Mimosine increases the expressions of tyrosine phosphorylated protein in mouse seminal vesicles / La mimosina aumenta la expresión de la proteína tirosina fosforilada en las vesículas seminales del ratón

Acute effect of purified mimosine (MiMo) extracted from Leucaena leucocephala on testicular histopathology has been documented with seminal vesicle (SV) atrophy. Since protein phosphorylation and seminal secretions play important roles in sperm physiology, this study aimed to study the alteration of substances including tyrosine phosphorylated (TyrPho) proteins in seminal vesicle treated with MiMo. Male mice were divided into a control and experimental groups treated with purified MiMo at 3 doses of 15, 30, and 60 mg/KgBW, respectively for 35 consecutive days. The morphology and weights of SV were compared among groups. The levels of magnesium and fructosamine in SV fluid were assayed. The profiles of equally SV total proteins were compared using SDS-PAGE. The expression of seminal TyrPho proteins was detected by western blotting. Recent results showed the decreased weights of SV in MiMo treated mice compared to control. However MiMo in all doses did not affect the levels of magnesium and fructosamine in SV fluid. The SV protein expression of 130 and 55 kDas was obviously decreased in a high dose MiMo. In dose-dependent response, the expressions of 72 and 55 kDas TyrPho proteins of SV were increased. In conclusion, MiMo could affect SV morphological size and protein secretions especially TyrPho proteins.

El efecto agudo de la mimosina purificada (MiMo) extraída de Leucaena leucocephala en la histopatología testicular se ha documentado con atrofia de vesícula seminal (VS). Debido a que la fosforilación de proteínas y las secreciones seminales tienen un papel importante en la fisiología de los espermatozoides, este estudio tuvo como objetivo estudiar la alteración de sustancias como la proteína tirosina fosforilada (TyrPho) en vesículas seminales tratadas con MiMo. Los ratones se dividieron en un grupo control y un grupo experimental y se trataron con MiMo purificado en 3 dosis de 15, 30 y 60 mg / KgBW, respectivamente, durante 35 días seguidos. La morfología y los pesos de VS se compararon entre los grupos. Fueron analizados los niveles de magnesio y fructosamina en el fluido VS. Los perfiles de las proteínas totales de VS se compararon utilizando SDS-PAGE. La expresión de la proteína TyrPho en las vesículas seminales se detectó mediante transferencia de Western blot. Los resultados recientes muestran la disminución del peso de las VS en ratones tratados con MiMo, en comparación con el grupo control. Sin embargo, en ninguna de las dosis se vieron afectados por mimosina purificada los niveles de magnesio y fructosamina en el líquido de las VS. La expresión de la proteína en VS de 130 y 55 kDas disminuyó notablemente en una dosis alta de MiMo. En la respuesta dependiente de la dosis, aumentaron las expresiones de 72 y 55 kDas de las proteínas TyrPho en las VS. En conclusión, la mimosina purificada podría afectar el tamaño morfológico de las VS y la expresión de proteínas, especialmente las proteínas TyrPho.

Localization and changes of tyrosine phosphorylated proteins and ß actin in epididymis of rats treated with valproic acid / Localización y cambios de las proteínas tirosina fosforiladas y la ß actina en epidídimos de ratas tratadas con ácido valproico

Tyrosine phosphorylated proteins have been localized and identified in male reproductive tissues such as testis and capacitated/ acrosome reacted sperm except epididymis. The changes of such proteins are associated with decreased sperm quality of valproic acid treatment. This study aimed to investigate the presence and alterations of protein phosphorylation in epididymal epithelium and fluid of rats treated VPA. Sixteen adult male rats were divided into control and VPA-treated groups (n=8/ each). Treated rats were injected with VPA (500 mg/ kgBW, intraperitoneally) for 10 consecutive days. At the end of experiment, the monoclonal antiphosphotyrosine (clone 4G10) was used for immunohistochemistry to probe tyrosine phosphorylated proteins and also to examine the expression of such proteins using immuno-Western blotting in epididymal tissue and fluid. The result showed that positive reactivity of phosphorylated proteins was clearly observed in cytoplasmic principle cells, nuclei of apical & basal cells and sperm mass surrounded with epididymal fluids. The profiles of phosphorylated proteins in epididymal fluid were 182, 127, 80, 70, 57, 45, 34, and 31 kDas, respectively. Interestingly, VPA affected the changes of phosphorylated proteins and β actin in head, body, and tail epididymal fluids. We conclude that tyrosine phosphorylated proteins were detected in epididymal epithelium and fluid. The expressions of those proteins and actin were altered under VPA treating.

Las proteínas tirosina fosforiladas han sido localizadas e identificadas en tejidos reproductores masculinos tales como testículos y espermatozoides, capacitados a nivel acrosómico, excepto en el epidídimo. Los cambios de estas proteínas están asociadas con una disminución de la calidad del esperma en el tratamiento con ácido valproico (AVP). Este estudio tuvo como objetivo investigar la presencia y las alteraciones de la fosforilación de proteínas en el epitelio epididimal y en el fluido espermático de ratas tratadas con AVP. Dieciséis ratas macho adultas se dividieron en dos grupos: control y tratadas con AVP (n = 8 / cada uno). A las ratas tratadas se les inyectó AVP por vía intraperitoneal (500 mg / kg de peso corporal) durante 10 días consecutivos. Al final del experimento, se realizó inmunohistoquímica con la anti-fosfotirosina monoclonal (clon 4G10) para sondear las proteínas tirosina fosforiladas y también para examinar la expresión de tales proteínas usando inmunotransferencia Western, en tejido y fluido epididimarios. El resultado mostró reactividad positiva de proteínas fosforiladas en células citoplásmicas principales, en los núcleos de las células apicales y basales y en la masa de esperma rodeada por fluidos epididimarios. Los perfiles de proteínas fosforiladas en el fluido epididimal fueron 182, 127, 80, 70, 57, 45, 34 y 31 kDas, respectivamente. El AVP provocó cambios en las proteínas fosforiladas y en la β actina de los fluidos epididimarios de cabeza, cuerpo y cola del epidídimo. Concluimos que las proteínas tirosina fosforiladas se detectaron en el epitelio y el fluido epididimarios. Las expresiones de esas proteínas y de la β actina se alteraron bajo tratamiento con AVP.

Methotrexate changes the testicular tyrosine phosphorylated protein expression and seminal vesicle epithelia of adult rats / El metotrexato cambia la expresión de la proteína testicular-tirosina fosforilada y el epitelio vesicular seminal en ratas adultas

Methotrexate (MTX) is commonly used as a chemotherapy agent and immune system suppressant but its adverse effect on male reproductive system is still limited. This study aimed to investigate the effect of MTX on structure and functional proteins of testis and seminal vesicle. Adult male rats were divided into control and MTX groups (n =12). In 30 experimental days, the treated animals were injected with MTX (tail i.v., 75 mg/KgBW) at days 8 and 15. Then, the reproductive parameters and histology of both groups were examined. Thickness of seminal seminal vesicle epithelia was analyzed. Also, the expressions of testicular tyrosine phosphorylated proteins and steroidogenic acute regulatory (StAR) protein were investigated. The results showed that MTX could significantly decrease epididymal sperm concentration. In addition, the germ cell degeneration, increased spaces of interstitial tissues, and low epididymal sperm mass density were observed in MTX group. The thickness of seminal vesicle epithelia in MTX group was significantly lower than that of control group. Moreover, the intensity of testicular phosphorylated proteins of 31, 32, 72, and 85 kDas was significantly increased while of 42 and 47 kDas in MTX group was decreased as compared to control. The expression of testicular StAR protein in MTX group was also significantly decreased as compared to the control. In conclusion, MTX affects testicular and seminal tissues and changes testicular functional proteins in adult rats.

El metotrexato (MTX) se usa comúnmente como agente de quimioterapia y supresor del sistema inmunitario, pero su efecto adverso en el sistema reproductor masculino sigue siendo limitado. Este estudio tuvo como objetivo investigar el efecto del MTX sobre la estructura y las proteínas funcionales del testículo y la vesícula seminal. Ratas macho adultas se dividieron en grupos control y grupo con MTX (n = 12). En 30 días experimentales, a los animales tratados se les inyectó MTX (cola i.v., 75 mg / KgBW) los días 8 y 15. Luego, se examinaron los parámetros reproductivos y la histología de ambos grupos. Se analizó el espesor del epitelio de la vesícula seminal. Además, se investigaron las expresiones de la proteína tirosina testicular fosforilada y de la proteína reguladora aguda esteroidogénica (StAR). Los resultados mostraron que el MTX podría disminuir significativamente la concentración de espermatozoides epididimarios. Además, se observó la degeneración de las células germinales, el aumento de los espacios de los tejidos intersticiales y la baja densidad de masa del espermatozoide epididimal en el grupo de MTX. El grosor del epitelio de la vesícula seminal en el grupo MTX fue significativamente menor que el del grupo control. Además, la intensidad de las proteínas testiculares fosforiladas de 31, 32, 72 y 85 kDas aumentó significativamente, mientras que la de 42 y 47 kDas en el grupo MTX disminuyó en comparación con el control. La expresión de la proteína StAR testicular en el grupo MTX también se redujo significativamente en comparación con el control. En conclusión, el MTX afecta los tejidos testiculares y seminales y cambia las proteínas funcionales testiculares en ratas adultas.

A novel assay method for calcium calmodulin dependent phosphatase from bovine brain extract.

Calcium calmodulin dependent protein ser/thr phosphatase, also referred to as protein phosphatase 2B (PP2B), is rich in neural tissue, and plays an important role in the overall function of the nervous system. Routinely phosphatase assay employs, para-Nitrophenlylphosphate (p-NPP), as a substrate, is also extended to assay PP2B. However, in the present study, the differential spectral characterstic property of tyrosine and phopshotyrosine has been exploited to employ the latter as a candidate substrate for the PP2B assay. The specific activity of PP2B using phosphortyrosine in bovine Bos Taurus indicus brain extract (Bos Taurus indicus), was measured in presence of different metal ions like Ca2+, Mn2+ and Mg2+. Further modulators like dithiothreitol (DTT), calmodulin (CaM) and metal chelators such as EGTA and EDTA were applied to confirm the role of divalent cations and to determine calcium calmodulin dependent phoshphatase activity. PP2B activity was higher with phosphotyrosine in presence of Ca2+ than with p-NPP. Further experiments, involving calmodulin as a modulator, confirmed phosphotyrosine as a better substrate over p-NPP. Calmodulin further enhanced the effect of phosphotyrosine as a potential substrate confirming calcium calmodulin dependent phosphatase activity. Phosphotyrosine is proposed as a better substrate in assaying calcium dependent phosphatase activity when compared to para-nitrophenylphosphate.

Jiaotai Pill enhances insulin signaling through phosphatidylinositol 3-kinase pathway in skeletal muscle of diabetic rats / 中国结合医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of Jiaotai Pill (, JTP) at different constitutional proportions on insulin signaling through phosphatidylinositol 3-kinase (PI3K) pathway in the skeletal muscle of diabetic rats.</p><p><b>METHODS</b>The rat model of type 2 diabetes mellitus (T2DM) was established by intravenous injection of a small dose of streptozotoein plus high fat diet feeding. JTP at the same dosage of cinnamon and the increasing dosage of Coptis chinensis was administered to diabetic rats for nine weeks respectively. Plasma glucose and insulin levels were assayed. The expressions of proteins were determined by Western blot method.</p><p><b>RESULTS</b>All the three formulations of JTP decreased plasma glucose and fasting insulin levels as well as increased the protein expressions of insulin receptor β (InsRβ) subunit, insulin receptor substrate-1 (IRS-1), PI3K p85 subunit and glucose transporter 4 (GLUT4) in skeletal muscle. Meanwhile, JTP increased the tyrosine phosphorylation of InsRβ subunit and IRS-1, and reduced the serine phosphorylation of IRS-1 in skeletal muscle. Interestingly, the effect of JTP on improving insulin sensitivity was not dose-dependent. In contrast, JTP containing the least amount of Coptis chinensis exhibited the best effect.</p><p><b>CONCLUSION</b>JTP at different constitutional proportions attenuates the development of diabetes in a rat model of T2DM. The mechanism might be associated with enhancing insulin signaling through PI3K pathway in the skeletal muscle.</p>

Preferential Cytotoxic Effect of Genistein on G361 Melanoma Cells Via Inhibition of the Expression of Focal Adhesion Kinase

Resistance to the induction of apoptosis is a possible mechanism by which tumor cells can survive anti-neoplastic treatments. Melanoma is notoriously resistant to anti-neoplastic therapy. Previous studies have demonstrated focal adhesion kinase (FAK) overexpression in melanoma cell lines. Given its probable role in mediating resistance to apoptosis, many researchers have sought to determine whether the downregulation of FAK in melanoma cells would confer a greater sensitivity to anti-neoplastic agents. Genistein is a known inhibitor of protein-tyrosine kinase (PTK), which may attenuate the growth of cancer cells by inhibiting the PTK-mediated signaling pathway. This present study was undertaken to investigate the effect of genistein on the expression of FAK and cell cycle related proteins in the G361 melanoma cell line. Genistein was found to have a preferential cytotoxic effect on G361 melanoma cells over HaCaT normal keratinocytes. Genistein decreased the expression of 125 kDa phosphotyrosine kinase and the FAK protein in particular. Genistein treatment did not affect the expression of p53 in G361 cells in which p21 is upregulated. The expression of cyclin B and cdc2 was downregulated by genistein treatment. Taken together, our data indicate that genistein induces the decreased proliferation of G361 melanoma cells via the inhibition of FAK expression and regulation of cell cycle genes. This suggests that the use of genistein may be a viable approach to future melanoma treatments.

Somatostatin Receptors in Lung Cancer: From Function to Molecular Imaging and Therapeutics

Lung cancer is a deadly disease that is difficult to diagnose and even more difficult to treat effectively. Many pathways are known to affect tumor growth, and targeting these pathways provides the cornerstone by which cancer is treated. Somatostatin receptors (SSTR) are a family of G protein coupled receptors that signal to alter hormonal secretion, increase apoptosis, and decrease cellular proliferation. These receptors are expressed in many normal and malignant cells, including both small cell and non-small cell lung cancer. Synthetic analogs of SSTRs are commercially available, but their effects in lung cancer are still largely uncertain. Signaling pathway studies have shown that SSTRs signal through phosphotyrosine phosphatases to induce apoptosis as well as to decrease cell proliferation. Radiolabeled SSTR2 analogs are utilized for radiographic imaging of tumors, which, when combined with positron emission tomography-computed tomography (PET-CT) may improve detection of lung cancer. These radiolabeled SSTR2 analogs also hold promise for targeted chemotherapy as well as radiotherapy. In this review, we summarize what is known about SSTRs and focus our discussion on the knowledge as it relates to lung cancer biology, as well as discuss current and future uses of these receptors for imaging and therapy of lung cancer.

A double point mutation in PCL-gamma1 (Y509A/F510A) enhances Y783 phosphorylation and inositol phospholipid-hydrolyzing activity upon EGF stimulation

Growth factor stimulation induces Y783 phosphorylation of phosphoinositide-specific PLC-gamma1, and the subsequent activation of this enzyme in a cellular signaling cascade. Previously, we showed that a double point mutation, Y509A/F510A, of PLC-gamma1, abolished interactions with translational elongation factor 1-alpha. Here, we report that the Y509A/F510A mutant PLC-gamma1 displayed extremely high levels of Y783 phosphorylation and enhanced catalytic activity, compared to wild-type PLC-gamma1, upon treatment of COS7 cells with EGF. In quiescent COS7 cells, the Y509A/F510A mutant PLC-gamma1 exhibited a constitutive hydrolytic activity, whereas the wild-type counterpart displayed a basal level of activity. Upon treatment of COS7 cells with EGF, the Y783F mutation in Y509A/F510A PLC-gamma1 (Y509A/F510A/Y783F triple mutant) cells also led to an enhanced catalytic activity, whereas Y783F mutation alone displayed a basal level of activity. Our results collectively suggest that the Y509A/F510A mutant is more susceptible to receptor tyrosine kinase-induced Y783 phosphorylation than is wild-type PLC-gamma1, but no longer requires Y783 phosphorylation step for the Y509A/F510A mutant PLC-gamma1 activation in vivo.

Detection of phosphotyrosine in chronic myeloid leukemia cells with PY20 antibody and its clinical applications / 中国实验血液学杂志

The objective of this study was to investigate the specificity of detecting the phosphotyrosine level with anti-phosphotyrosine monoclonal antibody PY20 for diagnosis and prognosis of patients with chronic myeloid leukemia (CML) and the possibility of its clinical application. The positive rate of PY20 in 28 newly diagnosed CML patients was detected by flow cytometry using anti-PY20 antibody, the bcr-abl fusion gene was detected by nested RT-PCR, the Ph chromosome was measured by R-banding cytogenetic analysis, and the coincidence of PY20 positive rate with results of bcr-abl fusion gene and Ph chromosome detection was compared. In addition, the positive rate of PY20, the changes of bcr-abl fusion gene and Ph chromosome were determined in follow up 7 CML patients after allo-hematopoietic stem cell transplantation. The results indicated that the positive rates of PY20 in 28 newly diagnosed CML patients in groups of chronic phase (CP), accelerated phase (AP), and blast phase (BP) were (40.31% +/- 1.22)%, (77.28 +/- 1.14)% and (78.12 +/- 1.32)% respectively. The positive rate of PY20 in CP was lower than that in AP and BP (p < 0.05). There was no difference in positive rate of PY20 between AP and BP (p > 0.05). PY20 expression level of leukocytes from peripheral blood and bone marrow showed no difference (p < 0.05). The positive rates of PY20 in patients with CR, PR and NR were (15.56% +/- 1.51)%, (38.73% +/- 2.31)% and (60.43% +/- 2.04)% respectively. The positive and negative coincidence between PY20 and RT-PCR was 92.31% and 95.45% respectively. The positive and negative coincidence between PY20 and Ph Chromosome in newly diagnosed patients was 88.46% and 95.46% respectively. Ph chromosome and PY20 were all negative in 7 CML patients after allo-HSCT. Bcr-abl fusion gene was negative persistently in 5 patients, but in the other 2 patients, the fusion gene was persistently positive. In conclusion, the detection of the level of phosphotyrosine in CML cells has high sensitivity and specificity. The results of PY20 cell positive rate combined with detection of bcr/abl fusion gene and Ph chromosome might be useful in diagnosis as a good index of monitoring.

CD99 activates T cells via a costimulatory function that promotes raft association of TCR complex and tyrosine phosphorylation of TCR zeta

We investigated the co-stimulatory role of a cell-surface protein, CD99. Co-ligation of CD99 and suboptimal CD3 induced T-cell activation to a level comparable to that obtained with optimal CD3 or CD3+CD28. We also noted concomitant enhancement of the earliest T-cell receptor (TCR) signaling events. In addition, co-ligation of CD99 and CD3 led to translocation of TCR complexes into the lipid raft, without concomitant migration of CD99 to the raft, and consequent enhancement of TCR zeta-mediated signal 1. These data demonstrate the unique properties of CD99 co-stimulation that distinguish this molecule from CD28 and other raft-resident co-stimulatory factors.

Detection of phosphotyrosine in bcr-abl-positive cells with PY20 antibody and its clinical applications / 中华血液学杂志

<p><b>OBJECTIVE</b>To explore the specificity of anti-phosphotyrosine monoclonal antibody PY20 in bcr-abl+ cells and its possible clinical applications.</p><p><b>METHODS</b>Bcr-abl cell lines( K562, MEG-01) and bcr-abl- cells lines( Jurkat, MCF-7 )were stained with PY20. Phosphotyrosine protein of K562 and MEG-01 cells was detected by flow cytometry before and after treatment with imatinib. Phosphotyrosine protein in bone marrow cells from 49 patients with chronic myeloid leukemia (CML), Ph+ acute lymphoblastic leukemia(Ph(+) -ALL), Ph- ALL, acute myeloid leukemia (AML-M1, M2, M3, M5, FAB classification), chronic lymphocytic leukemia (CML) and 3 normal donor. Positive cells over 5% of total cells was considered positive cases for phosphotyrosine protein. The level of tyrosine phosphorylation was determined by median fluorescence intensity (MFI).</p><p><b>RESULTS</b>Bcr-abl cell lines and marrow cells from 10 CML patients and 8 ALL patients were all PY20-positive, while bcr-abl- cell lines and marrow cells from 18 leukemia patients and 3 normal donor were all PY20-negative. MFI decreased remarkably after blocked by imatinib in K562 cells and MEG-01 cells. The positive cell percent of marrow cells from 10 newly diagnosed CML patients and 9 imatinib-sensitive CML patients was (54.20 +/- 19.82)% and (14.84 +/- 6.17)% (P < 0.05), while that of 2 cases of imatinib-resistant was 64.3% and 57.2%. There was significant difference of MFI between imatinib-resistant patients and imatinib-sensitive patients (99.42 +/- 4.87 vs 46.41 +/- 4.67, P < 0.01).</p><p><b>CONCLUSION</b>PY20 monoclonal antibody is highly specific for bcr-abl+ cells. It might be useful in rapid detection of bcr-abl+ cells and sensitivity to imatinib of CML patients.</p>

Association of Killer Cell Ig-like Receptor (KIR) with an Adaptor Protein Shc

BACKGROUND: Cytotoxic function of killer cells is inhibited by specific recognition of class I MHC molecules on target cells by inhibitory killer Ig-like receptors (KIR) expressed on NK cells and some cytotoxic T cells. The inhibitory effect of KIR is accomplished by recruitment of SH2-containing protein tyrosine phosphatase (SHP) to the phosphotyrosine residues in the cytoplasmic tail. METHODS: By in vitro coprecipitation experiments and transfection analysis, we investigated the association of KIR with an adaptor protein Shc in Jurkat T cells. RESULTS: The cytoplasmic tail of KIR appeared to associate with an adaptor protein Shc in Jurkat T cell lysates. Similar in vitro experiments showed that phosphorylated KIR cytoplasmic tail bound SHP-1 and Shc in Jurkat T cell lysates. The association of KIR with Shc was further confirmed by transfection analysis in 293T cells. Interestingly, however, Shc appeared to be replaced by SHP-2 upon engagement of KIR in 293T cells. CONCLUSION: Our data indicate that KIR associate with an adaptor protein Shc in Jurkat T cells, and suggest that KIR might have an additional role which is mediated by this adaptor protein.

Tyrosine phosphatase and cytochrome P450 activity are critical in regulating store-operated calcium channels in human fibroblasts

Diverse signaling pathways have been proposed to regulate store-operated calcium entry (SOCE) in a wide variety of cell types. However, it still needs to be determined if all of these known pathways operate in a single cell type. In this study, we examined involvement of various signaling molecules in SOCE using human fibroblast cells (HSWP). Bradykinin (BK)-stimulated Ca2+ entry, previously shown to be via SOCE, is enhanced by the addition of vanadate, an inhibitor of tyrosine phosphatases. Furthermore, SOCE is regulated by cytochrome P-450, as demonstrated by the fact that the products of cytochrome P-450 activity (14,15 EET) stimulated SOCE while econazole, an inhibitor of cytochrome P450, suppressed BK-stimulated Ca2+ entry. In contrast, Ca2+ entry was unaffected by the guanylate cyclase inhibitor LY83583, or the membrane permeant cyclic GMP analog 8-bromo-cyclic GMP (8-Br-cGMP). Neither nitric oxide donors nor phorbol esters affected BK-stimulated Ca2+ entry. SOCE in HSWP cells is primarily regulated by tyrosine phosphorylation and the cytochrome P-450 pathway, but not by cyclic GMP, nitric oxide, or protein kinase C. Thus, multiple pathways do operate in a single cell type leading to the activation of Ca2+ entry and some of these signaling pathways are more prominently involved in regulating calcium entry in different cell types.

Differential analysis of tyrosine-phosphorylated proteins in human hepatocellular carcinoma cell lines with different metastasis potentials / 中华肝脏病杂志

<p><b>OBJECTIVES</b>To compare expressions of tyrosine-phosphorylated proteins in different hepatocellular carcinoma cell lines with different metastasis potential and to screen key molecules associated with HCC metastasis and recurrence.</p><p><b>METHODS</b>Using two-dimensional electrophoresis, Western blotting and MALDI-TOF-MS/MS, we analyzed tyrosine-phosphorylated protein profiles of Hep3B, MHCC97L and MHCC97H, HCC cell lines with different metastasis potentials.</p><p><b>RESULTS</b>10 spots were detected in Hep3B, 19 in MHCC97L and 17 in MHCC97H. Seventeen significantly different phosphotyrosine proteins in gel were identified by MALDI-TOF-MS/MS, including Annexin I.</p><p><b>CONCLUSION</b>The changed expression of tyrosine-phosphorylated proteins is associated with HCC metastasis and recurrence.</p>

Avaliação histológica e bioquímica da resposta celular ao enxerto de osso cortical bovino previamente submetido a altas temperaturas. Efeito da temperatura no preparo de enxerto xenógeno / Histological and biochemical analysis od cell responses to bovine cortical bone grafting previously submitted to high temperatures. Effect of the temperature on xenograft preparation

A despeito do sucesso no uso clínico de vários materiais para enxertos ósseos, os seus efeitos biológicos não são ainda completamente conhecidos. Este trabalho teve o propósito de avaliar a biocompatibilidade de dois materiais para enxerto ósseo, preparados a partir de osso cortical bovino, um desproteinizado a 100°C e outro a 1.000°C. Esses materiais em partículas com 1000-2000 mA,m foram implantados no tecido subcutâneo de 60 ratos. Os animais foram sacrificados após 10, 20, 30 e 60 dias, e as biópsias removidas para análise microscópica e perfil de fosfatases ácidas. A análise microscópica apresentou para ambos os materiais reação granulomatosa tipo corpo estranho de baixa renovação contendo macrófagos e células gigantes multinucleadas (presentes em maior número no osso tratado a 1000°C) em contato com o material, reação semelhante ao descrito na literatura para implantação subcutânea de osso alógeno mineralizado. Os níveis de fosfatase ácida lisossomal confirmaram um período de maior inflamação nos primeiros 10 dias pós-implantação, em resposta a cada um dos materiais. No tecido reacional ao osso desmineralizado a 1000°C notou-se fibrosamento maior e as células gigantes não exibiam indícios de atuarem na degradação do material. Por outro lado, a resposta celular ao osso 100°C indicou que ocorreu interação maior com as células gigantes e sinais de reabsorção. Os autores concluem que a temperatura de desproteinização modificou a respostá biológica, provavelmente devido a material orgânico no osso desproteinizado a 100°C. Esses materiais, ambos biocompatíveis, podem ser usados como de preenchimento ósseo-substitutos ou potenciais carreadores de proteínas morfogenéticas do osso.

Nonspecific association of 2',3'-cyclic nucleotide 3'-phosphodiesterase with the rat forebrain postsynaptic density fraction

The 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP), a protein of unknown function in vivo, is abundantly expressed in myelinating glia in two isoforms, CNP1 and CNP2. In this study, immunoblot analysis showed that CNP1 is the major isoform in adult forebrain, and that both isoforms are included in the postsynaptic density (PSD) fraction and tyrosine-phosphorylated at the basal level. However, subcellular distribution and detergent extraction data showed that CNP is nonspecifically associated with the PSD fraction. Immunocytochemistry revealed that CNP is detected, in a weak but punctate pattern, in dissociated rat hippocampal neurons of 3 days to 2 weeks in vitro. The CNP-positive punctae were distributed throughout soma and dendrites, and distinct from PSD95-positive ones. Immunoblot analysis indicated that CNP is also expressed in neuronal stem cell lines, HiB5 and F11. Interestingly, in addition to the known two isoforms, a new CNP isoform of MW 45 kDa was expressed in these cell lines and was the major type of isoform in F11 cells. Taken together, our data suggest that CNP is expressed in the early stage of in vitro development and nonspecifically included in the adult rat PSD fraction.

Hypoxia activates signal transducers and activators of transcription 5 (STAT5) and increases its binding activity to the GAS element in mammary epithelial cells

STATs (signal transducers and activators of transcription) are proteins with dual functions: signal transducers in the cytoplasm and transcriptional activators in the nucleus. STAT proteins act as transcription factors activated by phosphorylation on its tyrosine residues upon stimulation by various cytokines. The phosphorylated STAT molecules then form homo- or heterodimers through SH2-mediated interaction and translocate into the nucleus to activate the transcription of various target genes. STAT5 recognizes the interferon-gamma activated site TTCNNNGAA (GAS sequence) in the promoter region of the beta-casein gene. Except for prolactin-dependent beta-casein production in mammary gland cells, the biological consequences of STAT5a activation in various systems are not clear. Here we showed that STAT5a was phosphorylated 10 min after desferrioxamine (DFO) treatment, and reached a maximum induction at 4 h in mammary epithelial cells (HC11) and transfected COS-7 cells. Under hypoxic conditions (2% O2), a maximal phosphorylation of STAT5a was observed within 6 h. EMSA (electrophoretic mobility shift assay) showed that DFO or hypoxia enhanced the binding activities of STAT5a DNA to beta-casein gene promoter in mammary epithelial cells (HC11) and transfected COS-7 cells. These results showed that DFO or hypoxia induces tyrosine phosphorylation of STAT5a and also increases the binding activity of STAT5a DNA in mammary epithelial cells. Our data suggest that the STAT5 may act as a mediator in hypoxia-mediated gene expression.

Expression of epidermal growth factor receptor and related phosphorylation proteins in hypertrophic scars and normal skin / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To study the potential signal pathway involved in pathogenesis of hypertrophic scar formation.</p><p><b>METHODS</b>The samples of scar were obtained from patients with burn wound scars 6 - 28 months post-burn, while the samples of normal control skin came from the donor site of the same patients. Immunohistochemistry and light microscopy techniques were used to identify the expression of epidermal growth factor receptor (EGFR) and phosphotyrosine proteins (p-Tyr), as well as the phosphorylation of signal transducer and activator of transcription 3 (Stat3) in both hypertrophic scars (n = 6) and normal skin (n = 6).</p><p><b>RESULTS</b>Significant differences were observed in the p-Tyr and EGFR positive expression keratinocytes both in hypertrophic scars and normal skin. The expression of p-Tyr, EGFR and Stat3 protein was greater in hypertrophic scars than in normal skin. However, there was no significant difference in p-Stat3 expression between scar tissues and normal skin.</p><p><b>CONCLUSION</b>Different tyrosine kinase activity occurs in hypertrophic scars and normal cutaneous tissues. Initially, varied expression of EGFR is due to different ligand stimulations. However, phosphotyrosine protein and Stat3 are subsequently activated through phosphorylation. In scar tissues, although EGFR has an intrinsic tyrosine kinase activity when activated by EGFR correlated ligand, phosphorylation of Stat3 showed no significant changes. Therefore, cellular signal pathways are induced by EGFR, which might play a role in hypertrophic scar pathogenesis.</p>

The Effect of Hydrogen Peroxide on the Migration and FAK Activation in Lens Epithelial Cells

PURPOSE: Hydrogen peroxide has been implicated as a causative factor of various cellular dysfunction, cell death, transformation. In addition, oxidative stress has been suggested as a crucial inducer of cataract formation not only the nuclear-type cataract but also anterior polar type cataract. Transformation of lens epithelial cells accompanying accumulation of extracellular matrix molecules, and cell migration is observed in the cataract forming area of lens. In the present study, we investigated in the migration of lens epithelial cells and the activation of focal adhesion kinase(FAK), because there have been many reports showing that activation of FAK increased cell migration. METHOD: After treatment hygrogen peroxide in a dose-dependent on HLE B-3 cell line, we have performed immuno fluorenscence staing of actin stress fiber and migration assay, and then isolated total RNA to identify expression of MMP-2 from the cell line. To examine FAK activity, we are performed Phosphotyrosine Immunoblot analysis. RESULT: We observed the increased cell migration in response to hydrogen peroxide in a dose dependent manner. In addition, we observed that the phosphorylation of focal adhesion kinase was increased with the treatment of hydrogen peroxide. Also, we examined the expression of the matrix metalloproteinases-2(MMP-2) which disintegrates extracellular matrix and participates in cell migration. The result showed that the mRNA level of MMP-2 did not increase by hydrogen peroxide. CONCLUSIONS: The results suggest that hydrogen peroxide enhanced migration of lens epithelial cell, and that FAK may play a role in the process of cell migration. In conclusion, migration of lens epithelial cell and phosphorylation of focal adhesion kinase was increased by treatment of hydrogen peroxide. Thus oxidative stress plays a crucial role in the transformation of lens epithelial cells and anterior polar type cataract formation.

The Mechanisms of Antitumor Effect of Anti-p185HER2/neu Monoclonal Antibody and Peptide Mimetic

PURPOSE: Anti-p185HER2/neu monoclonal antibody (mAb) that can induce phenotypic reversion and monoclonal antibodies specific for the p185HER2/neu growth factor receptor that are able to diminish its kinase-signaling properties represent a specific advance in the therapy for p185HER2/neu-expressing human cancers. With mAb treatment, down-regulation of p185HER2/neu surface receptors and attenuation of the kinase-signaling properties have been observed and regarded as a basic phenomenon; however, the mechanisms for mAb-induced phenotypic reversion are not clear. METHODS: We used human tumor-cell lines of SK-BR-3, T6-17, and U373MG. With immunoprecipitation and Western blotting, we investigated the changes in p185HER2/neu receptor phosphorylation and the expression of signal-regulatory proteins (SIRPs) after mAb treatment. To identify the proteins interacting with Tat-binding protein-1 (TBP1), we used the Clonotech Gal4 matchmaker two-hybrid system. RESULTS: Minimal to moderate reduction in phosphotyrosine (pTyr) content was observed in SK-BR-3 and T6-17 cells with short-term (10-30 minutes) incubation after mAb treatment, but that did not alter total p185HER2/neu receptor density. SIRPs phosphorylation after peptide treatment was increased. With mAb treatment, three proteins were shown to interact with TBP1, and all of the interacting proteins are subunits of proteasome 26S. Collectively, anti- p185HER2/neu mAb or peptide down-regulates the surface receptors and attenuates the kinase signaling, which then both induces higher proteasome activity through increased TBP1 and increases SIRPs expres sion. CONCLUSION: Increased proteasomal activity may degrade abnormal proteins and increased SIRPs may regulate signal transduction toward the norm. Therefore, activation of a protein-degradation pathway and induction of signal-regulatory proteins may be possible mechanisms for the ultimate anti-tumor effects of the anti-p185HER2/neu mAb or peptide.