STRIPAK Dependent and Independent Phosphorylation of the SIN Kinase DBF2 Controls Fruiting Body Development and Cytokinesis during Septation and Ascospore Formation in Sordaria macrospora.

The supramolecular striatin-interacting phosphatases and kinases (STRIPAK) complex is highly conserved in eukaryotes and controls diverse developmental processes in fungi. STRIPAK is genetically and physically linked to the Hippo-related septation initiation network (SIN), which signals through a chain of three kinases, including the terminal nuclear Dbf2-related (NDR) family kinase DBF2. Here, we provide evidence for the function of DBF2 during sexual development and vegetative growth of the homothallic ascomycetous model fungus Sordaria macrospora. Using mutants with a deleted dbf2 gene and complemented strains carrying different variants of dbf2, we demonstrate that dbf2 is essential for fruiting body formation, as well as septum formation of vegetative hyphae. Furthermore, we constructed dbf2 mutants carrying phospho-mimetic and phospho-deficient codons for two conserved phosphorylation sites. Growth tests of the phosphorylation mutants showed that coordinated phosphorylation is crucial for controlling vegetative growth rates and maintaining proper septum distances. Finally, we investigated the function of DBF2 by overexpressing the dbf2 gene. The corresponding transformants showed disturbed cytokinesis during ascospore formation. Thus, regulated phosphorylation of DBF2 and precise expression of the dbf2 gene are essential for accurate septation in vegetative hyphae and coordinated cell division during septation and sexual spore formation.

Synergistic effect of microRNA and albumin-bound nanoparticles for inhibition of glioblastoma cancer cell proliferation

The functional significance of upregulation miR-34a in combination with albumin-bound paclitaxel nanoparticles in U251 glioblastoma cell line has been evaluated. The MTT assay determined that miR-34a and albumin-bound paclitaxel nanoparticles can reduce cell viability, but the combination of both factors has a stronger effect on cell viability. The application of qRT-PCR has demonstrated that the transduction of miR-34a could lead to exogenous upregulation of miR-34a level and downregulation of SURVIVIN. Moreover, treatment of U251 cells with miR-34a and nanoparticles together considerably inhibit SURVIVIN expression compared to miR-34a and nanoparticles alone. Flow cytometry showed that upon miR-34a overexpression cell cycle arrested in G1 phase, while treatment with nanoparticles increased the cell population in G2 phase. Upregulation of miR-34a along with treatment with nanoparticles elevated the number of cells arrested in G1/ G2 phases of the cell cycle. Expression of miR-34a with albumin-bound paclitaxel nanoparticles reduced cell viability, downregulated SURVIVIN and enhanced cell cycle arrest in G1/G2 phases. Thus, the upregulation of miR-34a with these nanoparticles are potential candidates therapeutic for glioblastoma cancer.