P2X7R: independent modulation of aquaporin 5 expression in CdCl2-injured alveolar epithelial cells.

The expression of aquaporin 5 in alveolar epithelial type I cells under conditions of cadmium-induced injury has not yet been discovered. We investigated the effect of the P2X7R agonist BzATP under this condition, since P2X7R is involved in altered regulation of aquaporin 5 in pulmonary fibrosis. CdCl2/TGF-ß1 treatment of lung epithelial MLE-12 cells was leading to increasing P2X7R, and aquaporin 5 protein levels. The aquaporin 5 expression was P2X7R-independent in MLE-12 cells under cadmium, as was shown in blocking experiments with oxATP. Further, the expression of both proteins increased after 24 h CdCl2/TGF-ß1 treatment of precision-cut lung slices, but decreased after 72 h. Using immunohistochemistry, the activation of the P2X7R with the agonist BzATP modulated the aquaporin 5 immunoreactivity in the alveolar epithelium of precision-cut lung slices from wild-type but not from P2X7R knockout mice. Similarly, aquaporin 5 protein was reduced in BzATP-treated immortal lung epithelial E10 cells. Surprisingly, untreated alveolar epithelial type II cells of P2X7R knockouts exhibited a pronounced apical immunoreactivity in addition to the remaining alveolar epithelial type I cells. BzATP exposure did not alter this distribution pattern, but increased the number of apoptotic alveolar epithelial type II cells in wild-type lung slices.

Up-regulation of Store-operated Ca2+ Entry and Nuclear Factor of Activated T Cells Promote the Acinar Phenotype of the Primary Human Salivary Gland Cells.

The signaling pathways involved in the generation and maintenance of exocrine gland acinar cells have not yet been established. Primary human salivary gland epithelial cells, derived from salivary gland biopsies, acquired an acinar-like phenotype when the [Ca(2+)] in the serum-free medium (keratinocyte growth medium, KGM) was increased from 0.05 mm (KGM-L) to 1.2 mm (KGM-H). Here we examined the mechanism underlying this Ca(2+)-dependent generation of the acinar cell phenotype. Compared with cells in KGM-L, those in KGM-H display enhancement of Orai1, STIM1, STIM2, and nuclear factor of activated T cells 1 (NFAT1) expression together with an increase in store-operated Ca(2+) entry (SOCE), SOCE-dependent nuclear translocation of pGFP-NFAT1, and NFAT-dependent but not NFκB-dependent gene expression. Importantly, AQP5, an acinar-specific protein critical for function, is up-regulated in KGM-H via SOCE/NFAT-dependent gene expression. We identified critical NFAT binding motifs in the AQP5 promoter that are involved in Ca(2+)-dependent up-regulation of AQP5. These important findings reveal that the Ca(2+)-induced switch of salivary epithelial cells to an acinar-like phenotype involves remodeling of SOCE and NFAT signaling, which together control the expression of proteins critically relevant for acinar cell function. Our data provide a novel strategy for generating and maintaining acinar cells in culture.

Increased aquaporin 1 and 5 membrane expression in the lens epithelium of cataract patients.

In this work we have analyzed the expression levels of the main aquaporins (AQPs) expressed in human lens epithelial cells (HLECs) using 112 samples from patients treated with cataract surgery and 36 samples from individuals treated with refractive surgery, with transparent lenses as controls. Aquaporin-1 (AQP1) is the main AQP, representing 64.1% of total AQPs in HLECs, with aquaporin-5 (AQP5) representing 35.9% in controls. A similar proportion of each AQP in cataract was found. Although no differences were found at the mRNA level compared to controls, a significant 1.65-fold increase (p=0.001) in AQP1protein expression was observed in HLECs from cataract patients, with the highest differences being found for nuclear cataracts (2.1-fold increase; p<0.001). A similar trend was found for AQP5 (1.47-fold increase), although the difference was not significant (p=0.161). Moreover we have shown increased membrane AQP5 protein expression in HLECs of patients with cataracts. No association of AQP1 or AQP5 expression levels with age or sex was observed in either group. Our results suggest regulation of AQP1 and AQP5 at the post-translational level and support previous observations on the implication of AQP1 and 5 in maintenance of lens transparency in animal models. Our results likely reflect a compensatory response of the crystalline lens to delay cataract formation by increasing the water removal rate.

AQP5 Variants Affect Tumoral Expression of AQP5 and Survival in Patients with Early Breast Cancer.

BACKGROUND: Our previous study showed the association of AQP5 upregulation with cancer proliferation and migration in breast cancer cell lines and with unfavorable prognosis in patients with early breast cancer (EBC). In the current study, we analyzed the association of AQP5 variants or their haplotypes with AQP5 expression and their prognostic impact for survival in patients with EBC. METHODS: Three AQP5 polymorphisms (rs74091166, rs3736309, and rs1964676) were selected based on the SNP database and genotyped using the Sequenom MassARRAY in 374 out of 447 patients with EBC in whom AQP5 expression had been investigated in our previous study. RESULTS: The allele frequencies of the selected variants in the current study were similar to those from Asian data previously reported. In a univariate analysis, both rs74091166 and rs1964676 were statistically associated with survival as a dominant model of minor allele. Moreover, a multivariate survival analysis revealed that the CC genotype of rs1964676 is an independent prognostic marker of survival in EBC patients, regardless of stage, tumor subtype, and adjuvant treatment [hazard ratio = 0.399, 0.384, and 0.205; p = 0.021, 0.027, and 0.016 for disease-free survival (DFS), distant DFS, and disease-specific survival, respectively]. In particular, the CT/TT genotype of rs1964676 showed an association with strong expression of AQP5 (58.6 vs. 26.0%; p = 0.001), without any associations with clinical or pathological characteristics including tumor subtype, stage, or histologic grade. CONCLUSION: The current study suggests AQP5 rs1964676 as a new potential prognostic marker in patients with EBC involved in AQP5 expression.

Vasoactive Intestinal Peptide Protects Salivary Glands against Structural Injury and Secretory Dysfunction via IL-17A and AQP5 Regulation in a Model of Sjögren Syndrome.

OBJECTIVE: Sjögren syndrome (SS) is an autoimmune disease involving exocrine glands. Currently, drugs that can improve both abnormal immunity and exocrine gland function are needed. The study aimed to investigate the effect and mechanism of vasoactive intestinal peptide (VIP) on the immune response and exocrine gland function in SS. METHODS: We investigated the effects of VIP on the immune response and secretory function of submandibular glands using NOD mice, and analyzed the expression of IL-17A and AQP5 (aquaporin 5). The submandibular gland cells from healthy 8-day-old Sprague-Dawley rats were used to observe the influence of VIP on AQP5 expression. RESULTS: Our study shows that treatment with VIP in an SS mouse model could not only reduce the immune injury to exocrine glands but also improve the secretory function of these glands. Furthermore, VIP was shown to improve the abnormal immune status by downregulating IL-17A expression in the exocrine glands. It also enhanced the secretory function of exocrine glands by upregulating AQP5 expression. CONCLUSIONS: Using a model of SS, we found that VIP could not only modulate the immune response but also affect exocrine gland function, and that these therapeutic effects were associated with IL-17A and AQP5 regulation.

Emodin ameliorates acute lung injury induced by severe acute pancreatitis through the up-regulated expressions of AQP1 and AQP5 in lung.

The present study investigates the ameliorating effects of emodin on acute lung injury (ALI) induced by severe acute pancreatitis (SAP). An ALI rat model was constructed by sodium ursodeoxycholate and they were divided into four groups: SHAM, ALI, emodin and dexamethasone (DEX) (n=24 per group). Blood samples and lung tissues were collected 6, 12 and 24 hours after the induction of SAP-associated ALI. Lung wet/dry ratio, blood gases, serum amylase and tumor necrosis factor-α (TNF-α) were measured at each time point. The expressions of AQP1 and AQP5 in lung tissue were detected by immunohistochemical staining, western blotting and real-time PCR. As the results show, there were no statistical differences in the levels of serum amylase, lung wet/dry ratio, blood gases indexes, serum TNF-α and pathological changes between emodin and DEX groups. However, significant differences were observed when compared with the ALI group. AQP1 and AQP5 expressions were significantly increased and lung oedemas were alleviated with the treatment of emodin and DEX. The expressions of AQP1 and AQP5 were significantly decreased in SAP-associated ALI rats. Emodin up-regulated the expression of AQP1 and AQP5, it could reduce pulmonary oedema and ameliorate SAP-induced ALI. Regulations on AQP1 and AQP5 expression had a great value in clinical application.

Hyperoxia stimulates the transdifferentiation of type II alveolar epithelial cells in newborn rats.

Supplemental oxygen treatment in preterm infants may cause bronchopulmonary dysplasia (BPD), which is characterized by alveolar simplification and vascular disorganization. Despite type II alveolar epithelial cell (AEC II) damage being reported previously, we found no decrease in the AEC II-specific marker, surfactant protein C (SP-C), in the BPD model in our previous study. We thus speculated that AEC II injury is not a unique mechanism of BPD-related pulmonary epithelial repair dysfunction and that abnormal transdifferentiation can exist. Newborn rats were randomly assigned to model (85% oxygen inhalation) and control groups (room air inhalation). Expressions of AEC I (aquaporin 5, T1α) and AEC II markers (SP-C, SP-B) were detected at three levels: 1) in intact lung tissue, 2) in AEC II isolated from rats in the two groups, and 3) in AEC II isolated from newborn rats, which were further cultured under either hyperoxic or normoxic conditions. In the model group, increased AEC I was observed at both the tissue and cell level, and markedly increased transdifferentiation was observed by immunofluorescent double staining. Transmission electron microscopy revealed morphological changes in alveolar epithelium such as damaged AECs, a fused air-blood barrier structure, and opened tight junctions in the model group. These findings indicate that transdifferentiation of AECs is not suppressed but rather is increased under hyperoxic treatment by compensation; however, such repair during injury cannot offset pulmonary epithelial air exchange and barrier dysfunction caused by structural damage to AECs.

Extracellular GTP is a potent water-transport regulator via aquaporin 5 plasma-membrane insertion in M1-CCD epithelial cortical collecting duct cells.

BACKGROUND/AIMS: Extracellular GTP is able to modulate some specific functions in neuron, glia and muscle cell models as it has been demonstrated over the last two decades. In fact, extracellular GTP binds its specific plasma membrane binding sites and induces signal transduction via [Ca(2+)]i increase. We demonstrate, for the first time, that extracellular GTP is able to modulate cell swelling in M1-CCD cortical collecting duct epithelial cells via upregulation of aquaporin 5 (AQP5) expression. METHODS: We used videoimaging, immunocitochemistry, flow cytometry, confocal techniques, Western blotting and RT-PCR for protein and gene expression analysis, respectively. RESULTS: We demonstrate that AQP5 mRNA is up-regulated 7 h after the GTP exposure in the cell culture medium, and its protein level is increased after 12-24 h. We show that AQP5 is targeted to the plasma membrane of M1-CCD cells, where it facilitates cell swelling, and that the GTP-dependent AQP5 up-regulation occurs via [Ca(2+)]i increase. Indeed, GTP induces both oscillating and transient [Ca(2+)]i increase, and specifically the oscillating kinetic appears to be responsible for blocking cell cycle in the S-phase while the [Ca(2+)]i influx, with whatever kinetic, seems to be responsible for inducing AQP5 expression. CONCLUSION: The role of GTP as a regulator of AQP5-mediated water transport in renal cells is of great importance in the physiology of renal epithelia, due to its possible physiopathological implications. GTP-dependent AQP5 expression could act as osmosensor. In addition, the data presented here suggest that GTP might play the same role in other tissues where rapid water transport is required for cell volume regulation and maintenance of the homeostasis.

Oxytocin regulates the expression of aquaporin 5 in the late-pregnant rat uterus.

Aquaporins (AQPs) are integral membrane channels responsible for the transport of water across a cell membrane. Based on reports that AQPs are present and accumulate in the female reproductive tract late in pregnancy, our aim was to study the expression of AQP isoforms (AQP1, 2, 3, 5, 8, and 9) at the end of pregnancy in rat in order to determine if they play a role in parturition. Reverse-transcriptase PCR revealed that specific Aqp mRNAs were detectable in the myometrium of non-pregnant and late-pregnancy (Days 18, 20, 21, and 22 of pregnancy) rat uteri. The expression of Aqp5 mRNA and protein were most pronounced on Days 18-21, and were dramatically decreased on Day 22 of pregnancy. In contrast, a significant increase was found in the level of Aqp5 transcript in whole-blood samples on the last day of pregnancy. The effect of oxytocin on myometrial Aqp5 expression in an organ bath was also investigated. The level of Aqp5 mRNA significantly decreased 5 min after oxytocin (10(-8) M) administration, similarly to its profile on the day of delivery; this effect was sensitive to the oxytocin antagonist atosiban. The vasopressin analog desmopressin (3.7 × 10(-8) M), on the other hand, did not alter the expression of Aqp5, but did increased the amount of Aqp2 mRNA, an effect that was atosiban-resistant. These results lead us to propose that oxytocin selectively influences the expression of Aqp5 at the end of pregnancy, and may participate in events that lead to parturition in the rat. The sudden increase of AQP5 in the blood on the last day of pregnancy may serve as a marker that indicates the initiation of delivery.

Reticulated Retinoic Acid Synthesis is Implicated in the Pathogenesis of Dry Eye in Aqp5 Deficiency Mice.

Purpose: Abnormalities in aquaporins are implicated in the pathological progression of dry eye syndrome. Retinoic acid (RA) regulates cellular proliferation, differentiation, and apoptosis in the cornea, thereby being associated with dry eye disease (DED). The objective of this study is to explore the underlying mechanisms responsible for RA metabolic abnormalities in corneas lacking aquaporin 5 (AQP5). Methods: Dry eye (DE) models were induced via subcutaneous scopolamine hydrobromide. Aqp5 knockout (Aqp5-/-) mice and DE mice were utilized to assess corneal epithelial alterations. Tear secretion, goblet cell counts, and corneal punctate defects were evaluated. The impact of Aqp5 on RA-related enzymes and receptors was investigated using pharmacological RA or SR (A JunB inhibitor), a transcription factor JunB inhibitor, treatment in mouse corneal epithelial cells (CECs), or human corneal epithelial cells (HCECs). The HCECs and NaCl-treated HCECs underwent quantitative real-time PCR (qRT-PCR), immunofluorescent, Western blot, and TUNEL assays. The regulation of transcription factor JunB on Aldh1a1 was explored via ChIP-PCR. Results: Aqp5 and Aldh1a1 were reduced in both CECs of DE mice and NaCl-induced HCECs. Aqp5-/- mice exhibited DE phenotype and reduced Aldh1a1. RA treatment reduced apoptosis, promoted proliferation, and improved the DE phenotype in Aqp5-/- mice. JunB enrichment in the Aldh1a1 promoter was identified by ChIP-PCR. SR significantly increased Aldh1a1 expression, Ki67, and ΔNp63-positive cells, and decreased TUNEL-positive cells in CECs and HCECs. Conclusions: Our findings demonstrated the downregulation of Aqp5 expression and aberrant RA metabolism in DE conditions. Knockout of Aqp5 resulted in reduced production of RA through activation of JunB, subsequently leading to the manifestation of DE symptoms.

Co-regulated pendrin and aquaporin 5 expression and trafficking in Type-B intercalated cells under potassium depletion.

BACKGROUND: We recently reported that aquaporin 5 (AQP5), a water channel never identified in the kidney before, co-localizes with pendrin at the apical membrane of type-B intercalated cells in the kidney cortex. Since co-expression of AQP5 and pendrin in the apical membrane domain is a common feature of several other epithelia such as cochlear and bronchial epithelial cells, we evaluated here whether this strict membrane association may reflect a co-regulation of the two proteins. To investigate this possibility, we analyzed AQP5 and pendrin expression and trafficking in mice under chronic K(+) depletion, a condition that results in an increased ability of renal tubule to reabsorb bicarbonate, often leads to metabolic alkalosis and is known to strongly reduce pendrin expression. METHODS: Mice were housed in metabolic cages and pair-fed with either a standard laboratory chow or a K(+)-deficient diet. AQP5 abundance was assessed by western blot in whole kidney homogenates and AQP5 and pendrin were localized by confocal microscopy in kidney sections from those mice. In addition, the short-term effect of changes in external pH on pendrin trafficking was evaluated by fluorescence resonance energy transfer (FRET) in MDCK cells, and the functional activity of pendrin was tested in the presence and absence of AQP5 in HEK 293 Phoenix cells. RESULTS: Chronic K(+) depletion caused a strong reduction in pendrin and AQP5 expression. Moreover, both proteins shifted from the apical cell membrane to an intracellular compartment. An acute pH shift from 7.4 to 7.0 caused pendrin internalization from the plasma membrane. Conversely, a pH shift from 7.4 to 7.8 caused a significant increase in the cell surface expression of pendrin. Finally, pendrin ion transport activity was not affected by co-expression with AQP5. CONCLUSIONS: The co-regulation of pendrin and AQP5 membrane expression under chronic K(+)-deficiency indicates that these two molecules could cooperate as an osmosensor to rapidly detect and respond to alterations in luminal fluid osmolality.

Lipopolysaccharide decreases aquaporin 5, but not aquaporin 3 or aquaporin 4, expression in human primary bronchial epithelial cells.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the changes in expression of aquaporins (AQP) during differentiation of human bronchial epithelial cells and the role of lipopolysaccharide (LPS) in AQP expression. METHODS: The levels of AQP3, AQP4 and AQP5 transcripts in human primary cultured bronchial epithelial cells were evaluated by real-time polymerase chain reaction at different time points before and after treatment with LPS. Western blotting was performed to assess the effects of LPS on AQP3, AQP4 and AQP5 expressions in normal human bronchial epithelial cells. Using pharmacological tools, the pathways involved in the regulation of LPS-induced changes in AQP5 were further explored. RESULTS: The levels of AQP3, AQP4 and AQP5 transcripts were increased during differentiation of human bronchial epithelial cells. Expression of AQP5, but not AQP3 or AQP4, was downregulated by LPS. LPS-induced downregulation of AQP5 was inhibited by p38 and c-Jun N-terminal kinase (JNK) inhibitors. CONCLUSIONS: This study demonstrated that LPS decreases AQP5, but not AQP3 or AQP4, expression in human primary bronchial epithelial cells. The downregulation of AQP5 expression is mediated through a p38/JNK signalling pathway.

Relationship between aquaporin-5 expression and saliva flow in streptozotocin-induced diabetic mice?

OBJECTIVE: To investigate the expression and distribution of AQP5 in submandibular acinar cells from sham- and streptozotocin (STZ)-treated mice in relation to the salivary flow. METHODS: Mice were sham or STZ injected. Distribution of AQP5 subcellular expression in submandibular glands was determined by immunohistochemistry. AQP5 labelling indices (LI), reflecting AQP5 subcellular distribution, were determined in acinar cells. Western blotting was performed to determine the expression of AQP5 in submandibular glands. Blood glycaemia and osmolality and saliva flow rates were also determined. RESULTS: AQP5 immunoreactivity was primarily located at the apical and apical-basolateral membranes of submandibular gland acinar cells from sham- and STZ-treated mice. No significant differences in AQP5 protein levels were observed between sham- and STZ-treated mice. Compared to sham-treated mice, STZ-treated mice had significant increased glycaemia, while no significant differences in blood osmolality were observed. Saliva flow rate was significantly decreased in STZ-treated mice as compared to sham-treated mice. CONCLUSIONS: In STZ-treated mice, significant reduction in salivary flow rate was observed without any concomitant modification in AQP5 expression and localization.

Proliferation inhibition of cisplatin and aquaporin 5 expression in human ovarian cancer cell CAOV3.

AIMS: The purpose of this study is to investigate the association between proliferation inhibition of cisplatin and aquaporin 5 (AQP5) expression and its regulation in ovarian carcinoma cell CAOV3. METHODS: Cell growth rate was measured by MTT after CAOV3 cells were incubated with cisplatin or NF-κB inhibitor PDTC. Western blot and RT-PCR were used to detect the expression of AQP5 and NF-κB p65. RESULTS: Our results showed that expression of AQP5, NF-κB in cytoplasm and karyon and IκBα in cytoplasm protein in CAOV3 cells can be induced to decrease by cisplatin with concentration-dependent manner, and there is a positive correlation between AQP5 protein and cell growth rate (r = 0.607, P < 0.05). When cells were incubated with 10 µg/ml cisplatin, AQP5, NF-κB p65, and IκBα increased rapidly at 6-12 h, but decreased at 24 h, remain on low level until to 72 h. Expression of AQP5 could be induced to decrease by PDTC, and a positive correlation between AQP5 protein expression and NF-κB p65 and IκBα (r = 0.894, 0.857; P < 0.05). CONCLUSIONS: Proliferation inhibition of cisplatin is related with AQP5 expression, and NF-κB may be involved in mechanism of AQP5 regulation. AQP5 will be potential target for therapy of ovarian carcinoma.

Human salivary gland acinar cells spontaneously form three-dimensional structures and change the protein expression patterns.

Applying tissue engineering principles to design an auto-secretory device is a potential solution for patients suffering loss of salivary gland function. However, the largest challenge in implementing this solution is the primary culture of human salivary gland cells, because the cells are highly differentiated and difficult to expand in vitro. This situation leads to the lack of reports on the in vitro cell biology and physiology of human salivary gland cells. This study used a low-calcium culture system to selectively cultivate human parotid gland acinar (PGAC) cells from tissues with high purity in cell composition. This condition enables PGAC cells to continuously proliferate and retain the phenotypes of epithelial acinar cells to express secreting products (α-amylase) and function-related proteins (aquaporin-3, aquaporin-5, and ZO-1). Notably, when the cells reached confluence, three-dimensional (3D) cell aggregates were observed in crowded regions. These self-formed cell spheres were termed post-confluence structures (PCSs). Unexpectedly, despite being cultured in the same media, cells in PCSs exhibited higher expression levels and different expression patterns of function-related proteins compared to the two-dimensional (2D) cells. Translocation of aquoporin-3 from cytosolic to alongside the cell boundaries, and of ZO-1 molecules to the boundary of the PCSs were also observed. These observations suggest that when PGAC cells cultured on the 2D substrate would form PCSs without the help of 3D scaffolds and retain certain differentiation and polarity. This phenomenon implies that it is possible to introduce 2D substrates instead of 3D scaffolds into artificial salivary gland tissue engineering.

Expression of aquaporin water channels in the vagina in premenopausal women.

INTRODUCTION: Aquaporins (AQPs) are membrane proteins that facilitate water movement across biological membranes. This study builds on a previous report on the distinct localization of AQPs in the rat vagina. AIM: The purposes of this study were to investigate the localization and expression of the AQPs in the vaginal tissue of premenopausal women. METHODS: Anterior vaginal tissue was collected during transvaginal uterine myomectomy or hysterectomy from 10 premenopausal women (mean age, 40 years) for Western blot and immunohistochemistry. MAIN OUTCOME MEASURES: The expression and cellular localization of AQP1-9 were determined in the human vagina by Western blot and immunohistochemistry. RESULTS: Immunolabeling showed that AQP1 was mainly expressed in the capillaries and venules of the vagina, AQP2 was expressed in the cytoplasm of the epithelium, AQP3 was mainly associated with the plasma membrane of the vaginal epithelium, and both AQP5 and AQP6 were expressed in the cytoplasm throughout all vaginal epithelium. Western blot analysis revealed bands at 28 kDa for AQP1, 2, 3, 5, and 6 proteins. However, AQP4, 7, 8, and 9 were not detected. CONCLUSIONS: The distinct localization of AQPs in the human vagina suggests that AQP1, 2, 3, 5, and 6 may play an important role in vaginal lubrication in women.

Caveolin-1 siRNA increases the pulmonary microvascular and alveolar epithelial permeability in rats.

BACKGROUND: Increased pulmonary microvascular and epithelial permeability are important contributors to pulmonary edema in acute lung injury. In this study, we used small interfering RNA (siRNA) to knock down caveolin-1 expression in rat lungs and to confirm the important role of caveolin-1 in regulating pulmonary edema. METHOD: After pulmonary injection of siRNA against caveolin-1 messenger RNA incorporated in liposomes with three concentrations of 0.4, 0.8, and 1.2 mg/kg, the gene silencing rate and the effects of caveolin-1 siRNA on aquaporin (AQP)-1, AQP-5, and epithelial sodium channel (ENaC) were detected. For pulmonary permeability analysis, Evans blue fluorimetry, ratios of albumin concentrations between blood and bronchoalveolar lavage, and wet/dry weight ratios were measured. The impacts of caveolin-1 suppression on interendothelial junctions were evaluated by the performance of electron microscopy and the analysis of vascular endothelial (VE)-cadherin Western blot. Alveolar wall thickness analysis and chest fluoroscopy were performed to determine the pulmonary edema degree. RESULTS: After 72 hours of injection, the gene silencing rate of caveolin-1 siRNA is about 87%. AQP-1, AQP-5, ENaC-α, ENaC-ß, ENaC-γ, and VE-cadherin protein levels were decreased by 63%, 66%, 80%, 90%, 89%, and 50%, respectively. Caveolin-1 siRNA also resulted in increasing microvascular and epithelial permeability and pulmonary edema. CONCLUSION: These data suggest that caveolin-1 plays an important part in regulating the pulmonary permeability by modifying AQP-1, AQP-5, ENaC, and VE-cadherin.

McH-lpr/lpr-RA1 mice: A novel spontaneous mouse model of autoimmune sialadenitis.

Many studies of the autoimmune disease Sjögren's syndrome have been performed using spontaneous mouse models. In the present study, we describe the characteristics of McH/lpr-RA1 mice and propose their use as a novel murine model of autoimmune sialadenitis. The McH/lpr-RA1 mouse is a recombinant congenic strain derived from generation F54 or more of MRL-Faslpr x (MRL- Faslpr x C3H- Faslpr) F1. We show for the first time that this mouse spontaneously develops autoimmune sialadenitis and vasculitis in submandibular gland tissues. Sialadenitis was accompanied by extensive inflammatory cell infiltration and tissue destruction. Immunohistochemical studies revealed that the salivary gland lesions strongly expressed four sialadenitis-related molecules: SSA and SSB (autoantigens of Sjögren's syndrome), gp91phox (an accelerator of reactive oxygen species production) and single strand DNA (a marker of apoptotic cells). In contrast, expression of aquaporin-5 (AQP5), which stimulates salivary secretion was weak or negligible. Statistical correlation analyses indicated that the apoptosis of salivary gland cells provoked by oxidative stress contributed to the severe sialadenitis and reduced expression of AQP5. Our study has demonstrated that McH/lpr-RA1 mice spontaneously develop the pathognomonic features of autoimmune sialadenitis and thus could be used as a new animal model of Sjögren's syndrome.

Inhibition and transcriptional silencing of a subtilisin-like proprotein convertase, PACE4/SPC4, reduces the branching morphogenesis of and AQP5 expression in rat embryonic submandibular gland.

The submandibular gland (SMG) develops through the epithelial-mesenchymal interaction mediated by many growth/differentiation factors including activin and BMPs, which are synthesized as inactive precursors and activated by subtilisin-like proprotein convertases (SPC) following cleavage at their R-X-K/R-R site. Here, we found that Dec-RVKR-CMK, a potent inhibitor of SPC, inhibited the branching morphogenesis of the rat embryonic SMG, and caused low expression of a water channel AQP5, in an organ culture system. Dec-RVKR-CMK also decreased the expression of PACE4, a SPC member, but not furin, another SPC member, suggesting the involvement of PACE4 in the SMG development. Heparin, which is known to translocate PACE4 in the extracellular matrix into the medium, and an antibody specific for the catalytic domain of PACE4, both reduced the branching morphogenesis and AQP5 expression in the SMG. The inhibitory effects of Dec-RVKR-CMK were partially rescued by the addition of recombinant BMP2, whose precursor is one of the candidate substrates for PACE4 in vivo. Further, the suppression of PACE4 expression by siRNAs resulted in decreased expression of AQP5 and inhibition of the branching morphogenesis in the present organ culture system. These observations suggest that PACE4 regulates the SMG development via the activation of some growth/differentiation factors.