasma membrane. The release of plectin from cells was measured by ELISA. The migration and dynamics of cell volume regulation of immortalized astrocytes were assessed by the wound-healing assay and calcein labeling, respectively.ResultsA positive correlation was found between plectin and AQP4 at the level of gene expression and protein localization in tumorous brain samples. Deficiency of plectin led to a decrease in the abundance and size of plasmalemmal AQP4 aggregates and altered distribution and bundling of the cytoskeleton. Astrocytes predominantly expressed P1c, P1e, and P1g plectin isoforms. The predominant plectin isoform associated with plasmalemmal AQP4 aggregates was P1c, which also affected the mobility of astrocytes most prominently. In the absence of plectin, the collective migration of astrocytes was impaired and the dynamics of cytoplasmic volume changes in peripheral cell regions decreased. Plectin's abundance on the plasma membrane surface and its release from cells were increased in the GBM cell lines.ConclusionsPlectin affects cellular properties that contribute to the pathology of GBM. The observed increase in both cell surface and released plectin levels represents a potential biomarker and therapeutic target in the diagnostics and treatment of GBMs.
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