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International Journal of Molecular... Aug 2021Thyroid hormone levels are usually genetically determined. Thyrocytes produce a unique set of enzymes that are dedicated to thyroid hormone synthesis. While thyroid...
Thyroid hormone levels are usually genetically determined. Thyrocytes produce a unique set of enzymes that are dedicated to thyroid hormone synthesis. While thyroid transcriptional regulation is well-characterized, post-transcriptional mechanisms have been less investigated. Here, we describe the involvement of ZFP36L2, a protein that stimulates degradation of target mRNAs, in thyroid development and function, by in vivo and in vitro gene targeting in thyrocytes. Thyroid-specific females were hypothyroid, with reduced levels of circulating free Thyroxine (cfT4) and Triiodothyronine (cfT3). Their hypothyroidism was due to dyshormonogenesis, already evident one week after weaning, while thyroid development appeared normal. We observed decreases in several thyroid-specific transcripts and proteins, such as and its transcriptional regulators ( and .1), and increased apoptosis in thyroids. , and .1 mRNAs were also reduced in knock-out thyrocytes in vitro (L2KO), in which we confirmed the increased apoptosis. Finally, in L2KO cells, we showed an altered response to TSH stimulation regarding both thyroid-specific gene expression and cell proliferation and survival. This result was supported by increases in P21/WAF1 and p-P38MAPK levels. Mechanistically, we confirmed as a target of ZFP36L2 in the thyroid since its levels were increased in both in vitro and in vivo models. In both models, the levels of mRNA, a potential inhibitor of activity, were increased. Overall, the data indicate that the regulation of mRNA stability by ZFP36L2 is a mechanism that controls the function and survival of thyrocytes.
Topics: Animals; Apoptosis; Cell Line; Cell Survival; Female; Gene Deletion; Gene Expression Regulation; Mice, Inbred C57BL; Mice, Mutant Strains; PAX8 Transcription Factor; Rats; Receptor, Notch1; Thyroid Gland; Thyrotropin; Tristetraprolin; Mice
PubMed: 34502288
DOI: 10.3390/ijms22179379 -
Clinical implications of tristetraprolin (TTP) modulation in the treatment of inflammatory diseases.Pharmacology & Therapeutics Nov 2022Abnormal regulation of pro-inflammatory cytokine and chemokine mediators can contribute to the excess inflammation characteristic of many autoimmune diseases, such as... (Review)
Review
Abnormal regulation of pro-inflammatory cytokine and chemokine mediators can contribute to the excess inflammation characteristic of many autoimmune diseases, such as rheumatoid arthritis, psoriasis, Crohn's disease, type 1 diabetes, and many others. The tristetraprolin (TTP) family consists of a small group of related RNA-binding proteins that bind to preferred AU-rich binding sites within the 3'-untranslated regions of specific mRNAs to promote mRNA deadenylation and decay. TTP deficient mice develop a severe systemic inflammatory syndrome consisting of arthritis, myeloid hyperplasia, dermatitis, autoimmunity and cachexia, due at least in part to the excess accumulation of proinflammatory chemokine and cytokine mRNAs and their encoded proteins. To investigate the possibility that increased TTP expression or activity might have a beneficial effect on inflammatory diseases, at least two mouse models have been developed that provide proof of principle that increasing TTP activity can promote the decay of pro-inflammatory and other relevant transcripts, and decrease the severity of mouse models of inflammatory disease. Animal studies of this type are summarized here, and we briefly review the prospects for harnessing these insights for the development of TTP-based anti-inflammatory treatments in humans.
Topics: Humans; Mice; Animals; Tristetraprolin; RNA, Messenger; Inflammation; Cytokines; Autoimmune Diseases
PubMed: 35525391
DOI: 10.1016/j.pharmthera.2022.108198 -
Biomolecular NMR Assignments Apr 2022Members of the tristetraprolin (TTP) family of RNA binding proteins (RBPs) regulate the metabolism of a variety of mRNA targets. In mammals, these proteins modulate many...
Backbone and sidechain H, N and C resonance assignments of the free and RNA-bound tandem zinc finger domain of the tristetraprolin family member from Selaginella moellendorffii.
Members of the tristetraprolin (TTP) family of RNA binding proteins (RBPs) regulate the metabolism of a variety of mRNA targets. In mammals, these proteins modulate many physiological processes, including immune cell activation, hematopoiesis, and embryonic development. Regulation of mRNA stability by these proteins requires that the tandem zinc finger (TZF) domain binds initially and directly to target mRNAs, ultimately leading to their deadenylation and decay. Proteins of this type throughout eukarya possess a highly conserved TZF domain, suggesting that they are all capable of high-affinity RNA binding. However, the mechanism of TTP-mediated mRNA decay is largely undefined. Given the vital role that these TTP family proteins play in maintaining RNA homeostasis throughout eukaryotes, we focused here on the first, key step in this process: recognition and binding of the TZF domain to target RNA. For these studies, we chose a primitive plant, the spikemoss Selaginella moellendorffii, which last shared a common ancestor with humans more than a billion years ago. Here we report the near complete backbone and side chain resonance assignments of the spikemoss TZF domain, including: (1) the assignment of the RNA-TZF domain complex, representing one of only two data sets currently available for the entire TTP family of proteins; and (2) the first NMR resonance assignments of the entire TZF domain, in the RNA-free form. This work will serve as the basis for further NMR structural investigations aimed at gaining insights into the process of RNA recognition and the mechanisms of TTP-mediated mRNA decay.
Topics: Animals; Family; Humans; Mammals; Nuclear Magnetic Resonance, Biomolecular; RNA; RNA, Messenger; Selaginellaceae; Tristetraprolin; Zinc Fingers
PubMed: 35279790
DOI: 10.1007/s12104-022-10073-8 -
Proceedings of the Japan Academy.... 2018Cytokines are critical mediators of inflammation and host immune defense. Cytokine production is regulated at both transcriptional and post-transcriptional levels.... (Review)
Review
Cytokines are critical mediators of inflammation and host immune defense. Cytokine production is regulated at both transcriptional and post-transcriptional levels. Post-transcriptional damping of inflammatory mRNAs is mediated by a set of RNA binding proteins (RBPs) interacting with cis-elements, such as AU-rich elements (ARE) and stem-loop structures. Whereas ARE-binding proteins such as tristetraprolin and a stem-loop recognizing protein, Roquin, downregulate cytokine mRNA abundance by recruiting a CCR4-NOT deadenylase complex, another stem-loop RBP, Regnase-1, acts as an endoribonuclease, directly degrading target cytokine mRNAs. These RBPs control translation-active or -inactive mRNAs in distinct intracellular locations. The presence of various RBPs regulating mRNAs in distinct locations enables elaborate control of cytokines under inflammatory conditions. Dysregulation of cytokine mRNA decay leads to pathologies such as the development of autoimmune diseases or impaired activation of immune responses. Here we review current knowledge about the post-transcriptional regulation of immune responses by RBPs and the importance of their alteration during inflammatory pathology and autoimmunity.
Topics: Amino Acid Sequence; Animals; Cytokines; Humans; Immunity; Lymphocyte Activation; RNA-Binding Proteins; T-Lymphocytes; Transcription, Genetic
PubMed: 29887569
DOI: 10.2183/pjab.94.017 -
Cell Death & Disease Jul 2021Acute lung injury induced by ischemia-reperfusion (I/R)-associated pulmonary inflammation is associated with high rates of morbidity. Despite advances in the clinical...
Acute lung injury induced by ischemia-reperfusion (I/R)-associated pulmonary inflammation is associated with high rates of morbidity. Despite advances in the clinical management of lung disease, molecular therapeutic options for I/R-associated lung injury are limited. Zinc finger protein 36 (ZFP36) is an AU-rich element-binding protein that is known to suppress the inflammatory response. A ZFP36 binding site occurs in the 3' UTR of the cAMP-response element-binding protein (CREB) binding protein (CREBBP) gene, which is known to interact with apoptotic proteins to promote apoptosis. In this study, we investigate the involvement of ZFP36 and CREBBP on I/R-induced lung injury in vivo and in vitro. Intestinal ischemia/reperfusion (I/R) activates inflammatory responses, resulting in injury to different organs including the lung. Lung tissues from ZFP36-knockdown mice and mouse lung epithelial (MLE)-2 cells were subjected to either Intestinal I/R or hypoxia/reperfusion, respectively, and then analyzed by Western blotting, immunohistochemistry, and real-time PCR. Silico analyses, pull down and RIP assays were used to analyze the relationship between ZFP36 and CREBBP. ZFP36 deficiency upregulated CREBBP, enhanced I/R-induced lung injury, apoptosis, and inflammation, and increased I/R-induced lung fibrosis. In silico analyses indicated that ZFP36 was a strong negative regulator of CREBBP mRNA stability. Results of pull down and RIP assays confirmed that ZFP36 direct interacted with CREBBP mRNA. Our results indicated that ZFP36 can mediate the level of inflammation-associated lung damage following I/R via interactions with the CREBBP/p53/p21/Bax pathway. The downregulation of ZFP36 increased the level of fibrosis.
Topics: Acute Lung Injury; Animals; Apoptosis; CREB-Binding Protein; Cell Line; Cyclin-Dependent Kinase Inhibitor p21; Cytokines; Disease Models, Animal; Epithelial-Mesenchymal Transition; Inflammation Mediators; Intestines; Lung; Mice, Inbred C57BL; Mice, Knockout; Pulmonary Fibrosis; Reperfusion Injury; Signal Transduction; Tristetraprolin; Tumor Suppressor Protein p53; bcl-2-Associated X Protein; Mice
PubMed: 34238924
DOI: 10.1038/s41419-021-03950-y -
Frontiers in Immunology 2022Aging results in enhanced myelopoiesis, which is associated with an increased prevalence of myeloid leukemias and the production of myeloid-derived suppressor cells...
Aging results in enhanced myelopoiesis, which is associated with an increased prevalence of myeloid leukemias and the production of myeloid-derived suppressor cells (MDSCs). Tristetraprolin (TTP) is an RNA binding protein that regulates immune-related cytokines and chemokines by destabilizing target mRNAs. As TTP expression is known to decrease with age in myeloid cells, we used TTP-deficient (TTPKO) mice to model aged mice to study TTP regulation in age-related myelopoiesis. Both TTPKO and myeloid-specific TTPKO (cTTPKO) mice had significant increases in both MDSC subpopulations M-MDSCs (CD11bLy6CLy6G) and PMN-MDSCs (CD11bLy6CLy6G), as well as macrophages (CD11bF4/80) in the spleen and mesenteric lymph nodes; however, no quantitative changes in MDSCs were observed in the bone marrow. In contrast, gain-of-function TTP knock-in (TTPKI) mice had no change in MDSCs compared with control mice. Within the bone marrow, total granulocyte-monocyte progenitors (GMPs) and monocyte progenitors (MPs), direct antecedents of M-MDSCs, were significantly increased in both cTTPKO and TTPKO mice, but granulocyte progenitors (GPs) were significantly increased only in TTPKO mice. Transcriptomic analysis of the bone marrow myeloid cell populations revealed that the expression of CC chemokine receptor 2 (CCR2), which plays a key role in monocyte mobilization to inflammatory sites, was dramatically increased in both cTTPKO and TTPKO mice. Concurrently, the concentration of CC chemokine ligand 2 (CCL2), a major ligand of CCR2, was high in the serum of cTTPKO and TTPKO mice, suggesting that TTP impacts the mobilization of M-MDSCs from the bone marrow to inflammatory sites during aging regulation of the CCR2-CCL2 axis. Collectively, these studies demonstrate a previously unrecognized role for TTP in regulating age-associated myelopoiesis through the expansion of specific myeloid progenitors and M-MDSCs and their recruitment to sites of injury, inflammation, or other pathologic perturbations.
Topics: Mice; Animals; Myeloid-Derived Suppressor Cells; Receptors, CCR2; Tristetraprolin; Ligands; Chemokines; Cytokines; Chemokines, CC
PubMed: 36263047
DOI: 10.3389/fimmu.2022.1002163 -
The Journal of Clinical Investigation May 2022Pregnancy is associated with substantial physiological changes of the heart, and disruptions in these processes can lead to peripartum cardiomyopathy (PPCM). The...
Pregnancy is associated with substantial physiological changes of the heart, and disruptions in these processes can lead to peripartum cardiomyopathy (PPCM). The molecular processes that cause physiological and pathological changes in the heart during pregnancy are not well characterized. Here, we show that mTORc1 was activated in pregnancy to facilitate cardiac enlargement that was reversed after delivery in mice. mTORc1 activation in pregnancy was negatively regulated by the mRNA-destabilizing protein ZFP36L2 through its degradation of Mdm2 mRNA and P53 stabilization, leading to increased SESN2 and REDD1 expression. This pathway impeded uncontrolled cardiomyocyte hypertrophy during pregnancy, and mice with cardiac-specific Zfp36l2 deletion developed rapid cardiac dysfunction after delivery, while prenatal treatment of these mice with rapamycin improved postpartum cardiac function. Collectively, these data provide what we believe to be a novel pathway for the regulation of mTORc1 through mRNA stabilization of a P53 ubiquitin ligase. This pathway was critical for normal cardiac growth during pregnancy, and its reduction led to PPCM-like adverse remodeling in mice.
Topics: Animals; Cardiomyopathies; Female; Mechanistic Target of Rapamycin Complex 1; Mice; Myocytes, Cardiac; Nuclear Proteins; Peripartum Period; Peroxidases; Pregnancy; Pregnancy Complications, Cardiovascular; RNA, Messenger; Transcription Factors; Tristetraprolin; Tumor Suppressor Protein p53
PubMed: 35316214
DOI: 10.1172/JCI154491 -
Biochemical Society Transactions Oct 2016Twenty years ago, the first description of a tristetraprolin (TTP) knockout mouse highlighted the fundamental role of TTP in the restraint of inflammation. Since then,... (Review)
Review
Twenty years ago, the first description of a tristetraprolin (TTP) knockout mouse highlighted the fundamental role of TTP in the restraint of inflammation. Since then, work from several groups has generated a detailed picture of the expression and function of TTP. It is a sequence-specific RNA-binding protein that orchestrates the deadenylation and degradation of several mRNAs encoding inflammatory mediators. It is very extensively post-translationally modified, with more than 30 phosphorylations that are supported by at least two independent lines of evidence. The phosphorylation of two particular residues, serines 52 and 178 of mouse TTP (serines 60 and 186 of the human orthologue), has profound effects on the expression, function and localisation of TTP. Here, we discuss the control of TTP biology via its phosphorylation and dephosphorylation, with a particular focus on recent advances and on questions that remain unanswered.
Topics: Amino Acid Sequence; Animals; Humans; Inflammation; Mice, Knockout; Phosphoric Monoester Hydrolases; Phosphorylation; Serine; Signal Transduction; Tristetraprolin
PubMed: 27911715
DOI: 10.1042/BST20160166 -
Experimental and Therapeutic Medicine Sep 2022CD47 is expressed in all human cancer cells, including head and neck cancer, and initiates a signaling cascade to inhibit macrophage phagocytosis. However, the mechanism...
CD47 is expressed in all human cancer cells, including head and neck cancer, and initiates a signaling cascade to inhibit macrophage phagocytosis. However, the mechanism underlying CD47 overexpression has not been elucidated in radioresistant head and neck cancer. The present study demonstrated that decreased Tristetraprolin (TTP) expression induced a sustained overexpression of CD47 using reverse transcription-quantitative PCR and western blotting, and that CD47 overexpression prevented phagocytosis using a phagocytosis assay in a radioresistant HN31R cell line. Subsequently, using TTP transfection, RNA interference, duel-luciferase assay and EMSA, it was revealed that TTP transfection enhanced phagocytosis through degradation of CD47 mRNA by directly binding to CD47 AREs within the CD47 3'UTR. Based on our previous study, methylation-specific PCR and western blotting revealed that DNMT1 was overexpressed in radioresistant HN31R cell line and TTP expression was decreased epigenetically by DMNT1 associated DNA methylation. Overall, these findings provided novel insight into the role of TTP as a biomarker of CD47-positive head and neck cancer patients.
PubMed: 35978923
DOI: 10.3892/etm.2022.11478 -
Developmental Cell Dec 2020Bacterial infection triggers a cytokine storm that needs to be resolved to maintain the host's wellbeing. Here, we report that ablation of mA methyltransferase subunit...
Bacterial infection triggers a cytokine storm that needs to be resolved to maintain the host's wellbeing. Here, we report that ablation of mA methyltransferase subunit METTL14 in myeloid cells exacerbates macrophage responses to acute bacterial infection in mice, leading to high mortality due to sustained production of pro-inflammatory cytokines. METTL14 depletion blunts Socs1 mA methylation and reduces YTHDF1 binding to the mA sites, which diminishes SOCS1 induction leading to the overactivation of TLR4/NF-κB signaling. Forced expression of SOCS1 in macrophages depleted of METTL14 or YTHDF1 rescues the hyper-responsive phenotype of these macrophages in vitro and in vivo. We further show that LPS treatment induces Socs1 mA methylation and sustains SOCS1 induction by promoting Fto mRNA degradation, and forced FTO expression in macrophages mimics the phenotype of METTL14-depleted macrophages. We conclude that mA methylation-mediated SOCS1 induction is required to maintain the negative feedback control of macrophage activation in response to bacterial infection.
Topics: Adenosine; Alpha-Ketoglutarate-Dependent Dioxygenase FTO; Animals; Cells, Cultured; Feedback, Physiological; Female; HEK293 Cells; Humans; Macrophage Activation; Male; Methylation; Methyltransferases; Mice; Mice, Inbred C57BL; RAW 264.7 Cells; RNA Processing, Post-Transcriptional; RNA Stability; RNA, Messenger; RNA-Binding Proteins; Signal Transduction; Suppressor of Cytokine Signaling 1 Protein; Toll-Like Receptor 4; Tristetraprolin; Up-Regulation
PubMed: 33220174
DOI: 10.1016/j.devcel.2020.10.023