The role of AGK in thrombocytopoiesis and possible therapeutic strategies

Blood ◽  
2020 ◽  
Vol 136 (1) ◽  
pp. 119-129
Author(s):  
Haojie Jiang ◽  
Zhuo Yu ◽  
Nan Ding ◽  
Mina Yang ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Kinase Activity ◽  
Jak2 V617f ◽  
Extramedullary Hematopoiesis ◽  
Janus Kinase ◽  
Stat3 Signaling ◽  
Sengers Syndrome ◽  
Novel Strategy ◽  
Domain Peptide ◽  
Risk Of Hemorrhage ◽  
Megakaryocyte Differentiation

Abstract Abnormal megakaryocyte development and platelet production lead to thrombocytopenia or thrombocythemia and increase the risk of hemorrhage or thrombosis. Acylglycerol kinase (AGK) is a mitochondrial membrane kinase that catalyzes the formation of phosphatidic acid and lysophosphatidic acid. Mutation of AGK has been described as the major cause of Sengers syndrome, and the patients with Sengers syndrome have been reported to exhibit thrombocytopenia. In this study, we found that megakaryocyte/platelet-specific AGK-deficient mice developed thrombocytopenia and splenomegaly, mainly caused by inefficient bone marrow thrombocytopoiesis and excessive extramedullary hematopoiesis, but not by apoptosis of circulating platelets. It has been reported that the G126E mutation arrests the kinase activity of AGK. The AGK G126E mutation did not affect peripheral platelet counts or megakaryocyte differentiation, suggesting that the involvement of AGK in megakaryocyte development and platelet biogenesis was not dependent on its kinase activity. The Mpl/Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (Stat3) pathway is the major signaling pathway regulating megakaryocyte development. Our study confirmed that AGK can bind to JAK2 in megakaryocytes/platelets. More interestingly, we found that the JAK2 V617F mutation dramatically enhanced the binding of AGK to JAK2 and greatly facilitated JAK2/Stat3 signaling in megakaryocytes/platelets in response to thrombopoietin. We also found that the JAK2 JAK homology 2 domain peptide YGVCF617CGDENI enhanced the binding of AGK to JAK2 and that cell-permeable peptides containing YGVCF617CGDENI sequences accelerated proplatelet formation. Therefore, our study reveals critical roles of AGK in megakaryocyte differentiation and platelet biogenesis and suggests that targeting the interaction between AGK and JAK2 may be a novel strategy for the treatment of thrombocytopenia or thrombocythemia.

NS-018, a Potent Novel JAK2 Inhibitor, Effectively Treats Murine MPN Induced by the Janus Kinase 2 (JAK2) V617F Mutant

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4106-4106 ◽  
Author(s):  
Kotaro Shide ◽  
Yohei Nakaya ◽  
Takuro Kameda ◽  
Haruko Shimoda ◽  
Tomonori Hidaka ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Myeloid Cells ◽  
Body Weight Loss ◽  
Jak2 V617f ◽  
Extramedullary Hematopoiesis ◽  
Janus Kinase ◽  
Vehicle Group ◽  
Control Groups ◽  
Jak2 Inhibitor ◽  
Dose Dependent

Abstract Abstract 4106 An activating mutation in the Janus kinase 2 gene (JAK2) (G1849T, which produces JAK2 V617F) occurs at a high frequency in Bcr-Abl-negative myeloproliferative neoplasms (MPNs). JAK2 V617F induces cytokine-independent growth in cell lines and, in murine models, recapitulates much of the pathobiology observed in MPN patients, suggesting that small-molecule inhibitors targeting JAK2 may be therapeutically useful. Some orally bioavailable inhibitors of JAK2 are already in clinical trials. NS-018 is a novel JAK2 inhibitor that inhibits JAK2 enzyme activity with an IC50 value of less than 1 nM. NS-018 shows 30–50-fold selectivity for JAK2 over other JAK-family kinases such as JAK1, JAK3 and TYK2. We tested NS-018 in a murine model of MPN induced by JAK2 V617F. Mice expressing JAK2 V617F controlled by the H2Kb promoter (V617F-TG mice) show an MPN phenotype: leukocytosis, thrombocytosis, progressive anemia, hepatosplenomegaly with extramedullary hematopoiesis, megakaryocyte hyperplasia and bone marrow fibrosis. They also exhibit body weight loss and high mortality compared to wild-type controls. Bone-marrow cells show constitutive activation of STAT5 and cytokine-independent growth of erythroid colony-forming units (CFU-E). NS-018 inhibited cytokine-independent CFU-E growth and constitutive activation of STAT5 in V617F-TG cells in vitro. For in vivo experiments, V617F-TG mice were divided into treatment and vehicle control groups after disease was established at 12 weeks after birth. NS-018 was administered for 24 weeks by oral gavage at doses of 25 mg/kg or 50 mg/kg bid, and the control groups received vehicle only. Mice were monitored by blood counts, and a subset of mice was euthanized for detailed histopathology and fluorescence activated cell sorting analysis. During the study, 12 of 34 mice died in the vehicle group, whereas 1 of 36 mice died in the 50 mg/kg group. There was a statistically significant prolongation of survival in the 50 mg/kg group (p<0.01). Mice treated with NS-018 gained more weight than vehicle-treated mice, and were comparable to wild-type mice. V617F-TG at 12 weeks old showed severe leukocytosis with average white blood cell counts of 24 × 1010/L. After two weeks of NS-018 treatment, the leukocyte count was reduced to 59% in 25 mg/kg group and 39% in the 50 mg/kg group compared to vehicle group, and the effect was maintained until the end of the study. The inhibitory effect of NS-018 on T or B lymphocytes was much less than on myeloid cells. The 50 mg/kg group showed no progression of anemia. NS-018 treatment also improved hepatosplenomegaly in a dose-dependent manner. In the spleen, Mac-1/Gr-1+ myeloid cells associated with extramedullary hematopoiesis were significantly decreased, and B220+ B cells were increased by NS-018 treatment. In correlation with reduction of organ weights and infiltrating myeloid cells, there was also clear evidence of a dose-dependent reduction in the histopathology of extramedullary hematopoiesis in the spleen, liver, and lungs of NS-018-treated mice. In contrast to the improvement in the pathology of these organs, NS-018 had little impact on the progression of fibrosis and megakaryocyte hyperplasia in bone marrow. No significant toxicity was observed in treated mice. In conclusion, NS-018 demonstrated therapeutic efficacy in a murine model of MPN induced by JAK2 V617F. In V617F-TG, which closely mimics human MPN, NS-018 significantly improved survival, body weight loss, hepatosplenomegaly, leukocytosis and anemia progression, thus confirming the viability of a targeted-therapy approach in managing JAK2 V617F positive MPNs. On the basis of these preclinical experiments, NS-018 appears to be an excellent candidate for phase I/II studies in patients with Bcr-Abl-negative MPNs. Disclosures: Nakaya: Nippon Shinyaku Co., Ltd: Employment. Homan:Nippon Shinyaku Co., Ltd: Employment. Kotera:Nippon Shinyaku Co., Ltd: Employment. Shibayama:Nippon Shinyaku Co., Ltd: Employment. Naito:Nippon Shinyaku Co., Ltd: Employment. Shimoda:Nippon Shinyaku Co., Ltd: Research Funding.

scholarly journals Brevilin A, a Novel Natural Product, Inhibits Janus Kinase Activity and Blocks STAT3 Signaling in Cancer Cells

PLoS ONE ◽  
2013 ◽  
Vol 8 (5) ◽  
pp. e63697 ◽  
Author(s):  
Xing Chen ◽  
Yuping Du ◽  
Jing Nan ◽  
Xinxin Zhang ◽  
Xiaodong Qin ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Natural Product ◽  
Kinase Activity ◽  
Janus Kinase ◽  
Stat3 Signaling

scholarly journals Emerin Represses STAT3 Signaling through Nuclear Membrane-Based Spatial Control

2021 ◽  
Vol 22 (13) ◽  
pp. 6669
Author(s):  
Byongsun Lee ◽  
Seungjae Lee ◽  
Younggwang Lee ◽  
Yongjin Park ◽  
Jaekyung Shim
Keyword(s):  
Muscular Dystrophy ◽  
Nuclear Membrane ◽  
Target Genes ◽  
Janus Kinase ◽  
C2c12 Cells ◽  
Specific Gene ◽  
Lamin A ◽  
Stat3 Signaling ◽  
Exact Function ◽  
Muscle Homeostasis

Emerin is the inner nuclear membrane protein involved in maintaining the mechanical integrity of the nuclear membrane. Mutations in EMD encoding emerin cause Emery-Dreifuss muscular dystrophy (EDMD). There has been accumulating evidence that emerin regulation of specific gene expression is associated with this disease, but the exact function of emerin has still less revealing. Here, we have shown that emerin downregulates signal transducers and activators of transcription 3 (STAT3) signaling, activated exclusively by Janus-kinase (JAK). Deletion mutation experiments showed that the lamin-binding domain of emerin is essential for the inhibition of STAT3 signaling. Emerin interacted directly and co-localized with STAT3 in the nuclear membrane. Emerin knockdown induced STAT3 target genes Bcl2 and Survivin to increase cell survival signals and suppress hydrogen peroxide-induced cell death in HeLa cells. Specifically, downregulation of BAF or lamin A/C increases STAT3 signaling, suggesting that correct-localized emerin by assembling with BAF and lamin A/C acts as an intrinsic inhibitor against STAT3 signaling. In C2C12 cells, emerin knockdown induced STAT3 target gene, Pax7, and activated abnormal myoblast proliferation associated with muscle wasting in skeletal muscle homeostasis. Our results indicate that emerin downregulates STAT3 signaling by inducing retention of STAT3 and delaying STAT3 signaling in the nuclear membrane. This mechanism provides clues to the etiology of emerin-related muscular dystrophy and could be a new therapeutic target for treatment.

scholarly journals Primary Myelofibrosis-Related Renal Disorders Treated with a Janus Kinase Inhibitor

2021 ◽  
pp. 1-9
Author(s):  
Mea Asou ◽  
Tomohiko Asakawa ◽  
Makoto Araki ◽  
Takashi Ehara ◽  
Tsunekazu Hishima ◽  
...  
Keyword(s):  
Interstitial Nephritis ◽  
Kinase Inhibitor ◽  
White Blood Cells ◽  
Primary Myelofibrosis ◽  
Myeloproliferative Disorders ◽  
Detailed Examination ◽  
Extramedullary Hematopoiesis ◽  
Janus Kinase ◽  
Interstitial Tissue ◽  
Renal Disorders

Extramedullary hematopoiesis is widely known to occur in patients with primary myelofibrosis (PMF). Autopsy studies on individuals with PMF revealed that extramedullary hematopoiesis occurred in the kidneys in 35% of the cases, but there is little awareness regarding such lesions. A 63-year-old man was diagnosed with PMF based on a detailed examination of persistent high white blood cells. An examination of the patient’s medical records revealed an increased white blood cell count, deterioration of kidney function, and urinary protein excretion developed simultaneously. Thus, a kidney biopsy was performed. Advanced lymphocyte invasion was recognized in the interstitial tissue, and the tubular structure was highly disrupted. Based on these findings, he was diagnosed with interstitial nephritis. However, because of the large number of cells with nuclear atypia in the stroma, additional immunohistochemical staining was also performed, such as glycophorin A, naphthol AS-D, myeloperoxidase, and CD42b. As a result, invasion of three lineages of immature cells, erythroblasts, megakaryocytes, and granulocytes, was identified. Renal dysfunction resulting from interstitial cellular infiltration due to extramedullary hematopoiesis was therefore diagnosed. Treatment with ruxolitinib was initiated after a renal biopsy and the rate of decline in renal function was slightly reduced. Although, in myeloproliferative disorders, proliferative glomerular lesions are widely considered to be renal disorders, there is little awareness regarding interstitial lesions. Extramedullary hematopoiesis of the kidney in PMF is not uncommon, but 40% of cases are reportedly misdiagnosed as interstitial nephritis. Because extramedullary hematopoiesis can be controlled by ruxolitinib, early detection is important.

scholarly journals Increased Hypothalamic Signal Transducer and Activator of Transcription 3 Phosphorylation after Hindbrain Leptin Injection

Endocrinology ◽  
2010 ◽  
Vol 151 (4) ◽  
pp. 1509-1519 ◽  
Author(s):  
Marieke Ruiter ◽  
Patricia Duffy ◽  
Steven Simasko ◽  
Robert C. Ritter
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Fourth Ventricle ◽  
Leptin Receptor ◽  
Janus Kinase ◽  
Signal Transducer ◽  
Solitary Tract ◽  
Stat3 Signaling ◽  
Stat3 Phosphorylation ◽  
Transcription 3

Reduction of food intake and body weight by leptin is attributed largely to its action in the hypothalamus. However, the signaling splice variant of the leptin receptor, LRb, also is expressed in the hindbrain, and leptin injections into the fourth cerebral ventricle or dorsal vagal complex are associated with reductions of feeding and body weight comparable to those induced by forebrain leptin administration. Although these observations suggest direct hindbrain action of leptin on feeding and body weight, the possibility that hindbrain leptin administration also activates the Janus kinase/signal transducer and activator of transcription 3 (STAT3) signaling in the hypothalamus has not been investigated. Confirming earlier work, we found that leptin produced comparable reductions of feeding and body weight when injected into the lateral ventricle or the fourth ventricle. We also found that lateral and fourth ventricle leptin injections produced comparable increases of STAT3 phosphorylation in both the hindbrain and the hypothalamus. Moreover, injection of 50 ng of leptin directly into the nucleus of the solitary tract also increased STAT3 phosphorylation in the hypothalamic arcuate and ventromedial nuclei. Increased hypothalamic STAT3 phosphorylation was not due to elevation of blood leptin concentrations and the pattern of STAT3 phosphorylation did not overlap distribution of the retrograde tracer, fluorogold, injected via the same cannula. Our observations indicate that even small leptin doses administered to the hindbrain can trigger leptin-related signaling in the forebrain, and raise the possibility that STAT3 phosphorylation in the hypothalamus may contribute to behavioral and metabolic changes observed after hindbrain leptin injections.

A natural product phillygenin suppresses osteosarcoma growth and metastasis by regulating the SHP-1/JAK2/STAT3 signaling

2021 ◽  
Vol 85 (2) ◽  
pp. 307-314
Author(s):  
Xiaomin Ding ◽  
Danqing Lu ◽  
Jianbo Fan
Keyword(s):  
Cell Growth ◽  
Signaling Pathway ◽  
Janus Kinase ◽  
Potential Candidate ◽  
Osteosarcoma Cell ◽  
Cancer Cell Growth ◽  
Functional Roles ◽  
Stat3 Signaling ◽  
Stat3 Signaling Pathway

ABSTRACT Osteosarcoma represents one of the most devastating cancers due to its high metastatic potency and fatality. Osteosarcoma is insensitive to traditional chemotherapy. Identification of a small molecule that blocks osteosarcoma progression has been a challenge in drug development. Phillygenin, a plant-derived tetrahydrofurofuran lignin, has shown to suppress cancer cell growth and inflammatory response. However, how phillygenin plays functional roles in osteosarcoma has remained unveiled. In this study, we showed that phillygenin inhibited osteosarcoma cell growth and motility in vitro. Further mechanistic studies indicated that phillygenin blocked STAT3 signaling pathway. Phillygenin led to significant downregulation of Janus kinase 2 and upregulation of Src homology region 2 domain-containing phosphatase 1. Gene products of STAT3 regulating cell survival and invasion were also inhibited by phillygenin. Therefore, our studies provided the first evidence that phillygenin repressed osteosarcoma progression by interfering STAT3 signaling pathway. Phillygenin is a potential candidate in osteosarcoma therapy.

scholarly journals P019 Colonic mucosal kinase activity, cytokine and chemokine profiles in inflammatory bowel disease

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S139-S140
Author(s):  
E Brand ◽  
B Roosenboom ◽  
B Malvar Fernandez ◽  
L Lutter ◽  
E van Koolwijk ◽  
...  
Keyword(s):  
Inflammatory Bowel Disease ◽  
Bowel Disease ◽  
Kinase Activity ◽  
Cell Signalling ◽  
Explant Culture ◽  
Janus Kinase ◽  
Oncostatin M ◽  
Healthy Control ◽  
Inflammatory Bowel ◽  
The Difference

Abstract Background With the approval of tofacitinib, an oral Janus Kinase (JAK) inhibitor, modulation of kinase activity has been added to the therapeutic armamentarium of inflammatory bowel disease (IBD). Despite its established efficacy, at least a third of patients will not respond to this or other therapeutic options such as anti-tumour necrosis factor (TNF), anti-interleukin (IL)23/IL12 compounds or vedolizumab. A better understanding of the inflammatory profile could aid in tailoring drugs to individual patients. We therefore explored mucosal cytokine, chemokine and kinase activity profiles in IBD. Methods Colonic mucosal biopsies were collected from (1) patients with Crohn’s disease (CD, N = 8), (2) patients with ulcerative colitis (UC, N = 8) and (3) healthy controls (N = 4). IBD samples were collected both from inflamed and non-inflamed tissue from the same patients. All IBD patients were biological-naïve and had not used corticosteroids in the past 3 months. Biopsies were snap frozen for later kinase activity determination or directly used in a 24-h explant culture. Whole biopsy kinase activity (tyrosine, serine and threonine kinases) was assessed using the Pamgene platform. A 64-analyte panel was examined in the supernatant of the cultured biopsies employing a multiplex assay (Luminex). Results Whole-biopsy kinase activity differed between inflamed and non-inflamed mucosa of IBD patients, with more overall tyrosine kinase activity in inflamed mucosa in UC, and serine/threonine kinase activity in inflamed mucosa in CD as compared with non-inflamed mucosa (Figure 1). The kinase activity profile of non-inflamed mucosa of CD and UC patients was similarly different from mucosa of healthy control participants (Figure 2). The cytokine and chemokine profile of inflamed biopsies differed from non-inflamed IBD biopsies and healthy control biopsies, with higher levels of S100A8, TNFα, IL-6, oncostatin M (OSM) and triggering receptor expressed on myeloid cells-1 (TREM-1), amongst others (Figure 3). Conclusion In IBD, inflammation in the mucosa can be characterised both by explant-culture and kinase activity assessment. The difference in kinase activity between non-inflamed IBD mucosa and healthy control mucosa suggests the presence of sub-clinical alterations in cell signalling. The observed differences in the kinase, cytokine and chemokine profiles underscore the importance of this approach in the elucidation of the pathophysiology in IBD.

scholarly journals STAT5 is Expressed in CD34+/CD38− Stem Cells and Serves as a Potential Molecular Target in Ph-Negative Myeloproliferative Neoplasms

Cancers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1021 ◽  
Author(s):  
Emir Hadzijusufovic ◽  
Alexandra Keller ◽  
Daniela Berger ◽  
Georg Greiner ◽  
Bettina Wingelhofer ◽  
...  
Keyword(s):  
Stem Cells ◽  
Myeloproliferative Neoplasms ◽  
Jak2 V617f ◽  
Primary Myelofibrosis ◽  
Janus Kinase ◽  
Signaling Cascades ◽  
Nuclear Compartment ◽  
Downstream Signaling ◽  
Direct Targeting ◽  
Calr Mutations

Janus kinase 2 (JAK2) and signal transducer and activator of transcription-5 (STAT5) play a key role in the pathogenesis of myeloproliferative neoplasms (MPN). In most patients, JAK2 V617F or CALR mutations are found and lead to activation of various downstream signaling cascades and molecules, including STAT5. We examined the presence and distribution of phosphorylated (p) STAT5 in neoplastic cells in patients with MPN, including polycythemia vera (PV, n = 10), essential thrombocythemia (ET, n = 15) and primary myelofibrosis (PMF, n = 9), and in the JAK2 V617F-positive cell lines HEL and SET-2. As assessed by immunohistochemistry, MPN cells displayed pSTAT5 in all patients examined. Phosphorylated STAT5 was also detected in putative CD34+/CD38− MPN stem cells (MPN-SC) by flow cytometry. Immunostaining experiments and Western blotting demonstrated pSTAT5 expression in both the cytoplasmic and nuclear compartment of MPN cells. Confirming previous studies, we also found that JAK2-targeting drugs counteract the expression of pSTAT5 and growth in HEL and SET-2 cells. Growth-inhibition of MPN cells was also induced by the STAT5-targeting drugs piceatannol, pimozide, AC-3-019 and AC-4-130. Together, we show that CD34+/CD38− MPN-SC express pSTAT5 and that pSTAT5 is expressed in the nuclear and cytoplasmic compartment of MPN cells. Whether direct targeting of pSTAT5 in MPN-SC is efficacious in MPN patients remains unknown.

Sign in / Sign up

Export Citation Format

Share Document