IL-13 upregulates GPIIb expression in megakaryocytic cell lines via STAT6

Interleukins in Platelet Biology: Unraveling the Complex Regulatory Network

Interleukins, a diverse family of cytokines produced by various cells, play crucial roles in immune responses, immunoregulation, and a wide range of physiological and pathological processes. In the context of megakaryopoiesis, thrombopoiesis, and platelet function, interleukins have emerged as key regulators, exerting significant influence on the development, maturation, and activity of megakaryocytes (MKs) and platelets. While the therapeutic potential of interleukins in platelet-related diseases has been recognized for decades, their clinical application has been hindered by limitations in basic research and challenges in drug development. Recent advancements in understanding the molecular mechanisms of interleukins and their interactions with MKs and platelets, coupled with breakthroughs in cytokine engineering, have revitalized the field of interleukin-based therapeutics. These breakthroughs have paved the way for the development of more effective and specific interleukin-based therapies for the treatment of platelet disorders. This review provides a comprehensive overview of the effects of interleukins on megakaryopoiesis, thrombopoiesis, and platelet function. It highlights the potential clinical applications of interleukins in regulating megakaryopoiesis and platelet function and discusses the latest bioengineering technologies that could improve the pharmacokinetic properties of interleukins. By synthesizing the current knowledge in this field, this review aims to provide valuable insights for future research into the clinical application of interleukins in platelet-related diseases.

Expression of arachidonic acid-metabolizing cytochrome P450s in human megakaryocytic Dami cells

Cytochrome P450s (P450s) are involved in the metabolism of arachidonic acid (ARA), and ARA metabolites are associated with various cellular signaling pathways, such as blood hemostasis and inflammation. The present study demonstrates the expression of ARA-metabolizing P450s in the human megakaryocytic Dami cells using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunublotting analysis followed by activity assays using ARA as a substrate. In addition to the previously identified CYP5A1, both protein and mRNAs of CYP1A1, 2U1, and 2J2 bands were detected. Ethoxyresorufin-O-deethylase (EROD) activity was observed in Dami cells, and its activity was significantly decreased after treatment with the P450 inhibitor SKF-525A when compared to the control groups (60% reduction, P < 0.001). CYP1A1 protein expression in Dami cells was induced by 3-methylenecholantheren. This increase in CYP1A1 protein level was correlated with enhanced EROD activity (fourfold increase vs. the control), as well as with increased metabolites, such as 20-hydroxyeicosatrienoic acid (20-HETE), 14, 15-EET (14-,15-epoxyeicosatrienoic acid), and 14, 15-dihydroxyeicosatrienoic acid (14, 15-DHET). The expression of soluble epoxide hydrolase, an enzyme responsible for the synthesis of DHETs from EETs, was confirmed by RT-PCR. Furthermore, 15 ARA metabolites, including 8,9-EET, 14,15-EET, and 20-HETE, were detected by LC-MS/MS in ARA-treated Dami cells, and their levels were decreased with the treatment of the SKF-525A. The present data suggest the possibility that the P450s play a role in the metabolism of ARA and other CYP-related substrates in human megakaryocytes and that P450 expression in megakaryocytic cell lines may predict their existences in platelets with functional activities.

Signal transducer and activator of transcription 6 directly regulates human ORMDL3 expression

Orosomucoid-like 3 (ORMDL3) has been associated with asthma and a series of autoimmune disorders, and is involved in endoplasmic reticulum-mediated inflammatory responses. However, its clinical significance and the molecular mechanism underlying its expression are still largely unclear. To elucidate the mechanisms of human ORMDL3 transcriptional regulation, we cloned a 1.5 kb genomic DNA fragment containing the putative promoter region and evaluated its transcriptional activity in a luciferase reporter system by deletion analysis. We identified a 68 bp region that functions as a minimal promoter. Bioinformatics analysis predicted that the -64 to -56 bp region contained a signal transducer and activator of transcription 6 (STAT6) binding site. Electrophoretic mobility shift assay and chromatin immunoprecipitation demonstrated that STAT6 bound to its binding site within the ORMDL3 promoter. STAT6 over-expression or knockdown trans-activated or trans-inhibited, respectively, the ORMDL3 promoter containing the STAT6-binding motif. Treatment with interleukins 4 or 13 increased ORMDL3 promoter activity as well as endogenous ORMDL3 expression. Immunoprecipitation and ChIP/Re-ChIP assays revealed that STAT6 and p300 exist in the same protein complex that binds to the ORMDL3 promoter. Our study confirmed that STAT6 plays important roles in regulating the expression of human ORMDL3 by directly binding to the promoter region, which may shed light on a possible role in various human diseases.