Platelet-derived growth factor-BB increases expression of connexin 43 in an extracellular-regulated protein kinase-dependent manner in bladder smooth muscle cells

Exosomes from human urine-derived stem cells carry NRF1 to alleviate bladder fibrosis via regulating miR-301b-3p/TGFβR1 pathway

Bladder outlet obstruction (BOO) is a common disease that always make the bladder develops from inflammation to fibrosis. This study was to investigate the effect of exosomes from human urine-derived stem cells (hUSCs) on bladder fibrosis after BOO and the underlying mechanism. The BOO mouse model was established by inserting a transurethral catheter, ligation of periurethral wire, and removal of the catheter. Mouse primary bladder smooth muscle cells (BSMCs) were isolated and treated with TGFβ1 to mimic the bladder fibrosis model in vitro. Exosomes from hUSCs (hUSC-Exos) were injected into the bladder of BOO mice and added into the culture of TGFβ1-induced BSMCs. The associated factors in mouse bladder tissues and BSMCs were detected. It was confirmed that the treatment of hUSC-Exos alleviated mouse bladder fibrosis and down-regulated fibrotic markers (a-SMA and collagen III) in bladder tissues and TGFβ1-induced BSMCs. Overexpression of NRF1 in hUSC-Exos further improved the effects of hUSC-Exos on bladder fibrosis both in vivo and in vitro. TGFβR1 was a target of NRF1 and miR-301b-3p, and miR-301b-3p was a target of NRF1. It was next characterized that hUSC-Exos carried NRF1 to up-regulate miR-301B-3p, thereby reducing TGFβR1level. Our results illustrated that hUSC-Exos carried NRF1 to alleviate bladder fibrosis through regulating miR-301b-3p/TGFβR1 pathway.

Overexpression of MiR-29b-3p Inhibits Atrial Remodeling in Rats by Targeting PDGF-B Signaling Pathway

Purpose

Studies have found that microRNAs (miRNAs) are closely associated with atrial fibrillation, but their specific mechanism remains unclear. The purpose of this experiment is to explore the function of miR-29b-3p in regulating atrial remodeling by targeting PDGF-B signaling pathway and thereby also explore the potential mechanisms.

Methods

We randomly divided twenty-four rats into four groups. Caudal intravenous injections of angiotensin-II (Ang-II) were administered to establish atrial fibrosis models. Expressions of miR-29b-3p and PDGF-B were then tested via RT-PCR, western blot, and immunohistochemistry. Binding sites were then analyzed via the bioinformatics online software TargetScan and verified by Luciferase Reporter. We used Masson staining to detect the degree of atrial fibrosis, while immunofluorescence and western blot were used to detect the expressions of Collagen-I and a-SMA. We used immunohistochemistry and western blot to detect the expression of connexin 43 (Cx43).

Results

In comparison with the Ang-II group, miR-29b-3p was seen to lower the degree of atrial fibrosis, decrease the expression of fibrosis markers such as Collagen-I and a-SMA, and increase the protein expression of Cx43. MiR-29b-3p can lower the expression of PDGF-B, while the Luciferase Reporter showed that PDGF-B is the verified target gene of miR-29b-3p.

Conclusions

MiR-29b-3p was able to reduce atrial structural and electrical remodeling in the study's rat fibrosis model. This biological function may be expressed through the targeted regulation of the PDGF-B signaling pathway.

PDGF-mediated PI3K/AKT/β-catenin signaling regulates gap junctions in corpus cavernosum smooth muscle cells

Erectile dysfunction (ED) is the most common sexual disorder that men report to healthcare providers. Gap junctions (GJs) are thought to be responsible for synchronous shrinkage of corpus cavernosum smooth muscle cells (CCSMCs), and play thus an important role in the maintenance of an erection. Hypoxia has been suggested as a pathological mechanism underlying ED. Here we demonstrate that hypoxia increased the expression of platelet-derived growth factor (PDGF) and the main GJ component connexin (Cx)43 in CCSMCs. Inhibiting PDGF receptor (PDGFR) activity decreased Cx43 expression. Treatment with different concentrations of PDGF increased the levels of phosphorylated protein kinase B (AKT), β-catenin, and Cx43, whereas inhibition of PDGFR or activation of phosphatidylinositol 3 kinase (PI3K)/AKT signaling altered β-catenin and Cx43 expression. Meanwhile, silencing β-catenin resulted in the downregulation of Cx43. These results demonstrate that PDGF secretion by CCSMCs and vascular endothelial cells is enhanced under hypoxic conditions, leading to increased Cx43 expression through PI3K/AKT/β-catenin signaling and ultimately affecting GJ function in ED. Thus, targeting this pathway is a potential therapeutic strategy for the treatment of ED.

Structural and functional changes in gap junctional intercellular communication in a rat model of overactive bladder syndrome induced by partial bladder outlet obstruction

The aim of the present study was to investigate the association between connexin (Cx)43 levels and alterations in gap junctional mediation of intercellular communication in overactive bladder syndrome (OAB), and to examine the effects of connexin inhibitor on this condition. Adult female Wistar rats with OAB following partial bladder outlet obstruction (PBBO) (OAB group, n=37) and sham-operated rats (control group, n=17) were studied. The ultrastructure of the rat detrusor was observed by transmission electron microscopy and the protein expression levels of Cx43 were analyzed using western blot analysis. Furthermore, bladder detrusor cells in both groups were cultured and cells in the OAB group were randomly divided into ten groups. In nine of these groups, 18-β glycyrrhetinic acid (18β-GA) was administered at various doses and durations. All groups were compared using fluorescence redistribution after photobleaching and a laser scanning confocal microscope. Cystometry demonstrated that gap junctions were an abundant mechanism among adjacent cells, and Cx43 protein expression levels were increased in the OAB group following 6 weeks of obstruction, as compared with the control group. Mean fluorescence recovery rates in the OAB group were significantly increased, as compared with the control group (P<0.01). Mean fluorescence recovery rates were noted following 18β-GA administration. These results suggested that upregulation of Cx43 induces structural and functional alterations in gap junctional intercellular communication following PBOO, and connexin inhibitors may be a novel therapeutic strategy for the clinical treatment of OAB.

MiR-133 modulates TGF-β1-induced bladder smooth muscle cell hypertrophic and fibrotic response: implication for a role of microRNA in bladder wall remodeling caused by bladder outlet obstruction

Bladder outlet obstruction (BOO) evokes urinary bladder wall remodeling significantly, including the phenotype shift of bladder smooth muscle cells (BSMCs) where transforming growth factor-beta1 (TGF-β1) plays a pivotal role given the emerging function of modulating cellular phenotype. miR-133 plays a role in cardiac and muscle remodeling, however, little is known about its roles in TGF-β1-induced BSMC hypertrophic and fibrotic response. Here, we verified BOO induced bladder wall remodeling and TGF-β1 expression mainly located in bladder endothelium. Furthermore, we uncovered miR-133a/b expression profile in BOO rats, and then explored its regulated effects on BSMCs' phenotypic shift. Our study found that miR-133 became down-regulated during rat bladder remodeling. Next, we sought to examine whether the expression of miR-133 was down-regulated in primary BSMCs in response to TGF-β1 stimulation and whether forced overexpression of miR-133 could regulate profibrotic TGF-β signaling. We found that stimulation of BSMCs with exogenous TGF-β1 of increasing concentrations resulted in a dose-dependent decrease of miR-133a/b levels and transfection with miR-133 mimics attenuated TGF-β1-induced α-smooth muscle actin, extracellular matrix subtypes and fibrotic growth factor expression, whereas it upregulated high molecular weight caldesmon expression compared with the negative control. Also, downregulation of p-Smad3, not p-Smad2 by miR-133 was detected. Additionally, miR-133 overexpression suppressed TGF-β1-induced BSMC hypertrophy and proliferation through influencing cell cycle distribution. Bioinformatics analyses predicted that connective tissue growth factor (CTGF) was the potential target of miR-133, and then binding to the 3'-untranslated region of CTGF was validated by luciferase reporter assay. These results reveal a novel regulator for miR-133 to modulate TGF-β1-induced BSMC phenotypic changes by targeting CTGF through the TGF-β-Smad3 signaling pathway. A novel antifibrotic functional role for miR-133 is presented which may represent a potential target for diagnostic and therapeutic strategies in bladder fibrosis.

Gap junction modulation and its implications for heart function

Gap junction communication (GJC) mediated by connexins is critical for heart function. To gain insight into the causal relationship of molecular mechanisms of disease pathology, it is important to understand which mechanisms contribute to impairment of gap junctional communication. Here, we present an update on the known modulators of connexins, including various interaction partners, kinases, and signaling cascades. This gap junction network (GJN) can serve as a blueprint for data mining approaches exploring the growing number of publicly available data sets from experimental and clinical studies.