Mechanical stretch is a highly selective regulator of gene expression in human bladder smooth muscle cells.
Application of mechanical stimuli has been shown to alter gene expression in bladder smooth muscle cells (SMC). To date, only a limited number of "stretch-responsive" genes in this cell type have been reported. We employed oligonucleotide arrays to identify stretch-sensitive genes in primary culture human bladder SMC subjected to repetitive mechanical stimulation for 4 h. Differential gene expression between stretched and nonstretched cells was assessed using Significance Analysis of Microarrays (SAM). Expression of 20 out of 11,731 expressed genes ( approximately 0.17%) was altered >2-fold following stretch, with 19 genes induced and one gene (FGF-9) repressed. Using real-time RT-PCR, we tested independently the responsiveness of 15 genes to stretch and to platelet-derived growth factor-BB (PDGF-BB), another hypertrophic stimulus for bladder SMC. In response to both stimuli, expression of 13 genes increased, 1 gene (FGF-9) decreased, and 1 gene was unchanged. Six transcripts (HB-EGF, BMP-2, COX-2, LIF, PAR-2, and FGF-9) were evaluated using an ex vivo rat model of bladder distension. HB-EGF, BMP-2, COX-2, LIF, and PAR-2 increased with bladder stretch ex vivo, whereas FGF-9 decreased, consistent with expression changes observed in vitro. In silico analysis of microarray data using the FIRED algorithm identified c-jun, AP-1, ATF-2, and neurofibromin-1 (NF-1) as potential transcriptional mediators of stretch signals. Furthermore, the promoters of 9 of 13 stretch-responsive genes contained AP-1 binding sites. These observations identify stretch as a highly selective regulator of gene expression in bladder SMC. Moreover, they suggest that mechanical and growth factor signals converge on common transcriptional regulators that include members of the AP-1 family.
Urological Diseases Research Center, Department of Urology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA. rosalyn.adam@childrens.harvard.edu <rosalyn.adam@childrens.harvard.edu>
Rosalyn M
RM
Adam
Samuel H
SH
Eaton
Carlos
C
Estrada
Ashish
A
Nimgaonkar
Shu-Ching
SC
Shih
Lois E H
LE
Smith
Isaac S
IS
Kohane
Darius
D
Bägli
Michael R
MR
Freeman
D000465:Algorithms; D000818:Animals; D000077214:Becaplermin; D001665:Binding Sites; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002478:Cells, Cultured; D019295:Computational Biology; D051546:Cyclooxygenase 2 / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000378:metabolism; D005260:Female; D051525:Fibroblast Growth Factor 9 / Q000096:biosynthesis / Q000378:metabolism; D005786:Gene Expression Regulation; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6 / Q000378:metabolism; D053605:Leukemia Inhibitory Factor; D009130:Muscle, Smooth / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D025542:Neurofibromin 1 / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D009841:Oligonucleotides / Q000737:chemistry; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D044464:Receptor, PAR-2 / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013314:Stress, Mechanical; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000378:metabolism; D001743:Urinary Bladder / Q000378:metabolism*
C525718:BMP2 protein, human; C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; C496459:FGF9 protein, human; D051525:Fibroblast Growth Factor 9; C587883:HBEGF protein, human; C587885:Hbegf protein, rat; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D025542:Neurofibromin 1; D009841:Oligonucleotides; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D012333:RNA, Messenger; D044464:Receptor, PAR-2; D018808:Transcription Factor AP-1; D016212:Transforming Growth Factor beta; D000077214:Becaplermin; D004815:Epidermal Growth Factor; D051546:Cyclooxygenase 2