Glucocorticoids inhibit induced and non-induced mRNA accumulation of genes encoding hyaluronan synthases (HAS): hydrocortisone inhibits HAS1 activation by blocking the p38 mitogen-activated protein kinase signalling pathway

Stuhlmeier, Karl M.; Pollaschek, Christine

doi:10.1093/rheumatology/keh014

Cited by 30 publications

(30 citation statements)

References 25 publications

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“…HAS mRNAs have been found to be responsive to TGF␤ in a wide variety of cultured cells (13,15,16,(23)(24)(25)(26)(27)(28)(29)(30)(31)(32). The particular HAS gene involved, however, appears to be highly cell-and tissue-dependent.…”

Section: Discussionmentioning

confidence: 99%

A Rapid Transient Increase in Hyaluronan Synthase-2 mRNA Initiates Secretion of Hyaluronan by Corneal Keratocytes in Response to Transforming Growth Factor β

Guo

Kanter

Funderburgh

et al. 2007

Journal of Biological Chemistry

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Keratocytes of the corneal stroma produce transparent extracellular matrix devoid of hyaluronan (HA); however, in corneal pathologies and wounds, HA is abundant. We previously showed primary keratocytes cultured under serum-free conditions to secrete matrix similar to that of normal stroma, but serum and transforming growth factor ␤ (TGF␤) induced secretion of fibrotic matrix components, including HA. This study found HA secretion by primary bovine keratocytes to increase rapidly in response to TGF␤, reaching a maximum in 12 h and then decreasing to <5% of the maximum by 48 h. Cell-free biosynthesis of HA by cell extracts also exhibited a transient peak at 12 h after TGF␤ treatment. mRNA for hyaluronan synthase enzymes HAS1 and HAS2 increased >10-and >50-fold, respectively, in 4 -6 h, decreasing to near original levels after 24 -48 h. Small interfering RNA against HAS2 inhibited the transient increase of HAS2 mRNA and completely blocked HA induction, but small interfering RNA to HAS1 had no effect on HA secretion. HAS2 mRNA was induced by a variety of mitogens, and TGF␤ acted synergistically to induce HAS2 by as much as 150-fold. In addition to HA synthesis, treatment with TGF␤ induced degradation of fluorescein-HA added to culture medium. These results show HA secretion by keratocytes to be initiated by a rapid transient increase in the HAS2 mRNA pool. The very rapid induction of HA expression in keratocytes suggests a functional role of this molecule in the fibrotic response of keratocytes to wound healing. Hyaluronan (HA)2 is a high molecular weight, nonsulfated glycosaminoglycan abundant in most tissues, where it acts as a hydrating agent and an organizer of extracellular matrix scaffolding via specific interactions with matrix proteins containing hyaluronectin domains (for review see Ref. 1). The corneal stroma, unlike most vertebrate tissues, is virtually devoid of HA. During active corneal wound healing and in corneas with various chronic pathologies, however, hyaluronan becomes abundant in the corneal stroma (2, 3).The corneal stroma maintains transparency to light by virtue of the highly organized structure of its collagenous extracellular matrix. Collagen fibrils of the stroma exhibit highly regular parallel alignment and spacing. This spacing is controlled by collagen-associated small leucine-rich proteoglycans that form glycosaminoglycan cross-links between adjacent fibrils (4). Disruption of the fibril spacing is a major cause of loss of corneal transparency in scarring and stromal pathological conditions (5). In scars, interfibrillar glycosaminoglycan cross-links are altered or eliminated, and spaces without fibrils, known as "lakes," have been identified (5). The almost ubiquitous presence of HA in nontransparent corneas suggests a relationship between the large hydrodynamic volume occupied by HA molecules and the disruption of the stromal ultrastructure. Additionally, the recent recognition of the diverse bioactivity of HA (6) raises the potential that matrix production by stromal keratocytes may...

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Section: Discussionmentioning

confidence: 99%

A Rapid Transient Increase in Hyaluronan Synthase-2 mRNA Initiates Secretion of Hyaluronan by Corneal Keratocytes in Response to Transforming Growth Factor β

Guo

Kanter

Funderburgh

et al. 2007

Journal of Biological Chemistry

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“…No distinct expression pattern was observed in patient samples obtained during disease progression or remission, possibly reflecting treatment of many patients with prednisone and/or dexamethasone, which are known to play a significant role in tissue-specific regulation, activation, and/or suppression of HAS genes and production of HA. 25,26 Cloning and sequencing of HAS1 variants…”

Section: Longitudinal Analysis Of Has1 and Variants In MM Patientsmentioning

confidence: 99%

Intronic splicing of hyaluronan synthase 1 (HAS1): a biologically relevant indicator of poor outcome in multiple myeloma

Adamia

Reiman

Crainie

et al. 2005

Blood

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“…As demonstrated earlier (20,31), a series of cycles are routinely tested to define optimal PCR conditions for a given gene. Viability of cells was confirmed by phase contrast microscopy and occasionally by staining cells with trypan blue.…”

Section: Quality Control and Data Analysismentioning

confidence: 99%

Effects of Leflunomide on Hyaluronan Synthases (HAS): NF-κB-Independent Suppression of IL-1-Induced HAS1 Transcription by Leflunomide

Stuhlmeier¹

2005

The Journal of Immunology

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Despite evidence that points to unfettered hyaluronic acid (HA) production as a culprit in the progression of rheumatic disorders, little is known about differences in regulation and biological functions of the three hyaluronan synthase (HAS) genes. Testing the effects of drugs with proven anti-inflammatory effects could help to clarify biological functions of these genes. In this study, we demonstrate that leflunomide suppresses HA release in fibroblast-like synoviocytes (FLS) in a dose-dependent manner. We further demonstrate that leflunomide suppresses HA synthase activity, as determined by 14C-glucuronic acid incorporation assays. Additional experiments revealed that in FLS, leflunomide specifically blocked the induction of HAS1. HAS2 and HAS3, genes that are, in contrast to HAS1, constitutively expressed in FLS, are not significantly affected. Leflunomide can function as a NF-κB inhibitor. However, EMSA experiments demonstrate that at the concentrations used, leflunomide neither interferes with IL-1β- nor with PMA-induced NF-κB translocation. Furthermore, reconstituting the pyrimidine synthase pathway did not lead to the restoration of IL-1β-induced HAS1 activation. More importantly, two tyrosine kinase inhibitors mimicked the effect of leflunomide in that both blocked IL-1β-induced HAS1 activation without affecting HAS2 or HAS3. These data point at HAS1 activation as the possible cause for unfettered HA production in rheumatoid arthritis and might explain, at least in part, the beneficial effects of leflunomide treatment. These findings also support the concept that IL-1β-induced HAS1 activation depends on the activation of tyrosine kinases, and indicate that leflunomide blocks HA release by suppressing tyrosine kinases rather than through inhibition of NF-κB translocation.

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Glucocorticoids inhibit induced and non-induced mRNA accumulation of genes encoding hyaluronan synthases (HAS): hydrocortisone inhibits HAS1 activation by blocking the p38 mitogen-activated protein kinase signalling pathway

Abstract: Our data demonstrate that glucocorticoids suppress all genes encoding hyaluronan. We speculate that inhibition of HAS genes might account for the beneficial effect of glucocorticoid treatment, and also for the detrimental effects of long-term use.

Cited by 30 publications

References 25 publications

A Rapid Transient Increase in Hyaluronan Synthase-2 mRNA Initiates Secretion of Hyaluronan by Corneal Keratocytes in Response to Transforming Growth Factor β

A Rapid Transient Increase in Hyaluronan Synthase-2 mRNA Initiates Secretion of Hyaluronan by Corneal Keratocytes in Response to Transforming Growth Factor β

Intronic splicing of hyaluronan synthase 1 (HAS1): a biologically relevant indicator of poor outcome in multiple myeloma

Effects of Leflunomide on Hyaluronan Synthases (HAS): NF-κB-Independent Suppression of IL-1-Induced HAS1 Transcription by Leflunomide

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