Using gene chips to identify organ‐specific, smooth muscle responses to experimental diabetes: potential applications to urological diseases

Abstract

OBJECTIVE To identify early diabetes‐related alterations in gene expression in bladder and erectile tissue that would provide novel diagnostic and therapeutic treatment targets to prevent, delay or ameliorate the ensuing bladder and erectile dysfunction. MATERIALS AND METHODS The RG‐U34A rat GeneChip® (Affymetrix Inc., Sunnyvale, CA, USA) oligonucleotide microarray (containing ≈8799 genes) was used to evaluate gene expression in corporal and male bladder tissue excised from rats 1 week after confirmation of a diabetic state, but before demonstrable changes in organ function in vivo. A conservative analytical approach was used to detect alterations in gene expression, and gene ontology (GO) classifications were used to identify biological themes/pathways involved in the aetiology of the organ dysfunction. RESULTS In all, 320 and 313 genes were differentially expressed in bladder and corporal tissue, respectively. GO analysis in bladder tissue showed prominent increases in biological pathways involved in cell proliferation, metabolism, actin cytoskeleton and myosin, as well as decreases in cell motility, and regulation of muscle contraction. GO analysis in corpora showed increases in pathways related to ion channel transport and ion channel activity, while there were decreases in collagen I and actin genes. CONCLUSIONS The changes in gene expression in these initial experiments are consistent with the pathophysiological characteristics of the bladder and erectile dysfunction seen later in the diabetic disease process. Thus, the observed changes in gene expression might be harbingers or biomarkers of impending organ dysfunction, and could provide useful diagnostic and therapeutic targets for a variety of progressive urological diseases/conditions (i.e. lower urinary tract symptoms related to benign prostatic hyperplasia, erectile dysfunction, etc.).

Proteomics Analysis Identifies Molecular Targets Related to Diabetes Mellitus-associated Bladder Dysfunction

“…Other proteins, including myosin regulatory light chain 2-B smooth muscle isoform (Mrlcb) and Argbp2 showed STZ-induced increases at 1 week but no significant change at 2 months. Consistent with our 2D DIGE results for Mrlcb and calponin (Cnn1), in a recent genome expression analysis Hipp et al (20) found significant increases in Mrlcb and decreases in Cnn1 after 1 week of STZ-induced diabetes. 48 proteins showed STZ-induced differential expression 2 months after the confirmation of STZ-induced hyperglycemia.…”

Molecular Targets for Diabetes Mellitus-associated Erectile Dysfunction

“…the different isoforms of collagens at both the transcriptional (32,33) and translational levels (Ref. 42 and this study) has yet to be determined.…”

“…Animal Preparation-Diabetes was induced in male Fischer 344 rat (Taconic Farms, Germantown, NY; 8 -10 weeks old and weighing 200 -240 g) with a single intraperitoneal injection of STZ (35 mg/kg) dissolved in citrate buffer (0.6 M citric acid, 0.08 M Na 2 HPO 4 , pH 4.6) as described previously (33,42,49). The age-matched control (AMC) rats received an injection of vehicle only.…”

“…Measurement of Intracorporal Pressure/Systemic Blood Pressure (ICP/BP)-One week or 2 months following confirmation of STZinduced diabetes, the rats were anesthetized with pentobarbital sodium (35 mg/kg intraperitoneally), and erectile function was determined by measuring the ICP/BP ratio following electrical stimulation of the cavernous nerve as described previously (33,49). Briefly, an incision was made in the perineum, and a window was made in the ischiocavernosus muscle to expose the corpus cavernosum.…”

“…There have been major advances in the identification of genes and signaling pathways involved in erectile dysfunction (17,(32)(33)(34); however, to our knowledge, there are no studies that have been conducted to characterize the protein changes at the proteome level. As there is a modest correlation between transcription and protein expression levels, there are obvious opportunities to advance our molecular understanding of the disease by direct measurements of protein changes.…”