Glucose Starvation Causes ptauS409 Increase in N2a Cells Through ATF3/PKAcα Signaling Pathway.

In this work, we report that glucose starvation (GS) causes ptauS409 increase, which may participate in GS-induced neurites retraction in neuro-2a (N2a) cells. Upon GS treatment, PKAcα was stimulated at mRNA and protein levels. Luciferase reporter gene assays indicated that GS regulated PKAcα expression through a core promoter (-345 to -95 bp upstream the transcription starting site) consisting of a cis-acting element of Activating Transcription Factor 3 (ATF3). Knockdown and over-expression experiments demonstrate that ATF3 transcriptionally regulated PKAcα expression. Moreover, GS stimulated ATF3 expression in a time-dependent manner. These findings reveal that glucose starvation induces ptauS409 increase in N2a cells through an ATF3- PKAcα axis, which shed some light on the relationship between brain glucose metabolism and neurodegenerative diseases.

[Effect of DSA on Vascular Endothelial Cell Injury in NK Cell -Mediated ADCC].

OBJECTIVE: To investigate the injury effect of anti-donor specific antibody (DSA) on human umbilical vein enolothelial cells (HUVEC) in NK-mediated antibody-dependent cell cytotoxity (ADCC). METHODS: The peripheral blood of 10 healthy donors was colleced for allo-HSCT of AML patients diagnosed in Department of Hemology of the Tumor Hospital affiliated to Shanxi Medical University, then the peripheral blood NK cells were isolated and used as the effector cells; the HUVEC of passages 9-6 were selected and co-cultured with DSA, then the DSA-binding HUVEC were used as the target cells (CDH group), while the DSA-unbinding HUVEC were used as negative control (UDH group). After co-culture of effecor cells with target cells, the expression of IFN-γ was detected by flow cytometry and the HUVEC activity was detected by using MTT method, so as to indirectily reflect the injury effect of DSA-mediated ADCC on endothelial cells. RESULTS: With the increase of effector-target (E:T) ratio, the activity of HUVEC decreased, the expression level of IFN-γ increased. Under the some effector-target ratio (1∶1, 10∶1, 20∶1), the activity of HUVEC in CDH group was significantly lower than that of UDH group, and the expression of IFN-γ was significantly higher than that of the UDH group (P<0.05). CONCLUSION: DSA can damage vascular endothelial cells through the ADCC effect mediated by NK cells.

Hepatocyte nuclear factor 1 alpha (HNF1A) regulates transcription of O-GlcNAc transferase in a negative feedback mechanism.

O-GlcNAc transferase (OGT)-catalyzed protein O-GlcNAcylation is implicated in diverse cellular events. In the present study, we report the regulation of ogt transcription by the hepatocyte nuclear factor 1 homologue A (HNF1A) in HEK293T cells. We first identified a core ogt promoter (-150 to +200 bp) and confirmed its binding to the transcription factor HNF1A. We found that HNF1A regulates ogt transcription in a time-dependent manner and that O-GlcNAcylation of HNF1A represses ogt transcription. Electron-transfer dissociation based tandem mass spectrometry analysis revealed 14 O-GlcNAc sites on HNF1A, six of which are predominantly modified, including Ser303/304 , Ser471 , Ser560 and Thr563/564 . We further found that loss of O-GlcNAcylation at Ser303/304 or Thr563/564 significantly elevates ogt transcription. These findings highlight a negative feedback mechanism for ogt transcription, which partially explains the homeostasis of cellular O-GlcNAcylation.