TPR domain of Ser/Thr phosphatase of Aspergillus oryzae shows no auto-inhibitory effect on the dephosphorylation activity

Ser/Thr protein phosphatases in fungi: structure, regulation and function

Reversible phospho-dephosphorylation of proteins is a major mechanism for the control of cellular functions. By large, Ser and Thr are the most frequently residues phosphorylated in eukar-yotes. Removal of phosphate from these amino acids is catalyzed by a large family of well-conserved enzymes, collectively called Ser/Thr protein phosphatases. The activity of these enzymes has an enormous impact on cellular functioning. In this work we pre-sent the members of this family in S. cerevisiae and other fungal species, and review the most recent findings concerning their regu-lation and the roles they play in the most diverse aspects of cell biology.

Glioma targeting peptide in combination with the P53 C terminus inhibits glioma cell proliferation in vitro

Glioma is a prevalent malignant primary brain tumor in adults, the treatment for which remains a challenge due to its high infiltration and recurrence. Hence, treatments that lead to the suppression of glioma cell migration and invasion may be used in addition to surgery to increase the therapeutic outcome. In this study, we aimed to construct a multifunctional protein that would exert an effect on glioma cell proliferation and migration. The protein is named GL1-P53C-11R and it consists of the glioma-targeting peptide GL1 (G), the P53 C terminus (Pc) and the cell-penetrating peptide arginine (R). GL1-P53C-R was expressed with the fusion protein ZZ and immunofluorescence analysis showed effective delivery of the fused ZZ-GL1-P53C-R protein represented as ZZ-GPcR. The ZZ-GPcR exhibited an inhibitory effect on the proliferation, migration and invasion of U87ΔEGFR cells. Western blotting results indicated that it caused significant changes in the expression levels of cell cycle and apoptotic proteins. Flow cytometric analysis showed increase apoptosis. Our findings suggest that the P53C in the fusion protein ZZ-GPcR can enter into glioma cells to exert its inhibitory effect.

Inhibition of cell proliferation, migration and invasion by a glioma-targeted fusion protein combining the p53 C terminus and MDM2-binding domain

OBJECTIVES

The aim of this study was to develop multifunctional fusion proteins for targeting and delivering therapy elements into glioma cells.

MATERIALS AND METHODS

Multifunctional fusion proteins were expressed in Escherichia coli and purified using Ni-NTA resin affinity chromatography. Human glioma cells and primary astrocytes were used to analyse their functions. Targeting proteins location to glioma cells was observed by confocal microscopy. Effects of cell viability and proliferation were evaluated using the Cell Counting Kit 8 and colony formation assays. Glioma cell migration and invasion were assessed using transwell assays, and apoptosis was analysed by flow cytometry. In addition, changes in expression of proteins related to the cell cycle and apoptosis were determined by Western blotting.

RESULTS

The protein with highest bioactivity was GL1-riHA2-p53c+m-TAT (GHPc+mT), which combines glioma-targeting peptide GL1 (G), and C terminus (Pc) and mouse double minute domains (Pm) of p53, with the destabilizing lipid membrane peptide riHA2 (H) and cell-penetrating peptide TAT (T). The purified fusion protein was stable in cell culture medium and specifically targeted, and was internalized by, epidermal growth factor receptor (EGFR)-overexpressing glioma cells (U87ΔEGFR). It inhibited cell proliferation, migration and invasion, while flow cytometric analysis showed increased apoptosis. In addition, GHPc+mT caused significant changes in expression of proteins related to the cell cycle and apoptosis.

CONCLUSION

GHPc+mT is a multifunctional protein combining targeting, inhibition of glioma cell proliferation and induction of apoptosis, providing some potential to be developed into an effective protein drug delivery system for glioma therapy.

Expressed sequence tags of Aspergillus fumigatus: Extension of catalogue and their evaluation as putative drug targets and/or diagnostic markers

Aspergillus fumigatus a fungal pathogen is implicated in a spectrum of allergic and invasive disorders in humans. Validation of transcriptome of pathogen is essential for understanding its virulence mechanism and to identify new therapeutic targets/diagnostic markers. In order to rapidly identify genes of Aspergillus fumigatus we adopted sequencing of cDNA clones. Our earlier effort has lead to identification of 68 expressed sequence tags of Aspergillus fumigatus. Present study describes 52 more expressed sequence tags generated by sequencing 200 phage clones of a non-normalized cDNA library. One of the cDNA clones comprised of the complete coding region for tetratricopeptide repeat domain protein gene. Various homology search algorithms were employed to assign functions to expressed sequence tags coding for hypothetical proteins, and relevance of these expressed sequence tags or their protein products as drug targets/diagnostic markers was examined by searching for homologues in fungi and human.