Presence and localization of aquaporin-6 in rat parotid acinar cells

Matsuki-Fukushima, Miwako; Hashimoto, Sadamitsu; Shimono, Masaki; Satoh, Kazue; Fujita-Yoshigaki, Junko; Saito, Hiroshi

doi:10.1007/s00441-007-0558-4

Cited by 25 publications

(28 citation statements)

References 42 publications

(51 reference statements)

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“…91 Significant upregulation of AQP6 expression was observed in rats exposed to chronic alkalosis or water loading, but not chronic acidosis. 92 Expression of AQP6 in rat gastrointestinal epithelium, near tight junctions and secretory granule membranes in rat parotid acinar cells, and in some ovarian cancers [93][94][95] has suggested other possible roles in tissues involving acid-base regulation, although the physiological significance of AQP6 in these systems…”

Section: Mammalian Aquaporinmentioning

confidence: 99%

Fundamental structural and functional properties of Aquaporin ion channels found across the kingdoms of life

Kourghi

Pei

Ieso

et al. 2018

Clin Exp Pharma Physio

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Aquaporin (AQP) channels in the major intrinsic protein (MIP) family are known to facilitate transmembrane water fluxes in prokaryotes and eukaryotes. Some classes of AQPs also conduct ions, glycerol, urea, CO , nitric oxide, and other small solutes. Ion channel activity has been demonstrated for mammalian AQPs 0, 1, 6, Drosophila Big Brain (BIB), soybean nodulin 26, and rockcress AtPIP2;1. More classes are likely to be discovered. Newly identified blockers are providing essential tools for establishing physiological roles of some of the AQP dual water and ion channels. For example, the arylsulfonamide AqB011 which selectively blocks the central ion pore of mammalian AQP1 has been shown to impair migration of HT29 colon cancer cells. Traditional herbal medicines are sources of selective AQP1 inhibitors that also slow cancer cell migration. The finding that plant AtPIP2;1 expressed in root epidermal cells mediates an ion conductance regulated by calcium and protons provided insight into molecular mechanisms of environmental stress responses. Expression of lens MIP (AQP0) is essential for maintaining the structure, integrity and transparency of the lens, and Drosophila BIB contributes to neurogenic signalling pathways to control the developmental fate of fly neuroblast cells; however, the ion channel roles remain to be defined for MIP and BIB. A broader portfolio of pharmacological agents is needed to investigate diverse AQP ion channel functions in situ. Understanding the dual water and ion channel roles of AQPs could inform the development of novel agents for rational interventions in diverse challenges from agriculture to human health.

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Section: Mammalian Aquaporinmentioning

confidence: 99%

Fundamental structural and functional properties of Aquaporin ion channels found across the kingdoms of life

Kourghi

Pei

Ieso

et al. 2018

Clin Exp Pharma Physio

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“…In Xenopus Laevis oocytes expressing AQP6, Hg 2+ has also been demonstrated to stimulate transport of glycerol and urea [80]. Currently, we found the presence of AQP6 associated with secretory granule membranes in the rat parotid acinar cells [84]. In the granule membrane isolated from the purified secretory granules, anti‐AQP6 antibody specifically recognized 33 kDa band by western blotting, indicating the presence of AQP6 in secretory granule membrane of rat parotid acinar cells, as Figure 3 shows.…”

Section: Role Of Aqps In Secretory Granule Swellingmentioning

confidence: 99%

Role of aquaporins and regulation of secretory vesicle volume in cell secretion

Saito

Matsuki-Fukushima

Hashimoto

2008

J Cellular Molecular Medi

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In exocrine glands, secretory proteins synthesized in the rough endoplasmic reticulum (RER) exhibit vectorial transport from ER through a succession of membrane-bounded components such as Golgi complex, condensing vacuoles and secretory granules. The secretory granules migrate to particular locations within the cell close to the apical membrane prior to the release of their contents into the acinar lumen. Currently, to release intragranular contents, secretory granules have been demonstrated to transiently dock and fuse at ‘porosome’, a permanent cup-shaped structures at the cell membranes. Then swelling of secretory granules occurs to allow explusion of intragranular contents. In this process, water and ion fluxes in the granule membrane appear to contribute to maintain secretory granule integrity and morphology via osmoregulation in secretory granules. Aquaporins (AQPs) are a family of small, hydrophobic, integral membrane proteins, which function as channels to permeate water and small solutes. The AQPs reside constitutively at the plasma membrane in most cell types. However, recent studies have demonstrated that the AQPs are present in secretory granules in exocrine glands, synaptic vesicles and intracellular vesicles in liver and kidney, implying that AQPs in secretory granules and vesicles are involved in their volume regulation. This paper reviews the possible role of AQPs on secretory granules, especially in exocrine glands, in secretory function.

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“…Recently AQP6 has also been observed in parotid gland acinar cells [2] and in the inner ear [3, 4]. AQP6 has low water permeability and primarily transports anions [5].…”

Section: Introductionmentioning

confidence: 99%

Aquaporin 6 binds calmodulin in a calcium-dependent manner

Rabaud¹,

Song²,

Wang³

et al. 2009

Biochemical and Biophysical Research Communications

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Aquaporin 6 (AQP6) is an anion channel that is expressed primarily in acid secreting α-intercalated cells of the kidney collecting duct. In addition, AQP6 anion channel permeability is gated by low pH. Inspection of the N-terminus of AQP6 revealed a putative calmodulin binding site. AQP6-expressing CHO-K1 cell lysates were mixed with calmodulin beads and AQP6 was pulled down in the presence of calcium. Mutagenesis of the N-terminal calmodulin binding site in full length mouse AQP6 resulted in a loss of calmodulin binding activity. Mouse and human AQP6 calmodulin binding site peptides bound dansyl-calmodulin with a dissociation constant of approximately 1 μM. The binding of AQP6 to calmodulin may be an important key to determining the physiological role of AQP6 in the kidney.

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Presence and localization of aquaporin-6 in rat parotid acinar cells

Cited by 25 publications

References 42 publications

Fundamental structural and functional properties of Aquaporin ion channels found across the kingdoms of life

Fundamental structural and functional properties of Aquaporin ion channels found across the kingdoms of life

Role of aquaporins and regulation of secretory vesicle volume in cell secretion

Aquaporin 6 binds calmodulin in a calcium-dependent manner

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