High expression of MYH9 inhibits apoptosis of non-small cell lung cancer cells through activating the AKT/c-Myc pathway / 南方医科大学学报

OBJECTIVE@#To investigate the role of myosin heavy chain 9 (MYH9) in regulation of cell proliferation, apoptosis, and cisplatin sensitivity of non-small cell lung cancer (NSCLC).@*METHODS@#Six NSCLC cell lines (A549, H1299, H1975, SPCA1, H322, and H460) and a normal bronchial epithelial cell line (16HBE) were examined for MYH9 expression using Western blotting. Immunohistochemical staining was used to detect MYH9 expression in a tissue microarray containing 49 NSCLC and 43 adjacent tissue specimens. MYH9 knockout cell models were established in H1299 and H1975 cells using CRISPR/Cas9 technology, and the changes in cell proliferation cell were assessed using cell counting kit-8 (CCK8) and clone formation assays; Western blotting and flow cytometry were used to detect apoptosis of the cell models, and cisplatin sensitivity of the cells was evaluated using IC50 assay. The growth of tumor xenografts derived from NSCLC with or without MYH9 knockout was observed in nude mice.@*RESULTS@#MYH9 expression was significantly upregulated in NSCLC (P < 0.001), and the patients with high MYH9 expression had a significantly shorter survival time (P=0.023). In cultured NSCLC cells, MYH9 knockout obviously inhibited cell proliferation (P < 0.001), promoted cell apoptosis (P < 0.05), and increased their chemosensitivity of cisplatin. In the tumor-bearing mouse models, the NSCLC cells with MYH9 knockout showed a significantly lower growth rate (P < 0.05). Western blotting showed that MYH9 knockout inactivated the AKT/c- Myc axis (P < 0.05) to inhibit the expression of BCL2- like protein 1 (P < 0.05), promoted the expression of BH3- interacting domain death agonist and the apoptosis regulator BAX (P < 0.05), and activated apoptosis-related proteins caspase-3 and caspase-9 (P < 0.05).@*CONCLUSION@#High expression of MYH9 contributes to NSCLC progression by inhibiting cell apoptosis via activating the AKT/c-Myc axis.

Whole-transcriptome sequencing analysis of placental differential miRNA expression profile in Down syndrome / 南方医科大学学报

OBJECTIVE@#To identify new biomarkers and molecular pathogenesis of Down syndrome (DS) by analyzing differentially expressed miRNAs in the placentas and their biological pathways.@*METHODS@#Whole transcriptome sequencing was used to identify the differentially expressed miRNAs in DS (n=3) and normal placental samples (n=3) diagnosed by prenatal diagnosis. The target genes were predicted using miRWalk, Targetscan and miRDB, and GO and KEGG pathway analyses were performed for gene enrichment studies.@*RESULTS@#We identified a total of 82 differentially expressed miRNAs in the placental tissues of DS, including 29 up-regulated miRNAs (fold change ≥2, P < 0.05) and 15 down-regulated miRNAs (fold change ≥2, P < 0.05), among which 10 miRNAs with relatively high expression abundance were selected for further analysis, including 4 up-regulated and 6 down-regulated miRNAs. These selected miRNAs shared the common target genes BTBD3 and AUTS2, both of which were associated with neurodevelopment. GO analysis showed that the target genes of the selected miRNAs were mainly enriched in protein binding, hydrolytic enzymes, metal ion binding protein combining, transferase activity, nucleotide, cytoplasmic constituents, nucleus composition, transcriptional regulation, RNA metabolism regulation, DNA-dependent RNA polymerase Ⅱ promoter transcriptional regulation, eye development, and sensory organ development. KEGG enrichment analysis showed that the target genes of these differentially expressed miRNAs were involved in the signaling pathways including tumor-related signaling pathway, PI3K-Akt signaling pathway, Ras signaling pathway, Rap1 signaling pathway, cytoskeletal regulatory signaling pathway, purine metabolization-related signaling pathway and P53 signaling pathway.@*CONCLUSION@#The differentially expressed miRNAs may play important roles in placental damage and pregnancy pathology in DS and provide clues for the prevention and treatment of mental retardation-related diseases.

Kindlin-2 loss in condylar chondrocytes causes spontaneous osteoarthritic lesions in the temporomandibular joint in mice / 国际口腔科学杂志·英文版

The progressive destruction of condylar cartilage is a hallmark of the temporomandibular joint (TMJ) osteoarthritis (OA); however, its mechanism is incompletely understood. Here, we show that Kindlin-2, a key focal adhesion protein, is strongly detected in cells of mandibular condylar cartilage in mice. We find that genetic ablation of Kindlin-2 in aggrecan-expressing condylar chondrocytes induces multiple spontaneous osteoarthritic lesions, including progressive cartilage loss and deformation, surface fissures, and ectopic cartilage and bone formation in TMJ. Kindlin-2 loss significantly downregulates the expression of aggrecan, Col2a1 and Proteoglycan 4 (Prg4), all anabolic extracellular matrix proteins, and promotes catabolic metabolism in TMJ cartilage by inducing expression of Runx2 and Mmp13 in condylar chondrocytes. Kindlin-2 loss decreases TMJ chondrocyte proliferation in condylar cartilages. Furthermore, Kindlin-2 loss promotes the release of cytochrome c as well as caspase 3 activation, and accelerates chondrocyte apoptosis in vitro and TMJ. Collectively, these findings reveal a crucial role of Kindlin-2 in condylar chondrocytes to maintain TMJ homeostasis.

The mechanism of enriched environment repairing the learning and memory impairment in offspring of prenatal stress by regulating the expression of activity-regulated cytoskeletal-associated and insulin-like growth factor-2 in hippocampus

BACKGROUND@#Prenatal stress can cause neurobiological and behavioral defects in offspring; environmental factors play a crucial role in regulating the development of brain and behavioral; this study was designed to test and verify whether an enriched environment can repair learning and memory impairment in offspring rats induced by prenatal stress and to explore its mechanism involving the expression of insulin-like growth factor-2 (IGF-2) and activity-regulated cytoskeletal-associated protein (Arc) in the hippocampus of the offspring.@*METHODS@#Rats were selected to establish a chronic unpredictable mild stress (CUMS) model during pregnancy. Offspring were weaned on 21st day and housed under either standard or an enriched environment. The learning and memory ability were tested using Morris water maze and Y-maze. The expression of IGF-2 and Arc mRNA and protein were respectively measured by using RT-PCR and Western blotting.@*RESULTS@#There was an elevation in the plasma corticosterone level of rat model of maternal chronic stress during pregnancy. Maternal stress's offspring exposed to an enriched environment could decrease their plasma corticosterone level and improve their weight. The offspring of maternal stress during pregnancy exhibited abnormalities in Morris water maze and Y-maze, which were improved in an enriched environment. The expression of IGF-2, Arc mRNA, and protein in offspring of maternal stress during pregnancy was boosted and some relationships existed between these parameters after being exposed enriched environment.@*CONCLUSIONS@#The learning and memory impairment in offspring of prenatal stress can be rectified by the enriched environment, the mechanism of which is related to the decreasing plasma corticosterone and increasing hippocampal IGF-2 and Arc of offspring rats following maternal chronic stress during pregnancy.

Ezrin Promotes the Proliferation, Migration, and Invasion of Ovarian Cancer Cells / 生物医学与环境科学（英文）

Objective@#The underlying mechanism of Ezrin in ovarian cancer (OVCA) is far from being understood. Therefore, this study aimed to assess the role of Ezrin in OVCA cells (SKOV3 and CaOV3) and investigate the associated molecular mechanisms.@*Methods@#We performed Western blotting, reverse transcription-quantitative polymerase chain reaction, MTT, cell colony, cell wound healing, transwell migration and invasion, RhoA and Rac active pull down assays, and confocal immunofluorescence experiments to evaluate the functions and molecular mechanisms of Ezrin overexpression or knockdown in the proliferation and metastasis of OVCA cells.@*Results@#The ectopic expression of Ezrin significantly increased cell proliferation, invasiveness, and epithelial-mesenchymal transition (EMT) in OVCA cells. By contrast, the knockdown of endogenous Ezrin prevented OVCA cell proliferation, invasiveness, and EMT. Lastly, we observed that Ezrin can positively regulate the active forms of RhoA rather than Rac-1 in OVCA cells, thereby promoting robust stress fiber formation.@*Conclusion@#Our results indicated that Ezrin regulates OVCA cell proliferation and invasiveness by modulating EMT and induces actin stress fiber formation by regulating Rho-GTPase activity, which provides novel insights into the treatment of the OVCA.

Cardiac protein expression patterns are associated with distinct inborn exercise capacity in non-selectively bred rats

In the present study, we successfully demonstrated for the first time the existence of cardiac proteomic differences between non-selectively bred rats with distinct intrinsic exercise capacities. A proteomic approach based on two-dimensional gel electrophoresis coupled to mass spectrometry was used to study the left ventricle (LV) tissue proteome of rats with distinct intrinsic exercise capacity. Low running performance (LRP) and high running performance (HRP) rats were categorized by a treadmill exercise test, according to distance run to exhaustion. The running capacity of HRPs was 3.5-fold greater than LRPs. Protein profiling revealed 29 differences between HRP and LRP rats (15 proteins were identified). We detected alterations in components involved in metabolism, antioxidant and stress response, microfibrillar and cytoskeletal proteins. Contractile proteins were upregulated in the LVs of HRP rats (α-myosin heavy chain-6, myosin light chain-1 and creatine kinase), whereas the LVs of LRP rats exhibited upregulation in proteins associated with stress response (aldehyde dehydrogenase 2, α-crystallin B chain and HSPβ-2). In addition, the cytoskeletal proteins desmin and α-actin were upregulated in LRPs. Taken together, our results suggest that the increased contractile protein levels in HRP rats partly accounted for their improved exercise capacity, and that proteins considered risk factors to the development of cardiovascular disease were expressed in higher amounts in LRP animals.

Overexpression of ezrin and galectin-3 as predictors of poor prognosis of cervical cancer

The aim of this study was to explore the correlation of ezrin and galectin-3 expressions with prognosis in cervical cancer. The immunohistochemical method was applied to detect ezrin and galectin-3 expressions in normal cervix tissues (n=30), cervicitis tissues (n=28), cervical intraepithelial neoplasia (CIN) tissues (classified as I-III, n=89), and cervical carcinoma tissues (n=84). Follow-up was conducted for 5 to 78 months to analyze the correlation of protein expressions with prognosis. Ezrin and galectin-3 expressions in cervical cancer were significantly higher than in normal cervix, cervicitis and CIN (all P<0.05), and expressions in CIN were significantly higher than in normal cervix and cervicitis (both P<0.05). The expressions of ezrin and galectin-3 were both related with histological grade, deep myometrial invasion and lymph node metastasis (all P<0.05). Spearman analysis showed that ezrin expression was positively correlated with galectin-3 expression in cervical cancer (r=0.355, P<0.05). The survival rate of patients with high expressions of ezrin and galectin-3 was significantly lower than those with low expressions of proteins (both P<0.05). The expressions of ezrin and galectin-3, histological grade, depth of stromal invasion, and lymph node metastasis are risk factors affecting the survival rate of patients with cervical cancer. The expressions of ezrin and galectin-3 were correlated with the development of cervical cancer, and overexpressions of those proteins were indicative of poor prognosis in patients with cervical cancer.

Proteomics Analysis for Helicobacter pylori-infected Gastric Mucosa / 대한소화기학회지

BACKGROUND/AIMS: Helicobacter pylori infection is linked to the development of gastric cancer. H. pylori-associated gastric inflammation is considered to be the first important step in the histogenesis of such neoplasia. However, studies that compare proteome of gastric mucosa infected with or without H. pylori are lacking. METHODS: We employed proteomics analysis on the endoscopic biopsy specimens of gastric mucosa obtained from two groups (30 cases): healthy subjects without H. pylori infection (15 cases), and gastritis patients with H. pylori infection (15 cases). The pooled proteins obtained from gastric mucosa infected with or without H. pylori were separated by two-dimensional gel electrophoresis and analyzed by a computer-aided program. The altered protein expressions were then identified by mass spectrometry and validated by Western blotting and immunohistochemistry. RESULTS: On mass spectrometry using MALDI TOF(TM) Analyzer, the up-regulation of Keratin 1, ezrin, adenosine triphosphate (ATP) synthase subunit alpha mitochondrial isoform c, Keratin type I cytoskeletal 19, and Keratin type I cytoskeletal 9 were identified; in contrast, 71 kd heat shock cognate protein, ATP synthase subunit alpha mitochondrial precursor, and annexin IV were down-regulated. Among them, membrane cytoskeleton linker ezrin was validated using Western blot and immunohistochemistry. CONCLUSIONS: Expression of ezrin was significantly different between the gastric mucosa with and without H. pylori infection. Therefore, ezrin could be considered a promising potential molecular marker for detecting H. pylori infection in gastric mucosa.

Screening of natural phenolic compounds for potential to inhibit bacterial cell division protein FtsZ.

FtsZ plays an important role in bacterial cell division by polymerizing to form the Z ring at the site of cytokinesis. Phytochemicals are known to disrupt bacterial cell division through inhibition of FtsZ assembly. In the present study phytochemicals like eugenol, trans-cinnamic acid, 4-formyl cinnamic acid, naringenin and caffeic acid were were tested for their potential to inhibit cell division. Effect of these antimicrobial compounds on the growth of E. coli was determined and the inhibition of FtsZ assembly in vitro was investigated. The present study revealed trans-cinnamic acid as the most potent inhibitor of FtsZ assembly.

TGF-beta1-induced PINCH-1-ILK-alpha-parvin complex formation regulates mesangial cell proliferation and hypertrophy

TGF-beta1-induced glomerular mesangial cell (GMC) injury is a prominent characteristic of renal pathology in several kidney diseases, and a ternary protein complex consisting of PINCH-1, integrin-linked kinase (ILK) and alpha-parvin plays a pivotal role in the regulation of cell behavior such as cell proliferation and hypertrophy. We report here that PINCH-1-ILK-alpha-parvin (PIP) complex regulates the TGF-beta1-induced cell proliferation and hypertrophy in cultured rat GMCs. When GMCs were treated with TGF-beta1 for 1, 2 and 3 days, the PIP complex formation was up-regulated after 1 day, but it was down-regulated on day 2. Cell numbers were significantly elevated on day 2, but dramatically decreased on day 3. In contrast, a significant increase in cellular protein contents was observed 3 days after TGF-beta1-treatment. TGF-beta1 induced early increase of caspase-3 activity. In GMCs incubated with TGF-beta1 for 2 days, cytosolic expression of p27(Kip1) was dramatically reduced, but its nuclear expression was remarkably elevated. A significantly decreased expression of phospho-Akt (Ser 473) was observed in the cells treated with TGF-beta1 for 1 day. TGF-beta1 induced early increase of phospho-p27(Kip1) (Thr 157) expression with subsequent decrease, and similar responses to TGF-beta1 were observed in the p38 phosphorylation (Thr 180/Thr 182). Taken together, TGF-beta1 differently regulates the PIP complex formation of GMCs in an incubation period-dependant fashion. The TGF-beta1-induced up- and down-regulation of the PIP complex formation likely contributes to the pleiotropic effects of TGF-beta1 on mesangial cell proliferation and hypertrophy through cellular localization of p27(Kip1) and alteration of Akt and p38 phosphorylation. TGF-beta1-induced alteration of the PIP complex formation may be importantly implicated in the development and progression of glomerular failure shown in several kidney diseases.

beta PAK-interacting exchange factor may regulate actin cytoskeleton through interaction with actin

p21-activated kinase (PAK)-interacting exchange factor (PIX) is known to be involved in regulation of Cdc42/Rac GTPases and PAK activity. PIX binds to the proline-rich region of PAK, and regulates biological events through activation of Cdc42/Rac GTPase. To further investigate the role of PIX we produced monoclonal antibodies (Mab) against beta PAK. Three clones; N-C6 against N-terminal half and C-A3 and C-B7 against C- terminal half of beta PAK were generated and characterized. N-C6 Mab detected beta PAK as a major band in most cell lines. C-A3 Mab recognizes GIT-binding domain (GBD), but it does not interfere with GIT binding to beta PAK. Using C-A3 Mab possible beta PAK interaction with actin in PC12 cells was examined. beta PAK Mab (C-A3) specifically precipitated actin of the PC12 cell lysates whereas actin Mab failed to immunoprecpitate beta PAK. Co-sedimentation of PC12 cell lysates with the polymerized F-actin resulted in the recovery of most of beta PAK in the cell lysates. These results suggest that beta PAK may not interact with soluble actin but with polymerized F-actin and revealed that beta PAK constitutes a functional complex with actin. These data indicate real usefulness of the beta PAK Mab in the study of beta PAK role(s) in regulation of actin cyoskeleton.

Expression of Beta-catenin and E-cadherin in Early Gastric Cancer: Correlation with Clinicopathologic Parameters / 대한소화기학회지

BACKGROUND/AIMS: Beta-catenin is known to perform two unrelated functions in cadherin-mediated cell to cell adhesion system and Wnt pathway. Recent studies reported cytoplasmic and nuclear accumulation of beta-catenin by Wnt signaling and/or abnormal Wnt pathway in cancer cells. Nuclear accumulations of beta-catenin have a crucial role in early tumor growth and initiation of invasive growth in gastric cancer. METHODS: We carried out clinicopathological and immunohistochemical studies for beta-catenin, p53, E-cadherin, and Ki-67 in the specimens from 60 early gastric cancer patients who were treated with curative resections. RESULTS: Twenty-five (41.7%) and twenty-nine (48.3%) cases showed a nuclear and cytoplasmic expression of beta-catenin, respectively. There were significant correlations between nuclear expression of beta-catenin and well-differentiated and intestinal type of early gastric carcinoma. Cytoplasmic expression of beta-catenin had significant correlations with nuclear expression of beta-catenin (p=0.011). CONCLUSIONS: Nuclear expression of beta-catenin is significantly influenced by histological grade, Lauren classification and cytoplasmic expression of beta-catenin in early gastric cancer. These findings suggest that nuclear expression of beta-catenin is correlated with early tumorigenesis and initiation of invasive growth in gastric cancer.

Gene Expression Profiling of Breast Cancers with Emphasis of beta-Catenin Regulation

To gain molecular understanding of carcinogenesis of breast cancer, gene expression profiles were analyzed using cDNA microarray representing 4,600 cDNAs in 10 breast cancer samples and the adjacent noncancerous breast tissues from the same patients. The alterations in gene expression levels were confirmed by reversetranscription PCR in four randomly selected genes. Genes that were differently expressed in cancer and noncancerous tissues were identified. 106 (of which 55 were known) and 49 (of which 28 were known) genes were up- or down-regulated, respectively, in greater than 60% of the breast cancer samples. In cancer tissues, genes related to cell cycle, transcription, metabolism, cell structure/motility and signal transduction were mostly up-regulated. Furthermore, three cancer tissues showing immunohistochemically aberrant accumulation of beta-catenin in the nucleus and/or cytoplasm revealed down-regulation of Siah and Axin genes and up-regulation of Wnt and c-myc genes. These findings were highly consistent with Wnt signaling pathway associated with beta-catenin regulation previously suggested by others. Our studies, therefore, provide not only a molecular basis to understand biological processes of breast cancer but also useful resources to define the mechanism of beta-catenin expression in tumorigenesis of breast cancer.

Expression of beta-catenin in Hepatocellular Carcinoma in Relation to Tumor Cell Proliferation and Cyclin D1 Expression

Alteration of beta-catenin expression has been implicated in the development of hepatocellular carcinoma (HCC). It has been also reported that beta-catenin can influence the tumor cell proliferation or cyclin D1 expression, one of the target factors of beta-catenin. We performed an immunohistochemical analysis of beta-catenin and cyclin D1 in 77 patients with resected HCCs, and examined the relationships between the expressions of beta-catenin and cyclin D1, and other pathologic parameters including the mitotic index. Altered expressions of beta-catenin including nonnuclear overexpression and nuclear expression were detected in 58.4% of HCCs (45/77) and showed significant correlations with large tumor size, poor histologic grade, and high tumor stage. The mean mitotic index of HCCs with nuclear expression (3.2 +/- 3.0) and nonnuclear overexpression (2.7 +/- 2.5) was significantly higher than that of tumors with no overexpression (1.7 +/- 1.4) (p=0.018 and 0.038, respectively), however, no correlation was noted between the expressions of cyclin D1 and beta;-catenin. In addition, nonnuclear overexpression out of two altered expression patterns was more frequent (37.7% versus 20.8%) as well as pathologically more significant than nuclear expression. These results indicate that the altered expression of beta-catenin in HCC may play an important role in tumor progression by stimulating tumor cell proliferation, and nonnuclear overexpression may have pathologic significance in HCC.

Relationship between Utrophin and Regenerating Muscle Fibers in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a dystrophinopathy, and its associated gene is located on Xp21. Moreover, utrophin, a recently identified structural homologue of dystrophin is reported to be up-regulated in DMD. In order to investigate the association between utrophin and muscle regeneration in DMD, an immunohistochemical study using antibodies to utrophin, dystrophin, vimentin and desmin was carried out in 17 cases of DMD, 3 cases of polymyositis and 1 case of dermatomyositis. Dystrophin was negative in almost all cases of DMD, but positive in all cases of inflammatory myopathy (IM). Utrophin was positive in 94.0% of DMD and in 75.0% of IM. 36.4% of the myofibers were positive in DMD, as compared to 10.5% in IM (p=0.001). In both groups, utrophin positivity was present most commonly in small regenerating fibers (p=0.001, 0.013). Vimentin and desmin were intensely positive in regenerating fibers in all cases of DMD and IM. 34.4% and 35.4% of myofibers were positive for vimentin and desmin in DMD, as compared to 21.8% and 20.9% in IM (p=0.001, 0.001). In both groups, vimentin and desmin positivity were present most commonly in small regenerating fibers (p=0.001, 0.001). The staining intensities of utrophin, vimentin and desmin were also higher in small regenerating fibers. These results show that utrophin up-regulation is regeneration-associated, and that it is proportional to the quantity of regenerating myofibers, but is not specific for DMD.

Expression Patterns of E-cadherin and beta-catenin According to Clinicopathological Characteristics of Hepatocellular Carcinoma / 대한간학회지

BACKGROUND/AIMS: E-cadherin is involved in intercellular binding and cellular polarity formation. beta-catenin plays a fundamental role in regulation of the E-cadherin cell adhesion complex. The abnormalities of the components of the complex may disrupt this adhesive function. We investigated the expression patterns of E-cadherin and beta-catenin to determine the clinical significance of these proteins in hepatocellular carcinoma. MATERIALS/METHODS: Thirty-six hepaticellular carcinoma tissues and adjacent non-tumor specimens were analyzed. Subcellular distribution of E-cadherin and beta-catenin was examined by immunohistochemistry staining. We evaluated the patterns of the expression, and investigated the relationship with the cause of HCC; level of AFP; TNM stage; tumor size; growth types; metastasis; differentiation grade of HCC; and presence of portal vein thrombosis. RESULTS: Immunohistochemistry showed that all non-tumor tissues had membranous type staining of E-cadherin. All non-tumor tissues showed cytoplasmic type staining of beta-catenin, but no beta-catenin accumulation in nuclei was found. 58% (21/36) of HCC showed positive expression of E-cadherin in cytoplasmic membrane. The cytoplasmic expression of beta-catenin in HCC was 83% (30/36); nuclear expression in 14% (5/36); and no staining in 3% (1/36). Nuclear beta-catenin expression was observed in none (0/4) of the well-differentiated HCC; 17%(3/9) of moderate-differentiated HCC; and 17%(2/6) of poorly-differentiated HCC. There were no relationships between E-cadherin and beta-catenin expression with other clinicopathologic factors. CONCLUSIONS: Loss of cytoplasmic staining of E-cadherin and nuclear accumulation of beta-catenin were observed in HCC. Nuclear accumulation of beta-catenin was not found in well differentiated HCC but was found in poorly differentiated HCC.

ATP-induced focal adhesion kinase activity is negatively modulated by phospholipase D2 in PC12 cells

Extracellular ATP has been known to modulate various cellular responses including mitogenesis, secretion and morphogenic activity in neuronal cells. In the ATP-induced morphogenic activity, focal adhesion kinase(s) such as Fak have been suggested to play a critical role. Binding of ATP to its specific cell surface receptor in PC12 cells induces phospholipase D (PLD) activity. However, the role of PLD on ATP-induced Fak activation in PC12 cells remains unclear. In this study, we investigated the role of PLD on the ATP-induced Fak activation and paxillin phosphorylation using two established cell lines: wild type PLD2- and lipase-inactive mutant PLD2-inducible PC12 cells. Stimulation of cells with ATP caused PLD2 activation via classical protein kinase C activation. ATP also induced Fak activation, and paxillin phosphorylation, and were dramatically reduced by wild type PLD2 overexpression but not by lipase-inactive mutant PLD2 overexpression. When the PC12 cells were pretreated with propranolol, a specific inhibitor for phosphatidic acid phosphohydrolase resulting in the accumulation of PA, ATP-induced Fak activation and paxillin phosphorylation were also reduced. We found that inhibition of tyrosine phosphatases by pervanadate completely blocked PLD2-dependent Fak and paxillin dephosphorylation. Taken together, we suggest that PLD2 activity might play a negative role in ATP-induced Fak and paxillin phosphorylation possibly through tyrosine phosphatases.

Fosforilación en células eucarióticas: papel de fosfatasas y quinasas en la biología, patogenia y control de protozoosis tisulares y sanguíneas / Phosphorylation in eukaryotic cells: role of phosphatases and kinases in biology, pathogenesis and control of intracellular and bloodstream protozoa

Cells respond to environmental or cellular changes, rapidly switching protein activities from one state to another. In eukaryotes, a way to achieve these changes is through protein phosphorylation cycles, involving independent protein kinase and protein phosphatase activities. Current evidences show that phosphatases and kinases are also involved in the molecular basis of immune response and in diseases such as diabetes obesity and Alzheimer. In protozoan parasites like Trypanosoma and Leishmania, several kinases and phosphatases have been identified, many of them have been cloned but in several cases their biological role remains undetermined. In this review, the state-of-the art is summarized and the role of phosphatases and kinases in biological phenomena such as remodeling, invasion and pathogenic capacity of protozoan parasites is described. The real chance to use these components of signal transduction pathways as target for chemotherapeutic intervention is also discussed