scholarly journals HBP1 Repression of the p47phox Gene: Cell Cycle Regulation via the NADPH Oxidase

2004 ◽  
Vol 24 (7) ◽  
pp. 3011-3024 ◽  
Author(s):  
Stephen P. Berasi ◽  
Mei Xiu ◽  
Amy S. Yee ◽  
K. Eric Paulson
Keyword(s):  
Cell Cycle ◽  
Nadph Oxidase ◽  
Cell Cycle Regulation ◽  
Dominant Negative ◽  
Cellular Growth ◽  
Superoxide Production ◽  
Regulatory Subunit ◽  
Dominant Negative Mutant ◽  
Ros Generation ◽  
Cycle Regulation

ABSTRACT Several studies have linked the production of reactive oxygen species (ROS) by the NADPH oxidase to cellular growth control. In many cases, activation of the NADPH oxidase and subsequent ROS generation is required for growth factor signaling and mitogenesis in nonimmune cells. In this study, we demonstrate that the transcriptional repressor HBP1 (HMG box-containing protein 1) regulates the gene for the p47phox regulatory subunit of the NADPH oxidase. HBP1 represses growth regulatory genes (e.g., N-Myc, c-Myc, and cyclin D1) and is an inhibitor of G1 progression. The promoter of the p47phox gene contains six tandem high-affinity HBP1 DNA-binding elements at positions −1243 to −1318 bp from the transcriptional start site which were required for repression. Furthermore, HBP1 repressed the expression of the endogenous p47phox gene through sequence-specific binding. With HBP1 expression and the subsequent reduction in p47phox gene expression, intracellular superoxide production was correspondingly reduced. Using both the wild type and a dominant-negative mutant of HBP1, we demonstrated that the repression of superoxide production through the NADPH oxidase contributed to the observed cell cycle inhibition by HBP1. Together, these results indicate that HBP1 may contribute to the regulation of NADPH oxidase-dependent superoxide production through transcriptional repression of the p47phox gene. This study defines a transcriptional mechanism for regulating intracellular ROS levels and has implications in cell cycle regulation.

scholarly journals Regulation of the Cell Cycle by Focal Adhesion Kinase

1998 ◽  
Vol 143 (7) ◽  
pp. 1997-2008 ◽  
Author(s):  
Ji-He Zhao ◽  
Heinz Reiske ◽  
Jun-Lin Guan
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Cell Cycle Regulation ◽  
Cell Cycle Progression ◽  
Dominant Negative ◽  
Brdu Incorporation ◽  
Dominant Negative Mutant ◽  
Wild Type ◽  
Erk Activation ◽  
Cycle Regulation

In this report, we have analyzed the potential role and mechanisms of integrin signaling through FAK in cell cycle regulation by using tetracycline-regulated expression of exogenous FAK and mutants. We have found that overexpression of wild-type FAK accelerated G1 to S phase transition. Conversely, overexpression of a dominant-negative FAK mutant ΔC14 inhibited cell cycle progression at G1 phase and this inhibition required the Y397 in ΔC14. Biochemical analyses indicated that FAK mutant ΔC14 was mislocalized and functioned as a dominant-negative mutant by competing with endogenous FAK in focal contacts for binding signaling molecules such as Src and Fyn, resulting in a decreases of Erk activation in cell adhesion. Consistent with this, we also observed inhibition of BrdU incorporation and Erk activation by FAK Y397F mutant and FRNK, but not FRNKΔC14, in transient transfection assays using primary human foreskin fibroblasts. Finally, we also found that ΔC14 blocked cyclin D1 upregulation and induced p21 expression, while wild-type FAK increased cyclin D1 expression and decreased p21 expression. Taken together, these results have identified FAK and its associated signaling pathways as a mediator of the cell cycle regulation by integrins.

scholarly journals Cell cycle regulation in Aspergillus by two protein kinases

1996 ◽  
Vol 317 (3) ◽  
pp. 633-641 ◽  
Author(s):  
Stephen A. OSMANI ◽  
Xiang S. YE
Keyword(s):  
Cell Cycle ◽  
Protein Kinases ◽  
Cell Cycle Regulation ◽  
Cell Cycle Progression ◽  
Human Cells ◽  
Dominant Negative ◽  
Cyclin B ◽  
Cyclin Dependent Kinases ◽  
Cycle Regulation ◽  
Mitotic Regulation

Great progress has recently been made in our understanding of the regulation of the eukaryotic cell cycle, and the central role of cyclin-dependent kinases is now clear. In Aspergillus nidulans it has been established that a second class of cell-cycle-regulated protein kinases, typified by NIMA (encoded by the nimA gene), is also required for cell cycle progression into mitosis. Indeed, both p34cdc2/cyclin B and NIMA have to be correctly activated before mitosis can be initiated in this species, and p34cdc2/cyclin B plays a role in the mitosis-specific activation of NIMA. In addition, both kinases have to be proteolytically destroyed before mitosis can be completed. NIMA-related kinases may also regulate the cell cycle in other eukaryotes, as expression of NIMA can promote mitotic events in yeast, frog or human cells. Moreover, dominant-negative versions of NIMA can adversely affect the progression of human cells into mitosis, as they do in A. nidulans. The ability of NIMA to influence mitotic regulation in human and frog cells strongly suggests the existence of a NIMA pathway of mitotic regulation in higher eukaryotes. A growing number of NIMA-related kinases have been isolated from organisms ranging from fungi to humans, and some of these kinases are also cell-cycle-regulated. How NIMA-related kinases and cyclin-dependent kinases act in concert to promote cell cycle transitions is just beginning to be understood. This understanding is the key to a full knowledge of cell cycle regulation.

PKC-δ-dependent activation of oxidative stress in adipocytes of obese and insulin-resistant mice: role for NADPH oxidase

2005 ◽  
Vol 288 (2) ◽  
pp. E405-E411 ◽  
Author(s):  
Ilana Talior ◽  
Tamar Tennenbaum ◽  
Toshio Kuroki ◽  
Hagit Eldar-Finkelman
Keyword(s):  
Oxidative Stress ◽  
Nadph Oxidase ◽  
Oxidase Inhibitor ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Ros Generation ◽  
Ros Production ◽  
Insulin Resistant ◽  
Glucose Depletion ◽  
Causative Factors

Oxidative stress is thought to be one of the causative factors contributing to insulin resistance and type 2 diabetes. Previously, we showed that reactive oxygen species (ROS) production is significantly increased in adipocytes from high-fat diet-induced obese and insulin-resistant mice (HF). ROS production was also associated with the increased activity of PKC-δ. In the present studies, we hypothesized that PKC-δ contributes to ROS generation and determined their intracellular source. NADPH oxidase inhibitor diphenyleneiodonium chloride (DPI) reduced ROS levels by 50% in HF adipocytes, and inhibitors of NO synthase (l-NAME, 1 mM), xanthine oxidase (allopurinol, 100 μM), AGE formation (aminoguanidine, 10 μM), or the mitochondrial uncoupler (FCCP, 10 μM) had no effect. Rottlerin, a selective PKC-δ inhibitor, suppressed ROS levels by ∼50%. However, neither GÖ-6976 nor LY-333531, effective inhibitors toward conventional PKC or PKC-β, respectively, significantly altered ROS levels in HF adipocytes. Subsequently, adenoviral-mediated expression of wild-type PKC-δ or its dominant negative mutant (DN-PKC-δ) in HF adipocytes resulted in either a twofold increase in ROS levels or their suppression by 20%, respectively. In addition, both ROS levels and PKC-δ activity were sharply reduced by glucose depletion. Taken together, these results suggest that PKC-δ is responsible for elevated intracellular ROS production in HF adipocytes, and this is mediated by high glucose and NADPH oxidase.

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