scholarly journals Novel role of STAT3 in microglia-dependent neuroinflammation after experimental subarachnoid haemorrhage

2021 ◽  
pp. svn-2021-001028
Author(s):  
Zhiyuan Vera Zheng ◽  
Junfan Chen ◽  
Hao Lyu ◽  
Sin Yu Erica Lam ◽  
Gang Lu ◽  
...  
Keyword(s):  
Subarachnoid Haemorrhage ◽  
Inflammatory Responses ◽  
Morphological Changes ◽  
Neuronal Loss ◽  
Signalling Pathway ◽  
Janus Kinase ◽  
Signal Transducer ◽  
Experimental Subarachnoid Haemorrhage ◽  
Stat3 Signalling

Background and purposeSignal transducer and activator of transcription 3 (STAT3) may contribute to the proinflammation in the central nervous system diseases by modulating the microglial responses. Thus, this study was intended to investigate the effect of STAT3 on microglia-dependent neuroinflammation and functional outcome after experimental subarachnoid haemorrhage (SAH).MethodsThe SAH model was established by endovascular perforation in the mouse. Real-time PCR (RtPCR) and western blot were used to examine the dynamic STAT3 signalling pathway responses after SAH. To clarify the role of the STAT3 signalling pathway in the microglia-dependent neuroinflammation after SAH, the microglia-specific STAT3 knockout (KO) mice were generated by the Cre-LoxP system. The neurological functions were assessed by Catwalk and Morris water maze tests. Neuronal loss after SAH was determined by immunohistochemistry staining. Microglial polarisation status after STAT3 KO was then examined by RtPCR and immunofluorescence.ResultsThe STAT3 and Janus kinase-signal transducer 2 activated immediately with the upregulation and phosphorylation after SAH. Downstream factors and related mediators altered dynamically and accordingly. Microglial STAT3 deletion ameliorated the neurological impairment and alleviated the early neuronal loss after SAH. To investigate the underlying mechanism, we examined the microglial reaction after STAT3 KO. STAT3 deletion reversed the increase of microglia after SAH. Loss of STAT3 triggered the early morphological changes of microglia and primed microglia from M1 to M2 polarisation. Functionally, microglial STAT3 deletion suppressed the SAH-induced proinflammation and promoted the anti-inflammation in the early phase.ConclusionsSTAT3 is closely related to the microglial polarisation transition and modulation of microglia-dependent neuroinflammation. Microglial STAT3 deletion improved neurological function and neuronal survival probably through promoting M2 polarisation and anti-inflammatory responses after SAH. STAT3 may serve as a promising therapeutic target to alleviate early brain injury after SAH.

The Role of Janus Kinase/Signal Transducer and Activator of Transcription Signalling on Preventing Intestinal Ischemia/Reperfusion Injury with Dexmedetomidine

2020 ◽  
Vol 20 (5) ◽  
pp. 3295-3302 ◽  
Author(s):  
Xuekang Zhang ◽  
Jun Zhou ◽  
Qian Hu ◽  
Zhengren Liu ◽  
Qiuhong Chen ◽  
...  
Keyword(s):  
Intestinal Ischemia ◽  
Caspase 3 ◽  
Ischemia Reperfusion ◽  
Subcutaneous Administration ◽  
Janus Kinase ◽  
Signal Transducer ◽  
Jak2 Inhibitor ◽  
Intestinal Ischemia Reperfusion ◽  
Stat3 Signalling

Dexmedetomidine (Dex) works as a crucial agent for the treatment of intestinal ischemia/reperfusion (I/R), but its mechanism remains unclear. Recent articles demonstrated the pivotal role of Janus kinase/signal transducer and activator of transcription (JAK2/STAT3) signalling in I/R. Therefore, it is reasonable to explore the associated mechanism of JAK2/STAT3 signalling in Dex treatment. The study purpose was to evaluate the JAK2/STAT3 signalling regulatory mechanisms of Dex in preventing I/R. Anaesthetized rats were subjected to superior mesenteric artery occlusion consisting of 1 h of ischemia and 2 h of reperfusion while served as controls. Animals received subcutaneous administration of 50 μg/kg Dex, JAK1 and JAK2 inhibitor, Ruxolitinib, selective JAK2 inhibitor, 10 mg/kg AG490 or STAT inhibitor and 0.4 mg/kg rapamycin; or Dex-treatment in the presence of α2-adrenoceptor antagonists Atip or Dex-treatment alone after I/R. Injury was scored histologically, apoptosis was detected via the apoptotic mediators caspase-3 and Bcl-2/Bax and the degree of activation of the JAK/STAT pathway was evaluated. Dex inhibited I/R injury by decreasing apoptosis significantly with rescue of cleaved caspase-3 and the Bcl-2/Bax ratio. Furthermore, phosphorylation of JAK2, STAT1 and STAT3 was affected, suggesting the involvement of activated JAK/STAT in response to Dex. Meanwhile, the JAK2 or STAT inhibitors AG490 and rapamycin, but not Ruxolitinib, exhibited a similar but even greater JAK2 and STAT3 regulatory effect, thus leading to a greater benefit. JAK2/STAT3 activation is crucial to the diminishing effect of Dex on mesenteric I/R injury; however, the efficacy and timing of Dex administration should be considered in clinical practice.

scholarly journals The role of signal transducer and activator of transcription 5 in the inhibitory effects of GH on adipocyte differentiation

2003 ◽  
Vol 30 (2) ◽  
pp. 139-150 ◽  
Author(s):  
HE Richter ◽  
T Albrektsen ◽  
N Billestrup
Keyword(s):  
Tyrosine Phosphorylation ◽  
Janus Kinase ◽  
Peroxisome Proliferator ◽  
Transactivation Domain ◽  
Signal Transducer ◽  
Inhibitory Effects ◽  
Preadipocyte Differentiation ◽  
Peroxisome Proliferator Activated Receptor ◽  
Fatty Acid Binding

GH inhibits primary rat preadipocyte differentiation and expression of late genes required for terminal differentiation. Here we show that GH-mediated inhibition of fatty acid-binding protein aP2 gene expression correlates with the activation of the Janus kinase-2/signal transducer and activator of transcription (STAT)-5 signalling pathway. Within minutes of treatment, GH induced the tyrosine phosphorylation, nuclear localization and DNA binding of STAT5. Importantly, there was no evidence that STAT5 acted via an interaction with peroxisome proliferator-activated receptor gamma. To further understand the mechanism of STAT5 action, we reconstituted the inhibition of aP2 in a non-adipogenic cell line. Using this system, we showed that the ability of GH to inhibit a 520 bp aP2 reporter was largely dependent upon the presence of either STAT5A or STAT5B. Mutant analysis confirmed that the tyrosine phosphorylation of STAT5 was essential for this signalling. However, STAT5's C-terminal transactivation domain was fully dispensable for this inhibition. Taken together, these data confirm a key regulatory role of STAT5 in adipose tIssue and point to STAT5 as the repressing modulator of GH-mediated inhibition in primary preadipocytes.

scholarly journals The use of Drosophila Melanogaster as a Model Organism to study the effect of Innate Immunity on Metabolism

2020 ◽  
Author(s):  
Abeer Mohbeddin ◽  
Nawar Haj Ahmed ◽  
Layla Kamareddine
Keyword(s):  
Drosophila Melanogaster ◽  
Fat Body ◽  
Model Organism ◽  
Fruit Fly ◽  
Janus Kinase ◽  
Signal Transducer ◽  
Metabolic Homeostasis ◽  
Stat Signaling ◽  
Stat Pathway

Apart from its traditional role in disease control, recent body of evidence has implicated a role of the immune system in regulating metabolic homeostasis. Owing to the importance of this “immune-metabolic alignment” in dictating a state of health or disease, a proper mechanistic understanding of this alignment is crucial in opening up for promising therapeutic approaches against a broad range of chronic, metabolic, and inflammatory disorders like obesity, diabetes, and inflammatory bowel syndrome. In this project, we addressed the role of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) innate immune pathway in regulating different metabolic parameters using the Drosophila melanogaster (DM) fruit fly model organism. Mutant JAK/STAT pathway flies with a systemic knockdown of either Domeless (Dome) [domeG0282], the receptor that activates JAK/STAT signaling, or the signal-transducer and activator of transcription protein at 92E (Stat92E) [stat92EEY10528], were used. The results of the study revealed that blocking JAK/STAT signaling alters the metabolic profile of mutant flies. Both domeG0282 and stat92EEY10528 mutants had an increase in body weight, lipid deprivation from their fat body (lipid storage organ in flies), irregular accumulation of lipid droplets in the gut, systemic elevation of glucose and triglyceride levels, and differential down-regulation in the relative gene expression of different peptide hormones (Tachykinin, Allatostatin C, and Diuretic hormone 31) known to regulate metabolic homeostasis in flies. Because the JAK/STAT pathway is evolutionary conserved between invertebrates and vertebrates, our potential findings in the fruit fly serves as a platform for further immune-metabolic translational studies in more complex mammalian systems including humans.

scholarly journals The JAK/STAT signaling pathway: from bench to clinic

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Xiaoyi Hu ◽  
Jing li ◽  
Maorong Fu ◽  
Xia Zhao ◽  
Wei Wang
Keyword(s):  
Signaling Pathway ◽  
Current Knowledge ◽  
Janus Kinase ◽  
Signal Transducer ◽  
Quarter Century ◽  
Cellular Processes ◽  
Stat Signaling ◽  
Cancer And Inflammation ◽  
Stat Pathway

AbstractThe Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway was discovered more than a quarter-century ago. As a fulcrum of many vital cellular processes, the JAK/STAT pathway constitutes a rapid membrane-to-nucleus signaling module and induces the expression of various critical mediators of cancer and inflammation. Growing evidence suggests that dysregulation of the JAK/STAT pathway is associated with various cancers and autoimmune diseases. In this review, we discuss the current knowledge about the composition, activation, and regulation of the JAK/STAT pathway. Moreover, we highlight the role of the JAK/STAT pathway and its inhibitors in various diseases.

The Role of STAT3 Signaling in Different Types of Cancers: A Comprehensive Review

2020 ◽  
Vol 16 (3) ◽  
pp. 189-198
Author(s):  
Kaviarasan Lakshmanan ◽  
Gowramma Byran ◽  
Sravanthi Bandlamudi ◽  
Praveen Thaggikuppe Krishnamurthy
Keyword(s):  
Cancer Progression ◽  
Myeloid Leukemia ◽  
Inflammatory Responses ◽  
Vital Role ◽  
Signal Transducer ◽  
Stat3 Signaling ◽  
Solid Malignancies ◽  
Different Types ◽  
Tumor Growth And Metastasis

Signal transducer and activator of transcription (STAT3) is an important transcription factor capable of mediating or even driving cancer progression through hyperactivation or gain-offunction mutations. It plays a key role in regulating host immune and inflammatory responses and in the pathogenesis of many cancers. However, compelling evidence suggests that STAT3 is constitutively activated in many cancers and plays a vital role in tumor growth and metastasis. Hyperactive STAT3 is also implicated in various hematopoietic and solid malignancies, such as chronic and acute myeloid leukemia, melanoma or prostate cancer. The classical understanding of STAT functions is linked to their phosphorylated parallel dimer conformation, in which they induce gene transcription. In this review, we discuss the functions and the roles of STAT3 signal in various types of cancers.

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