Identification of a protein-tyrosine phosphatase (SHP1) different from that associated with acid phosphatase in rat prostate

Targeting pathogenic macrophages by the application of SHP-1 agonists reduces inflammation and alleviates pulmonary fibrosis

Idiopathic pulmonary fibrosis is a progressive fibrotic disorder with no cure that is characterized by deterioration of lung function. Current FDA-approved drugs for IPF delay the decline in lung function, but neither reverse fibrosis nor significantly improve overall survival. SHP-1 deficiency results in hyperactive alveolar macrophages accumulating in the lung, which contribute to the induction of pulmonary fibrosis. Herein, we investigated whether employing a SHP-1 agonist ameliorates pulmonary fibrosis in a bleomycin-induced pulmonary fibrosis murine model. Histological examination and micro-computed tomography images showed that SHP-1 agonist treatment alleviates bleomycin-induced pulmonary fibrosis. Reduced alveolar hemorrhage, lung inflammation, and collagen deposition, as well as enhanced alveolar space, lung capacity, and improved overall survival were observed in mice administered the SHP-1 agonist. The percentage of macrophages collected from bronchoalveolar lavage fluid and circulating monocytes in bleomycin-instilled mice were also significantly reduced by SHP-1 agonist treatment, suggesting that the SHP-1 agonist may alleviate pulmonary fibrosis by targeting macrophages and reshaping the immunofibrotic niche. In human monocyte-derived macrophages, SHP-1 agonist treatment downregulated CSF1R expression and inactivated STAT3/NFκB signaling, culminating in inhibited macrophage survival and perturbed macrophage polarization. The expression of pro-fibrotic markers (e.g., MRC1, CD200R1, and FN1) by IL4/IL13-induced M2 macrophages that rely on CSF1R signaling for their fate-determination was restricted by SHP-1 agonist treatment. While M2-derived medium promoted the expression of fibroblast-to-myofibroblast transition markers (e.g., ACTA2 and COL3A1), the application of SHP-1 agonist reversed the transition in a dose-dependent manner. Our report indicates that pharmacological activation of SHP-1 ameliorates pulmonary fibrosis via suppression of CSF1R signaling in macrophages, reduction of pathogenic macrophages, and the inhibition of fibroblast-to-myofibroblast transition. Our study thus identifies SHP-1 as a druggable target for the treatment of IPF, and suggests that the SHP-1 agonist may be developed as an anti-pulmonary fibrosis medication that both suppresses inflammation and restrains fibroblast-to-myofibroblast transition.

SHP1 tyrosine phosphatase gets involved in host defense against Streptococcus agalactiae infection and BCR signaling pathway in Nile tilapia (Oreochromis niloticus)

Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1), a kind of protein tyrosine phosphatases (PTPs), is a critical regulator of antigen receptor signal transduction. Signal transduction of BCR is regulated by phosphatases in teleost as in mammals. In this study, SHP1 from Nile tilapia (Oreochromis niloticus) (OnSHP1) was identified and characterized, including the expression pattern against bacterial infection and regulation function in BCR signaling pathway. The open reading frame of OnSHP1 contains 1749 bp of nucleotide sequence, encoding a protein of 582 amino acids. The OnSHP1 protein was highly conversed compared to that of other species, including two amino-terminal SH2 domains at the N terminus and a PTP catalytic domain. Transcriptional expression analysis revealed that OnSHP1 was detected in all examined tissues and highly expressed in spleen. The up-regulated OnSHP1 expression was observed in peripheral blood, spleen and anterior kidney following challenge with Streptococcus agalactiae or lipopolysaccharide (LPS) in vivo, as well as that displayed in leukocytes stimulated with S. agalactiae or LPS in vitro. Further, after induction with mouse anti-tilapia IgM monoclonal antibody in vitro, OnSHP1 was significantly up-regulated in leukocytes. When spleen leukocytes treated with PTP Inhibitor II in vitro, the phosphorylation level of OnSHP1 at the phosphorylation sites (Y⁵³⁵ and Y⁵⁵⁷) and the cytoplasmic free Ca²⁺ concentration were up-regulated significantly. Overall, the findings of this study indicate that SHP1 gets involved in host defense against bacterial infection and BCR signaling pathway in Nile tilapia.

Three new pigment protein tyrosine phosphatases inhibitors from the insect parasite fungus Cordyceps gracilioides: terreusinone A, pinophilin C and cryptosporioptide A

Three new pigment compounds--terreusinone A (1), pinophilin C (2) and cryptosporioptide A (3)-were isolated from a solid culture of Cordyceps gracilioides. The structures of these compounds were determined by extensive spectroscopic analysis including HRESIMS, 1D- and 2D-NMR. The structure of terreusinone A (1) was further confirmed by single-crystal X-ray crystallographic diffraction analysis. In an in vitro activity assay, 1, 2 and 3 exhibited high inhibitory activity against PTP1B, SHP2, CDC25B, LAR and SHP1. Terreusinone A (1) inhibited PTP1B, SHP2, CDC25B, LAR and SHP1 enzyme with IC50 values 12.5, >50, 4.1, 10.6, 5.6 µg/mL, respectively; pinophilin C (2) with IC50 values 6.8, 8.0, 4.5, 4.7, 3.4 µg/mL, respectively; and cryptosporioptide A (3) with IC50 values 7.3, 5.7, 7.6, >50, 4.9 µg/mL, respectively.

Prostate anatomy in motheaten viable (me(v)) mice with mutations in the protein tyrosine phosphatase SHP-1

OBJECTIVE

To study prostate and seminal vesicle anatomy in viable motheaten (mev) with mutations in PTPN6 gene leading to a severe reduction in the activity of protein tyrosine phosphatase SHP-1. Homozygous mev mice exhibit multiple anomalies that include immunodeficiencies, increased proliferation of macrophage, neutrophil, and erythrocyte progenitors, decreased bone density and sterility.

MATERIAL AND METHOD

We analyzed macro- and microscopic anatomy of the seminal vesicle and prostate macro- and microscopic anatomy of 5 mev/mev and 8 wt/wt adult 7 week old mice. Computerized morphometric analysis was performed to measure the relative changes appearing in the epithelial volume of the different prostatic lobes.

RESULTS

All mice studied revealed normal genital organs (penis, testis, epididymis, vas deferens) and bladder. The seminal vesicle was absent in all mev/mev individuals analyzed, being normal and very noticeable in wt/wt mice. The different glands that compose the prostatic complex (anterior, ventral and dorso-lateral prostate) were atrophied in mev/mev mice: anterior prostate 0.4 times, ventral 0.19 times, dorsal 0.35 times and lateral 0.28 times those of the respective regions in wt/wt mice. Microscopically, mev/mev mice revealed scarce and large prostatic ducts, acini severely atrophic with empty lumen and scarce loose epithelial component forming tufts and infoldings, and hyperplastic changes in fibromuscular stroma.

CONCLUSIONS

The prostate of mev/mev mice exhibits signs of aberrant differentiation and the resulting phenotype may be related to the loss of function of SHP-1. Prostatic anomalies in these mice affect, together with defects in sperm maduration, for their sterility. These data suggest SHP-1 plays an important role in prostate epithelial morphogenesis.

Role of protein tyrosine phosphatases in the modulation of insulin signaling and their implication in the pathogenesis of obesity-linked insulin resistance

Insulin resistance is a major disorder that links obesity to type 2 diabetes mellitus (T2D). It involves defects in the insulin actions owing to a reduced ability of insulin to trigger key signaling pathways in major metabolic tissues. The pathogenesis of insulin resistance involves several inhibitory molecules that interfere with the tyrosine phosphorylation of the insulin receptor and its downstream effectors. Among those, growing interest has been developed toward the protein tyrosine phosphatases (PTPs), a large family of enzymes that can inactivate crucial signaling effectors in the insulin signaling cascade by dephosphorylating their tyrosine residues. Herein we briefly review the role of several PTPs that have been shown to be implicated in the regulation of insulin action, and then focus on the Src homology 2 (SH2) domain-containing SHP1 and SHP2 enzymes, since recent reports have indicated major roles for these PTPs in the control of insulin action and glucose metabolism. Finally, the therapeutic potential of targeting PTPs for combating insulin resistance and alleviating T2D will be discussed.

The regulatory roles of phosphatases in cancer

The relevance of potentially reversible post-translational modifications required for controlling cellular processes in cancer is one of the most thriving arenas of cellular and molecular biology. Any alteration in the balanced equilibrium between kinases and phosphatases may result in development and progression of various diseases, including different types of cancer, though phosphatases are relatively under-studied. Loss of phosphatases such as PTEN (phosphatase and tensin homologue deleted on chromosome 10), a known tumour suppressor, across tumour types lends credence to the development of phosphatidylinositol 3-kinase inhibitors alongside the use of phosphatase expression as a biomarker, though phase 3 trial data are lacking. In this review, we give an updated report on phosphatase dysregulation linked to organ-specific malignancies.

Angiotensin-II-induced apoptosis requires regulation of nucleolin and Bcl-xL by SHP-2 in primary lung endothelial cells

Angiotensin II (Ang II) is a key proapoptotic factor in fibrotic tissue diseases. However, the mechanism of Ang-II-induced cell death in endothelial cells has not been previously elucidated. Using the neutral comet assay and specific receptor antagonists and agonists, we found that Ang-II-mediated apoptosis in primary pulmonary endothelial cells required the AT2 receptor. Ang II caused cytochrome c release from the mitochondria concurrent with caspase-3 activation and DNA fragmentation, and apoptosis was suppressed by an inhibitor of Bax-protein channel formation, implicating mitochondrial-mediated apoptosis. There was no evidence that the extrinsic apoptotic pathway was involved, because caspase-9, but not caspase-8, was activated by Ang-II treatment. Apoptosis required phosphoprotein phosphatase activation, and inhibition of the SHP-2 phosphatase (encoded by Ptpn11) blocked cell death. Reduced levels of anti-apoptotic Bcl-2-family members can initiate intrinsic apoptosis, and we found that Ang-II treatment lowered cytosolic Bcl-x(L) protein levels. Because the protein nucleolin has been demonstrated to bind Bcl-x(L) mRNA and prevent its degradation, we investigated the role of nucleolin in Ang-II-induced loss of Bcl-x(L). RNA-immunoprecipitation experiments revealed that Ang II reduced the binding of nucleolin to Bcl-x(L) mRNA in an AU-rich region implicated in instability of Bcl-x(L) mRNA. Inhibition of SHP-2 prevented Ang-II-induced degradation of Bcl-x(L) mRNA. Taken together, our findings suggest that nucleolin is a primary target of Ang-II signaling, and that Ang-II-activated SHP-2 inhibits nucleolin binding to Bcl-x(L) mRNA, thus affecting the equilibrium between pro- and anti-apoptotic members of the Bcl-2 family.

Knockdown of protein tyrosine phosphatase SHP-1 inhibits G1/S progression in prostate cancer cells through the regulation of components of the cell-cycle machinery

SHP-1, a haematopoietic cell-specific tyrosine phosphatase, is also expressed in human prostate. In this study, we report that SHP-1 depletion in PC-3 cells induced by small interfering RNAs causes G1 phase cell-cycle arrest accompanied by changes in some components of the cell-cycle machinery. SHP-1 knockdown increases p27(Kip1) (p27) protein stability, its nuclear localization and p27 gene transcription. These effects could be mediated by PI3K-AKT pathway as SHP-1 interacts with PI3K regulating its activity and p110 catalytic subunit phosphorylation. The increase in p27 protein stability could also because of reduced cyclin-dependent kinase (CDK2) activity. SHP-1 knockdown decreases the CDK6 levels, inducing retinoblastoma protein hypophosphorylation, downregulation of cyclin E and thereby a decrease in the CDK2 activity. However, the codepletion of SHP-1 and p27 does not produce re-entry into the cycle, implying that p27 is not required to maintain cell-cycle arrest induced by SHP-1 depletion. The maintenance of the PC-3 cell anti-proliferative response after p27 loss could be because of mislocalization of CDK2 induced by SHP-1 knockdown. This study shows that SHP-1 depletion promotes cell-cycle arrest by modulating the activity of cell-cycle regulators and suggests that SHP-1 may be required for the proper functioning of events governing cell-cycle progression.

Tumoral prostate shows different expression pattern of somatostatin receptor 2 (SSTR2) and phosphotyrosine phosphatase SHP-1 (PTPN6) according to tumor progression

Prostate proliferation is dependent of androgens and many peptide hormones. Recent reports suggest that SSTR2 and SHP-1 were two fundamental components on antiproliferative effect of somatostatin. Many studies on SHP-1 revealed that the expression of this protein was diminished or abolished in several of the cancer cell lines and tissues examined. However, it is necessary to confront the cell lines data with real situation in cancer cases. Our studies have shown that epithelial expressions of both proteins, SHP-1 and SSTR2, in normal and benign hyperplasia are localized in the luminal side of duct and acinar cells. Also, SSTR2 is expressed in stromal cells. In malignant prostate tissue, SHP-1 was diminished in 28/45 cases or absent in 12/45 cases, whereas SSTR2 epithelial was diminished in 38/45 cases or lost in only 2/45 cases. The intensity of immunostained was highly negative correlated with Gleason grade for two proteins.

The Src homology 2 domain tyrosine phosphatases SHP-1 and SHP-2: diversified control of cell growth, inflammation, and injury

Interest in the diverse biology of protein tyrosine phosphatases that are encoded by more than 100 genes in the human genome continues to grow at an accelerated pace. In particular, two cytoplasmic protein tyrosine phosphatases composed of two Src homology 2 (SH2) NH2-terminal domains and a C-terminal protein-tyrosine phosphatase domain referred to as SHP-1 and SHP-2 are known to govern a host of cellular functions. SHP-1 and SHP-2 modulate progenitor cell development, cellular growth, tissue inflammation, and cellular chemotaxis, but more recently the role of SHP-1 and SHP-2 to directly control cell survival involving oxidative stress pathways has come to light. SHP-1 and SHP-2 are fundamental for the function of several growth factor and metabolic pathways yielding far reaching implications for disease pathways and disorders such as diabetes, neurodegeneration, and cancer. Although SHP-1 and SHP-2 can employ similar or parallel cellular pathways, these proteins also clearly exert opposing effects upon downstream cellular cascades that affect early and late apoptotic programs. SHP-1 and SHP-2 modulate cellular signals that involve phosphatidylinositol 3-kinase, Akt, Janus kinase 2, signal transducer and activator of transcription proteins, mitogen-activating protein kinases, extracellular signal-related kinases, c-Jun-amino terminal kinases, and nuclear factor-kappaB. Our progressive understanding of the impact of SHP-1 and SHP-2 upon multiple cellular environments and organ systems should continue to facilitate the targeted development of treatments for a variety of disease entities.

[Phosphotyrosine phosphatase SHP-1, somatostatin and prostate cancer]

We review the mechanisms involved in prostatic growth based on androgens and product of neuroendocrine secretion, with special reference to the role of somatostatin (SS) in the inhibition of neoplastic growth. Our contributions in the field confirm the antiproliferative effect of SS on the prostate is mediated by phosphotyrosine phosphatase SHP-1, that is present in human prostate. This enzyme plays a role in the control of prostatic cell proliferation and in the progression of prostate cancer. Besides, we consider its presence may determine the therapeutic potential of SS in the control of prostate cancer.