Collagen I Induces Discoidin Domain Receptor (DDR) 1 Expression through DDR2 and a JAK2-ERK1/2-mediated Mechanism in Primary Human Lung Fibroblasts

Abstract

Discoidin domain receptors (DDRs) DDR1 and DDR2 are receptor tyrosine kinases with the unique ability among receptor tyrosine kinases to respond to collagen. Several signaling molecules have been implicated in DDR signaling, including Shp-2, Src, and MAPK pathways, but a detailed understanding of these pathways and their transcriptional targets is still lacking. Similarly, the regulation of the expression of DDRs is poorly characterized with only a few inflammatory mediators, such as lipopolysaccharide and interleukin-1␤ identified as playing a role in DDR1 expression. DDRs have been reported to induce the expression of various genes including matrix metalloproteinases and bone morphogenetic proteins, but the regulatory mechanisms underlying DDR-induced gene expression remain to be determined. The aim of the present work was to elucidate the molecular mechanisms implicated in the expression of DDRs and to identify DDR-induced signaling pathways and target genes. Our data show that collagen I induces the expression of DDR1 in a dose-and time-dependent manner in primary human lung fibroblasts. Furthermore, activation of DDR2, JAK2, and ERK1/2 MAPK signaling pathways was essential for collagen I-induced DDR1 and matrix metalloproteinase 10 expression. Finally, inhibition of the ERK1/2 pathway abrogated DDR1 expression by blocking the recruitment of the transcription factor polyoma enhancer A-binding protein 3 to the DDR1 promoter. Our data provide new insights into the molecular mechanisms of collagen I-induced DDR1 expression and demonstrate an important role for ERK1/2 activation and the recruitment of polyoma enhancer-A binding protein 3 to the DDR1 promoter. Discoidin domain receptors (DDRs)2 are non-integrin collagen receptors and constitute a unique subfamily of receptor tyrosine kinases containing a discoidin homology region in their extracellular domain (1). There are two related DDRs: DDR1 and DDR2. DDR1 is mainly expressed in epithelial cells, particularly of the lung, kidney, mammary gland, and gastrointestinal tract, whereas DDR2 is primarily found in cells of mesenchymal origin, such as fibroblasts and smooth muscle cells (1, 2). DDR1 is primarily activated by collagens I-IV and VIII, whereas DDR2 responds to collagen I and to a lesser extent to collagens II, III, and V but does not interact with collagen IV (3, 4). DDR2 has one isoform, whereas five DDR1 isoforms are generated by alternative splicing: DDR1a, b, c, d, and e. DDRs have been implicated in the expression of pro-inflammatory mediators and matrix-degrading enzymes and play an important role in processes such as migration, proliferation, extracellular matrix (ECM) remodeling and wound repair (2, 5-7). Moreover, studies in vivo and in vitro have implicated DDRs in various fibrotic and fibroproliferative conditions such as cancer, atherosclerosis, inflammation, arthritis, and fibrosis of the kidney, liver, skin, and lung (1, 2, 8 -13).The wide range of processes regulated upon DDR stimulation suggests that DDRs may exert their effects via mult...

Discoidin domain receptor 1 expression in activated T cells is regulated by the ERK MAP kinase signaling pathway

“…These observations are also supported by our results showing that PMA, which in T cells activates ERK MAPK through PKC [Bradshaw et al, 1996;Morley, 1997], induces DDR1 expression by a mechanism involving both PKC and ERK MAPK pathways. Our findings are in concordance with a recent study demonstrating the involvement of ERK MAP Kinase in the expression of DDR1 by primary lung fibroblasts [Ruiz and Jarai, 2011]. In contrast to our results, p38 MAPK has recently been involved in the expression of DDR2 in vascular smooth muscle cells in response to hypoxia [Chen et al, 2008;Shyu et al, 2009].…”

“…Activation of ERK can regulate the activation of several transcription factors in T cells including Fos, Elk-1 and members of the Ets family [Dong et al, 2002]. A recent study showed that in bronchial lung fibroblasts, ERK regulates DDR1 expression by activating the PEA3 transcription factor [Ruiz and Jarai, 2011]. Whether PEA3 or other transcription factors regulate DDR1 expression in activated T cells is not determined.…”

“…However, some transcriptional factors such as p53 [Ongusaha et al, 2003] and ATF-4 [Lin et al, 2010] were identified as regulators of DDR expression in different cell types. The promoter region of DDR1 gene contains potential binding sites for p53 [Sakuma et al, 1996], AP-1, PEA3 [Ruiz and Jarai, 2011], and NF-kB [Kamohara et al, 2001] transcriptional factors. The fact that our results showed that JNK is dispensable to TCR-induced DDR1 expression argues against the implication of AP-1 in the expression of DDR1 in activated T cells.…”

Targeting of Discoidin Domain Receptor 2 (DDR2) Prevents Myofibroblast Activation and Neovessel Formation During Pulmonary Fibrosis

“…59,60 The expression of DDR1 in lung fibroblasts, although positive, was reported to rely on DDR2 signaling. 51 Whatever, multitarget effect is a common characteristic for most kinase inhibitors, which sometimes is conducive to enhancing their efficacy in inhibiting disease progression. For instance, dasatinib suppression of Src activity may additionally contribute to the action of this drug on TGF-β-induced myofibroblast events because Src kinase was reported to serve as a key mediator of TGF-β-p38 pathway.…”

“…Even collagen I was reported to induce DDR1 expression in human lung fibroblasts, this process was demonstrated to rely on the activation of DDR2 signaling. 51 In addition to through direct regulation of cell differentiation, DDR2 may raise the abundance of myofibroblast subsets through advancing the recruitment of its precursor cells. One such evidence In the early phase of fibrotic reaction, transforming growth factor (TGF)-β stimulation of lung fibroblasts induces up-regulated expression of DDR2, which may enable DDR2 to cooperate with TGF-β receptor to activate p38 and Akt, consequently leading to the cell phenotypic transition toward myofibroblasts.…”