Aberrant splicing of the cyclin-dependent kinase-associated phosphatase, KAP, promotes glioblastoma invasion in a Cdc2-dependent manner. However, the mechanism by which this occurs is unknown. Here we show that miR-26a, which is often amplified in glioblastoma, promotes invasion in phosphatase and tensin homolog (PTEN)-competent and PTEN-deficient glioblastoma cells by directly downregulating KAP expression. Mechanistically, we find that KAP binds and activates ROCK2. Thus, RNA-mediated downregulation of KAP leads to decreased ROCK2 activity and this, in turn, increases Rac1-mediated invasion. In addition, the decrease in KAP expression activates the cyclin-dependent kinase, Cdk2, and this directly promotes invasion by increasing retinoblastoma phosphorylation, E2F-dependent Cdc2 expression and Cdc2-mediated inactivation of the actomyosin inhibitor, caldesmon. Importantly, glioblastoma cell invasion mediated by this pathway can be antagonized by Cdk2/Cdc2 inhibitors in vitro and in vivo. Thus, two distinct RNA-based mechanisms activate this novel KAP/ROCK2/Cdk2-dependent invasion pathway in glioblastoma.
Acid alpha-glucosidase (GAA) deficiency causes Pompe disease, a lethal lysosomal glycogen storage disease for which no effective treatment currently exists. We investigated the endocytic process in deficient cells of human recombinant GAA produced in Chinese hamster ovary cells, and the potential of GAA-deficient Japanese acid maltase-deficient quail as a model for evaluating the enzyme replacement therapy for Pompe disease. After 24-h incubation with a single dose of recombinant enzyme, intracellular GAA and glycogen levels in deficient human fibroblasts were normalized, and this correction lasted for 7 d. The 110-kD precursor recombinant enzyme was processed to the 76-kD mature form within 24 h after uptake. Intracellular GAA levels in deficient quail fibroblasts and myoblasts were similarly corrected to their average normal levels within 24 h. Differences existed in the efficiency of endocytosis among subfractions of the enzyme, and among different cell types. Fractions with a larger proportion of precursor GAA were endocytosed more efficiently. Quail fibroblasts required a higher dose, 4200 nmol.h-1.mL-1 to normalize intracellular GAA levels than human fibroblasts, 1290 nmol.h-1.mL-1, whereas primary quail myoblasts required 2800 nmol.h-1.mL-1. In all three cell lines, the endocytosed enzyme localized to the lysosomes on immunofluorescence staining, and the endocytosis was inhibited by mannose 6-phosphate (Man-6-P) added to the culture medium. Despite structural differences in Man-6-P receptors between birds and mammals, these studies illustrate that Man-6-P receptor mediated endocytosis is present in quail muscle cells, and demonstrate the potential of acid maltase-deficient quail to test receptor mediated enzyme replacement therapy for Pompe disease.
This study was performed with the aim to investigate the correlations of tumor necrosis factor-alpha (TNF-α) gene promoter polymorphisms with the risk of thymoma-associated myasthenia gravis (T-MG) in a northern Chinese Han population. Between June 2005 and June 2015, 305 MG patients (150 males and 155 females, MG group) and 293 healthy volunteers (negative control (NC) group) were enrolled in this study. Among the MG patients, there were 121 patients with thymoma-associated MG (T-MG group) and 184 without T-MG (NT-MG group). Enzyme-linked immunosorbent assay (ELISA) was used for the serum TNF-α level. Polymerase chain reaction-restriction fragment length polymorphism was conducted to determine genotype and allele frequencies of TNF-α gene promoter -1031T/C, -857C/T and -863C/A. The haplotype was analyzed with the SHEsis software. Logistic regression analysis was performed for correlations between TNF-α gene promoter polymorphisms and the risk of T-MG. The T-MG group had higher frequencies of the CT/TT genotype and T allele of -857C/T than the NT-MG and NC groups. The frequencies of the CC genotype and C allele of -1031T/C were higher in the T-MG group than in the NT-MG and NC groups, and higher in male patients in the T-MG group than in male patients in the NC group. TTA and TTC haplotypes exhibited lower frequencies in the T-MG group than in the NT-MG group. The ocular MG patients exhibited lower frequencies of the TT genotype and T allele of -857C/T than the generalized MG patients did. The TNF-α level was elevated in the T-MG group compared with that in the NC and NT-MG groups, indicating that the TC+CC and CT+TT genotypes were increased compared with the TT and CC genotypes in the -1031T/C and -857C/T, respectively. Logistic regression analysis suggested that expressions of anti-acetylcholine receptor antibodies, Osserman's classification, -1031T/C and -857C/T polymorphisms and the TTA haplotype were the independent risk factors for T-MG. These findings reveal that TNF-α -1031T/C and -857C/T polymorphisms and the TTA haplotype may be correlated with the occurrence of T-MG in a Northern Chinese Han population.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.