Identification of a novel aquaporin, AQP12, expressed in pancreatic acinar cells

Itoh, Tomohiro; Rai, Tatemitsu; Kuwahara, Michio; Ko, Shigeru B. H.; Uchida, Shinichi; Sasaki, Sei; Ishibashi, Keiichiro

doi:10.1016/j.bbrc.2005.03.046

Cited by 180 publications

(129 citation statements)

References 15 publications

Supporting

Mentioning

125

Contrasting

Order By: Relevance

“…It was found that aspartic acid and glutamine substitutions of asparagine (N192D, N192Q) in AQP1 resulted in defective plasma membrane expression (25), indicating a key role of asparagine in the first NPA motif. AQP11 (NPC) and AQP12 (NPT) that have altered alanine in the first NPA motif also cannot reach plasma membrane (11,12), suggesting that alanine in NPA motifs is also important for plasma membrane trafficking. However, our previous studies indicated that deletion of one or two NPA motifs did not affect AQP1 protein expression and plasma membrane targeting in transfected cells, providing the first evidence against an important role of NPA motifs in aquaporin biogenesis (13).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

NPA motifs play a key role in plasma membrane targeting of aquaporin‐4

Guan

et al. 2010

IUBMB Life

View full text Add to dashboard Cite

SummaryThe two highly conserved NPA motifs (asparagine-prolinealanine, NPA) are the most important structural domains that play a crucial role in water-selective permeation in aquaporin water channels. However, the functions of NPA motifs in aquaporin (AQP) biogenesis remain largely unknown. Few AQP members with variations in NPA motifs such as AQP11 and AQP12 do not express in the plasma membrane, suggesting an important role of NPA motifs in AQP plasma membrane targeting. In this study, we examined the role of the two NPA motifs in AQP4 plasma membrane targeting by mutagenesis. We constructed a series of AQP4 mutants with NPA deletions or single amino acid substitutions in AQP4-M1 and AQP4-M23 isoforms and analyzed their expression patterns in transiently transfected FRT and COS-7 cells. Western blot analysis showed similar protein bands of all the AQP4 mutants and the wild-type AQP4. AQP4 immunofluorescence indicated that deletion of one or both NPA motifs resulted in defective plasma membrane targeting, with apparent retention in endoplasmic reticulum (ER). The A99T mutant mimicking AQP12 results in ER retention, whereas the A99C mutant mimicking AQP11 expresses normally in plasma membrane. Furthermore, the AQP4-M1 but not the M23 isoform with P98A substitution in the first NPA motif can target to the plasma membrane, indicating an interaction of Nterminal sequence of AQP4-M1 with the first NPA motif. These results suggest that NPA motifs play a key role in plasma membrane expression of AQP4 but are not involved in AQP4 protein synthesis and degradation. The NPA motifs may interact with other structural domains in the regulation of membrane trafficking during aquaporin biogenesis.

show abstract

Section: Discussionmentioning

confidence: 99%

“…However, the functions of NPA motifs in AQP biogenesis remain largely unknown. Few AQP members with variations in NPA motifs such as AQP11 and AQP12 do not express in the plasma membrane (11,12), suggesting an important role of NPA motifs in AQP plasma membrane targeting.…”

Section: Introductionmentioning

confidence: 99%

NPA motifs play a key role in plasma membrane targeting of aquaporin‐4

Guan

et al. 2010

IUBMB Life

View full text Add to dashboard Cite

show abstract

“…AQPs 11 and 12 are thought to function as water channels but have yet to be fully characterised (Ishibashi, 2009). Notably, the sequence of the NPA motifs within AQP11 and 12 deviates from the conserved NPA of the other AQPs (Ikeda et al, 2010, Itoh et al, 2005.…”

Section: Structure and Function Of Aqpsmentioning

confidence: 99%

“…AQP11 and 12 appear to lack the conserved NPA motifs, being NPC and NPT in AQPs 11 (Ikeda et al, 2010) and 12 (Itoh et al, 2005), respectively. Interestingly mutation of the alanine of the AQP4 NPA motif to threonine to mimic AQP12 resulted in retention within the endoplasmic reticulum of mammalian cell lines, whereas mutation of this alanine to cysteine, mimicking AQP11, expresses normally in plasma membrane (Guan et al, 2010).…”

Section: Localisation and Retention Signalsmentioning

confidence: 99%

An emerging consensus on aquaporin translocation as a regulatory mechanism

Conner

Bill

Conner

2012

Molecular Membrane Biology

View full text Add to dashboard Cite

Water can pass through the cell membrane relatively slowly by diffusion. However, in order to maintain water homeostasis, the rapid and specific regulation of cellular water flow is mediated by the aquaporin (AQP) family of membrane protein water channels. Thirteen human AQPs have been identified to date and the majority are highly specific for water while others show selectivity for water, glycerol and other small solutes. The wide range of tissues that are known to express AQPs is reflected by their involvement in many physiological processes and diseases. Receptor mediated translocation, via hormone activation, is an established method of AQP regulation, especially for AQP2. There is now an emerging consensus that the rapid and reversible translocation of other AQPs from intracellular vesicles to the plasma membrane, triggered by a range of stimuli, can confer increased membrane permeability. This review examines new advances that have identified molecular mechanisms of AQP regulation; these include the role of cytoskeletal proteins, kinases, calcium and retention or localisation signals as well as specific triggers of AQP translocation. This article reviews current knowledge of AQP regulation with a focus on rapid and dynamic regulation of sub-cellular AQP translocation in response to a specific trigger.3

show abstract

“…AQP8 is reportedly permeable to ammonia [3] . The majority of aquaporins are constitutively expressed in the plasma membrane (AQP0, 1,3,4,7,8,9,10), while others are almost exclusively restricted to intracellular membranes (AQP6, 11,12) [4] .…”

Section: Introductionmentioning

confidence: 99%

Pregnant phenotype in aquaporin 8-deficient mice

et al. 2011

View full text Add to dashboard Cite

Aim: Aquaporin 8 (AQP8) is expressed within the female reproductive system but its physiological function reminds to be elucidated. This study investigates the role of AQP8 during pregnancy using AQP8-knockout (AQP8-KO) mice. Methods: Homozygous AQP8-KO mice were mated, and the conception rate was recorded. AQP8-KO pregnant mice or their offspring were divided into 5 subgroups according to fetal gestational day (7, 13, 16, 18 GD) and newborn. Wild type C57 pregnant mice served as the control group. The number of pregnant mice, total embryos and atrophic embryos, as well as fetal weight, placental weight and placental area were recorded for each subgroup. The amount of amniotic fluid in each sac at 13, 16, and 18 GD was calculated. Statistical significance was determined by analysis of variance of factorial design and chi-square tests. Results: Conception rates did not differ significantly between AQP8-KO and wild type mice. AQP8-KO pregnant mice had a significantly higher number of embryos compared to wild type controls. Fetal/neonatal weight was also significantly greater in the AQP8-KO group compared to age-matched wild type controls. The amount of amniotic fluid was greater in AQP8-KO pregnant mice than wild type controls, although the FM/AFA (fetal weight/amniotic fluid amount) did not differ. While AQP8-KO placental weight was significantly larger than wild type controls, there was no evidence of placental pathology in either group. Conclusion: The results suggest that AQP8 deficiency plays an important role in pregnancy outcome.

show abstract

Identification of a novel aquaporin, AQP12, expressed in pancreatic acinar cells

Cited by 180 publications

References 15 publications

NPA motifs play a key role in plasma membrane targeting of aquaporin‐4

NPA motifs play a key role in plasma membrane targeting of aquaporin‐4

An emerging consensus on aquaporin translocation as a regulatory mechanism

Pregnant phenotype in aquaporin 8-deficient mice

Contact Info

Product

Resources

About