Winnie Waichi Shum

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Male infertility is often caused by sperm that have low motility and interact poorly with the oocyte. Spermatozoa acquire these crucial functions in the epididymis. A low luminal bicarbonate (HCO(3)(-)) concentration and low pH keep sperm quiescent during their maturation and storage in this organ. This review describes how epididymal epithelial cells(More)
Aquaporin 1 (AQP1) is the major water channel in the renal proximal tubule (PT) and thin descending limb of Henle, but its regulation remains elusive. Here, we investigated the effect of ANG II, a key mediator of body water homeostasis, on AQP1 expression in immortalized rat proximal tubule cells (IRPTC) and rat kidney. Real-time PCR on IRPTC exposed to ANG(More)
In the epididymis, spermatozoa acquire their ability to become motile and to fertilize an egg. A luminal acidic pH and a low bicarbonate concentration help keep spermatozoa in a quiescent state during their maturation and storage in this organ. Net proton secretion is crucial to maintain the acidity of the luminal fluid in the epididymis. A sub-population(More)
The epithelium that lines the epididymal duct establishes the optimal milieu in which spermatozoa mature, acquire motility, and are stored. This finely tuned environment also protects antigenic sperm against pathogens and autoimmunity, which are potential causes of transient or permanent infertility. The epididymal epithelium is pseudostratified and(More)
A subset of basal cells (BCs) in the initial segment (IS) of the mouse epididymis has a slender body projection between adjacent epithelial cells. We show here that these projections occasionally cross the apical tight junctions and are in contact with the luminal environment. Luminal testicular factors are critical for the establishment of the IS(More)
Extracellular purinergic agonists regulate a broad range of physiological functions via P1 and P2 receptors. Using the epididymis as a model system in which luminal acidification is essential for sperm maturation and storage, we show here that extracellular ATP and its hydrolysis product adenosine trigger the apical accumulation of vacuolar H(+)-ATPase(More)
Water and solute transport in the efferent ducts and epididymis are important for the establishment of the appropriate luminal environment for sperm maturation and storage. Aquaporin 9 (AQP9) is the main water channel in the epididymis, but its regulation is still poorly understood. Components of the kinin-kallikrein system (KKS), leading to the production(More)
Extracellular ATP is essential for the function of the epididymis and spermatozoa, but ATP release in the epididymis remains uncharacterized. We investigated here whether epithelial cells release ATP into the lumen of the epididymis, and we examined the role of the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl(-) and HCO(3)(-) conducting(More)
Luminal acidification in the epididymis is an important process for the regulation of male fertility. Low pH and low bicarbonate concentration are among key factors that keep spermatozoa in a dormant state while they mature and are stored in this organ. Although significant bicarbonate reabsorption is achieved by principal cells in the proximal regions of(More)
Our previous study has shown that basal cells sense luminal factors by forming a narrow body projection that can cross epithelial tight junctions. As a first step toward characterizing the structural plasticity of basal cells, in this study, we followed their appearance and morphology in the rat epididymis and vas deferens (VD) during postnatal development(More)