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

Allograft inflammatory factor-1 enhances inflammation and oxidative stress via the NF-κB pathway of bladder urothelium in diabetic rat model

OBJECTIVES

To explore the role of allograft inflammatory factor-1 (AIF-1) both in diabetic rat bladder urothelium and in high-glucose-treated human urothelial cell line (SV-HUC-1).

METHODS

Inflammation and oxidative stress (OS) promote diabetic cystopathy (DCP), but the mechanisms are not fully understood. The expression level of AIF-1 in diabetic rat bladder urothelium and in the SV-HUC-1 cells treated with high glucose was detected using tissue immunofluorescence, immunohistochemistry and western blot assays. AIF-1 was knocked down and NF-κB was suppressed with the specific inhibitor BAY 11-7082 in high-glucose-treated SV-HUC-1 cells.

RESULTS

High-glucose condition induced AIF-1 upregulation in vivo and in vitro. The up-regulated AIF-1 induced the production of inflammatory factors IL-6 and TNF-α and elevation of ROS. Informatics analysis suggested that NF-κB pathway is implicated in DCP. Through knockdown of AIF-1, we confirmed that AIF-1 simulated NF-κB pathway by enhancing the phosphorylation of IκB (p-IκB) and promoting the translocation of NF-κB p65 from cytoplasm into nucleus. Additionally, High-glucose-induced inflammation in SV-HUC-1 cells was attenuated by the addition of NF-κB inhibitor.

CONCLUSIONS

This study provides novel information to understand the molecular regulation mechanisms of AIF-1 in DCP.

Potential role of oxidative stress in the pathogenesis of diabetic bladder dysfunction

Diabetes mellitus is a chronic metabolic disease, posing a considerable threat to global public health. Treating systemic comorbidities has been one of the greatest clinical challenges in the management of diabetes. Diabetic bladder dysfunction, characterized by detrusor overactivity during the early stage of the disease and detrusor underactivity during the late stage, is a common urological complication of diabetes. Oxidative stress is thought to trigger hyperglycaemia-dependent tissue damage in multiple organs; thus, a growing body of literature has suggested a possible link between functional changes in urothelium, muscle and the corresponding innervations. Improved understanding of the mechanisms of oxidative stress could lead to the development of novel therapeutics to restore the redox equilibrium and scavenge excessive free radicals to normalize bladder function in patients with diabetes.

Experimental long-term diabetes mellitus alters the transcriptome and biomechanical properties of the rat urinary bladder

Diabetes mellitus (DM) is the leading cause of chronic kidney disease and diabetic nephropathy is widely studied. In contrast, the pathobiology of diabetic urinary bladder disease is less understood despite dysfunctional voiding being common in DM. We hypothesised that diabetic cystopathy has a characteristic molecular signature. We therefore studied bladders of hyperglycaemic and polyuric rats with streptozotocin (STZ)-induced DM. Sixteen weeks after induction of DM, as assessed by RNA arrays, wide-ranging changes of gene expression occurred in DM bladders over and above those induced in bladders of non-hyperglycaemic rats with sucrose-induced polyuria. The altered transcripts included those coding for extracellular matrix regulators and neural molecules. Changes in key genes deregulated in DM rat bladders were also detected in db/db mouse bladders. In DM rat bladders there was reduced birefringent collagen between detrusor muscle bundles, and atomic force microscopy showed a significant reduction in tissue stiffness; neither change was found in bladders of sucrose-treated rats. Thus, altered extracellular matrix with reduced tissue rigidity may contribute to voiding dysfunction in people with long-term DM. These results serve as an informative stepping stone towards understanding the complex pathobiology of diabetic cystopathy.

Identification of key genes in type 2 diabetes-induced erectile dysfunction rats with stem cell therapy through high-throughput sequencing and bioinformatic analysis

Diabetes mellitus erectile dysfunction (DMED) is a frequent complication of diabetes. Mesenchymal stem cell (MSC) therapy was demonstrated to improve erectile function in DMED. However, the pathogenesis of DMED and the mechanism by which MSCs function are still unclear. We established a rat model of DMED and gave MSC therapy through intracavernous injection. After transcriptome sequencing of rats' penile tissue, we identified a total of 1,097 overlapped differentially expressed genes (DEGs) of the normal control group, DMED group, and MSC-treated group, containing 189 upregulated genes and 908 downregulated genes. The enriched functions of upregulated DEGs included extracellular matrix organisation (GO:0030198), extracellular structure organisation (GO:0043062), and wound healing (GO:0042060), PPAR signalling pathway (rno03320), arachidonic acid metabolism (rno00590) and retinol metabolism (rno00830). The enriched functions of downregulated DEGs included peptidase activity (GO:0052547), hair follicle development (GO:0001942), intermediate filament-based process (GO:0045103), nitrogen metabolism (rno00910), aldosterone-regulated sodium reabsorption (rno04960) and retinol metabolism (rno00830). We constructed a PPI network with 547 nodes and 2,365 edges and identified 15 hub genes with high connectivity degree. In summary, 15 hub genes with potential roles in the development of ED were identified. Further functional research would be required to elucidate the molecular mechanism underlying misregulated genes.

Systems analysis of benign bladder disorders: insights from omics analysis

The signaling pathways and effectors that drive the response of the bladder to nonmalignant insults or injury are incompletely defined. Interrogation of biological systems has been revolutionized by the ability to generate high-content data sets that capture information on a variety of biomolecules in cells and tissues, from DNA to RNA to proteins. In oncology, such an approach has led to the identification of cancer subtypes, improved prognostic capability, and has provided a basis for precision treatment of patients. In contrast, systematic molecular characterization of benign bladder disorders has lagged behind, such that our ability to uncover novel therapeutic interventions or increase our mechanistic understanding of such conditions is limited. Here, we discuss existing literature on the application of omics approaches, including transcriptomics and proteomics, to urinary tract conditions characterized by pathological tissue remodeling. We discuss molecular pathways implicated in remodeling, challenges in the field, and aspirations for omics-based research in the future.

Path of translational discovery of urological complications of obesity and diabetes

Diabetes mellitus (DM) is a prevalent chronic disease. Type 1 DM (T1DM) is a metabolic disorder that is characterized by hyperglycemia in the context of absolute lack of insulin, whereas type 2 DM (T2DM) is due to insulin resistance-related relative insulin deficiency. In comparison with T1DM, T2DM is more complex. The natural history of T2DM in most patients typically involves a course of obesity to impaired glucose tolerance, to insulin resistance, to hyperinsulinemia, to hyperglycemia, and finally to insulin deficiency. Obesity is a risk factor of T2DM. Diabetes causes some serious microvascular and macrovascular complications, such as retinopathy, nephropathy, neuropathy, angiopathy and stroke. Urological complications of obesity and diabetes (UCOD) affect quality of life, but are not well investigated. The urological complications in T1DM and T2DM are different. In addition, obesity itself affects the lower urinary tract. The aim of this perspective is to review the available data, combined with the experience of our research teams, who have spent a good part of last decade on studies of association between DM and lower urinary tract symptoms (LUTS) with the aim of bringing more focus to the future scientific exploration of UCOD. We focus on the most commonly seen urological complications, urinary incontinence, bladder dysfunction, and LUTS, in obesity and diabetes. Knowledge of these associations will lead to a better understanding of the pathophysiology underlying UCOD and hopefully assist urologists in the clinical management of obese or diabetic patients with LUTS.

Gene expression profile comparison in the penile tissue of diabetes and cavernous nerve injury-induced erectile dysfunction rat model

PURPOSE

To investigate the effects of cavernous nerve injury (CNI) on gene expression profiles in the cavernosal tissue of a CNI-induced erectile dysfunction (ED) model and to provide a basis for future investigations to discover potential target genes for ED treatment.

MATERIALS AND METHODS

Young adult rats were divided randomly into 2 groups: sham operation and bilateral CN resection. At 12 weeks after CNI we measured erectile responses and performed microarray experiments and gene set enrichment analysis to reveal gene signatures that were enriched in the CNI-induced ED model. Alterations in gene signatures were compared with those in the diabetes-induced ED model. The diabetic-induced ED data is taken from GSE2457.

RESULTS

The mean ratio of intracavernosal pressure/blood pressure for the CNI group (0.54±0.4 cmH2O) was significantly lower than that in the sham operation group (0.73±0.8 cmH2O, p<0.05). Supervised and unsupervised clustering analysis showed that the diabetes- and CNI-induced ED cavernous tissues had different gene expression profiles from normal cavernous tissues. We identified 46 genes that were upregulated and 77 genes that were downregulated in both the CNI- and diabetes-induced ED models.

CONCLUSIONS

Our genome-wide and computational studies provide the groundwork for understanding complex mechanisms and molecular signature changes in ED.

The interplay of extracellular matrix and microbiome in urothelial bladder cancer

Many pathological changes in solid tumours are caused by the accumulation of genetic mutations and epigenetic molecular alterations. In addition, tumour progression is profoundly influenced by the environment surrounding the transformed cells. The interplay between tumour cells and their microenvironment has been recognized as one of the key determinants of cancer development and is being extensively investigated. Data suggest that both the extracellular matrix and the microbiota represent microenvironments that contribute to the onset and progression of tumours. Through the introduction of omics technologies and pyrosequencing analyses, a detailed investigation of these two microenvironments is now possible. In urological research, assessment of their dysregulation has become increasingly important to provide diagnostic, prognostic and predictive biomarkers for urothelial bladder cancer. Understanding the roles of the extracellular matrix and microbiota, two key components of the urothelial mucosa, in the sequelae of pathogenic events that occur in the development and progression of urothelial carcinomas will be important to overcome the shortcomings in current bladder cancer treatment strategies.

Animal models of erectile dysfunction

Erectile dysfunction (ED) is a prevalent male sexual dysfunction with profound adverse effects on the physical and the psychosocial health of men and, subsequently, on their partners. The expanded use of various types of rodent models has produced some advances in the study of ED, and neurophysiological studies using various animal models have provided important insights into human sexual dysfunction. At present, animal models play a key role in exploring and screening novel drugs designed to treat ED.

Differentially expressed angiogenic genes in diabetic erectile tissue - results from a microarray screening

Diabetes-induced metabolic derangements promote endothelial malfunction, contributing to erectile dysfunction (ED). However, it remains unclear which angiogenic molecular mechanisms are deregulated in diabetic corpus cavernosum (CC). We investigated early and late alterations in cavernosal angiogenic gene expression associated to diabetes. Angiogenic changes were assessed in penile tissue of streptozotocin-induced Wistar rats, in an early (2-week) and established stage (8-week) of diabetes. Differentially expressed genes were identified by microarrays and expression data validated by quantitative real-time PCR (qrt-PCR). At protein level, quantitative immunohistochemistry confirmed the arrays data and dual immunofluorescence for selected alterations and α-smooth muscle actin (α-SMA) identified the cellular location of target proteins. The selected differentially expressed genes were also evaluated in human non-diabetic and diabetic CC by quantitative immunolabeling. At 2-week diabetes there was no differential gene expression between non-diabetic and diabetic CC. At 8-week, 10 genes were found down-regulated in diabetics. The results were validated by qrt-PCR for the insulin-like growth factor-1 (Igf1) and the natriuretic peptide receptor-1 (Npr1) genes. Dual immunofluorescence for IGF-1/ α-SMA showed predominant localization of IGF-1 in SM. NPR-1 expression was diffuse and mostly present in trabecular fibroblasts and SM. Quantitative immunostaining confirmed the decreased expression of both proteins in diabetic tissues. Concordantly, we detected a significant reduction in IGF-1 and NPR-1 protein expressions in human diabetic samples. Microarray analysis identified 10 angiogenic-related molecules deregulated in CC of established diabetes. Among them, IGF-1 and NPR-1 were significantly down-regulated and might result in preventive/therapeutic targets for ED management.

Markers of erectile dysfunction

With the development and marketing of oral pharmacotherapy that is both noninvasive and successful in treating erectile dysfunction (ED), the quest to identify markers of organic ED lost ground. Indeed, the multi-factorial nature of ED may have led many researchers to conclude that searching for a universal marker of ED was futile. However, the realization that ED is strongly correlated with the overall health of men, and may act as a predictor for the development of cardiovascular disease (CVD) and diabetes, has stimulated interest in identifying genes that can distinguish organic ED. In addition, the potential ability to suggest to the patient that ED is reversible (i.e., psychogenic) with a simple test would be of significance to both the physician and patient, as well as for reimbursement issues for therapy by insurance companies. Such a marker may also act as a non-subjective measure of the degree of ED and the efficacy of treatment. This review discusses the importance of identifying such markers and recent work identifying potential markers in human patients.

Silencing MaxiK activity in corporal smooth muscle cells initiates compensatory mechanisms to maintain calcium homeostasis

INTRODUCTION

The MaxiK potassium channel is regulated by voltage and intracellular calcium, and plays a critical role in regulating intracellular calcium concentration ([Ca(2+) ](i)), which is the ultimate determinant of smooth muscle tone. Tight control of corpus cavernosum smooth muscle (CCSM) tone is critically important and misregulation can result in erectile dysfunction.

AIM

Because of the tight functional linkage of MaxiK and calcium channel activity, the aim of this study was to determine the effects of silencing and pharmacological inhibition of MaxiK on calcium homeostasis and intercellular calcium signaling in CCSM cells.

METHODS

We compared changes in the basal intracellular [Ca(2+) ](i) and parameters defining intercellular calcium wave (ICW) spread in 48 hours MaxiK silenced CCSM cells vs. acute blockade of the channel with iberiotoxin. To analyze changes occurring in gene expression we performed micro-array analysis following MaxiK silencing for 48 hours.

MAIN OUTCOME MEASURES

Changes in Fura-2 fluorescence intensities were measured to evaluate basal [Ca(2+) ](i) levels and ICW parameters. Microarray analysis of global gene expression was performed.

RESULTS

Forty-eight hours after MaxiK silencing the basal [Ca(2+) ](i) , the ICW amplitude and spread among CCSM cells were not markedly different in silenced compared to mock transfected controls, whereas short-term blockade significantly increased basal [Ca(2+) ](i) level and amplified Ca(2+) signaling among CCSM cells. Micro-array analysis showed that several genes within Ca(2+) homeostasis and smooth muscle tone regulation pathways had significantly altered expression.

CONCLUSIONS

Our results indicate that while short-term blockade of the MaxiK channel is associated with an increase in basal [Ca(2+) ](i), Ca(2+) homeostasis is restored during the 48 hours period following silencing. We hypothesize that the different pathways regulating [Ca(2+) ](i) and CCSM tone are linked through molecular crosstalk and that their coordinated regulation is part of a compensatory mechanism aimed to maintain Ca(2+) homeostasis and CCSM tone.

Oxidative stress status accompanying diabetic bladder cystopathy results in the activation of protein degradation pathways

OBJECTIVE

• To investigate the role that oxidative stress plays in the development of diabetic cystopathy.

MATERIALS AND METHODS

• Comparative gene expression in the bladder of non-diabetic and streptozotocin (STZ)-induced 2-month- old diabetic rats was carried out using microarray analysis. • Evidence of oxidative stress was investigated in the bladder by analyzing glutathione S-transferase activity, lipid peroxidation, and carbonylation and nitrosylation of proteins. • The activity of protein degradation pathways was assessed using Western blot analysis.

RESULTS

• Analysis of global gene expression showed that detrusor smooth muscle tissue of STZ-induced diabetes undergoes significant enrichment in targets involved in the production or regulation of reactive oxygen species (P = 1.27 × 10(-10)). The microarray analysis was confirmed by showing that markers of oxidative stress were all significantly increased in the diabetic bladder. • It was hypothesized that the sequelae to oxidative stress would be increased protein damage and apoptosis. • This was confirmed by showing that two key proteins involved in protein degradation (Nedd4 and LC3B) were greatly up-regulated in diabetic bladders compared to controls by 12.2 ± 0.76 and 4.4 ± 1.0-fold, respectively, and the apoptosis inducing protein, BAX, was up-regulated by 6.76 ± 0.76-fold.

CONCLUSION

• Overall, the findings obtained in the present study add to the growing body of evidence showing that diabetic cystopathy is associated with oxidative damage of smooth muscle cells, and results in protein damage and activation of apoptotic pathways that may contribute to a deterioration in bladder function.

The bladder extracellular matrix. Part I: architecture, development and disease

From the earliest studies with epithelial cells implanted into detrusor muscle to later experiments on smooth muscle in defined collagen gels, cell niche and extracellular matrix (ECM) have been clearly shown to orchestrate cellular behavior and fate whether quiescent, migratory, or proliferative. Normal matrix can revert transformed cells to quiescence, and damaged matrix can trigger malignancy or dedifferentiation. ECM influence in disease, development, healing and regeneration has been demonstrated in many other fields of study, but a thorough examination of the roles of ECM in bladder cell activity has not yet been undertaken. Structural ECM proteins, in concert with adhesive proteins, provide crucial structural support to the bladder. Both structural and nonstructural components of the bladder have major effects on smooth muscle function, through effects on matrix rigidity and signaling through ECM receptors. While many ECM components and receptors identified in the bladder have specific known functions in the vascular smooth musculature, their function in the bladder is often less well defined. In cancer and obstructive disease, the ECM has a critical role in pathogenesis. The challenge in these settings will be to find therapies that prevent hyperproliferation and encourage proper differentiation, through an understanding of matrix effects on cell biology and susceptibility to therapeutics.

Mammalian target of rapamycin (mTOR) induces proliferation and de-differentiation responses to three coordinate pathophysiologic stimuli (mechanical strain, hypoxia, and extracellular matrix remodeling) in rat bladder smooth muscle

Maladaptive bladder muscle overgrowth and de-differentiation in human bladder obstructive conditions is instigated by coordinate responses to three stimuli: mechanical strain, tissue hypoxia, and extracellular matrix remodeling.( 1,2) Pathway analysis of genes induced by obstructive models of injury in bladder smooth muscle cells (BSMCs) identified a mammalian target of rapamycin (mTOR)-specific inhibitor as a potential pharmacological inhibitor. Strain-induced mTOR-specific S6K activation segregated differently from ERK1/2 activation in intact bladder ex vivo. Though rapamycin's antiproliferative effects in vascular smooth muscle cells are well known, its effects on BSMCs were previously unknown. Rapamycin significantly inhibited proliferation of BSMCs in response to mechanical strain, hypoxia, and denatured collagen. Rapamycin inhibited S6K at mTOR-sensitive phosphorylation sites in response to strain and hypoxia. Rapamycin also supported smooth muscle actin expression in response to strain or hypoxia-induced de-differentiation. Importantly, strain plus hypoxia synergistically augmented mTOR-dependent S6K activation, Mmp7 expression and proliferation. Forced expression of wild-type and constitutively active S6K resulted in loss of smooth muscle actin expression. Decreased smooth muscle actin, increased Mmp7 levels and mTOR pathway activation during in vivo partial bladder obstruction paralleled our in vitro studies. These results point to a coordinate role for mTOR in BSMCs responses to the three stimuli and a potential new therapeutic target for myopathic bladder disease.

Molecular targets for diabetes mellitus-associated erectile dysfunction

Protein expression profiles in rat corporal smooth muscle tissue were compared between animal models of streptozotocin-induced diabetes mellitus (STZ-DM) and age-matched controls (AMCs) at 1 week and 2 months after induction of hyperglycemia with STZ treatment. At each time point, protein samples from four STZ-DM and four AMC rat corpora tissues were prepared independently and analyzed together across multiple quantitative two-dimensional gels using a pooled internal standard sample to quantify expression changes with statistical confidence. A total of 170 spots were differential expressed among the four experimental groups. A subsequent mass spectrometry analysis of the 170 spots identified a total of 57 unique proteins. Network analysis of these proteins using MetaCore suggested altered activity of transcriptional factors that are of too low abundance to be detected by the two-dimensional gel method. The proteins that were down-regulated with diabetes include isoforms of collagen that are precursors to fibril-forming collagen type 1; Hsp47, which assists and mediates the proper folding of procollagen; and several proteins whose abundance is controlled by sex hormones (e.g. CRP1 and A2U). On the other hand, proteins seen or predicted to be up-regulated include proteins involved in cell apoptosis (e.g. p53, 14-3-3-gamma, Serpinf1, Cct4, Cct5, and Sepina3n), proteins that neutralize the biological activity of nerve growth factor (e.g. anti-NGF 30), and proteins involved in lipid metabolism (e.g. apoA-I and apoA-IV). Subsequent Western blot validation analysis of p53, 14-3-3-gamma, and Hsp47 confirmed increased p53 and 14-3-3-gamma and decreased Hsp47 levels in separate samples. According to the results from the Western blot analysis, Hsp47 protein showed a approximately 3-fold decrease at 1 week and was virtually undetectable at 2 months in diabetic versus control. Taken together, our results identify novel candidate proteins playing a role in erectile dysfunction in diabetes resulting from STZ treatment.

Pharmacogenetics and pharmacogenomics of sexual dysfunction: current status, gaps and potential applications

Although treatment of different types of sexual dysfunction has improved in the past decade with the introduction of phosphodiesterase type 5 inhibitors and selective serotonin reuptake inhibitors, response rates to these targeted therapies are variable. There are a number of studies in the published literature that provide proof-of-concept that genetic variation contributes to the variable response. Pharmacogenomics will most likely be one part of our therapeutic armamentarium in the future and will provide a stronger scientific basis for optimizing drug therapy on the basis of each patient’s genetic constitution. This article will review English language medical literature on the state-of-the-art genetic polymorphisms of drug targets, transporters and signaling molecules as well as pharmacogenetic studies of sexual dysfunction and suggested possible applications. Collectively, the data demonstrate that pharmacogenomics in the field of sexual medicine is still in its infancy. More research will provide further intriguing new discoveries in years to come.

The mechanism of opiorphin-induced experimental priapism in rats involves activation of the polyamine synthetic pathway

Intracorporal injection of plasmids encoding opiorphins into retired breeder rats can result in animals developing a priapic-like condition. Microarray analysis demonstrated that following intracorporal gene transfer of plasmids expressing opiorphins the most significantly upregulated gene in corporal tissue was the ornithine decarboxylase gene (ODC). Quantitative RT-PCR confirmed the upregulation of ODC, as well as other genes involved in polyamine synthesis, such as arginase-I and -II, polyamine oxidase, spermidine synthase, spermidine acetyltransferase (SAT), and S-adenosylmethionine decarboxylase. Western blot analysis demonstrated upregulation of arginase-I and -II, ODC, and SAT at the protein level. Levels of the polyamine putrescine were upregulated in animals treated with opiorphin-expressing plasmids compared with controls. A direct role for the upregulation of polyamine synthesis in the development of the priapic-like condition was supported by the observation that the ODC inhibitor 1,3-diaminopropane, when added to the drinking water of animals treated with plasmids expressing opiorphins, prevented experimental priapism. We also demonstrate that in sickle cell mice, another model of priapism, there is increased expression of the mouse opiorphin homologue in corporal tissue compared with the background strain at a life stage prior to evidence of priapism. At a life stage when there is onset of priapism, there is increased expression of the enzymes involved in polyamine synthesis (ODC and arginase-I and -II). Our results suggest that the upregulation of enzymes involved in the polyamine synthetic pathway may play a role in the development of experimental priapism and represent a target for the prevention of priapism.

An exploratory pathways analysis of temporal changes induced by spinal cord injury in the rat bladder wall: insights on remodeling and inflammation

BACKGROUND

Spinal cord injuries (SCI) can lead to severe bladder pathologies associated with inflammation, fibrosis, and increased susceptibility to urinary tract infections. We sought to characterize the complex pathways of remodeling, inflammation, and infection in the urinary bladder at the level of the transcriptome in a rat model of SCI, using pathways analysis bioinformatics.

METHODOLOGY/PRINCIPAL FINDINGS

Experimental data were obtained from the study of Nagatomi et al. (Biochem Biophys Res Commun 334: 1159). In this study, bladders from rats subjected to surgical SCI were obtained at 3, 7 or 25 days post-surgery, and Affymetrix GeneChip Rat Genome U34A arrays were used for cRNA hybridizations. In the present study, Ingenuity Pathways Analysis (Ingenuity Systems, www.ingenuity.com) of differentially expressed genes was performed. Analysis of focus genes in networks, functional analysis, and canonical pathway analysis reinforced our previous findings related to the presence of up-regulated genes involved in tissue remodeling, such as lysyl oxidase, tropoelastin, TGF-beta1, and IGF-1. This analysis also highlighted a central role for inflammation and infection, evidenced by networks containing genes such as CD74, S100A9, and THY1.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that tissue remodeling, infection, inflammation, and tissue damage/dysfunction all play a role in the urinary bladder, in the complex response to SCI.

Vcsa1 acts as a marker of erectile function recovery after gene therapeutic and pharmacological interventions

PURPOSE

We identified molecular markers of erectile function, particularly those responding to erectile dysfunction treatment.

MATERIALS AND METHODS

Sprague-Dawley retired breeder rats were intracorporeally injected with pVAX-hSlo, pSMAA-hSlo or the control plasmid pVAX. One week later the intracorporeal pressure-to-blood pressure ratio and gene expression were determined by microarray analysis and quantitative reverse transcriptase-polymerase chain reaction. Rat corporeal cells were transfected in vitro with pVAX-hSlo, pSMAA-hSlo or pVAX and the change in gene expression was determined. We also determined whether Vcsa1 expression was changed after pharmacotherapy using tadalafil.

RESULTS

Animals treated with vectors expressing hSlo had significantly improved erectile function compared to that in controls, accompanied by changed expression of a subset of genes. Vcsa1 was one of the genes that was most changed in expression (the third of approximately 31,000 with greater than 10-fold up-regulation). Changes in gene expression were different than those observed in corporeal cells transfected in vitro, distinguishing gene expression changes that were a direct effect of hSlo over expression. When tadalafil was administered in retired breeder rats, the Vcsa1 transcript increased 4-fold in corporeal tissue compared to that in untreated controls.

CONCLUSIONS

Our study identifies a set of genes that are changed in response to improved erectile function, rather than as a direct effect of treatment. We noted Vcsa1 may act as marker of the restoration of erectile function after gene transfer and pharmacotherapy.

Transcription of G-protein coupled receptors in corporeal smooth muscle is regulated by the endogenous neutral endopeptidase inhibitor sialorphin

PURPOSE

Several reports suggest that the rat Vcsa1 gene is down-regulated in models of erectile dysfunction. The Vcsa protein product sialorphin is an endogenous neutral endopeptidase inhibitor and its down-regulation could result in prolonged activation of G-protein activated signaling pathways by their peptide agonists. We investigated whether Vcsa1 down-regulation could result in an adaptive change in GPCR (G-protein coupled receptor) expression.

MATERIALS AND METHODS

Gene expression in cultured rat corporeal smooth muscle cells following treatment with siRNA directed against Vcsa1 or the neutral endopeptidase gene was analyzed using microarray and quantitative reverse transcriptase-polymerase chain reaction. In rats Vcsa1 is one of the most down-regulated genes following bilateral transection of the cavernous nerves. In that animal model we also investigated whether Vcsa1 down-regulation was accompanied by similar changes in gene expression in corporeal smooth muscle cells in which Vcsa1 was knocked down in vitro.

RESULTS

Microarray analysis and quantitative reverse transcriptase-polymerase chain reaction demonstrated that corporeal smooth muscle cells treated in vitro with siRNA against Vcsa1 resulted in GPCR up-regulation as a functional group. In contrast, treatment of corporeal smooth muscle cells that lowered neutral endopeptidase activity resulted in decreased GPCR expression. These results suggest that the peptide product of Vcsa1, sialorphin, can effect GPCR expression by acting on neutral endopeptidase. In animals with bilaterally transected cavernous nerves the decreased Vcsa1 expression is accompanied by increased GPCR expression in cavernous tissue.

CONCLUSIONS

These experiments suggest that the mechanism by which Vcsa1 modulates erectile function is partly mediated through changes in GPCR expression.

Treatment strategies for diabetic patients suffering from erectile dysfunction

Erectile dysfunction is a common complication of diabetes. Clinical practice has no treatment modality specifically designed for the difficult to treat diabetic erectile dysfunction due to the multifactorial and complex pathophysiology of development. PDE type 5 inhibitors are the first-line treatment option. Non-responders should have total and free testosterone checked and testosterone replacement is recommended for hypogonadal patients. For patients who cannot take PDE type 5 inhibitors, or are proven non-responders, the vacuum constriction device continues to serve as a major treatment option. Intracavernosal injection is the most effective medical therapy for diabetic erectile dysfunction despite its high dropout rate. Use of the Medicated Urethral System for Erection to overcome the disadvantages of needle injection is disappointing due to lack of effectiveness. Penile prosthesis will continue to play an important role in diabetic patients with severe erectile dysfunction in coming years.

Proteomics analysis identifies molecular targets related to diabetes mellitus-associated bladder dysfunction

Protein expression profiles in rat bladder smooth muscle were compared between animal models of streptozotocin-induced diabetes mellitus (STZ-DM) and age-matched controls at 1 week and 2 months after induction of hyperglycemia with STZ treatment. At each time point, protein samples from four STZ-DM and four age-matched control rat bladder tissues were prepared independently and analyzed together across multiple DIGE gels using a pooled internal standard sample to quantify expression changes with statistical confidence. A total of 100 spots were determined to be significantly changing among the four experimental groups. A subsequent mass spectrometry analysis of the 100 spots identified a total of 56 unique proteins. Of the proteins identified by two-dimensional DIGE/MS, 10 exhibited significant changes 1 week after STZ-induced hyperglycemia, whereas the rest showed differential expression after 2 months. A network analysis of these proteins using MetaCore suggested induction of transcriptional factors that are too low to be detected by two-dimensional DIGE and identified an enriched cluster of down-regulated proteins that are involved in cell adhesion, cell shape control, and motility, including vinculin, intermediate filaments, Ppp2r1a, and extracellular matrix proteins. The proteins that were up-regulated include proteins involved in muscle contraction (e.g. Mrlcb and Ly-GDI), in glycolysis (e.g. alpha-enolase and Taldo1), in mRNA processing (e.g. heterogeneous nuclear ribonucleoprotein A2/B1), in inflammatory response (e.g. S100A9, Annexin 1, and apoA-I), and in chromosome segregation and migration (e.g. Tuba1 and Vil2). Our results suggest that the development of diabetes-related complications in this model involves the down-regulation of structural and extracellular matrix proteins in smooth muscle that are essential for normal muscle contraction and relaxation but also induces proteins that are associated with cell proliferation and inflammation that may account for some of the functional deficits known to occur in diabetic complications of bladder.