Regulation Of BMP4 Expression Research Articles

199 Regulation of BMP-4 Expression by Inflammatory Cytokines

199 Regulation of BMP-4 Expression by Inflammatory Cytokines

298 Regulation and Function of BMP-4 Expression in the Inflamed Gastric Mucosa

BACKGROUND/AIMS: We previously reported that inhibition of Bone Morphogenetic Protein (BMP) signaling In Vivo, leads to enhancement of Helicobacter pylori (HP)-induced gastric inflammation suggesting that the BMPs can exert novel anti-inflammatory actions in the stomach. The aim of this study was to examine the function and the regulation of BMP-4 expression in gastric inflammation. METHODS: Inflammation was induced by infection of 3 month-old C57BL/6-BMP-4-β-gal/+ mice with HP. Animals were analyzed 2 months after inoculation. Expression of BMP-4 was assessed by X-Gal staining and QRT-PCR. Morphology of the gastric mucosa was examined in sections stained with H&E. Phosphorylation of Smad1-5-8 was determined by immunohistochemistry with anti-phospho-Smad1-5-8 antibodies (abs). Expression of INF-γ was measured by QRT-PCR. Gastric mesenchymal and mucus cells were isolated from the canine gastric mucosa and characterized by staining with anti-vimentin abs and the lectin GSII, respectively. Phosphorylation of STAT1 and ERK2 and expression of BMP-4 in the mesenchymal cells were assessed by western blots. IL-8 expression in the mucus cells was measured by QRT-PCR. INF-γ, IL-17-α, IL-12 and IL23 content in supernatants of cultures of mouse splenocytes and dendritic cells was measured by ELISA. RESULTS: Analysis of mucosal sections of C57BL/6-BMP-4-β-gal/+ mice stained with X-gal, demonstrated that BMP-4 is expressed in the mesenchymal layers of the gastric mucosa. HP induced inflammatory changes in the gastric mucosa and it stimulated the expression of both INF-γ and BMP-4. Phospho-Smad1-5-8 staining of the inflamed gastric mucosa indicated the presence of positively stained nuclei in gastric epithelial cells, but not in mesenchymal cells, or in cells of the inflammatory infiltrate. INF-γ induced the phosphorylation of both STAT-1 and ERK2 and it induced BMP-4 protein expression in the mesenchymal cells. Incubation of the cells with inhibitors of both STAT-1 and ERK2 phosphorylation abrogated the stimulatory effect of INF-γ. BMP-4 failed to affect LPS-induced release of INF-γ, IL-17-α, IL-12 and IL-23 in cultures of mouse splenocytes and dendritic cells. In contrast, BMP-4 potently inhibited both basal and TNF-α stimulated IL-8 gene expression in cultures of isolated mucus cells. CONCLUSIONS: Inflammatory stimuli induce the expression of BMP-4 both In Vivo and In Vitro, through mechanisms that appear to involve the activation of both ERK2 and STAT-1. BMP-4, in turn, inhibits the expression of inflammatory molecules in epithelial, but not in immune cells, suggesting that BMP-4 is a novel anti-inflammatoy peptide released by the mesenchyme to modulate the inflammatory response of the gastric epithelium.

Endogenous Bmp4 in myoblasts is required for myotube formation in C2C12 cells

Background Our previous study revealed the indispensable activity of endogenous bone morphogenetic protein (Bmp) prior to differentiation induction of C2C12 myoblasts for myogenesis. Here we investigated the Bmp isoform responsible for endogenous Bmp activity during differentiation and its role in myogenesis. Methods Gene expression of Bmp4 during myogenesis was evaluated in C2C12 cells. Effects of inhibition of the Bmp pathway on myogenesis were examined. Cells expressing Bmp4 and regulation of Bmp4 expression in myoblasts were explored. Results The expression of Bmp4 increased with the progression of myogenesis, although the extent of the increase after differentiation induction was smaller than that before the induction. Down-regulation of Bmp signal components including Bmp4, Bmpr2, and Alk2/3 inhibited the emergence of positive cells for myosin heavy chain II. The treatments also decreased the Myogenin expression. Treatment with cytosine arabinoside decreased the expression of Bmp4. Also, Bmp4 expression was also lower in isolated myotubes than in residual cells. Expression of Rgm c was higher in the myotube fraction. Transcription of Bmp4 was repressed by the conditioned medium of mixed cells consisting of myoblasts and myotubes. Conclusion Bmp4 expressed in myoblasts has a positive role in myotube formation/maturation through myogenin expression. The presence of myotubes inhibits Bmp4 expression in proliferating myoblasts through transcriptional regulation, although the expression is intrinsically increased with time of culture. General significance Taken previous results on involvement of Bmp in the commitment of osteoblasts and adipocytes with the present results together, Bmp may act as a general promoter of mesenchymal cell differentiation.

Vitamin A regulation of BMP4 expression in the male germ line

The molecular mechanisms leading to male infertility in vitamin A deficient (VAD) rodents have never been fully elucidated. Here, we report an interaction between BMP4 and retinoid signaling pathways in germ cells that may help clarify the biochemical basis of VAD. Adult germ cells, in particular spermatogonia, expressed BMP4 at both the mRNA and protein levels. BMP4 expression was significantly up-regulated in the testes of VAD mice and was down-regulated in freshly isolated germ cells and VAD testes by retinol, but not retinoic acid. The retinoid-responsive gene, RARβ, was not induced in germ cells following retinoid treatment. Examination of BMP4 promoter usage in spermatogonia and the VAD testis revealed that germ cells utilize the recently characterized BMP4 intron 2 promoter, in addition to the classical 1A and 1B promoters. The observed decrease in BMP4 in response to retinol was mediated by the 1A and intron 2 promoters of the BMP4 gene. Our results reflect a direct requirement for retinoids by germ cells for the resumption of spermatogenesis in VAD animals via mechanisms that involve the suppression of BMP4 expression.