Effects of heat shock on change of HSC70/HSP68,acid and alkaline phosphatases before and after rat partial hepatectomy

INTRODUCTIONOnly the liver has the great capability ofregeneration in mammal.Few hepatocytes are inthe phase of division in the normal liver of an adultmammal (including human beings),but theremaining hepatocytes can be induced to proliferatequickly by partial hepatectomy (PH),and,to somedegree,they stop dividing and re-differentiate intocells functioning as hepatocytes.This shows

Synthesis of tanshinoneⅡA analogues and their inhibitory activities against Cdc25 phosphatases

Two series of tanshinone ⅡA derivatives were synthesized and evaluated for their antitumor activities as Cdc25 phosphatase inhibitors. Most of them demonstrated potent Cdc25 inhibitory activity and powerful cytotoxicity against A549 tumor cell line, producing IC50 values in very low micromolar range. At last, the preliminary SAR was discussed.

Protein phosphatases and chromatin modifying complexes in the inflammatory cascade in acute pancreatitis

Acute pancreatitis is an inflammation of the pancreas that may lead to systemic inflammatory response syndrome and death due to multiple organ failure. Acinar cells, together with leukocytes, trigger the inflammatory cascade in response to local damage of the pancreas. Amplification of the inflammatory cascade requires up-regulation of proinflammatory cytokines and this process is mediated not only by nuclear factor κB but also by chromatinmodifying complexes and chromatin remodeling. Among the different families of histone acetyltransferases, the p300/CBP family seems to be particularly associated with the inflammatory process. cAMP activates gene expression via the cAMP-responsive element (CRE) and the transcription factor CRE-binding protein (CREB). CREB can be phosphorylated and activated by different kinases, such as protein kinase A and MAPK, and then it recruits the histone acetyltransferase co-activator CREB-binding protein (CBP) and its homologue p300. The recruitment of CBP/p300 and changes in the level of histone acetylation are required for transcription activation. Transcriptional repression is also a dynamic and essential mechanism of down-regulation of genes for resolution of inflammation, which seems to be mediated mainly by protein phosphatases (PP1, PP2A and MKP1) and histone deacetylases(HDACs) .Class HDACs are key transcriptional regulators whose activities are controlled via phosphorylationdependent nucleo/cytoplasmic shuttling. PP2A is responsible for dephosphorylation of class HDACs, triggeringnuclear localization and repression of target genes, whereas phosphorylation triggers cytoplasmic localization leading to activation of target genes. The potential benefit from treatment with phosphodiesterase inhibitors and histone deacetylase inhibitors is discussed.

Counter-regulatory phosphatases TNAP and NPP1 temporally regulate tooth root cementogenesis

Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate （Pi） to mineral inhibitor pyrophosphate （PPi）, where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase （TNAP） and ectonucleotide pyrophosphatase/phosphodiesterase 1 （NPP1）. The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enppl null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enppl gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.

A description of alkaline phosphatases from marine organisms

Alkaline phosphatases(APs) are non-specifi c phosphohydrolases, and they are widely used in clinical diagnostics and biological studies. APs are widespread in nature and exhibit dif ferent structural formulations. Based on the diversity of biogenetic sources, APs exhibit temperature-propensity traits, and they are classifi ed as psychrophilic, mesophilic, and thermophilic. In this article, the characteristics of psychrophilic APs from marine organisms were described, accompanied by a simple description of APs from other organisms. This review will facilitate better utilization of marine APs in the biotechnology fi eld.

Metabolic regulation by protein tyrosine phosphatases

Obesity and the metabolic syndrome and their associated morbidities are major public health issues, whose prevalence will continue to increase in the foreseeable future. Aberrant signaling by the receptors for leptin and insulin plays a pivotal role in development of the metabolic syndrome. More complete molecular-level understanding of how both of these key signaling pathways are regulated is essential for full characterization of obesity, the metabolic syndrome, and type lI diabetes, and for developing novel treatments for these diseases. Phosphorylation of proteins on tyrosine residues plays a key role in mediating the effects of leptin and insulin on their target cells. Here, we discuss the molecular methods by which protein tyrosine phosphatases, which are key physiological regulators of protein phosphorylation in vivo, affect signaling by the leptin and insulin receptors in their major target tissues.

Mammalian-like Purple Acid Phosphatases in Plants

Introduction Purple acid phosphatases （PAPs） comprise of a family of binuclear metal-containing hydrolases, some members of which have been isolated and characterized from animal, plant and fungal sources . PAPs not only catalyze the hydrolyses of a wide range of phosphate esters and anhydrides under acidic reaction conditions, but also catalyze the generation of hydroxyl radicals in a Fenton-like reaction, by virtue of the presence of a redox-active binuclear metal center. Inmammals,

Functional repertoire of protein kinases and phosphatases in synaptic plasticity and associated neurological disorders

Protein phosphorylation and dephosphorylation are two essential and vital cellular mechanisms that regulate many receptors and enzymes through kinases and phosphatases.Ca^2+- dependent kinases and phosphatases are responsible for controlling neuronal processing;balance is achieved through opposition.During molecular mechanisms of learning and memory,kinases generally modulate positively while phosphatases modulate negatively.This review outlines some of the critical physiological and structural aspects of kinases and phosphatases involved in maintaining postsynaptic structural plasticity.It also explores the link between neuronal disorders and the deregulation of phosphatases and kinases.

Protein tyrosine phosphatases:emerging role in cancer therapy resistance

Background:Tyrosine phosphorylation of intracellular proteins is a posttranslational modification that plays a regulatory role in signal transduction during cellular events.Dephosphorylation of signal transduction proteins caused by protein tyrosine phosphatases(PTPs)contributed their role as a convergent node to mediate cross-talk between signaling pathways.In the context of cancer,PTP-mediated pathways have been identified as signaling hubs that enabled cancer cells to mitigate stress induced by clinical therapy.This is achieved by the promotion of constitutive activation of growth-stimulatory signaling pathways or modulation of the immune-suppressive tumor microenvironment.Preclinical evidences suggested that anticancer drugs will release their greatest therapeutic potency when combined with PTP inhibitors,reversing drug resistance that was responsible for clinical failures during cancer therapy.Areas covered:This review aimed to elaborate recent insights that supported the involvement of PTP-mediated pathways in the development of resistance to targeted therapy and immune-checkpoint therapy.Expert opinion:This review proposed the notion of PTP inhibition in anticancer combination therapy as a potential strategy in clinic to achieve long-term tumor regression.Ongoing clinical trials are currently underway to assess the safety and efficacy of combination therapy in advanced-stage tumors.

Recent progress on the structure of Ser/Thr protein phosphatases

PP1, PP2A and PP2B, belonging to the PPP family of Ser/Thr protein phosphatases, participate in regulating many important physiological processes, such as cell cycle control, regulation of cell growth and division regulation, etc. The sequence homology between them is relatively high, and ter- tiary structure is conserved. Because of the complexity of the structure of PP2A and the diversity of its regulatory subunits, its structure is less well known than those of PP1 and PP2B. The PP2A holoen- zyme consists of a heterodimeric core enzyme, comprising a scaffolding subunit and a catalytic sub- unit, as well as a variable regulatory subunit. In this study, the subunit compositions, similarities and differences between the Ser/Thr protein phsphatases structures are summarized.

Protein Tyrosine Phosphatases Mediate the Signaling Pathway of Stomatal Closure of Vicia faba L.

: The regulation of stomatal movement is one of the most important signaling networks in plants. The H+-ATPase at the plasma membrane of guard cells plays a critical role in the stomata opening, while there are some conflicting results regarding the effectiveness of the plasma membrane H+-ATPase inhibitor, vanadate, in inhibiting stomata opening. We observed that 2 mmol/L vanadate hardly inhibited light-stimulated stomata opening in epidermal peels of Vicia faba L., but significantly inhibited dark- and ABA-induced stomatal closure. These results cannot be explained with the previous findings that H+-ATPase was inhibited by vanadate. In view of the fact that vanadate is an inhibitor of protein tyrosine phosphatases (PTPases), we investigated whether the stomatal movement regulated by vanadate is through the regulation of PTPase. As expected, phenylarsine oxide (PAO), a specific inhibitor of PTPase, has very similar effects and even more effective than vanadate. Typical PTPase activity was found in guard cells of V. faba; moreover, the phosphatase activity could be inhibited by both vanadate and PAO. These results not only provide a novel explanation for conflicting results about vanadate modulating stomatal movement, but also provide further evidence for the involvement of PTPases in modulating signal transduction of stomatal movement.

Inhibiting SHP2 reduces glycolysis, promotes microglial M1 polarization, and alleviates secondary inflammation following spinal cord injury in a mouse model

Reducing the secondary inflammatory response, which is partly mediated by microglia, is a key focus in the treatment of spinal cord injury. Src homology 2-containing protein tyrosine phosphatase 2(SHP2), encoded by PTPN11, is widely expressed in the human body and plays a role in inflammation through various mechanisms. Therefore, SHP2 is considered a potential target for the treatment of inflammation-related diseases. However, its role in secondary inflammation after spinal cord injury remains unclear. In this study, SHP2 was found to be abundantly expressed in microglia at the site of spinal cord injury. Inhibition of SHP2 expression using siRNA and SHP2 inhibitors attenuated the microglial inflammatory response in an in vitro lipopolysaccharide-induced model of inflammation. Notably, after treatment with SHP2 inhibitors, mice with spinal cord injury exhibited significantly improved hind limb locomotor function and reduced residual urine volume in the bladder. Subsequent in vitro experiments showed that, in microglia stimulated with lipopolysaccharide, inhibiting SHP2 expression promoted M2 polarization and inhibited M1 polarization. Finally, a co-culture experiment was conducted to assess the effect of microglia treated with SHP2 inhibitors on neuronal cells. The results demonstrated that inflammatory factors produced by microglia promoted neuronal apoptosis, while inhibiting SHP2 expression mitigated these effects. Collectively, our findings suggest that SHP2 enhances secondary inflammation and neuronal damage subsequent to spinal cord injury by modulating microglial phenotype. Therefore, inhibiting SHP2 alleviates the inflammatory response in mice with spinal cord injury and promotes functional recovery postinjury.

Phosphatases of regenerating liver： a novel target in human solid tumors

Protein tyrosine phosphorylation is a major posttranslational modification used by cells to regulate signal transduction and essentially participate in every aspect of cellular physiologic and pathogenic processes. The protein tyrosine phosphatase （PTP） super family of enzymes coordinately function with protein tyrosine kinases in signaling pathways that underlie a broad spectrum of fundamental physiological processes. Abnormal regulation of tyrosine phosphorylation or deregulation of phosphorylation is known to result in neoplastic or non-neoplastic diseases. Having evolved into separate families that are structurally and mechanistically distinct, PTPs have been implicated in a variety of diseases and efforts have been made to seek therapeutic clues from them. The phosphatases of regenerating liver （PRL） PRL-1, PRL-2, PRL-3 （also known as PTP4A1, PTP4A2, and PTP4A3, respectively） constitute a subfamily of the protein tyrosine phosphatases that have been suggested to play a key role in oncogenic and metastatic phenotypes.5 Here we review what is known about this novel class of small, prenylated phosphatases and its value in diagnosis and therapy of solid tumors.

Inhibition of Model Compound of Purple Acid Phosphatases on Growth of Aerobacter aerogenes Investigated by Microcalorimetry

Microcalorimetry was used to study the inhibitory or antibiotic action of six kinds of the model compounds of purple acid phosphatases on a strain of Aerobacter aerogenes . Difference in their capacities to inhibit the metabolism of this bacterium was observed. The extent and duration of the inhibitory effect on the metabolism as judged from the growth rate constant, k , and the half inhibitory concentration, IC 50 , varied with the different drugs. The rate constant k of A. aerogenes (in the log phase) in the presence of the compounds decreased with the increasing of concentrations. The experimental results reveal that the order of the antibiotic activity of the compounds is: LD 1>LD 2>LD 3>XF 1>LD 4～LD 5.

RNAi screen to identify protein phosphatases that regulate the NF-kappaB signaling

NF-kappaB plays a critical role in cell survival,apoptosis,and inflammatory responses.Serine/threoninespecific phosphatases(PPs)represent the second major class of enzymes that catalyze the dephosphorylation of proteins.The roles of PPs regulating NF-kappaB activities are poorly understood.Here we describe an RNAi-based screen to identify the PPs that involve in regulating NFkappaB signaling.Thirty-four candidate PPs siRNAs were synthesized and primarily screened by NF-kappaB reporter gene assay in HeLa cells.PHLPP,one of the protein phosphatase type 2C family members(PP2C),was identified as a positive regulator of NF-kappaB signaling.Knock-down of PHLPP dramatically attenuated TNFα-stimulated NF-kappaB transcriptional activation.Knockdown of PHLPP led to enhancement of NF-kappaB/p65 nuclear import and retention,but decreased TNFα-induced phosphorylation at Ser276 on p65.This critical phosphorylation was also drastically reduced by knock-down of PKCalpha and Akt1,two important serine/threonine kinases dephosphorylated by PHLPP.The results together suggest that PHLPP-Akt-PKC may represent an important signaling loop that activates NF-kappaB/p65 signaling through critical serine phosphorylation.

Comparative genetic analysis of Arabidopsis purple acid phosphatases AtPAP10, AtPAP12, and AtPAP26 provides new insights into their roles in plant adaptation to phosphate deprivation

Induction and secretion of acid phosphatases （APases） is thought to be an adaptive mechanism that helps plants survive and grow under phosphate （Pi） deprivation, in Arabidopsis, there are 29 purple acid phosphatase （AtPAP） genes. To systematically investigate the roles of different AtPAPs, we first identified knockout or knock-down T-DNA lines for all 29 AtPAP genes. Using these atpap mutants combined with in-gel and quantitative APase enzyme assays, we demonstrated that AtPAP12 and AtPAP26 are two major intracellular and secreted APases in Arabidopsis while AtPAPlo is mainly a secreted APase. On Pi-deficient （P-） medium or P- medium supplemented with the organophosphates ADP and fructose-6-phosphate （Fru-6-P）, growth of atpaplo was significantly reduced whereas growth of atpap12 was only moderately reduced, and growth of atpap26 was nearly equal to that of the wild type （WT）. Overexpression of the AtPAP12 or AtPAP26 gene, however, caused plants to grow better on P- or P- medium supplemented with ADP or Fru-6-P. Interest-ingly, Pi levels are essentially the same for the WT and overexpressing lines, although these two types of plants have significantly different growth phenotypes. These results suggest that the APases may have other roles besides enhancing internal Pi recycling or releasing Pi from external organophosphates for plant uptake.

Trehalose-6-phosphate phosphatases are involved in trehalose synthesis and metamorphosis in Bactrocera minax

Trehalose is the principal sugar circulating in the hemolymph of insects,and trehalose synthesis is catalyzed by trehalose-6-phosphate synthase(TPS)and trehalose-6-phosphate phosphatase(TPP).Insect TPS is a fused enzyme containing both TPS do-main and TPP domain.Thus,many insects do not possess TPP genes as TPSs have re-placed the function of TPPs.However,TPPs are widely distributed across the dipteran insects,while the roles they play remain largely unknown.In this study,3 TPP genes from notorious dipteran pest Bactrocera minax(BmiTPPB,BmiTPPCl,and BmiTPPC2)were identified and characterized.The different temporal-spatial expression patterns of 3 BmiTPPs implied that they exert different functions in B.minax.Recombinant BmiTPPs were heterologously expressed in yeast cells,and all purified proteins exhibited enzy-matic activities,despite the remarkable disparity in performance between BmiTPPB and BmiTPPCs.RNA interference revealed that all BmiTPPs were successfully downregulated after double-stranded RNA injection,leading to decreased trehalose content and increased glucose content.Also,suppression of BmiTPPs significantly affected expression of down-stream genes and increased the mortality and malformation rate.Collectively,these results indicated that all 3 BmiTPPs in B.minax are involved in trehalose synthesis and metamor-phosis.Thus,these genes could be evaluated as insecticidal targets for managing B.minax,andevenforotherdipteranpests.

Two mitochondrial phosphatases,PP2c63 and Sal2,are required for posttranslational regulation of the TCA cycle in Arabidopsis

Protein phosphorylation is a well-established post-translational mechanism that regulates protein functions and metabolic pathways.It is known that several plant mitochondrial proteins are phosphorylated in a reversible manner.However,the identities of the protein kinases/phosphatases involved in this mech-anism and their roles in the regulation of the tricarboxylic acid(TCA)cycle remain unclear.In this study,we isolated and characterized plants lacking two mitochondrially targeted phosphatases(Sal2 and PP2c63)along with pyruvate dehydrogenase kinase(PDK),Protein-protein interaction analysis,quantitative phos-phoproteomics,and enzymatic analyses revealed that PDK specifically regulates pyruvate dehydrogenase complex(PDC),while PP2c63 nonspecifically regulates PDC.When recombinant PP2c63 and Sal2 proteins were added to mitochondria isolated from mutant plants,protein-protein interaction and enzymatic analyses showed that PP2c63 directly phosphorylates and modulates the activity of PDC,while Sal2 only indirectly affects TCA cycle enzymes.Characterization of steady-state metabolite levels and fluxes in the mutant lines further revealed that these phosphatases regulate flux through the TCA cycle,and that altered metabolism in the sa/2 pp2c63 double mutant compromises plant growth.These results are discussed in the context of current models of the control of respiration in plants.

Roles of protein tyrosine phosphatases in reproduction and related diseases

Protein tyrosine phosphatases(PTPs)remove phosphate groups from protein tyrosine residues to regulate various cell signaling processes,subsequently affecting the growth,metabolism,differentiation,immune response,and other cellular processes.Several studies have investigated the functions of PTPs in tumor and organism immunity.However,only a few studies have focused on their roles in reproductive disorders.Therefore,in this review,we summarize the roles and underlying molecular mechanisms of PTPs in infertility,spontaneous abortion,pregnancy-induced hypertension,gestational diabetes mellitus,early embryonic developmental abnormalities,and preterm birth.This review can contribute to future research on PTPs and their potential applications as targets in the treatment of reproductive diseases.

Hepatoprotective effects of Xiaoyao San formula on hepatic steatosis and inflammation via regulating the sex hormones metabolism

BACKGROUND The modified Xiaoyao San(MXS)formula is an adjuvant drug recommended by the National Health Commission of China for the treatment of liver cancer,which has the effect of preventing postoperative recurrence and metastasis of hepatocellular carcinoma and prolonging patient survival.However,the molecular mechanisms underlying that remain unclear.AIM To investigate the role and mechanisms of MXS in ameliorating hepatic injury,steatosis and inflammation.METHODS A choline-deficient/high-fat diet-induced rat nonalcoholic steatohepatitis(NASH)model was used to examine the effects of MXS on lipid accumulation in primary hepatocytes.Liver tissues were collected for western blotting and immunohisto chemistry(IHC)assays.Lipid accumulation and hepatic fibrosis were detected using oil red staining and Sirius red staining.The serum samples were collected for biochemical assays and NMR-based metabonomics analysis.The inflammation/lipid metabolism-related signaling and regulators in liver tissues were also detected to reveal the molecular mechanisms of MXS against NASH.RESULTS MXS showed a significant decrease in lipid accumulation and inflammatory response in hepatocytes under metabolic stress.The western blotting and IHC results indicated that MXS activated AMPK pathway but inhibited the expression of key regulators related to lipid accumulation,inflammation and hepatic fibrosis in the pathogenesis of NASH.The metabonomics analysis systemically indicated that the arachidonic acid metabolism and steroid hormone synthesis are the two main target metabolic pathways for MXS to ameliorate liver inflammation and hepatic steatosis.Mechanistically,we found that MXS protected against NASH by attenuating the sex hormone-related metabolism,especially the metabolism of male hormones.CONCLUSION MXS ameliorates inflammation and hepatic steatosis of NASH by inhibiting the metabolism of male hormones.Targeting male hormone related metabolic pathways may be the potential therapeutic approach for NASH.