Phosphoprotein Phosphatases ; Kinetics ; Protein Phosphatase 2/metabolism*

OBJECTIVETo determine whether the muscle-specific glycogen-targeting regulatory subunit of the glucogen bound protein phosphatase 1 (PPP1R3) gene 5 bp deletion/insertion(D/I) within 3'-untranslated region ( 3'-UTR) polymorphism is associated with type 2 diabetes in Chinese Han population in Hefei region of Anhui province.

METHODSThe PPP1R3 gene 3'-UTR 5 bp D/I polymorphism was detected by polymerase chain reaction in 268 patients with type 2 diabetes and 106 normal controls.

RESULTS(1) The distributions of the frequency of three genotypes and two alleles of the PPP1R3 gene 5 bp D/I polymorphism showed no significant difference between the type 2 diabetic cases and the normal controls. (2) In both the cases and controls, there was no significant difference in age at onset, duration of disease, blood glucose, blood lipid profile, blood pressure, insulin sensitive index, body mass index, and waist hip ratio between the three genotypic groups(P 0.05). (3) The PPP1R3 gene 3'-UTR polymorphism in Chinese Han population in Hefei region of Anhui province was found to be similar to that in both Japanese population and Canadian population, and to be different from that in Piman Indians and the Caucasians in Sweden.

CONCLUSIONThe PPP1R3 gene 5 bp D/I within 3'-UTR polymorphism taking on genetic variation among the different races of mankind may not play a critical role in the development of type 2 diabetes mellitus in Chinese Hans of Hefei region in Anhui province.

3' Flanking Region ; genetics ; Aged ; Alleles ; Diabetes Mellitus, Type 2 ; enzymology ; genetics ; pathology ; Female ; Gene Frequency ; Genotype ; Humans ; Male ; Middle Aged ; Mutagenesis, Insertional ; Phosphoprotein Phosphatases ; genetics ; Polymorphism, Genetic ; Protein Phosphatase 1 ; Sequence Deletion

OBJECTIVETo investigate the role of mitogen activated protein kinase phosphatase-1 (MKP-1) in mediating acquired multidrug resistance in pancreatic adenocarcinoma cell line SW1990/Fu.

METHODSTo detect MKP-1 mRNA expression, Northern blot analysis was carried out in well established drug resistant pancreatic adenocarcinoma cell line SW1990/Fu, SW1990 and MiaPaCa-2 cell lines. To further elucidate the exact role of MKP-1, Western blot hybridization was performed in these three cell lines.

RESULTSNorthern blot analysis of total RNA isolated from SW1990/Fu, SW1990 and MiaPaCa-2 cell lines revealed the presence of the 2400 bp MKP-1 transcript 7 at relatively high levels in pancreatic cancer cell lines SW1990 and MiaPaCa-2. In the SW1990/Fu, the MKP-1 transcript was detectable at very low level. Densitometric analysis with normalization to 7S indicated that MKP-1 mRNA expression level was significantly decreased in SW1990/Fu in comparison with the parental and MiaPaCa-2 cell lines. MKP-1 protein expression level in SW1990/Fu detected by Western blot was coincident with mRNA level.

CONCLUSIONSMKP-1 may be involved in acquired multidrug resistance in pancreatic adenocarcinoma, and we could hypothesized that alterations of intra-cellular transduction signal system acts as an important role in multidrug resistance of tumor cells.

Adenocarcinoma ; drug therapy ; enzymology ; pathology ; Blotting, Northern ; Blotting, Western ; Cell Cycle Proteins ; biosynthesis ; genetics ; physiology ; Cell Line, Tumor ; Down-Regulation ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Dual Specificity Phosphatase 1 ; Humans ; Immediate-Early Proteins ; biosynthesis ; genetics ; physiology ; Pancreatic Neoplasms ; drug therapy ; enzymology ; pathology ; Phosphoprotein Phosphatases ; biosynthesis ; genetics ; physiology ; Protein Phosphatase 1 ; Protein Tyrosine Phosphatases ; biosynthesis ; genetics ; physiology ; RNA, Messenger ; genetics

OBJECTIVETo study the association of muscle-specific glycogen-targeting regulatory subunit of the glucogen-bound protein phosphatase 1 (PPP1R3) gene codon 905 Asp/Tyr polymorphism with type 2 diabetes in Chinese Han population in Hefei region of Anhui province.

METHODSPPP1R3 gene Asp905Tyr polymorphism was detected by polymerase chain reaction and appropriate restriction enzyme (PCR-RFLP) in 262 type 2 diabetic cases and 104 normal controls. Case and control groups were divided into subgroups by body mass index (BMI) 25 kg/m2.

RESULTSWhen PPP1R3 gene Asp905Tyr polymorphism was not associated with type 2 diabetes mellitus. When subjects with BMI < 25 kg/m2 and Tyr/Tyr genotypes were used as reference. Subjects with Asp905 and BMI > or = 25 kg/m2 had a 3.69-fold increase of risk suffering from type 2 diabetes (OR = 3.69, 95% CI: 1.38-8.89, P=0.006).

CONCLUSIONSPPP1R3 gene Asp905Tyr polymorphism did not seem to play a critical role in the development of type 2 diabetes mellitus in Han population of Chinese in Anhui province but interaction between the Asp905 and BMI cause the increase of risk of type 2 diabetes.

Adult ; Alleles ; Aspartic Acid ; genetics ; China ; epidemiology ; ethnology ; Diabetes Mellitus, Type 2 ; epidemiology ; etiology ; genetics ; Female ; Gene Frequency ; Genotype ; Humans ; Male ; Middle Aged ; Obesity ; complications ; Phosphoprotein Phosphatases ; genetics ; Polymerase Chain Reaction ; Polymorphism, Genetic ; Polymorphism, Restriction Fragment Length ; Protein Phosphatase 1 ; Risk Factors ; Tyrosine ; genetics

OBJECTIVETo study the changes in expression and activity of protein phosphatases type 2A (PP2A ) during differentiation of NB4 and NB4-MR2 cells induced by all-trans retinoic acid (ATRA), and evaluate the role of PP2A in MR2 resistance to ATRA.

METHODSATRA, okadaic acid (OKA) and ATRA + OKA at the same dosage were incubated with NB4 and MR2 cells respectively. Wright's staining and NBT reduction test were employed to evaluate the change in the cells. The CD11b expression was measured by flow cytometry. The activity of PP2A was evaluated by serine/threonine phosphatase assay system, and the level of PP2A subunits was detected by Western blot.

RESULTS1) Wright's staining, NBT reduction test and flow cytometry results showed OKA could augment the differentiation of NB4 induced by ATRA, and OKA + ATRA induced slight differentiation of MR2 cells. 2) Phosphatase assay showed a decrease in PP2A phosphatase activity [(534 +/- 43) pmol x min(-1) x microg protein(-1)] in NB4 after ATRA treatment, accompanied with that activity [(959 +/- 83) pmol x min(-1) x microg protein(-1)] in untreated NB4 cells. OKA enhanced the inhibitory effect of ATRA on the activity in NB4. When OKA + ATRA was incubated with MR2, PP2A in the cells was significantly decreased [(229 +/- 23) pmol x min(-1) x microg protein(-1)]. 3) Western blot analysis showed that the level of PP2A catalytic subunit (PP2A/C) was decreased during the course of ATRA-induced NB4 cell differentiation, whereas expressions of every subunits of PP2A in MR2 cells were somewhat unaltered.

CONCLUSIONExpression of PP2A/C and activity of PP2A is decreased during differentiation of NB4 induced by ATRA, and no repression of the PP2 activity maybe related to MR2 resistance to ATRA.

Cell Differentiation ; drug effects ; Cell Line, Tumor ; Humans ; Leukemia, Promyelocytic, Acute ; metabolism ; pathology ; Okadaic Acid ; pharmacology ; Phosphoprotein Phosphatases ; metabolism ; Protein Phosphatase 2 ; antagonists & inhibitors ; metabolism ; Tretinoin ; pharmacology

Curcumin provides various biological effects through its anti-inflammatory and antioxidant properties. Moreover, curcumin exerts a neuroprotective effect against ischemic condition-induced brain damage. Protein phosphatase 2A (PP2A) is a ubiquitous serine and threonine phosphatase with various cell functions and broad substrate specificity. Especially PP2A subunit B plays an important role in nervous system. This study investigated whether curcumin regulates PP2A subunit B expression in focal cerebral ischemia. Cerebral ischemia was induced surgically by middle cerebral artery occlusion (MCAO). Adult male rats were injected with either vehicle or curcumin (50 mg/kg) 1 h after MCAO and cerebral cortex tissues were isolated 24 h after MCAO. A proteomics study, reverse transverse-PCR and Western blot analyses were performed to examine PP2A subunit B expression levels. We identified a reduction in PP2A subunit B expression in MCAO-operated animals using a proteomic approach. However, curcumin treatment prevented injury-induced reductions in PP2A subunit B levels. Reverse transverse-PCR and Western blot analyses confirmed that curcumin treatment attenuated the injury-induced reduction in PP2A subunit B levels. These findings can suggest that the possibility that curcumin maintains levels of PP2A subunit B in response to cerebral ischemia, which likely contributes to the neuroprotective function of curcumin in cerebral ischemic injury.
Adult ; Animals ; Blotting, Western ; Brain ; Brain Ischemia* ; Cerebral Cortex ; Curcumin* ; Humans ; Infarction, Middle Cerebral Artery ; Male ; Nervous System ; Neuroprotective Agents ; Phosphoprotein Phosphatases ; Protein Phosphatase 2* ; Proteomics ; Rats ; Rats, Sprague-Dawley* ; Serine ; Substrate Specificity

The most important molecular mechanisms of intraneuronal signal transduction are those mediated by calcium and reversible protein phosphorylation. Although many studies pursued the activation of the protein kinases in the nervous system, there are only few reports focused on the protein phosphatases. In this article, the authors report the effects of cyclosporin A (CSA), an inhibitor of calcineurin, on the calcium signaling-related molecules such as ERKs, calmodulin-dependent kinase II (CaMKII) and CREB in the rat hippocampus. The authors also report the effects of cyclosporin A on the electroconvulsive shock (ECS)-induced seizure and the activation of ERKs. Calcineurin is a protein phosphatase that is abundant in the brain and regulated by calcium and calmodulin. It is proposed that calcineurin plays central roles in the synaptic plasticity and neuronal apoptosis. CSA (50 mg/kg) increased the phosphorylation of ERK, CaMKII and CREB. The treatment of of CSA increased the duration of tonic phase of seizure induced by ECS and augmented the phosphorylation of ERKs after ECS. These results suggested the protective role of calcineurin against the excessive electrical and molecular activities in the brain.
Animals ; Apoptosis ; Brain* ; Calcineurin ; Calcium ; Calcium-Calmodulin-Dependent Protein Kinase Type 2 ; Calmodulin ; Cyclosporine* ; Electroshock ; Hippocampus ; Nervous System ; Neurons ; Phosphoprotein Phosphatases ; Phosphorylation ; Phosphotransferases ; Plastics ; Protein Kinases ; Rats* ; Seizures ; Signal Transduction*

Metastasis is one of hallmarks of cancer and a major cause of cancer death. Combatting metastasis is highly challenging. To overcome these difficulties, researchers have focused on physical properties of metastatic cancer cells. Metastatic cancer cells from patients are softer than benign cancer or normal cells. Changes of viscoelasticity of cancer cells are related to the keratin network. Unexpectedly, keratin network is dynamic and regulation of keratin network is important to the metastasis of cancer. Keratin is composed of heteropolymer of type I and II. Keratin connects from the plasma membrane to nucleus. Several proteins including kinases, and protein phosphatases bind to keratin intermediate filaments. Several endogenous compounds or toxic compounds induce phosphorylation and reorganization of keratin network in cancer cells, leading to increased migration. Continuous phosphorylation of keratin results in loss of keratin, which is one of the features of epithelial mesenchymal transition (EMT). Therefore, several proteins involved in phosphorylation and reorganization of keratin also have a role in EMT. It is likely that compounds controlling phosphorylation and reorganization of keratin are potential candidates for combating EMT and metastasis.
Carcinogenesis* ; Cell Membrane ; Epithelial-Mesenchymal Transition* ; Humans ; Intermediate Filaments ; Neoplasm Metastasis ; Phosphoprotein Phosphatases ; Phosphorylation* ; Phosphotransferases

OBJECTThe authors studied the influence of CO(2) pneumoperitoneum on intracellular pH and signal transduction arising from cancer cell multiplication in laparoscopic tumor operation.

METHODThey set up a simulation of pneumoperitoneum under different CO(2) pressure, and then measured the variation of intracellular pH (pHi) at different time and the activity of protein kinase C (PKC) and protein phosphatase 2a (PP2a) at the end of the pneumoperitoneum. After 1 week, the concentration of cancer cells in the culture medium was calculated.

RESULTWhen the pressure of CO(2) pneumoperitoneum was 0, 10, 20, 30 mmHg respectively, the average pHi was 7.273, 7.075, 6.783, 6.693 at the end of the pneumoperitoneum; PKC activity was 159.4, 168.5, 178.0, 181.6 nmol/(g.min) and PP2a was 4158.3, 4066.9, 3984.0, 3878.5 nmol/(g.min) respectively. After 1 week, the cancer cells concentration was 2.15 x 10(5), 2.03 x 10(5), 2.20 x 10(5), 2.18 x 10(5) L(-1).

CONCLUSIONCO(2) pneumoperitoneum could promote acidosis in cancer cells, inducing the activation of protein kinase C and deactivation of protein phosphatase 2a, but it could not accelerate the mitosis rate of the cancer cells.

Animals ; Breast Neoplasms ; chemistry ; metabolism ; Carbon Dioxide ; administration & dosage ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; Enzyme Activation ; drug effects ; Hydrogen-Ion Concentration ; Intracellular Fluid ; chemistry ; Phosphoprotein Phosphatases ; metabolism ; Pneumoperitoneum, Artificial ; methods ; Protein Kinase C ; metabolism ; Protein Phosphatase 2 ; Rats ; Signal Transduction ; drug effects

This study was aimed to investigate the effect of AG490, a JAK2 inhibitor, on expression of PHLPP and p-Akt in K562. K562 cells were treated with different concentrations of AG490. The proliferation of K562 cells was examined by WST-1 assay and apoptosis of K562 cells was detected by flow cytometry with Annexin V-FITC/PI double staining. The expressions of PHLPP, phosphorate-Akt (p-Akt) and total Akt protein were detected by Western blot. The results indicated that AG490 inhibited the proliferation of K562 cells in concentration-and time-dependent manners, with the IC(50) 338.0 µmol/L in 48 h. AG490 100 µmol/L also induced apoptosis of K562 cells in a time-dependent manner. AG490 100 µmol/L time-dependently down-regulated the protein expression of p-Akt and PHLPP, but without significant effect on expression of total Akt. It is concluded that AG490 can inhibit proliferation and induce apoptosis of K562 cells through down-regulation of p-Akt expression, but inhibiting efficacy of AG490 on K562 proliferation also may be limited due to the down-regulation of p-Akt regulatory protein PHLPP expression.
Cell Proliferation ; drug effects ; Down-Regulation ; Humans ; K562 Cells ; Nuclear Proteins ; metabolism ; Phosphoprotein Phosphatases ; metabolism ; Tyrphostins ; pharmacology