70 research outputs found
Benefits of Combined All-Trans Retinoic Acid and Arsenic Trioxide Treatment of Acute Promyelocytic Leukemia Cells and Further Enhancement by Inhibition of Atypically Expressed Transglutaminase 2
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Plasma Membrane Factor XIIIA Transglutaminase Activity Regulates Osteoblast Matrix Secretion and Deposition by Affecting Microtubule Dynamics
Transglutaminase activity, arising potentially from transglutaminase 2 (TG2) and
Factor XIIIA (FXIIIA), has been linked to osteoblast differentiation where it is
required for type I collagen and fibronectin matrix deposition. In this study we
have used an irreversible TG-inhibitor to ‘block –and-track’
enzyme(s) targeted during osteoblast differentiation. We show that the
irreversible TG-inhibitor is highly potent in inhibiting osteoblast
differentiation and mineralization and reduces secretion of both fibronectin and
type I collagen and their release from the cell surface. Tracking of the dansyl
probe by Western blotting and immunofluorescence microscopy demonstrated that
the inhibitor targets plasma membrane-associated FXIIIA. TG2 appears not to
contribute to crosslinking activity on the osteoblast surface. Inhibition of
FXIIIA with NC9 resulted in defective secretory vesicle delivery to the plasma
membrane which was attributable to a disorganized microtubule network and
decreased microtubule association with the plasma membrane. NC9 inhibition of
FXIIIA resulted in destabilization of microtubules as assessed by cellular
Glu-tubulin levels. Furthermore, NC9 blocked modification of Glu-tubulin into
150 kDa high-molecular weight Glu-tubulin form which was specifically localized
to the plasma membrane. FXIIIA enzyme and its crosslinking activity were
colocalized with plasma membrane-associated tubulin, and thus, it appears that
FXIIIA crosslinking activity is directed towards stabilizing the interaction of
microtubules with the plasma membrane. Our work provides the first mechanistic
cues as to how transglutaminase activity could affect protein secretion and
matrix deposition in osteoblasts and suggests a novel function for plasma
membrane FXIIIA in microtubule dynamics
Infection‐driven activation of transglutaminase 2 boosts glucose uptake and hexosamine biosynthesis in epithelial cells
DATA AVAILABILITYThe mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD017117.International audienceTransglutaminase 2 (TG2) is a ubiquitously expressed enzyme with transamidating activity. We report here that both expression and activity of TG2 are enhanced in mammalian epithelial cells infected with the obligate intracellular bacteria Chlamydia trachomatis. Genetic or pharmacological inhibition of TG2 impairs bacterial development. We show that TG2 increases glucose import by up-regulating the transcription of the glucose transporter genes GLUT-1 and GLUT-3. Furthermore, TG2 activation drives one specific glucose-dependent pathway in the host, i.e., hexosamine biosynthesis. Mechanistically, we identify the glucosamine:fructose-6-phosphate amidotransferase (GFPT) among the substrates of TG2. GFPT modification by TG2 increases its enzymatic activity, resulting in higher levels of UDP-N-acetylglucosamine biosynthesis and protein O-GlcNAcylation. The correlation between TG2 transamidating activity and O-GlcNAcylation is disrupted in infected cells because host hexosamine biosynthesis is being exploited by the bacteria, in particular to assist their division. In conclusion, our work establishes TG2 as a key player in controlling glucose-derived metabolic pathways in mammalian cells, themselves hijacked by C. trachomatis to sustain their own metabolic needs
Cytosolic Guanine Nucledotide Binding Deficient Form of Transglutaminase 2 (R580a) Potentiates Cell Death in Oxygen Glucose Deprivation
Transglutaminase 2 (TG2) is a hypoxia-responsive protein that is a calcium-activated transamidating enzyme, a GTPase and a scaffolding/linker protein. Upon activation TG2 undergoes a large conformational change, which likely affects not only its enzymatic activities but its non-catalytic functions as well. The focus of this study was on the role of transamidating activity, conformation and localization of TG2 in ischemic cell death. Cells expressing a GTP binding deficient form of TG2 (TG2-R580A) with high basal transamidation activity and a more extended conformation showed significantly increased cell death in response to oxygen-glucose deprivation; however, targeting TG2-R580A to the nucleus abrogated its detrimental role in oxygen-glucose deprivation. Treatment of cells expressing wild type TG2, TG2-C277S (a transamidating inactive mutant) and TG2-R580A with Cp4d, a reversible TG2 inhibitor, did not affect cell death in response to oxygen-glucose deprivation. These findings indicate that the pro-cell death effects of TG2 are dependent on its localization to the cytosol and independent of its transamidation activity. Further, the conformational state of TG2 is likely an important determinant in cell survival and the prominent function of TG2 in ischemic cell death is as a scaffold to modulate cellular processes
Incorporation of chlorinated analogues of aliphatic amino acids during cell-free protein synthesis
Fluorogenic protein labelling: a review of photophysical quench mechanisms and principles of fluorogen design
A multidisciplinary investigation of a transglutaminase biocatalyst for organic synthesis applications
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