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Hu L, Xu C, Tang X, Yu S, Wang L, Li Q, Zhou X. Fine particulate matter promotes airway inflammation and mucin production by activating endoplasmic reticulum stress and the IRE1α/NOD1/NF‑κB pathway. Int J Mol Med 2023; 52:96. [PMID: 37654182 PMCID: PMC10555484 DOI: 10.3892/ijmm.2023.5299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/16/2023] [Indexed: 09/02/2023] Open
Abstract
Fine particulate matter (PM2.5) is a type of small particle that is <2.5 µm in diameter that may cause airway inflammation. Thus, the present study aimed to explore the effects of PM2.5 on endoplasmic reticulum (ER) stress and airway inflammation in human airway epithelial cells. For this purpose, HBE135‑E6E7 airway epithelial cells were cultured and exposed to specific concentrations of PM2.5 for various periods of time, and cell viability was determined using a Cell Counting Kit‑8 assay. The results of the present study demonstrated that exposure to PM2.5 increased the mRNA and protein expression levels of interleukin (IL)‑6, tumor necrosis factor (TNF)‑α and mucin 5AC (MUC5AC). Moreover, the expression levels of ER stress‑related proteins, such as glucose‑regulated protein 78, CCAAT‑enhancer binding protein homologous protein, activating transcription factor 6, protein kinase R‑like ER kinase (PERK), phosphorylated (p‑)PERK, inositol‑requiring enzyme 1α (IRE1α) and p‑IRE1α, and nucleotide‑binding oligomerization domain 1 (NOD1) expression levels were increased following exposure to PM2.5. Transfection with IRE1α small interfering RNA (siRNA) led to the increased production of IL‑6, TNF‑α and MUC5AC. Moreover, the expression of NOD1 and the translocation of NF‑κB p65 were inhibited following transfection with IRE1α siRNA. In addition, the results of the present study demonstrated that transfection with NOD1 siRNA decreased the production of IL‑6, TNF‑α and MUC5AC, and decreased the translocation of NF‑κB p65. The expression levels of IL‑6, TNF‑α and MUC5AC were increased in the HBE135‑E6E7 cells following treatment with C12‑iE‑DAP, a NOD1 agonist. Moreover, treatment with C12‑iE‑DAP led to the activation of NF‑κB p65. Collectively, the results of the present study suggest that PM2.5 promotes airway inflammation and mucin production by activating ER stress in HBE135‑E6E7 airway epithelial cells, and that the IRE1α/NOD1/NF‑κB pathway may be involved in this process.
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Affiliation(s)
- Lihua Hu
- Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University
- Hainan Province Clinical Medical Center of Respiratory Disease, Haikou, Hainan 570102
| | - Chaoqun Xu
- Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University
- Emergency and Trauma College, Hainan Medical University, Haikou, Hainan 579199, P.R. China
| | - Xiang Tang
- Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University
- Hainan Province Clinical Medical Center of Respiratory Disease, Haikou, Hainan 570102
| | - Shanjun Yu
- Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University
- Hainan Province Clinical Medical Center of Respiratory Disease, Haikou, Hainan 570102
| | - Lijun Wang
- Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University
- Hainan Province Clinical Medical Center of Respiratory Disease, Haikou, Hainan 570102
| | - Qi Li
- Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University
- Hainan Province Clinical Medical Center of Respiratory Disease, Haikou, Hainan 570102
| | - Xiangdong Zhou
- Department of Respiratory Medicine, The First Affiliated Hospital of Hainan Medical University
- Hainan Province Clinical Medical Center of Respiratory Disease, Haikou, Hainan 570102
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The microbiota-gut-kidney axis mediates host osmoregulation in a small desert mammal. NPJ Biofilms Microbiomes 2022; 8:16. [PMID: 35379849 PMCID: PMC8980004 DOI: 10.1038/s41522-022-00280-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 02/21/2022] [Indexed: 12/17/2022] Open
Abstract
Regulating sodium and water balances is crucial for survival of small, desert mammals. Studies demonstrate that the gut microbiota and their metabolites are involved in host energy homeostasis, but little is known on the interactions among salt loading, gut microbiota, and osmoregulation. The aim of this study was to fill this gap. Mongolian gerbils (Meriones unguiculatus) were offered drinking water (Con) and either water containing moderate (4%, MS) or high NaCl (8%, HS) ad libitum. Intake of HS reduced α diversity of the microbial community and, at the genus level, reduced the relative abundances of Rikenella and Christensenella but increased Atopobium. To confirm the function of gut microbiota in host osmoregulation, we transplanted caecal microbiota in HS gerbils. To cope with salt loading, the gerbils concentrated urine, resulting in negative energy balance and systemic inflammation. The HS gerbils increased hypothalamic arginine vasopressin and intestinal and renal aquaporin 2 to support water retention, and reduced intestinal and renal epithelial sodium channel α to promote sodium excretion. However, HS gerbils with caecal microbiota transplant (CMT) from Con donors maintained energy balance and osmoregulation, and had a much reduced systemic inflammation. Further, CMT from Con donors to HS recipients reshaped the gut microbiota, particularly by reducing Parabacteroides distasonis and Prevotella copri, and increasing Lactobacillus reuteri abundances, with a resulting increase in bacterial metabolites such as butyrate. These findings highlight a vital role of the microbiota-gut-kidney axis in mediating salt-related osmoregulation, allowing small mammals to adapt to high salt loads in a desert habitat.
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Ma Z, Hummel SL, Sun N, Chen Y. From salt to hypertension, what is missed? J Clin Hypertens (Greenwich) 2021; 23:2033-2041. [PMID: 34846798 PMCID: PMC8696232 DOI: 10.1111/jch.14402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/20/2021] [Accepted: 11/03/2021] [Indexed: 01/18/2023]
Abstract
Excess salt intake is viewed as a major contributor to hypertension and cardiovascular disease, and dietary salt restriction is broadly recommended by public health guidelines. However, individuals can have widely varying physiological responses to salt intake, and a tailored approach to evaluation and intervention may be needed. The traditional sodium related concepts are challenging to assess clinically for two reasons: (1) spot and 24-hour urine sodium are frequently used to evaluate salt intake, but are more suitable for population study, and (2) some adverse effects of salt may be blood pressure-independent. In recent years, previously unknown mechanisms of sodium absorption and storage have been discovered. This review will outline the limitations of current methods to assess sodium balance and discuss new potential evaluation methods and treatment targets.
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Affiliation(s)
- Zhiyi Ma
- Cardiology DepartmentBeijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijingChina
| | - Scott L. Hummel
- Ann Arbor Veterans Affairs Health SystemUniversity of Michigan Frankel Cardiovascular CenterAnn ArborMichiganUSA
| | - Ningling Sun
- Cardiology DepartmentHeart CenterPeking University People's HospitalBeijingChina
| | - Yuanyuan Chen
- Cardiology DepartmentHeart CenterPeking University People's HospitalBeijingChina
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Ji HJ, Kang N, Chen T, Lv L, Ma XX, Wang FY, Tang XD. Shen-ling-bai-zhu-san, a spleen-tonifying Chinese herbal formula, alleviates lactose-induced chronic diarrhea in rats. JOURNAL OF ETHNOPHARMACOLOGY 2019; 231:355-362. [PMID: 30071269 DOI: 10.1016/j.jep.2018.07.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 07/28/2018] [Accepted: 07/30/2018] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Shen-ling-bai-zhu-san (SLBZS) was firstly documented in ancient Chinese medical works "Tai Ping Hui Min He Ji Ju Fang" in Song-dynasty. It has been widely used for treating gastrointestinal disorders such as diarrhea with poor appetite for about 900 years. The present study is to observe the effects of SLBZS on high lactose diet-induced chronic diarrhea. MATERIALS AND METHODS Rats were subjected to a high lactose diet to induce chronic diarrhea, which were then administrated with SLBZS or smecta. General symptom, body weight, food consumption, water intake and fecal fluid content were recorded every day. The intestinal absorption function was determined by d-xylose uptake assay. The ultrastructures of intestine segments including jejunum, ileum, proximal and distal colon were observed by transmission electron microscopy. Additionally, sodium transport proteins including γ-epithelial sodium channel (ENAC-γ) and sodium/potassium-transporting ATPase subunit alpha-1 (ATP1A1) in distal colon were detected by immunohistochemistry and western blotting. RESULTS Diarrheal rats produced watery or loose, sticky feces, and presented inactiveness and grouping. A high lactose diet caused a significant decline in body weight, serum d-xylose level as well as food consumption rather than water intake. In contrast, general symptoms were improved to a certain extent and body weight loss was alleviated in the rats treated by SLBZS for one week. Fecal fluid content in diarrheal rats treated by SLBZS presented a gradual decrease trend with about 55% in the end, which was significantly less than the model group with about 81%. Meanwhile, SLBZS significantly improved the serum d-xylose level and reversed abnormal changes of tight junctions and microvilli in intestine. Additionally, SLBZS significantly modulated the abnormal expressions of ENAC-γ and ATP1A1 in distal colon of diarrheal rats. CONCLUSIONS These findings suggested that SLBZS exhibited ameliorating effects against lactose-induced diarrhea, which might be attributed to its modulations on intestinal absorption function as well as mucosal ultrastructure.
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Affiliation(s)
- Hai-Jie Ji
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, China; Postdoctoral Research Station, China Academy of Chinese Medical Sciences, Beijing 100700, China; Shanxi Province Academy of Traditional Chinese Medicine, Taiyuan 030012, China
| | - Nan Kang
- Affiliated Hospital of Jining Medical University, Jining, Shandong 272029, China
| | - Ting Chen
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, China
| | - Lin Lv
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, China
| | - Xiang-Xue Ma
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, China
| | - Feng-Yun Wang
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, China.
| | - Xu-Dong Tang
- Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing 100091, China.
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Mroz MS, Keating N, Ward JB, Sarker R, Amu S, Aviello G, Donowitz M, Fallon PG, Keely SJ. Farnesoid X receptor agonists attenuate colonic epithelial secretory function and prevent experimental diarrhoea in vivo. Gut 2014; 63:808-17. [PMID: 23916961 DOI: 10.1136/gutjnl-2013-305088] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
OBJECTIVE Bile acids are important regulators of intestinal physiology, and the nuclear bile acid receptor, farnesoid X receptor (FXR), is emerging as a promising therapeutic target for several intestinal disorders. Here, we investigated a role for FXR in regulating intestinal fluid and electrolyte transport and the potential for FXR agonists in treating diarrhoeal diseases. DESIGN Electrogenic ion transport was measured as changes in short-circuit current across voltage-clamped T84 cell monolayers or mouse tissues in Ussing chambers. NHE3 activity was measured as BCECF fluorescence in Caco-2 cells. Protein expression was measured by immunoblotting and cell surface biotinylation. Antidiarrhoeal efficacy of GW4064 was assessed using two in vivo mouse models: the ovalbumin-induced diarrhoea model and cholera toxin (CTX)-induced intestinal fluid accumulation. RESULTS GW4064 (5 μmol/L; 24 h), a specific FXR agonist, induced nuclear translocation of the receptor in T84 cells and attenuated Cl(-) secretory responses to both Ca(2+) and cAMP-dependent agonists. GW4064 also prevented agonist-induced inhibition of NHE3 in Caco-2 cells. In mice, intraperitoneal administration of GW4064 (50 mg/mL) also inhibited Ca(2+) and cAMP-dependent secretory responses across ex vivo colonic tissues and prevented ovalbumin-induced diarrhoea and CTX-induced intestinal fluid accumulation in vivo. At the molecular level, FXR activation attenuated apical Cl(-) currents by inhibiting expression of cystic fibrosis transmembrane conductance regulator channels and inhibited basolateral Na(+)/K(+)-ATPase activity without altering expression of the protein. CONCLUSIONS These data reveal a novel antisecretory role for the FXR in colonic epithelial cells and suggest that FXR agonists have excellent potential for development as a new class of antidiarrheal drugs.
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Affiliation(s)
- Magdalena S Mroz
- Department of Molecular Medicine, RCSI Education and Research Centre, Beaumont Hospital, , Dublin, Ireland
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Chanoux RA, Shubin CB, Robay A, Suaud L, Rubenstein RC. Hsc70 negatively regulates epithelial sodium channel trafficking at multiple sites in epithelial cells. Am J Physiol Cell Physiol 2013; 305:C776-87. [PMID: 23885065 DOI: 10.1152/ajpcell.00059.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The epithelial sodium channel (ENaC) plays an important role in homeostasis of blood pressure and of the airway surface liquid, and excess function of ENaC results in refractory hypertension (in Liddle's syndrome) and impaired mucociliary clearance (in cystic fibrosis). The regulation of ENaC by molecular chaperones, such as the 70-kDa heat shock protein Hsc70, is not completely understood. Our previously published data suggest that Hsc70 negatively affects ENaC activity and surface expression in Xenopus oocytes; here we investigate the mechanism by which Hsc70 acts on ENaC in epithelial cells. In Madin-Darby canine kidney cells stably expressing epitope-tagged αβγ-ENaC and with tetracycline-inducible overexpression of Hsc70, treatment with 5 μg/ml doxycycline increased total Hsc70 expression 20%. This increase in Hsc70 expression led to a decrease in ENaC activity and surface expression that corresponded to an increased rate of functional ENaC retrieval from the cell surface. In addition, Hsc70 overexpression decreased the association of newly synthesized ENaC subunits. These data support the hypothesis that Hsc70 inhibits ENaC functional expression at the apical surface of epithelia by regulating ENaC biogenesis and ENaC trafficking at the cell surface.
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Affiliation(s)
- Rebecca A Chanoux
- Division of Pulmonary Medicine and Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; and
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Kelly OB, Mroz MS, Ward JBJ, Colliva C, Scharl M, Pellicciari R, Gilmer JF, Fallon PG, Hofmann AF, Roda A, Murray FE, Keely SJ. Ursodeoxycholic acid attenuates colonic epithelial secretory function. J Physiol 2013; 591:2307-18. [PMID: 23507881 DOI: 10.1113/jphysiol.2013.252544] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Dihydroxy bile acids, such as chenodeoxycholic acid (CDCA), are well known to promote colonic fluid and electrolyte secretion, thereby causing diarrhoea associated with bile acid malabsorption. However, CDCA is rapidly metabolised by colonic bacteria to ursodeoxycholic acid (UDCA), the effects of which on epithelial transport are poorly characterised. Here, we investigated the role of UDCA in the regulation of colonic epithelial secretion. Cl(-) secretion was measured across voltage-clamped monolayers of T84 cells and muscle-stripped sections of mouse or human colon. Cell surface biotinylation was used to assess abundance/surface expression of transport proteins. Acute (15 min) treatment of T84 cells with bilateral UDCA attenuated Cl(-) secretory responses to the Ca(2+) and cAMP-dependent secretagogues carbachol (CCh) and forskolin (FSK) to 14.0 ± 3.8 and 40.2 ± 7.4% of controls, respectively (n = 18, P < 0.001). Investigation of the molecular targets involved revealed that UDCA acts by inhibiting Na(+)/K(+)-ATPase activity and basolateral K(+) channel currents, without altering their cell surface expression. In contrast, intraperitoneal administration of UDCA (25 mg kg(-1)) to mice enhanced agonist-induced colonic secretory responses, an effect we hypothesised to be due to bacterial metabolism of UDCA to lithocholic acid (LCA). Accordingly, LCA (50-200 μm) enhanced agonist-induced secretory responses in vitro and a metabolically stable UDCA analogue, 6α-methyl-UDCA, exerted anti-secretory actions in vitro and in vivo. In conclusion, UDCA exerts direct anti-secretory actions on colonic epithelial cells and metabolically stable derivatives of the bile acid may offer a new approach for treating intestinal diseases associated with diarrhoea.
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Affiliation(s)
- Orlaith B Kelly
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, Dublin, Ireland
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4-Phenylbutyric acid reduces endoplasmic reticulum stress, trypsin activation, and acinar cell apoptosis while increasing secretion in rat pancreatic acini. Pancreas 2013; 42:92-101. [PMID: 22889983 DOI: 10.1097/mpa.0b013e318259f6ca] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES Endoplasmic reticulum (ER) stress leads to misfolded proteins inside the ER and initiates unfolded protein response (UPR). Unfolded protein response components are involved in pancreatic function and activated during pancreatitis. However, the exact role of ER stress in the exocrine pancreas is unclear. The present study examined the effects of 4-phenylbutyric acid (4-PBA), an ER chaperone, on acini and UPR components. METHODS Rat acini were stimulated with cholecystokinin (10 pmol/L to 10 nmol/L) with or without preincubation of 4-PBA. The UPR components were analyzed, including chaperone-binding protein, protein kinaselike ER kinase, X-box-binding protein 1, c-Jun NH(2)-terminal kinase, CCAAT/enhancer-binding protein homologous protein, caspase 3, and apoptosis. Effects of 4-PBA were measured on secretion, calcium, and trypsin activation. RESULTS 4-Phenylbutyric acid led to an increase of secretion, whereas trypsin activation with supraphysiological cholecystokinin was significantly reduced. 4-Phenylbutyric acid prevented chaperone-binding protein up-regulation, diminished protein kinaselike ER kinase, and c-Jun NH2-terminal kinase phosphorylation, prohibited X-box-binding protein 1 splicing and CCAAT/enhancer-binding protein homologous protein expression, caspase 3 activation, and apoptosis caused by supraphysiological cholecystokinin. CONCLUSION By incubation with 4-PBA, beneficial in urea cycle deficiency, it was possible to enhance enzyme secretion to suppress trypsin activation, UPR activation, and proapoptotic pathways. The data hint new perspectives for the use of chemical chaperones in pancreatic diseases.
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Stewart GA, Ridsdale R, Martin EP, Na CL, Xu Y, Mandapaka K, Weaver TE. 4-Phenylbutyric acid treatment rescues trafficking and processing of a mutant surfactant protein-C. Am J Respir Cell Mol Biol 2012; 47:324-31. [PMID: 22461427 DOI: 10.1165/rcmb.2012-0003oc] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mutations in the SFTPC gene, encoding surfactant protein-C (SP-C), are associated with interstitial lung disease (ILD). Knowledge of the intracellular fate of mutant SP-C is essential in the design of therapies to correct trafficking/processing of the proprotein, and to prevent the formation of cytotoxic aggregates. We assessed the potential of a chemical chaperone to correct the trafficking and processing of three disease-associated mutant SP-C proteins. HEK293 cells were stably transfected with wild-type (SP-C(WT)) or mutant (SP-C(L188Q), SP-C(Δexon4), or SP-C(I73T)) SP-C, and cell lines with a similar expression of SP-C mRNA were identified. The effects of the chemical chaperone 4-phenylbutyric acid (PBA) and lysosomotropic drugs on intracellular trafficking to the endolysosomal pathway and the subsequent conversion of SP-C proprotein to mature peptide were assessed. Despite comparable SP-C mRNA expression, proprotein concentrations varied greatly: SP-C(I73T) was more abundant than SP-C(WT) and was localized to the cell surface, whereas SP-C(Δexon4) was barely detectable. In contrast, SP-C(L188Q) and SP-C(WT) proprotein concentrations were comparable, and a small amount of SP-C(L188Q) was localized to the endolysosomal pathway. PBA treatment restored the trafficking and processing of SP-C(L188Q) to SP-C(WT) concentrations, but did not correct the mistrafficking of SP-C(I73T) or rescue SP-C(Δexon4). PBA treatment also promoted the aggregation of SP-C proproteins, including SP-C(L188Q). This study provides proof of the principle that a chemical chaperone can correct the mistrafficking and processing of a disease-associated mutant SP-C proprotein.
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Affiliation(s)
- Gareth A Stewart
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., MLC7029, Cincinnati, OH 45229-3039, USA
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Zode GS, Bugge KE, Mohan K, Grozdanic SD, Peters JC, Koehn DR, Anderson MG, Kardon RH, Stone EM, Sheffield VC. Topical ocular sodium 4-phenylbutyrate rescues glaucoma in a myocilin mouse model of primary open-angle glaucoma. Invest Ophthalmol Vis Sci 2012; 53:1557-65. [PMID: 22328638 DOI: 10.1167/iovs.11-8837] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
PURPOSE Mutations in the myocilin gene (MYOC) are the most common known genetic cause of primary open-angle glaucoma (POAG). The purpose of this study was to determine whether topical ocular sodium 4-phenylbutyrate (PBA) treatment rescues glaucoma phenotypes in a mouse model of myocilin-associated glaucoma (Tg-MYOC(Y437H) mice). METHODS Tg-MYOC(Y437H) mice were treated with PBA eye drops (n = 10) or sterile PBS (n = 8) twice daily for 5 months. Long-term safety and effectiveness of topical PBA (0.2%) on glaucoma phenotypes were examined by measuring intraocular pressure (IOP) and pattern ERG (PERG), performing slit lamp evaluation of the anterior chamber, analyzing histologic sections of the anterior segment, and comparing myocilin levels in the aqueous humor and trabecular meshwork of Tg-MYOC(Y437H) mice. RESULTS Tg-MYOC(Y437H) mice developed elevated IOP at 3 months of age when compared with wild-type (WT) littermates (n = 24; P < 0.0001). Topical PBA did not alter IOP in WT mice. However, it significantly reduced elevated IOP in Tg-MYOC(Y437H) mice to the level of WT mice. Topical PBA-treated Tg-MYOC(Y437H) mice also preserved PERG amplitudes compared with vehicle-treated Tg-MYOC(Y437H) mice. No structural abnormalities were observed in the anterior chamber of PBA-treated WT and Tg-MYOC(Y437H) mice. Analysis of the myocilin in the aqueous humor and TM revealed that PBA significantly improved the secretion of myocilin and reduced myocilin accumulation as well as endoplasmic reticulum (ER) stress in the TM of Tg-MYOC(Y437H) mice. Furthermore, topical PBA reduced IOP elevated by induction of ER stress via tunicamycin injections in WT mice. CONCLUSIONS Topical ocular PBA reduces glaucomatous phenotypes in Tg-MYOC(Y437H) mice, most likely by reducing myocilin accumulation and ER stress in the TM. Topical ocular PBA could become a novel treatment for POAG patients with myocilin mutations.
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Affiliation(s)
- Gulab S Zode
- Howard Hughes Medical Institute, University of Iowa, Iowa City, Iowa, USA
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Basseri S, Lhoták S, Sharma AM, Austin RC. The chemical chaperone 4-phenylbutyrate inhibits adipogenesis by modulating the unfolded protein response. J Lipid Res 2010; 50:2486-501. [PMID: 19461119 DOI: 10.1194/jlr.m900216-jlr200] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Recent studies have shown a link between obesity and endoplasmic reticulum (ER) stress. Perturbations in ER homeostasis cause ER stress and activation of the unfolded protein response (UPR). Adipocyte differentiation contributes to weight gain, and we have shown that markers of ER stress/UPR activation, including GRP78, phospho-eIF2, and spliced XBP1, are upregulated during adipogenesis. Given these findings, the objective of this study was to determine whether attenuation of UPR activation by the chemical chaperone 4-phenylbutyrate (4-PBA) inhibits adipogenesis. Exposure of 3T3-L1 preadipocytes to 4-PBA in the presence of differentiation media decreased expression of ER stress markers. Concomitant with the suppression of UPR activation, 4-PBA resulted in attenuation of adipogenesis as measured by lipid accumulation and adiponectin secretion. Consistent with these in vitro findings, female C57BL/6 mice fed a high-fat diet supplemented with 4-PBA showed a significant reduction in weight gain and had reduced fat pad mass, as compared with the high-fat diet alone group. Furthermore, 4-PBA supplementation decreased GRP78 expression in the adipose tissue and lowered plasma triglyceride, glucose, leptin, and adiponectin levels without altering food intake. Taken together, these results suggest that UPR activation contributes to adipogenesis and that blocking its activation with 4-PBA prevents adipocyte differentiation and weight gain in mice.
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Affiliation(s)
- Sana Basseri
- Department of Medicine, McMaster University, St. Joseph's Healthcare Hamilton and the Henderson Research Centre, Hamilton, Ontario, L8N 4A6, Canada
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del Mónaco S, Assef Y, Kotsias BA. Epithelial sodium channel in a human trophoblast cell line (BeWo). J Membr Biol 2008; 223:127-39. [PMID: 18665318 DOI: 10.1007/s00232-008-9119-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 07/01/2008] [Indexed: 11/26/2022]
Abstract
The present study was performed to assay sodium currents in BeWo cells. These cells comprise a human trophoblast cell line which displays many of the biochemical and morphological properties similar to those reported for the in uterus proliferative cytotrophoblast. For whole-cell patch-clamp experiments, BeWo cells treated for 12 h with 100 nM aldosterone were exposed to 8Br-cAMP, a membrane-permeable cAMP analogue, to induce channel activity. Cells showed an amiloride-sensitive ion current (IC50 of 5.77 microM). Ion substitution experiments showed that the amiloride-sensitive current carried cations with a permeability rank order of Li+ > Na+ > K+ > NMDG (PLi/PNa = 1.3, PK/PNa = 0.6, PNMDG/PNa = 0.2). In cells pretreated with aldosterone, we observed that nearly half of successful patches had sodium channels with a linear conductance of 6.4 +/- 1.8 pS, a low voltage-independent Po and a PK/PNa of 0.19. Using RT-PCR, we determined that control cells express the alpha-, but not beta- and gamma-, epithelial sodium channel (ENaC) mRNA. When cells were treated with aldosterone (100 nM, 12 h), all alpha-, beta- and gamma-ENaC mRNAs were detected. The presence of ENaC subunit proteins in these cells was confirmed by Western blot analysis and immunolocalization with specific ENaC primary antibodies. In summary, our results suggest that BeWo cells express ENaC subunits and that aldosterone was able to modulate a selective response by generating amiloride-sensitive sodium currents similar to those observed in other human tissues.
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Affiliation(s)
- Silvana del Mónaco
- Laboratorio de Neurofisiología, Instituto de Investigaciones Médicas A. Lanari, University of Buenos Aires, C. de Malvinas 3150, Buenos Aires 1427, Argentina
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Prulière-Escabasse V, Planès C, Escudier E, Fanen P, Coste A, Clerici C. Modulation of epithelial sodium channel trafficking and function by sodium 4-phenylbutyrate in human nasal epithelial cells. J Biol Chem 2007; 282:34048-57. [PMID: 17890229 DOI: 10.1074/jbc.m702384200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sodium 4-phenylbutyrate (4-PBA) has been shown to correct the cellular trafficking of several mutant or nonmutant plasma membrane proteins such as cystic fibrosis transmembrane conductance regulator through the expression of 70-kDa heat shock proteins. The objective of the study was to determine whether 4-PBA may influence the functional expression of epithelial sodium channels (ENaC) in human nasal epithelial cells (HNEC). Using primary cultures of HNEC, we demonstrate that 4-PBA (5 mm for 6 h) markedly stimulated amiloride-sensitive sodium channel activity and that this was related to an increased abundance of alpha-, beta-, and gamma-ENaC subunits in the apical membrane. The increase in ENaC cell surface expression (i) was due to insertion of newly ENaC subunits as determined by brefeldin A experiments and (ii) was not associated with cell surface retention of ENaC subunits because endocytosis of ENaC subunits was unchanged. In addition, we find that ENaC co-immunoprecipitated with the heat shock protein constitutively expressed Hsc70, that has been reported to modulate ENaC trafficking, and that 4-PBA decreased Hsc70 protein level. Finally, we report that in cystic fibrosis HNEC obtained from two cystic fibrosis patients, 4-PBA increased functional expression of ENaC as demonstrated by the increase in amiloride-sensitive sodium transport and in alpha-, beta-, and gamma-ENaC subunit expression in the apical membrane. Our results suggest that in HNEC, 4-PBA increases the functional expression of ENaC through the insertion of new alpha-, beta-, and gamma-ENaC subunits into the apical membrane and also suggest that 4-PBA could modify ENaC trafficking by reducing Hsc70 protein expression.
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