Tatsuya Miyamoto

Functional Role for Piezo1 in Stretch-evoked Ca2+ Influx and ATP Release in Urothelial Cell Cultures

Background: The Piezo1 channel was recently identified as a genuine mechanosensor in mammalian cells. Results: Urothelial cells exhibited a Piezo1-dependent increase in cytosolic Ca2+ concentrations in response to mechanical stretch stimuli, leading to ATP release. Conclusion: Piezo1 senses extension of the bladder urothelium, which is converted into an ATP signal. Significance: Inhibition of Piezo1 might provide a new treatment for bladder dysfunction. The urothelium is a sensory structure that contributes to mechanosensation in the urinary bladder. Here, we provide evidence for a critical role for the Piezo1 channel, a newly identified mechanosensory molecule, in the mouse bladder urothelium. We performed a systematic analysis of the molecular and functional expression of Piezo1 channels in the urothelium. Immunofluorescence examination demonstrated abundant expression of Piezo1 in the mouse and human urothelium. Urothelial cells isolated from mice exhibited a Piezo1-dependent increase in cytosolic Ca2+ concentrations in response to mechanical stretch stimuli, leading to potent ATP release; this response was suppressed in Piezo1-knockdown cells. In addition, Piezo1 and TRPV4 distinguished different intensities of mechanical stimulus. Moreover, GsMTx4, an inhibitor of stretch-activated channels, attenuated the Ca2+ influx into urothelial cells and decreased ATP release from them upon stretch stimulation. These results suggest that Piezo1 senses extension of the bladder urothelium, leading to production of an ATP signal. Thus, inhibition of Piezo1 might provide a promising means of treating bladder dysfunction.

Functional roles of TRPV1 and TRPV4 in control of lower urinary tract activity: dual analysis of behavior and reflex during the micturition cycle

The present study used a dual analysis of voiding behavior and reflex micturition to examine lower urinary tract function in transient receptor potential vanilloid (TRPV)1 knockout (KO) mice and TRPV4 KO mice. In metabolic cage experiments conducted under conscious conditions (i.e., voluntary voiding behavior), TRPV4 KO mice showed a markedly higher voiding frequency (VF; 19.3 ± 1.2 times/day) and a smaller urine volume/voiding (UVV; 114 ± 9 μl) compared with wild-type (WT) littermates (VF: 5.2 ± 0.5 times/day and UVV: 380 ± 34 μl). Meanwhile, TRPV1 KO mice showed a similar VF to WT littermates (6.8 ± 0.5 times/day) with a significantly smaller UVV (276 ± 20 μl). Water intake among these genotypes was the same, but TRPV4 KO mice had a larger urine output than the other two groups. In cystometrogram experiments conducted in decerebrate unanesthetized mice (i.e., reflex micturition response), no differences between the three groups were found in any cystometrogram variables, including voided volume, volume threshold for inducing micturition contraction, maximal voiding pressure, and bladder compliance. However, both TRPV1 KO and TRPV4 KO mice showed a significant number of nonvoiding bladder contractions (NVCs; 3.5 ± 0.9 and 2.8 ± 0.7 contractions, respectively) before each voiding, whereas WT mice showed virtually no NVCs. These results suggest that in the reflex micturition circuit, a lack of either channel is involved in NVCs during bladder filling, whereas in the forebrain, it is involved in the early timing of urine release, possibly in the conscious response to the bladder instability.

Urothelial ATP exocytosis: Regulation of bladder compliance in the urine storage phase

The bladder urothelium is more than just a barrier. When the bladder is distended, the urothelium functions as a sensor to initiate the voiding reflex, during which it releases ATP via multiple mechanisms. However, the mechanisms underlying this ATP release in response to the various stretch stimuli caused by bladder filling remain largely unknown. Therefore, the aim of this study was to elucidate these mechanisms. By comparing vesicular nucleotide transporter (VNUT)-deficient and wild-type male mice, we showed that ATP has a crucial role in urine storage through exocytosis via a VNUT-dependent mechanism. VNUT was abundantly expressed in the bladder urothelium, and when the urothelium was weakly stimulated (i.e. in the early filling stages), it released ATP by exocytosis. VNUT-deficient mice showed reduced bladder compliance from the early storage phase and displayed frequent urination in inappropriate places without a change in voiding function. We conclude that urothelial, VNUT-dependent ATP exocytosis is involved in urine storage mechanisms that promote the relaxation of the bladder during the early stages of filling.

Decreased Expression of the Epithelial Ca2+ Channel TRPV5 and TRPV6 in Human Renal Cell Carcinoma Associated With Vitamin D Receptor

PURPOSE We investigated the expression of epithelial Ca(2+) channel TRPV (transient receptor potential vanilloid subfamily) 5 and 6, and vitamin D receptor in primary human renal cell carcinoma and benign peritumor tissues, and assessed the possible association between TRPV5/6 and vitamin D receptor expression. MATERIALS AND METHODS Fresh-frozen primary tumor and peritumor tissues from 27 patients diagnosed with renal cell carcinoma were analyzed for TRPV5/6 and vitamin D receptor expression by quantitative reverse transcriptase-polymerase chain reaction, Western blot and immunohistochemistry. RESULTS Quantitative reverse transcriptase-polymerase chain reaction revealed that TRPV5/6 and vitamin D receptor expression was decreased 38.11, 4.44 and 3.20 times in renal cell carcinoma vs normal kidney tissue (p = 0.012, 0.002 and 0.020, respectively). Relatively higher expression was noted for chromophobe renal cell carcinoma than for the other renal cell carcinoma subtypes. Vitamin D receptor mRNA expression significantly correlated with that of TRPV6 (r = 0.508, p = 0.007) and TRPV5 (r = 0.697, p = 0.032) in renal cell carcinoma. Western blot showed results similar to those of reverse transcriptase-polymerase chain reaction. Different expression was detected between kidney and renal cell carcinoma tissue. Immunohistochemical analysis verified strong detection of TRPV5/6 and vitamin D receptor in distal nephrons but demonstrated weak or no immunostaining much more often in renal cell carcinoma. CONCLUSIONS Decreased TRPV5/V6 expression was noted in renal cell carcinoma, which correlated with vitamin D receptor. Different expression was also detected among the different renal cell carcinoma histopathological subtypes. Our observations suggest that altered vitamin D receptor expression may be associated with renal cell carcinoma carcinogenesis via TRPV5/6.

The Clock mutant mouse is a novel experimental model for nocturia and nocturnal polyuria.

The pathophysiologies of nocturia (NOC) and nocturnal polyuria (NP) are multifactorial and their etiologies remain unclear in a large number of patients. Clock genes exist in most cells and organs, and the products of Clock regulate circadian rhythms as representative clock genes. Clock genes regulate lower urinary tract function, and a newly suggested concept is that abnormalities in clock genes cause lower urinary tract symptoms. In the present study, we investigated the voiding behavior of Clock mutant (ClockΔ19/Δ19) mice in order to determine the effects of clock genes on NOC/NP.

Metabolomics approach for male lower urinary tract symptoms: An identification of possible biomarkers and potential targets for new treatments

Purpose: We identified metabolites using a metabolomics approach and investigated the association between these metabolites and lower urinary tract symptoms. Materials and Methods: We used a 24‐hour bladder diary and I‐PSS (International Prostate Symptom Score) to assess micturition behavior and lower urinary tract symptoms in 58 male patients without apparent neurological disease. Lower urinary tract symptoms were defined as a total I‐PSS score of 8 or greater. Patients with a score of 7 or less were placed in the control group. A comprehensive study of plasma metabolites was also performed by capillary electrophoresis time‐of‐flight mass spectrometry. Metabolites were compared between the lower urinary tract symptoms and control groups using the Mann‐Whitney U test. Biomarkers of male lower urinary tract symptoms from the metabolites were analyzed using multivariable logistic regression analysis to determine the OR. Results: Of the 58 men 32 were in the lower urinary tract symptoms group and the remaining 26 were in the control group. The 24‐hour bladder diary showed that nocturnal urine volume, 24‐hour micturition frequency, nocturnal micturition frequency and the nocturia index were significantly higher in the lower urinary tract symptoms group. Metabolomics analysis identified 60 metabolites from patient plasma. Multivariate analysis revealed that increased glutamate and decreased arginine, asparagine and inosine monophosphate were significantly associated with lower urinary tract symptoms in males. Decreases in citrulline and glutamine could also be associated with male lower urinary tract symptoms. Conclusions: Male lower urinary tract symptoms may develop due to abnormal metabolic processes in some pathways. Potential new treatments for lower urinary tract symptoms can be developed by identifying changes in the amino acid profiles.

P2Y 6 -deficiency increases micturition frequency and attenuates sustained contractility of the urinary bladder in mice

The role of the P2Y6 receptor in bladder function has recently attracted a great deal of attention in lower urinary tract research. We conducted this study to determine contributions of the P2Y6 receptor in lower urinary tract function of normal phenotypes by comparing P2Y6-deficient mice and wild-type mice. In in vivo experiments, P2Y6-deficient mice had more frequent micturition with smaller bladder capacity compared to wild-type mice; however, there was no difference between these groups in bladder-filling pressure/volume relationships during cystometry under decerebrate, unanaesthetized conditions. Analysis of in vivo bladder contraction revealed significant difference between the 2 groups, with P2Y6-deficient mice presenting markedly shorter bladder contraction duration but no difference in peak contraction pressure. However, analysis of in vitro experiments showed no P2Y6 involvements in contraction and relaxation of bladder muscle strips and in ATP release by mechanical stimulation of primary-cultured urothelial cells. These results suggest that the P2Y6 receptor in the central nervous system, dorsal root ganglion, or both is involved in inhibition of bladder afferent signalling or sensitivity in the pontine micturition centre and that the receptor in the detrusor may be implicated in facilitation to sustain bladder contraction force.

Hemorrhagic Renal Angiomyolipoma in Pregnancy Effectively Managed by Immediate Cesarean Section and Elective Transcatheter Arterial Embolization: A Case Report

Abstract Renal angiomyolipoma (AML) is a benign renal tumor with a risk of rupture in intratumoral aneurysms. Although renal AML in pregnancy is rare, risk of rupture is greater. Management for AML and childbirth is important during pregnancy; however, it is undefined yet. We present a case of hemorrhagic angiomyolipoma in pregnancy that is effectively managed by immediate cesarean section and elective transcatheter arterial embolization.

Contralateral Adrenal Metastasis of Renal Cell Carcinoma Arising From a Horseshoe Kidney: An Initial Case Report.

A 71-year-old woman with a right adrenal mass detected by computed tomography was referred to our institution. Before 33 months, she had undergone a radical heminephrectomy for an 11-cm renal cell carcinoma (RCC) in the left moiety of a horseshoe kidney. The adrenal tumor was diagnosed as the metastasis of RCC. The tumor was subsequently removed in a laparoscopic adrenalectomy by a retroperitoneal approach. Pathologic examination revealed the mass to be the adrenal metastasis of RCC. To our knowledge, this is the initial report of a laparoscopic adrenalectomy for the adrenal metastasis of renal cell carcinoma arising from a horseshoe kidney.

SILODOSIN, A NOVEL ALPHA1A AR-SUPER SELECTIVE ANTAGONIST, RAPIDLY IMPROVES BOTHERSOME NOCTURIA IN PATIENTS WHO ARE RESISTANT TO TAMUSULOSIN/NAFTOPIDIL

whether they did or did not report retrograde ejaculation (REj) as an adverse event (AE) during the study. RESULTS: (Table) Of the silodosin (SIL)-treated patients, 335 had no REj (-REj), while 131 had REj (+REj). Baseline IPSS and Qmax were comparable between groups. At 12 weeks, improvements in IPSS (LOCF) and Qmax (LOCF) were significantly greater for SIL(-REj) vs placebo and for SIL(+REj) vs placebo. Improvements in symptoms and peak flow rate were greater in the SIL(+REj) vs the SIL(-REj) group, with a trend toward significance for Qmax. CONCLUSIONS: The 28.1% experiencing retrograde ejaculation with silodosin treatment experienced greater improvement in symptoms and clinically meaningful greater improvement in peak flow rate compared with those not having this effect. This observation suggests that silodosin relaxes the smooth musculature of the lower urinary and genital tracts sufficiently to induce retrograde ejaculation, and that such superior relaxation results in greater objective efficacy in terms of unobstructing patients with LUTS secondary to BPH.