Upregulation of PTPN1 aggravates endotoxemia-induced cardiac dysfunction through inhibiting mitophagy

OBJECTIVES

To investigate the role of protein tyrosine phosphatase non-receptor type 1 (PTPN1) in mitophagy during sepsis and its underlying mechanisms and determine the therapeutic potential of PTPN1 inhibitors in endotoxemia-induced cardiac dysfunction.

METHODS

A mouse model of endotoxemia was established by administering an intraperitoneal injection of lipopolysaccharide (LPS). The therapeutic effect of targeting PTPN1 was evaluated using its inhibitor Claramine (CLA). Mitochondrial structure and function as well as the expression of mitophagy-related proteins were evaluated. Rat H9c2 cardiomyocytes were exposed to mouse RAW264.7 macrophage-derived conditioned medium. Cryptotanshinone, a specific p-STAT3 (Y705) inhibitor, was used to confirm the role of STAT3 in PTPN1-mediated mitophagy following LPS exposure. Electrophoretic mobility shift and dual luciferase reporter assays were performed to discern the mechanisms by which STAT3 regulated the expression of PINK1 and PRKN.

RESULTS

CLA alleviated LPS-induced myocardial damage, cardiac dysfunction, and mitochondrial injury and dysfunction in the mouse heart. PTPN1 upregulation exacerbated LPS-induced mitochondrial injury and dysfunction in H9c2 cardiomyocytes, but inhibited LPS-induced mitophagy. LPS promoted the interaction between PTPN1 and STAT3 and reduced STAT3 phosphorylation at Tyr705 (Y705), which was required to inhibit mitophagy by PTPN1. Upon LPS stimulation, PTPN1 negatively regulated the transcription of PINK1 and PRKN through dephosphorylation of STAT3 at Y705. STAT3 regulated the transcription of PINK1 and PRKN by binding to STAT3-responsive elements in their promoters.

CONCLUSION

PTPN1 upregulation aggravates endotoxemia-induced cardiac dysfunction by impeding mitophagy through dephosphorylation of STAT3 at Y705 and negative regulation of PINK1 and PRKN transcription.

Tenuigenin activates the IRS1/Akt/mTOR signaling by blocking PTPN1 to inhibit autophagy and improve locomotor recovery in spinal cord injury

ETHNOPHARMACOLOGICAL RELEVANCE

Tenuigenin (TEN) is a main pharmacologically active component of Polygala tenuifolia Willd. (Polygalaceae), which has shown neuroprotective functions in Alzheimer's disease. Moreover, TEN also demonstrated an anti-oxidative impact in an in vitro model of Parkinson's disease, reducing damage and loss of dopaminergic neurons.

AIM

This work focuses on the impact of TEN on locomotor recovery following spinal cord injury (SCI) and underpinning molecules involved.

METHODS

A rat model of SCI was generated, and the rats were treated with TEN, oe-PTPN1 (PTP non-receptor type 1), a protein kinase B (Akt)/mammalian target of rapamycin (mTOR) antagonist LY294002, or an autophagy inhibitor 3-methyladenine (3-MA). Subsequently, locomotor function was detected. Pathological changes and neuronal activity in the spinal cord tissues were analyzed by hematoxylin and eosin staining, Nissl staining, and TUNEL assays. Protein expression of Beclin-1 and microtubule associated protein 1 light chain 3 beta (LC3B)-II/LC3B-I, PTPN1, IRS1, mTOR, and phosphorylated Akt (p-Akt) was analyzed by western blot assays. The LC3B expression was further examined by immunofluorescence staining.

RESULTS

Treatment with TEN restored the locomotor function of SCI rats, reduced the cavity area and cell apoptosis, upregulated growth-associated protein 43 and neurofilament 200, and decreased the Beclin-1 and LC3B-II/LC3B-I levels in the spinal cord. TEN suppressed PTPN1 protein level, while PTPN1 suppressed IRS1 protein to reduce the p-Akt and mTOR levels. Either PTPN1 overexpression or LY294002 treatment blocked the promoting effect of TEN on SCI recovery. However, treatment with 3-MA suppressed autophagy, which consequently rescued the locomotor function and reduced neuron loss induced by PTPN1.

CONCLUSION

This study demonstrates that TEN suppresses autophagy to promote function recovery in SCI rats by blocking PTPN1 and rescuing the IRS1/Akt/mTOR signaling.

Hederagenin Upregulates PTPN1 Expression in Aβ-Stimulated Neuronal Cells, Exerting Anti-Oxidative Stress and Anti-Apoptotic Activities

Alzheimer's disease (AD) is a prevalently neurodegenerative disease characterized by neuronal damage which is associated with amyloid-β (Aβ) accumulation. Hederagenin is a triterpenoid saponin, exerting anti-apoptotic, anti-oxidative, anti-inflammatory, anti-tumoral, and neuroprotective activities. However, its role in AD progression is still obscure. The aim of this study was to explore the influences of hederagenin on Aβ-caused neuronal injury in vitro. Neuronal cells were treated with Aβ25-35 (Aβ) to establish a cellular model of AD. Cell viability was assessed using cell counting kit-8 (CCK-8). Oxidative stress was evaluated by detecting reactive oxygen species (ROS) generation and superoxide dismutase (SOD) activity. Apoptosis was investigated using TUNEL staining and caspase-3 activity assays. Protein tyrosine phosphatase nonreceptor type 1 (PTPN1) was screened by bioinformatics analysis. Protein levels of PTPN1 and protein kinase B (Akt) were measured by western blotting. Hederagenin (2.5, 5, and 10 μM) alone did not affect viability of neuronal cells, but relieved Aβ-induced viability reduction. Hederagenin mitigated Aβ-induced increase in ROS accumulation and decrease in SOD activity. Hederagenin attenuated Aβ-induced increase in apoptotic rate and caspase-3 activity. PTPN1 was screened as a target of hederagenin against AD by bioinformatics analysis. Hederagenin treatment resisted Aβ-induced decrease in PTPN1 mRNA and protein levels in neuronal cells. PTPN1 silencing attenuated the suppressive functions of hederagenin in Aβ-stimulated oxidative stress and apoptosis. Hederagenin mitigated Aβ-induced Akt signaling inactivation by upregulating PTPN1 expression. In conclusion, hederagenin attenuates oxidative stress and apoptosis in neuronal cells stimulated with Aβ by promoting PTPN1/Akt signaling activation.

PTPN1 is a prognostic biomarker related to cancer immunity and drug sensitivity: from pan-cancer analysis to validation in breast cancer

Background

Protein tyrosine phosphatase non-receptor type 1 (PTPN1), a member of the protein tyrosine phosphatase superfamily, has been identified as an oncogene and therapeutic target in various cancers. However, its precise role in determining the prognosis of human cancer and immunological responses remains elusive. This study investigated the relationship between PTPN1 expression and clinical outcomes, immune infiltration, and drug sensitivity in human cancers, which will improve understanding regarding its prognostic value and immunological role in pan-cancer.

Methods

The PTPN1 expression profile was obtained from The Cancer Genome Atlas and Cancer Cell Line Encyclopedia databases. Kaplan-Meier, univariate Cox regression, and time-dependent receiver operating characteristic curve analyses were utilized to clarify the relationship between PTPN1 expression and the prognosis of pan-cancer patients. The relationships between PTPN1 expression and the presence of tumor-infiltrated immune cells were analyzed using Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data and Tumor Immune Estimation Resource. The cell counting kit-8 (CCK-8) assay was performed to examine the effects of PTPN1 level on the sensitivity of breast cancer cells to paclitaxel. Immunohistochemistry and immunoblotting were used to investigate the relationship between PTPN1 expression, immune cell infiltration, and immune checkpoint gene expression in human breast cancer tissues and a mouse xenograft model.

Results

The pan-cancer analysis revealed that PTPN1 was frequently up-regulated in various cancers. High PTPN1 expression was associated with poor prognosis in most cancers. Furthermore, PTPN1 expression correlated highly with the presence of tumor-infiltrating immune cells and the expression of immune checkpoint pathway marker genes in different cancers. Furthermore, PTPN1 significantly predicted the prognosis for patients undergoing immunotherapy. The results of the CCK-8 viability assay revealed that PTPN1 knockdown increased the sensitivity of MDA-MB-231 and MCF-7 cells to paclitaxel. Finally, our results demonstrated that PTPN1 was associated with immune infiltration and immune checkpoint gene expression in breast cancer.

Conclusion

PTPN1 was overexpressed in multiple cancer types and correlated with the clinical outcome and tumor immunity, suggesting it could be a valuable potential prognostic and immunological biomarker for pan-cancer.

High-expressed PTPN1 promotes tumor proliferation signature in human hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly prevalent malignant tumor that is associated with substantial morbidity and mortality rates. Despite the progress made in diagnostic technology, the survival rate of HCC patients remains unsatisfactory due to the complex nature and extensive metastasis of the disease. Consequently, the discovery of new molecular targets is of great practical significance for the diagnosis and treatment of HCC. Protein tyrosine phosphatases (PTPs) play a crucial role in cell signal transduction by catalyzing the dephosphorylation of tyrosine residues in proteins. The present study has revealed that the upregulation of protein tyrosine phosphatase non-receptor type 1 (PTPN1) is a characteristic feature of HCC and is associated with a poor prognosis. Additionally, our investigation into the functional roles of PTPN1-regulated genes in HCC has demonstrated that alterations in PTPN1 expression disrupt normal cell cycle progression metabolism. Additionally, the capacity for proliferation and migration of HCC cells was notably diminished subsequent to PTPN1 silencing, resulting in the prevention of cell entry into the S phase from the G1 phase. Our investigation indicates that PTPN1 may facilitate the onset and progression of HCC by disrupting the cell cycle, thereby presenting a promising molecular target for the diagnosis and treatment of liver cancer.

PTPN1 Deficiency Modulates BMPR2 Signaling and Induces Endothelial Dysfunction in Pulmonary Arterial Hypertension

Bone morphogenic protein receptor 2 (BMPR2) expression and signaling are impaired in pulmonary arterial hypertension (PAH). How BMPR2 signaling is decreased in PAH is poorly understood. Protein tyrosine phosphatases (PTPs) play important roles in vascular remodeling in PAH. To identify whether PTPs modify BMPR2 signaling, we used a siRNA-mediated high-throughput screening of 22,124 murine genes in mouse myoblastoma reporter cells using ID1 expression as readout for BMPR2 signaling. We further experimentally validated the top hit, PTPN1 (PTP1B), in healthy human pulmonary arterial endothelial cells (PAECs) either silenced by siRNA or exposed to hypoxia and confirmed its relevance to PAH by measuring PTPN1 levels in blood and PAECs collected from PAH patients. We identified PTPN1 as a novel regulator of BMPR2 signaling in PAECs, which is downregulated in the blood of PAH patients, and documented that downregulation of PTPN1 is linked to endothelial dysfunction in PAECs. These findings point to a potential involvement for PTPN1 in PAH and will aid in our understanding of the molecular mechanisms involved in the disease.

Targeting protein tyrosine phosphatase 1B in obesity-associated colon cancer: Possible role of sweet potato (Ipomoea batatas)

Protein tyrosine phosphatase 1B (PTP1B) has emerged as one of the links between obesity and colon cancer (CC). Anti-obesity and anti-CC attributes of sweet potato (Ipomoea batatas) reported sparsely. Here, we aimed to study the potential of PTP1B as a target in CC, particularly in obese population. Expression and genomic alteration frequency of PTPN1 (PTP1B) were checked in CC. Interacting partners of PTP1B through STRING and hub genes through Cytoscape (MCODE) were identified. Hub genes were subjected to functional enrichment analyses (via Metascape), differential gene expression, copy number variation, and single nucleotide variation analyses (GSCA database). Cancer-related pathways and associated immune infiltrates of the hub genes were checked too. Eleven sweet potato-derived compounds selected through drug likeness (DL) and toxicity filters were explored via molecular docking (AutoDock Vina) to reveal the interactions with PTP1B. Genomic alteration frequency of the PTPN1 was highest in CC compared to all the other TCGA cancers, and a high expression (RNA and protein) is also observed in CC that correlated well to a poor overall survival (OS). Furthermore, PTP1B and related proteins were enriched in different biological processes and signaling pathways related to carcinogenesis including epithelial-mesenchymal transition. Overall, PTP1B identified as a potential target in obesity-linked CC and sweet potato might exert its protective action by targeting the PTP1B. Sweet potato compounds (e.g., pelargonidin and luteolin) interacted with the catalytic P loop and the WPD loop of the PTP1B. Furthermore, MD simulation study ascertained that luteolin has the highest affinity against the PTP1B, whereas pelargonidin and quercetin showed good binding affinity too, thus can be explored further.

circMAP3K4 regulates insulin resistance in trophoblast cells during gestational diabetes mellitus by modulating the miR-6795-5p/PTPN1 axis

Background

Insulin resistance (IR) during gestational diabetes mellitus (GDM) has been linked to dysregulated insulin-PI3K/Akt pathway. A defective insulin-PI3K/Akt pathway and dysregulated circular RNA (circRNA) levels have been observed in the placentas of patients with GDM; however, the mechanisms underlying this association remain unclear.

Methods

circRNAs potentially associated with GDM were selected through bioinformatics analysis and initially identified by quantitative real-time PCR (qPCR) in 9 GDM patients and 9 healthy controls, of which circMAP3K4 was further validated in additional 84 samples by qPCR. circMAP3K4 identity and localization were verified. Pearson correlation analysis was applied to evaluate the correlation between circMAP3K4 expression in the placental tissues of GDM patients and IR-related indicators. An IR model of trophoblasts was constructed using glucosamine. Interactions between miR-6795-5p and circMAP3K4 or PTPN1 were confirmed using a dual-luciferase reporter assay. The circMAP3K4/miR-6795-5p/PTPN1 axis and key markers in the insulin-PI3K/Akt pathway in placentas and trophoblasts were evaluated through qRT-PCR, immunofluorescence, and western blotting. The role of circMAP3K4 in glucose metabolism and cell growth in trophoblasts was determined using the glucose uptake and CCK8 assay, respectively.

Results

circMAP3K4 was highly expressed in the placentas of patients with GDM and the IR trophoblast model; this was associated with a dysregulated insulin-PI3K/Akt pathway. circMAP3K4 in the placentas of GDM patients was positively correlated with weight gain during pregnancy and time-glucose area under the curve of OGTT. circMAP3K4 and PTPN1 could both bind to miR-6795-5p. miR-6795-5p and PTPN1 were downregulated and upregulated, respectively, in the placentas of GDM patients and the IR trophoblast model. circMAP3K4 silencing or miR-6795-5p overexpression partially reversed the decrease in glucose uptake, inhibition in cell growth, and downregulated IRS1 and Akt phosphorylation in IR-trophoblasts; this restoration was reversed upon co-transfection with an miR-6795-5p inhibitor or PTPN1.

Conclusion

circMAP3K4 could suppress the insulin-PI3K/Akt signaling pathway via miR-6795-5p/PTPN1 axis, probably contributing to GDM-related IR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03386-8.

Evaluation of Substitution of Small Branches with Roots of Desmodium gangeticum (Physicochemical Analysis, HPLC, and GC-MS Profiling) and In Silico Study of Pterocarpans for Pharmacological Target

The present research article proposes a conservative approach for the Desmodium gangeticum by using small branches instead of roots because the plant has many important chemical constituents that show different medicinal activity, so the plant's consumption is high. We studied here comparative preliminary phytochemical screening test and physicochemical analysis. The successive soxhlet extraction method was used for the successive extraction of roots and small branches with different solvents for comparative chemical profile study by HPLC and GC-MS. It was observed that many peaks in roots and small branches of the plant sample were almost similar, and the retention time of each peak in roots coincided with the retention of small branches of the sample. Therefore, the similarity was observed in roots and small branches of the Desmodium gangeticum plant in HPLC and GC-MS. The results obtained from HPLC analysis show that roots contain 0.00116% and small branches have 0.00026% of caffeic acid in Desmodium gangeticum. The small branches may have almost similar active chemical constituents like roots. In silico molecular docking study revealed that this plant's principal chemical constituents, pterocarpans, could be inhibitors of protein tyrosine phosphate kinase.

Nepetin Acts as a Multi-Targeting Inhibitor of Protein Tyrosine Phosphatases Relevant to Insulin Resistance

Protein tyrosine phosphatases (PTPs) are essential modulators of signal transduction pathways and has been implicated in many human diseases such as cancer, diabetes, obesity, autoimmune disorders, and neurological diseases, indicating that PTPs are next-generation drug targets. Since PTPN1, PTPN2, and PTPN11 have been reported to be negative regulators of insulin action, the identification of PTP inhibitors may be an effective strategy to develop therapeutic agents for the treatment of type 2 diabetes. In this study, we observed for the first time that nepetin inhibits the catalytic activity of PTPN1, PTPN2, and PTPN11 in vitro, indicating that nepetin acts as a multi-targeting inhibitor of PTPN1, PTPN2, and PTPN11. Furthermore, treatment of mature 3T3-L1 adipocytes with 20 μM nepetin stimulates glucose uptake through AMPK activation. Taken together, our findings provide evidence that nepetin, a multi-targeting inhibitor of PTPN1, PTPN2, and PTPN11, could be a promising therapeutic candidate for the treatment of type 2 diabetes.

Pharmacological Inhibition of miR-130 Family Suppresses Bladder Tumor Growth by Targeting Various Oncogenic Pathways via PTPN1

Previously, we have revealed that the miR-130 family (miR-130b, miR-301a, and miR-301b) functions as an oncomiR in bladder cancer. The pharmacological inhibition of the miR-130 family molecules by the seed-targeting strategy with an 8-mer tiny locked nucleic acid (LNA) inhibits the growth, migration, and invasion of bladder cancer cells by repressing stress fiber formation. Here, we searched for a functionally advanced target sequence with LNA for the miR-130 family with low cytotoxicity and found LNA #9 (A(L)^i^i^A(L)^T(L)^T(L)^G(L)^5(L)^A(L)^5(L)^T(L)^G) as a candidate LNA. LNA #9 inhibited cell growth in vitro and in an in vivo orthotopic bladder cancer model. Proteome-wide tyrosine phosphorylation analysis suggested that the miR-130 family upregulates a wide range of receptor tyrosine kinases (RTKs) signaling via the expression of phosphorylated Src (pSrc^Tyr416). SILAC-based proteome analysis and a luciferase assay identified protein tyrosine phosphatase non-receptor type 1 (PTPN1), which is implicated as a negative regulator of multiple signaling pathways downstream of RTKs as a target gene of the miR-130 family. The miR-130-targeted LNA increased and decreased PTPN1 and pSrc^Tyr416 expressions, respectively. PTPN1 knockdown led to increased tumor properties (cell growth, invasion, and migration) and increased pSrc^Tyr416 expression in bladder cancer cells, suggesting that the miR-130 family upregulates multiple RTK signaling by targeting PTPN1 and subsequent Src activation in bladder cancer. Thus, our newly designed miR-130 family targeting LNA could be a promising nucleic acid therapeutic agent for bladder cancer.

Combination of Sodium Cantharidinate with Cisplatin Synergistically Hampers Growth of Cervical Cancer

Background

Sodium cantharidinate (SC) has been broadly applied in lung cancer treatment in China, while its specific function in cervical cancer (CC), a great contributor to death of female reproductive system cancers, remains unclear. Our research evaluated the anti-tumor effects of SC in CC and the mechanism involved.

Methods

First, cisplatin (DDP)-resistant Caski-1 and ME180 cell lines were developed and treated with SC. The effects of SC on CC cell growth were then evaluated. Subsequently, the genes targeted by SC were predicted via the bioinformatics website. The correlations between PTPN1 expression and tumor stage, lymph node metastasis and tumor differentiation were examined. We further conducted rescue experiments by overexpressing PTPN1 in CC cells, followed by SC and cisplatin treatments. The activation of the PI3K/AKT pathway in CC cells, and the effect of SC on the growth and drug resistance of Caski-1 cells in vivo were investigated.

Results

The sensitivity of Caski-1 and ME180 cells to DDP was increased after SC treatment, which also enhanced the inhibitory effect of DDP on the cell growth. By prediction, we found that SC could target PTPN1. Patients with high expression of PTPN1 had higher clinical stage, lymph node metastasis and lower tumor differentiation. SC inhibited PTPN1 expression. Overexpression of PTPN1 attenuated the effect of SC. Furthermore, PTPN1 activated the PI3K/AKT pathway. Moreover, SC treatment inhibited the growth and drug resistance of Caski-1 cells in vivo.

Conclusion

SC promotes drug sensitivity of CC cells to DDP by targeting PTPN1, thereby impairing the PI3K/AKT pathway.

The phosphatase PTPN1/PTP1B is a candidate marker of better chemotherapy response in metastatic high-grade serous carcinoma

OBJECTIVE

To analyse the expression and clinical role of the phosphatase PTPN1 (PTP1B) in serous effusions.

METHODS

PTPN1 mRNA expression by quantitative RT-PCR was analysed in 83 high-grade serous carcinoma (HGSC) and 15 malignant mesothelioma (MM) effusions. PTP1B and phospho-PTP1B (pPTP1B) protein expression by immunohistochemistry was analysed in 62 HGSC and 44 MM effusions.

RESULTS

PTPN1 mRNA (P = .048), PTP1B protein (P = .047) and pPTP1B protein (P < .001) were overexpressed in HGSC compared to MM effusions. PTPN1 mRNA was additionally overexpressed in post-chemotherapy HGSC effusions compared to chemo-naïve effusions (P = .005). However, pPTP1B protein expression was higher in effusions from patients with FIGO stage III compared to stage IV (P = .006), and higher expressions of both PTPN1 mRNA (P = .041) and PTP1B protein (P = .035) in HGSC effusions were associated with better (complete) chemotherapy response at diagnosis. PTPN1 RNA and protein expression was unrelated to survival in HGSC, whereas a trend for shorter overall survival (P = .06) was found for MM patients whose tumours expressed pPTP1B protein.

CONCLUSION

PTPN1 is overexpressed in HGSC compared to MM effusions, and may be a marker of better chemotherapy response in the former. Whether PTPN1 activation is informative of adverse outcome in MM merits further investigation.

MiR-590-3p regulates cardiomyocyte P19CL6 proliferation, apoptosis and differentiation in vitro by targeting PTPN1 via JNK/STAT/NF-kB pathway

Cardiomyocyte differentiation is a multi-step process which involves a number of signalling pathways. microRNAs exhibit regulatory functions in various diseases and are involved in the signalling pathways in multiple physiological processes, but the specific functions of particular mRNAs is often not fully understood. of an example of this is that the role of miR-590-3p in the differentiation of cardiomyocytes remains unclear. In the current study, RT-qPCR was used to determine the expression of miR-590-3p in cardiomyocytes differentiated from the embryonic carcinoma cell line P19CL6. MTT, EdU, caspase-3 activity and flow cytometry assays were performed to examine the influence of miR-590-3p on cell behaviour. A luciferase assay was used to confirm binding between miR-590-3p and PTPN1. Western blotting was used to determine the relationship between the JNK/STAT/NF-kB pathway and PTPN1. The results inferred that miR-590-3p became heavily expressed in differentiated P19CL6. Knockdown miR-590-3p suppressed the cell proliferation while at the same time, accelerated apoptosis. Moreover, PTPN1 was identified as the target of miR-590-3p. More importantly, PTPN1 overexpression activated the JNK/STAT/NF-kB pathway and limited the differentiation of P19CL6. Thus the conclusions from this study are that miR-590-3p has the potential to regulate the proliferation, apoptosis and differentiation of cardiomyocyte P19CL6 in vitro by targeting PTPN1 via the JNK/STAT/NF-kB pathway.

Correcting abnormalities in miR-124/PTPN1 signaling rescues tau pathology in Alzheimer's disease

MicroRNAs have been implicated in diverse physiological and pathological processes. We previously reported that aberrant microRNA-124 (miR-124)/non-receptor-type protein phosphatase 1 (PTPN1) signaling plays an important role in the synaptic disorders associated with Alzheimer's disease (AD). In this study, we further investigated the potential role of miR-124/PTPN1 in the tau pathology of AD. We first treated the mice with intra-hippocampal stereotactic injections. Then, we used quantitative real-time reverse transcription PCR (qRT-PCR) to detect the expression of microRNAs. Western blotting was used to measure the level of PTPN1, the level of tau protein, the phosphorylation of tau at AD-related sites, and alterations in the activity of glycogen synthase kinase 3β (GSK-3β) and protein phosphatase 2 (PP2A). Immunohistochemistry was also used to detect changes in tau phosphorylation levels at AD-related sites and somadendritic aggregation. Soluble and insoluble tau protein was separated by 70% formic acid (FA) extraction to examine tau solubility. Finally, behavioral experiments (including the Morris water maze, fear conditioning, and elevated plus maze) were performed to examine learning and memory ability and emotion-related behavior. We found that artificially replicating the abnormalities in miR-124/PTPN1 signaling induced AD-like tau pathology in the hippocampus of wild-type mice, including hyperphosphorylation at multiple sites, insolubility and somadendritic aggregation, as well as learning/memory deficits. We also found that disruption of miR-124/PTPN1 signaling was caused by the loss of RE1-silencing transcription factor protein, which can be initiated by Aβ insults or oxidative stress, as observed in the brains of P301S mice. Correcting the deregulation of miR-124/PTPN1 signaling rescued the tau pathology and learning/memory impairments in the P301S mice. We also found that miR-124/PTPN1 abnormalities induced activation of glycogen synthase kinase 3 (GSK-3) and inactivation of protein phosphatase 2A (PP2A) by promoting tyrosine phosphorylation, implicating an imbalance in tau kinase/phosphatase. Thus, targeting the miR-124/PTPN1 signaling pathway is a promising therapeutic strategy for AD.

Protein tyrosine phosphatase PTPN1 modulates cell growth and associates with poor outcome in human neuroblastoma

Background

Protein tyrosine phosphatases (PTPs) regulate neuronal differentiation and survival, but their expression patterns and functions in human neuroblastoma (NB) are scarcely known. Here, we have investigated the function and expression of the non-receptor PTPN1 on human NB cell lines and human NB tumor samples.

Material/methods

NB tumor samples from 44 patients were analysed by immunohistochemistry using specific antibodies against PTPN1, PTPRH, PTPRZ1, and PTEN. PTPN1 knock-down, cell proliferation and tyrosine phosphorylation analyses, and RT-qPCR mRNA expression was assessed on SH-SY5Y, SMS-KCNR, and IMR-32 human NB cell lines.

Results

Knock-down of PTPN1 in SH-SY5Y NB cells resulted in increased tyrosine phosphorylation and cell proliferation. Retinoic acid-mediated differentiation of NB cell lines did not affect PTPN1 mRNA expression, as compared with other PTPs. Importantly, PTPN1 displayed high expression on NB tumors in association with metastasis and poor prognosis.

Conclusions

Our results identify PTPN1 as a candidate regulator of NB cell growth and a potential NB prognostic biomarker.

miR-125a-5p inhibits tumorigenesis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent and deadly cancers world-wide. miR-125a-5p is a tumor suppressor in HCC and other cancers, but its mechanisms of action during HCC tumorigenesis remain largely unknown. In this study, we found that miR-125a-5p expression was significantly lower in HCC tissues and cell lines than matched normal tissues and liver cells. miR-125a-5p overexpression inhibited HCC cell proliferation and induced apoptosis in vitro and in vivo, while miR-125a-5p knockdown had the opposite effects. In addition, PTPN1 and MAP3K11 were identified as targets of miR-125a-5p. Knocking down PTPN1 and MAP3K11 activated the JNK MAPK signaling pathway to suppress HCC cell proliferation and induce apoptosis. Our findings suggest that miR-125a-5p may be a useful therapeutic target for treatment of HCC patients.

PTPN1/2-mediated dephosphorylation of MITA/STING promotes its 20S proteasomal degradation and attenuates innate antiviral response

Upon cytosolic viral DNA stimulation, cGMP-AMP synthase (cGAS) catalyzes synthesis of 2'3'cGMP-AMP (cGAMP), which binds to the adaptor protein MITA (mediator of IRF3 activation, also called STING, stimulator of IFN genes) and induces innate antiviral response. How the activity of MITA/STING is regulated to avoid excessive innate immune response is not fully understood. Here we identified the tyrosine-protein phosphatase nonreceptor type (PTPN) 1 and 2 as MITA/STING-associated proteins. PTPN1 and PTPN2 are associated with MITA/STING following viral infection and dephosphorylate MITA/STING at Y245. Dephosphorylation of MITA/STING leads to its degradation via the ubiquitin-independent 20S proteasomal pathway, which is dependent on the intrinsically disordered region (IDR) of MITA/STING. Deficiencies of PTPN1 and PTPN2 enhance viral DNA-induced transcription of downstream antiviral genes and innate antiviral response. Our findings reveal that PTPN1/2-mediated dephosphorylation of MITA/STING and its degradation by the 20S proteasomal pathway is an important regulatory mechanism of innate immune response to DNA virus.

Association of PTPN1 polymorphisms with breast cancer risk: A case-control study in Chinese females

BACKGROUND

Breast cancer (BC) risk, development, and prognosis were closely related to obesity, diabetes mellitus, and metabolic syndrome. Protein tyrosine phosphatase, non-receptor type 1 (PTPN1) located on chromosome 20q13, could negatively regulate insulin and leptin signaling. In this study, we determined the association of PTPN1 polymorphisms with BC risk.

METHODS

We analyzed the distribution of 11 selected PTPN1 single nucleotide polymorphisms in Chinese female patients with BC (n = 953) and healthy controls (n = 963) based on a multicenter case-control study. The association of PTPN1 genotypes and haplotypes frequencies with BC risk were determined by logistic regression analysis. Analyses were further stratified by body mass index (BMI), waist-hip rate (WHR), diabetes mellitus history, and fasting plasma glucose level. The eQTL (expression Quantitative Trait Loci) analysis for PTPN1 was conducted by GTEx database.

RESULTS

There were significant differences between BC cases and control groups in menopausal status, number of births, and BMI. Four single nucleotide polymorphisms (SNPs; rs3215684, rs3787345, rs718049, and rs718050) decreased overall BC risk, and other seven SNPs showed no significant association with BC risk. In multivariate analysis, BMI and rs3215684 DT + DD genotype were identified as independent risk factors for BC, and mutated genotypes of rs3215684 were correlated with increased PTPN1 expression. There are no haplotypes showed different frequencies between cases and controls. In the stratified analysis, rs2206656 showed a significant association with decreased BC risk in the subgroup of BMI ≤ 24 kg/m ² , while rs3215684 and rs718049 showed lower BC risk in the subgroup of WHR > 0.85. Seven SNPs showed lower BC risk in the subgroup with diabetes mellitus history and/or fasting plasma glucose level ≥ 7 mM, while rs754118 decreased BC risk in the subgroup of fasting plasma glucose level < 7 mM.

CONCLUSION

Our findings suggest that PTPN1 SNPs associated with BC susceptibility in Chinese females, which also suggested a novel mechanism between obesity, diabetes mellitus, and BC risk.

Pristimerin inhibits glioma progression by targeting AGO2 and PTPN1 expression via miR-542-5p

Glioblastoma multiform is the most common and malignant primary tumor of the central nervous system in adults, the high recurrence rate and poor prognosis are critical priorities. Pristimerin is a naturally occurring quinone methide triterpenoid isolated from the Celastraceae and Hippocrateaceae families. Its anticancer effects have garnered considerable attention; nonetheless, the mechanisms of action remain unknown. To predict the hub genes of pristimerin, PharmMapper and the Coremine database were used to identify 13 potential protein targets; protein-protein interaction, for which functional enrichment analyses were performed. Compound-target, target-pathway, and compound-target-pathway networks were constructed using Cytoscape. Biological process analysis first revealed that enrichment of these target genes correlated with negative regulation of symbiont growth in the host, and regulation of chronic inflammatory response to antigenic stimulus. Survival analysis in cBioPortal showed that protein tyrosine phosphatase, non-receptor type 1 (PTPN1) and Argonaute 2 (AGO2) might be involved in the carcinogenesis, invasion, or recurrence of diffuse glioma. In addition, we observed that low-dose pristimerin inhibited the viability of glioma cells, while miR-542-5p in vitro; and reduced PTPN1 expression. Notably, high-dose pristimerin induced apoptosis. Furthermore, miR-542-5p silence with siRNA in glioma cells lead to the elevation in AGO2, and decreased PTPN1 level. The effect was obviously post pristimerin treatment and miR-542-5p suppression. In conclusion, pristimerin inhibited glioma progression through AGO2 and PTPN1 expression via a canonical miRNA-mediated mechanism.

Proteomic Maps of Human Gastrointestinal Stromal Tumor Subgroups

Gastrointestinal stromal tumor (GIST) is a common sarcoma of gastrointestinal tract (GIT) with high metastatic and recurrence rates, but the proteomic features are still less understood. Here we performed systematic quantitative proteome profiling of GIST from 13 patients classified into very low/low, intermediate and high risk subgroups. An extended cohort of GIST (n = 131) was used for immunohistochemical validation of proteins of interest. In total, 9177 proteins were quantified, covering 55.9% of the GIT transcriptome from The Human Protein Altas. Out of the 9177 quantified proteins, 4930 proteins were observed in all 13 cases with 517 upregulated and 187 downregulated proteins in tumorous tissues independent of risk stage. Pathway analysis showed that the downregulated proteins were mostly enriched in metabolic pathway, whereas the upregulated proteins mainly belonged to spliceosome pathway. In addition, 131 proteins showed differentially expressed patterns among GIST subgroups with statistical significance. The 13 GIST cases were classified into 3 subgroups perfectly based on the expression of these proteins. The intensive comparison of molecular phenotypes and possible functions of quantified oncoproteins, tumor suppressors, phosphatases and kinases between GIST subgroups was carried out. Immunohistochemical analysis of the phosphatase PTPN1 (n = 117) revealed that the GIST patients with high PTPN1 expression had low chances of developing metastasis. Collectively, this work provides valuable information for understanding the inherent biology and evolution of GIST.

A Novel MicroRNA-124/PTPN1 Signal Pathway Mediates Synaptic and Memory Deficits in Alzheimer's Disease

BACKGROUND

Synaptic loss is an early pathological event in Alzheimer's disease (AD), but its underlying molecular mechanisms remain largely unknown. Recently, microRNAs (miRNAs) have emerged as important modulators of synaptic function and memory.

METHODS

We used miRNA array and quantitative polymerase chain reaction to examine the alteration of miRNAs in AD mice and patients as well as the Morris water maze to evaluate learning and memory in the mice. We also used adeno-associated virus or lentivirus to introduce tyrosine-protein phosphatase non-receptor type 1 (PTPN1) expression of silencing RNAs. Long-term potentiation and Golgi staining were used to evaluate the synaptic function and structure. We designed a peptide to interrupt miR-124/PTPN1 interaction.

RESULTS

Here we report that neuronal miR-124 is dramatically increased in the hippocampus of Tg2576 mice, a recognized AD mouse model. Similar changes were observed in specific brain regions of affected AD individuals. We further identified PTPN1 as a direct target of miR-124. Overexpression of miR-124 or knockdown of PTPN1 recapitulated AD-like phenotypes in mice, including deficits in synaptic transmission and plasticity as well as memory by impairing the glutamate receptor 2 membrane insertion. Most importantly, rebuilding the miR-124/PTPN1 pathway by suppression of miR-124, overexpression of PTPN1, or application of a peptide that disrupts the miR-124/PTPN1 interaction could restore synaptic failure and memory deficits.

CONCLUSIONS

Taken together, these results identified the miR-124/PTPN1 pathway as a critical mediator of synaptic dysfunction and memory loss in AD, and the miR-124/PTPN1 pathway could be considered as a promising novel therapeutic target for AD patients.

Differential regulation of pro-inflammatory cytokine signalling by protein tyrosine phosphatases in pancreatic β-cells

Type 1 diabetes (T1D) is characterized by the destruction of insulin-producing β-cells by immune cells in the pancreas. Pro-inflammatory including TNF-α, IFN-γ and IL-1β are released in the islet during the autoimmune assault and signal in β-cells through phosphorylation cascades, resulting in pro-apoptotic gene expression and eventually β-cell death. Protein tyrosine phosphatases (PTPs) are a family of enzymes that regulate phosphorylative signalling and are associated with the development of T1D. Here, we observed expression of PTPN6 and PTPN1 in human islets and islets from non-obese diabetic (NOD) mice. To clarify the role of these PTPs in β-cells/islets, we took advantage of CRISPR/Cas9 technology and pharmacological approaches to inactivate both proteins. We identify PTPN6 as a negative regulator of TNF-α-induced β-cell death, through JNK-dependent BCL-2 protein degradation. In contrast, PTPN1 acts as a positive regulator of IFN-γ-induced STAT1-dependent gene expression, which enhanced autoimmune destruction of β-cells. Importantly, PTPN1 inactivation by pharmacological modulation protects β-cells and primary mouse islets from cytokine-mediated cell death. Thus, our data point to a non-redundant effect of PTP regulation of cytokine signalling in β-cells in autoimmune diabetes.