scholarly journals FGF9 and FGF10 use distinct signaling pathways to direct lung epithelial specification and branching

2019 ◽  
Author(s):  
Yongjun Yin ◽  
David M. Ornitz

AbstractFibroblast Growth Factors (FGFs) 9 and 10 are essential during the pseudoglandular stage of lung development. Mesothelial produced FGF9 is principally responsible for mesenchymal growth, whereas epithelial produced FGF9 and mesenchymal produced FGF10 guide lung epithelial development, and loss of either of these ligands affects epithelial branching. Because FGF9 and FGF10 activate distinct FGF receptors (FGFRs), we hypothesized that they would control distinct developmental mechanisms. Here, we show that FGF9 signaled through epithelial FGF receptor 3 (FGFR3) to directly promote distal epithelial fate specification and inhibit epithelial differentiation. By contrast, FGF10 signaled through epithelial FGFR2b to promote epithelial proliferation and differentiation. Furthermore, FGF9-FGFR3 signaling functionally opposed FGF10-FGFR2b signaling, and FGFR3 preferentially used downstream PI3K pathways, whereas FGFR2b relied on downstream RAS-MAPK pathways. These data demonstrate that within lung epithelial cells, different FGFRs function independently; they bind receptor-specific ligands and direct unique developmental functions through activation of distinct downstream signaling pathways.

2020 ◽  
Vol 13 (621) ◽  
pp. eaay4353 ◽  
Author(s):  
Yongjun Yin ◽  
David M. Ornitz

Fibroblast growth factors (FGFs) 9 and 10 are essential during the pseudoglandular stage of lung development. Mesothelium-produced FGF9 is principally responsible for mesenchymal growth, whereas epithelium-produced FGF9 and mesenchyme-produced FGF10 guide lung epithelial development, and loss of either of these ligands affects epithelial branching. Because FGF9 and FGF10 activate distinct FGF receptors (FGFRs), we hypothesized that they would control distinct developmental processes. Here, we found that FGF9 signaled through epithelial FGFR3 to directly promote distal epithelial fate specification and inhibit epithelial differentiation. By contrast, FGF10 signaled through epithelial FGFR2b to promote epithelial proliferation and differentiation. Furthermore, FGF9-FGFR3 signaling functionally opposed FGF10-FGFR2b signaling, and FGFR3 preferentially used downstream phosphoinositide 3-kinase (PI3K) pathways, whereas FGFR2b relied on downstream mitogen-activated protein kinase (MAPK) pathways. These data demonstrate that, within lung epithelial cells, different FGFRs function independently; they bind receptor-specific ligands and direct distinct developmental functions through the activation of distinct downstream signaling pathways.


2012 ◽  
Vol 6 (1) ◽  
pp. 8 ◽  
Author(s):  
Tiziana Grafone ◽  
Michela Palmisano ◽  
Chiara Nicci ◽  
Sergio Storti

Hematopoiesis, the process by which the hematopoietic stem cells and progenitors differentiate into blood cells of various lineages, involves complex interactions of transcription factors that modulate the expression of downstream genes and mediate proliferation and differentiation signals. Despite the many controls that regulate hematopoiesis, mutations in the regulatory genes capable of promoting leukemogenesis may occur. The <em>FLT3</em> gene encodes a tyrosine kinase receptor that plays a key role in controlling survival, proliferation and differentiation of hematopoietic cells. Mutations in this gene are critical in causing a deregulation of the delicate balance between cell proliferation and differentiation. In this review, we provide an update on the structure, synthesis and activation of the FLT3 receptor and the subsequent activation of multiple downstream signaling pathways. We also review activating FLT3 mutations that are frequently identified in acute myeloid leukemia, cause activation of more complex downstream signaling pathways and promote leukemogenesis. Finally, FLT3 has emerged as an important target for molecular therapy. We, therefore, report on some recent therapies directed against it.


2011 ◽  
Vol 300 (1) ◽  
pp. L81-L87 ◽  
Author(s):  
Sharmistha Bhattacharyya ◽  
Usha Gutti ◽  
Jose Mercado ◽  
Chad Moore ◽  
Harvey B. Pollard ◽  
...  

Cystic fibrosis (CF) is characterized by a massive proinflammatory phenotype in the lung, caused by mutations in the CFTR gene. IL-8 and other proinflammatory mediators are elevated in the CF airway, and the immediate mechanism may depend on disease-specific stabilization of IL-8 mRNA in CF lung epithelial cells. MAPK signaling pathways impact directly on IL-8 protein expression in CF cells, and we have hypothesized that the mechanism may also involve stabilization of the IL-8 mRNA. To test this hypothesis, we have examined the effects of pharmacological and molecular inhibitors of p38, and downstream MK2, ERK1/2, and JNK, on stability of IL-8 mRNA in CF lung epithelial cells. We previously showed that tristetraprolin (TTP) was constitutively low in CF and that raising TTP destabilized the IL-8 mRNA. We therefore also tested these effects on CF lung epithelial cells stably expressing TTP. TTP binds to AU-rich elements in the 3′-UTR of the IL-8 mRNA. We find that inhibition of p38 and ERK1/2 reduces the stability of IL-8 mRNA in parental CF cells. However, neither intervention further lowers TTP-dependent destabilization of IL-8 mRNA. By contrast, inhibition of the JNK-2 pathway has no effect on IL-8 mRNA stability in parental CF cell, but rather increases the stability of the message in cells expressing high levels of TTP. However, we find that inhibition of ERK1/2 or p38 leads to suppression of the effect of JNK-2 inhibition on IL-8 mRNA stability. These data thus lend support to our hypothesis that constitutive MAPK signaling and proteasomal activity might also contribute, along with aberrantly lower TTP, to the proinflammatory phenotype in CF lung epithelial cells by increasing IL-8 mRNA stability and IL-8 protein expression.


2021 ◽  
Vol 22 (16) ◽  
pp. 8388
Author(s):  
Soo-Jin Park ◽  
Tae-hyoun Kim ◽  
Kiram Lee ◽  
Min-Ah Kang ◽  
Hyun-Jae Jang ◽  
...  

Idiopathic pulmonary fibrosis (IPF) is a refractory interstitial lung disease for which there is no effective treatment. Although the pathogenesis of IPF is not fully understood, TGF-β and epithelial–mesenchymal transition (EMT) have been shown to be involved in the fibrotic changes of lung tissues. Kurarinone is a prenylated flavonoid isolated from Sophora Flavescens with antioxidant and anti-inflammatory properties. In this study, we investigated the effect of kurarinone on pulmonary fibrosis. Kurarinone suppressed the TGF-β-induced EMT of lung epithelial cells. To assess the therapeutic effects of kurarinone in bleomycin (BLM)-induced pulmonary fibrosis, mice were treated with kurarinone daily for 2 weeks starting 7 days after BLM instillation. Oral administration of kurarinone attenuated the fibrotic changes of lung tissues, including accumulation of collagen and improved mechanical pulmonary functions. Mechanistically, kurarinone suppressed phosphorylation of Smad2/3 and AKT induced by TGF-β1 in lung epithelial cells, as well as in lung tissues treated with BLM. Taken together, these results suggest that kurarinone has a therapeutic effect on pulmonary fibrosis via suppressing TGF-β signaling pathways and may be a novel drug candidate for pulmonary fibrosis.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ming Li ◽  
Susumu Ikehara

Mesenchymal stem cells (MSCs) are prototypical adult stem cells with the capacity for self-renewal and differentiation with a broad tissue distribution. MSCs not only differentiate into types of cells of mesodermal lineage but also into endodermal and ectodermal lineages such as bone, fat, cartilage and cardiomyocytes, endothelial cells, lung epithelial cells, hepatocytes, neurons, and pancreatic islets. MSCs have been identified as an adherent, fibroblast-like population and can be isolated from different adult tissues, including bone marrow (BM), umbilical cord, skeletal muscle, and adipose tissue. MSCs secrete factors, including IL-6, M-CSF, IL-10, HGF, and PGE2, that promote tissue repair, stimulate proliferation and differentiation of endogenous tissue progenitors, and decrease inflammatory and immune reactions. In this paper, we focus on the role of BM-derived MSCs in organ repair.


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