Positive and negative feedback loops in the p53 and mRNA 3′ processing pathways

Although the p53 network has been intensively studied, genetic analyses long hinted at the existence of components that remained elusive. Recent studies have shown regulation of p53 at the mRNA level mediated via both the 5′ and the 3′ untranslated regions and affecting the stability and translation efficiency of the p53 mRNA. Here, we provide evidence of a feedback loop between p53 and the poly(A)-specific ribonuclease (PARN), in which PARN deadenylase keeps p53 levels low in nonstress conditions by destabilizing p53 mRNA, and the UV-induced increase in p53 activates PARN deadenylase, regulating gene expression during DNA damage response in a transactivation-independent manner. This model is innovative because it provides insights into p53 function and the mechanisms behind the regulation of mRNA 3′ end processing in different cellular conditions.     

Expression of p53and C—myc genes and its clinical relevance in the hepatocellular carcinomatous and pericarcinomatous tissues

AIM：To investigate the possible roles of p53and C-myc genes in the primary hepatocellular carciogenesis and the relationship between the liver hyperplastic nodule(LHN)and hepatocellular carcinoma(HCC).METHODS:The expression of p53and C-myc genes was detcted immunohist-ochemically in 73and 60cases of HCCand pericarcinomatous tissues,respectively.RESULTS:The positive expression of p53in HCCwas significantly higher than that in pericarcinomatous tissues(P<0.050.In pericarcinomatous tissues,the p53 expression was observed onlyin LHN,but not in liver cirrhosis(LC)and normal liver tissues.The positive expression rate of C-myc in HCC or LHN was significantly higher than that in LCor normal liver tissues(P<0.05and P<0.01).however,no significant difference was found between HCCand LHN(P>0.05).The positive expression rate of p53and C-myc in HCCwas correlated with the histological differentiation,that in the poorly6 differentiated was significantly higher than that in well differentiated samples(P<0.05).CONCLUSION:The overexpression of p53and C-myc genes might play a orle in the carcinogenesis of HCC;And LHN seems a preneoplastic lesion related to hepatocarcinogenesis.No evidence supports that LC contribute directly to the hepatocarcinogenesis.     

Changes of p53 and Waf1p21 and cell proliferation in esophageal carcinogenesis

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Effects of 12-lipoxygenase and angiotensin Ⅱ on p21,p27 and p57 in rat diabetic glomeruli

正Objective To investigate the effects of 12-lipoxygenase(12-LO)and angiotensinⅡ(AngⅡ)on the CIP/KIP family of cyclin-dependent kinase inhibitors(CKIs)p21,p27 and p57 related to cell hypertrophy.Methods Mesangial cells were treated with high glucose for 24hours and 48 hours respectively.12(S)-hydroxyeicosa-     

telligible principle , interesting principle ,the p

长期以来,脑出血被公认为是死亡率和致残率很高的急性脑血管疾病,传统治疗手段及理论研究相对滞后,治疗效果也不尽人意[1],早期手术治疗仍然存在较大争议[2]。近年来,重组人活性凝血因子VII(rFVIIa)治疗急性期脑出血成为一个新的研究热点,各国学者围绕rFVIIa开展了一系列临床试验,以期望在传统的脑出血治疗上取得突破,试验结果令人鼓舞。rFVIIa的概述人凝血因子VII(FVII)是由肝脏合成的一种维生素K依赖的单链糖蛋白酶原,在体内作为外源性凝血途径的启动因子,发挥着重要的作用。正常人血浆中FVII的浓度很低。血管发生病变后,组织…     

Role of the p110δ PI 3-kinase in integrin and ITAM receptor signalling in platelets

We have investigated the function of the p110δ catalytic subunit of phosphoinositide 3-kinase (PI 3-kinase) in platelets using p110δ knock-out (p110δ^–/–) mice and p110δ knock-in (p110δ^D910A/D910A) mice, which express a catalytically inactive form of the enzyme. Aggregation to threshold concentrations of the GPVI-specific agonist, CRP, was partially reduced in p110δ^–/– and p110δ^D910A/D910A platelets. This inhibition was overcome by higher concentrations of CRP. The degree of inhibition was considerably weaker than that induced by LY294002 and wortmannin, which inhibit all isoforms of PI 3-kinase. p110δ^–/– platelets showed decreased spreading on fibrinogen- or von Willebrand factor (VWF)-coated surfaces under static conditions, whereas they spread normally on collagen. LY294002 had a more pronounced inhibitory effect on spreading on all three surfaces. Adhesion and aggregate formation of p110δ^–/– platelets to collagen or fibrinogen/VWF at intermediate/high rates of shear were normal. This study demonstrates a minor role for the p110δ catalytic subunit in mediating platelet activation by the collagen receptor GPVI and integrin αIIbβ3. The more pronounced inhibitory effect of LY294002 and wortmannin indicates that other isoforms of PI 3-kinase play a more significant role in signalling by the two platelet glycoprotein receptors.     

A preliminary study on the loss of heterozygosity at 17p13 in gastric and colorectal cancers

Ａｐｒｅｌｉｍｉｎａｒｙｓｔｕｄｙｏｎｔｈｅｌｏｓｓｏｆｈｅｔｅｒｏｚｙｇｏｓｉｔｙａｔ１７ｐ１３ｉｎｇａｓｔｒｉｃａｎｄｃｏｌｏｒｅｃｔａｌｃａｎｃｅｒｓＷＵＧｕｏＪｕｎ１，ＳＨＡＮＸｉａｎｇＮｉａｎ２，ＬＩＭｉｎｇＦａ２，ＳＨＩＳｈａｏＬ...     

Expression of p21~(WAF1) and p53 and polymorphism of p21~(WAF1) gene in gastric carcinoma

AIM:To investigate the relationship between expressionof p21~(WAF1) and p53 gene,and to evaluate the deletion andpolymorphism of p21~(WAF1) gene in gastric carcinoma (GC).METHODS:Expression of p21 and p53 proteins,anddeletion and polymorphism of p21 gene in GC wereexamined by streptavidin-peroxidase conjugated method(SP) and polymerase chain reaction-restriction fragmentlength polymorphism (PCR-RFLP) respectively.RESULTS:The expression of p21 and p53 was found in100% (20/20) and 0% (0/20) of normal gastric mucosae(NGM),92.5% (37/40) and 15.0% (6/40) of dysplasia (DP)and 39.8% (43/108) and 56.5% (61/108) of GC,respectively.The positive rate of p21 in GC was lower than that in NGMand DP (P<0.05),while the positive rate of p53 in GC washigher than that in NGM end DP (P<0.05).p21 and p53were significantly expressed in 63.3% (19/30) and 36.7%(11/30),35.0% (14/40) and 77.5% (31/40),26.7% (4/15)and 80.0% (12/15),30.8% (4/13) and 30.8% (4/13),and20.0% (2/10) and 30.0%,(3/10) of well-differentiated,poorly-differentiated,undifferentiated carcinomas,mucoidcarcinomas and signet ring cell carcinomas.The expressionof p21 in well-differentiated carcinomas was significantlyhigher than that in poorly-differentiated,un-differentiated,mucoid carcinomas and signet ring cell carcinomas (P<0.05).Contrarily,The expression of p53 was increased from well-differentiated to poorly-differentiated and un-differentiatedcarcinomas (P<0.05).The expression of p21 and p53 inpaired primary and metastatic GC (35.3% and 70.6%) wasdifferent from non-metastatic GC (62.5% and 42.5%)markedly (P<0.05).The expression of p21 in invasivesuperficial muscle (60.0%) was higher than that in invasivedeep muscle or total layer (35.2%) (P<0.05) and was higherin TNM stages Ⅰ (60.0%) and Ⅱ (56.2%) than in stages Ⅲ(27.9%) and Ⅳ (22.2%) (P<0.05),whereas the expressionof p53 did not correlate to invasion depth or TNM staging(P>0.05).The exoression patterns of p53 /p21-,and ofp53-/p21 were found in 5.0% and 82.5% of DP.Therewas a significant correlation between expression of p21and p53 (P<0.05).But there was no significant correlationbetween expression of both in GC (P>0.05).There was nodeletion in exon 2 of p21 gene in 30 cases of GC and 45cases of non-GC,but polymorphism of p21 gene at exon 2was found in 26.7% (8/30) of GC and 8.9% (4/45) of non- GC,a significant difference was found between GC andnon-GC (P<0.05).There was no significant relationbetween p21 expression of polymorphism (37.5%,3/8)and non-polymorphism (45.5%,10/22) in GC (P>0.05).CONCLUSION:The loss of p21 protein and abnormalexpression of p53 are related to carcinogenesis,differentiationand metastasis of GC.The expression of p21 is related toinvasion and clinical staging in GC intimately.Theexpression of p21 protein depends on p53 protein largelyin NGM and DP,but not in GC.No deletion of p21 gene inexon 2 can be found in GC.The polymorphism of p21 genemight be involved in gastric carcinogenesis.There is nosignificant association between polymorphism of p21 geneand expression of p21 protein.     

Genetic disruption of the PI3K regulatory subunits, p85α, p55α, and p50α, normalizes mutant PTPN11-induced hypersensitivity to GM-CSF

Juvenile myelomonocytic leukemia is a lethal disease of children characterized by hypersensitivity of hematopoietic progenitors to granulocyte macrophage-colony stimulating factor. Mutations in PTPN11, the gene encoding the protein tyrosine phosphatase Shp2, are common in juvenile myelomonocytic leukemia and induce hyperactivation of the phosphoinositide-3-kinase pathway. We found that genetic disruption of Pik3r1, the gene encoding the Class IA phosphoinositide-3-kinase regulatory subunits p85α, p55α and p50α, significantly reduced hyperproliferation and hyperphosphorylation of Akt in gain-of-function Shp2 E76K-expressing cells. Elevated protein levels of the phosphoinositide-3-kinase catalytic subunit, p110δ, in the Shp2 E76K-expressing Pik3r1-/- cells suggest that p110δ may be a crucial mediator of mutant Shp2-induced phosphoinositide-3-kinase hyperactivation. Consistently, treatment with the p110δ-specific inhibitor, IC87114, or the clinical grade pan-phosphoinositide-3-kinase inhibitor, GDC-0941, reduced granulocyte macrophage-colony stimulating factor hypersensitivity. Treatment with the farnesyltransferase inhibitor, tipifarnib, showed that Shp2 E76K induces hyperactivation of phosphoinositide-3-kinase by both Ras-dependent and Ras-independent mechanisms. Collectively, these findings implicate Class IA phosphoinositide-3-kinase as a relevant molecular target in juvenile myelomonocytic leukemia.     

Iron deficiency activates pro-inflammatory signaling in macrophages and foam cells via the p38 MAPK-NF-κB pathway

Background/objectives

Major bleeding in patients with acute coronary syndrome (ACS) increases the risk of recurrent ACS and mortality. However, the mechanism involved is poorly understood. Bleeding induces iron deficiency. Iron deficiency enhances inflammation in other diseases. Thus, in this paper, the particular effect of iron deficiency on atherosclerotic plaque destabilization, especially the pro-inflammatory role of iron deficiency in atheroma and the mechanism involved were investigated.

Methods

Extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase-9 (MMP-9) mRNA levels were investigated by RT-PCR. EMMPRIN and MMP-9 protein levels, nuclear factor (NF)-κB-p65 protein levels, peroxisome proliferator-activated receptor γ (PPARγ) protein levels, and mitogen-activated protein kinase (MAPK) phosphorylation were determined by western blotting. MMP-9 enzymatic activity was assayed by gelatin zymography.

Results

Iron deficiency enhanced EMMPRIN, MMP-9 production, and MMP-9 enzymatic activity in THP-1 derived macrophages and foam cells. Iron deficiency elicited the activation of NF-κB and p38 MAPK. By using the p38 inhibitor and NF-κB inhibitor, the study established that EMMPRIN and MMP-9 inductions by iron deficiency required the consecutive upstream activation of p38 MAPK and NF-κB. This pro-inflammatory action was not prevented by PPARγ agonist. Meanwhile, iron deficiency did not modulate PPARγ expression. Retinoid X receptor agonist suppressed the effects of iron deficiency on EMMPRIN , MMP-9, and NF-κB, but not on MAPK activation.

Conclusions

Iron deficiency enhances atheroma inflammation through p38 MAPK-NF-κB-EMMPRIN/MMP-9 pathway. Our findings provide a potential mechanism for the association of major bleeding with recurrent ACS and mortality in patients with ACS.     

Interplay between FAK, PKCδ, and p190RhoGAP in the regulation of endothelial barrier function

Disruption of either intercellular or extracellular junctions involved in maintaining endothelial barrier function can result in increased endothelial permeability. Increased endothelial permeability, in turn, allows for the unregulated movement of fluid and solutes out of the vasculature and into the surrounding connective tissue, contributing to a number of disease states, including stroke and pulmonary edema (Ermert et al., 1995; Lee and Slutsky, 2010; van Hinsbergh, 1997; Waller et al., 1996; Warboys et al., 2010). Thus, a better understanding of the molecular mechanisms by which endothelial cell junction integrity is controlled is necessary for development of therapies aimed at treating such conditions. In this review, we will discuss the functions of three signaling molecules known to be involved in regulation of endothelial permeability: focal adhesion kinase (FAK), protein kinase C delta (PKCδ), and p190RhoGAP (p190). We will discuss the independent functions of each protein, as well as the interplay that exists between them and the effects of such interactions on endothelial function.