1
|
Tang H, Zhou H, Zhang L, Tang T, Li N. Molecular mechanism of MLCK1 inducing 5-Fu resistance in colorectal cancer cells through activation of TNFR2/NF-κB pathway. Discov Oncol 2024; 15:159. [PMID: 38735014 PMCID: PMC11089027 DOI: 10.1007/s12672-024-01019-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 05/07/2024] [Indexed: 05/13/2024] Open
Abstract
BACKGROUND AND AIMS Chemotherapy resistance in colorectal cancer have been faced with significant challenges in recent years. Particular interest is directed to tumor microenvironment function. Recent work has, identified a small molecule named Divertin that prevents myosin light chain kinase 1(MLCK1) recruitment to the perijunctional actomyosin ring(PAMR), restores barrier function after tumor necrosis factor(TNF)-induced barrier loss and prevents disease progression in experimental inflammatory bowel disease. Studies have shown that MLCK is a potential target for affecting intestinal barrier function, as well as for tumor therapy. However, the relative contributions of MLCK expression and chemotherapy resistance in colorectal cancers have not been defined. METHODS Statistical analysis of MYLK gene expression differences in colorectal cancer patients and normal population and prognosis results from The Cancer Genome Atlas(TCGA) data. Cell activity was detected by Cell counting Kit-8. Cell proliferation was detected by monoclonal plate. The apoptosis was detected by flow cytometry and western blot. Determine the role of MLCK1 in inducing 5-Fluorouracil(5-Fu) resistance in colorectal cancer cells was detected by overexpression of MLCK1 and knock-down expression of MLCK1. RESULTS MLCK1 is expressed at different levels in different colorectal cancer cells, high MLCK1 expressing cell lines are less sensitive to 5-Fu, and low MLCK1 expressing cell lines are more sensitive to 5-Fu. MLCK1 high expression enhances resistance to 5-Fu in colorectal cancer cells and the sensitivity to 5-Fu was increased after knocking down the expression of MLCK1, that might be closely correlated to TNFR2/NF-κB pathway. CONCLUSIONS MLCK1 high expression can enhance resistance to 5-Fu in colorectal cancer cells and the sensitivity to 5-Fu was increased after knocking down the expression of MLCK1, that might be closely correlated to TNFR2/NF-κB pathway, which will provide a new method for the treatment of colorectal cancer patients who are resistant to 5-Fu chemotherapy.
Collapse
Affiliation(s)
- Huifen Tang
- Department of Hematology, The Affiliated Hospital, Hangzhou Normal University, 126# Wenzhou Road, Hangzhou, 310015, Zhejiang, People's Republic of China
| | - Hui Zhou
- Department of Hematology, The Affiliated Hospital, Hangzhou Normal University, 126# Wenzhou Road, Hangzhou, 310015, Zhejiang, People's Republic of China
| | - Liang Zhang
- Department of Hematology, The Affiliated Hospital, Hangzhou Normal University, 126# Wenzhou Road, Hangzhou, 310015, Zhejiang, People's Republic of China
| | - Tingting Tang
- Department of Hematology, The Affiliated Hospital, Hangzhou Normal University, 126# Wenzhou Road, Hangzhou, 310015, Zhejiang, People's Republic of China
| | - Ning Li
- Department of Hematology, The Affiliated Hospital, Hangzhou Normal University, 126# Wenzhou Road, Hangzhou, 310015, Zhejiang, People's Republic of China.
| |
Collapse
|
2
|
Song M, Zhang Z, Li Y, Xiang Y, Li C. Midgut microbiota affects the intestinal barrier by producing short-chain fatty acids in Apostichopus japonicus. Front Microbiol 2023; 14:1263731. [PMID: 37915855 PMCID: PMC10616862 DOI: 10.3389/fmicb.2023.1263731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 09/15/2023] [Indexed: 11/03/2023] Open
Abstract
Introduction The intestinal microbiota participates in host physiology and pathology through metabolites, in which short-chain fatty acids (SCFAs) are considered principal products and have extensive influence on intestine homeostasis. It has been reported that skin ulceration syndrome (SUS), the disease of Apostichopus japonicus caused by Vibrio splendidus, is associated with the alteration of the intestinal microbiota composition. Method To investigate whether the intestinal microbiota affects A. japonicus health via SCFAs, in this study, we focus on the SCFA profiling and intestinal barrier function in A. japonicus treated with V. splendidus. Results and discussion We found that V. splendidus could destroy the mid-intestine integrity and downregulate the expression of tight junction proteins ZO-1 and occludin in A. japonicus, which further dramatically decreased microorganism abundance and altered SCFAs contents. Specifically, acetic acid is associated with the largest number of microorganisms and has a significant correlation with occludin and ZO-1 among the seven SCFAs. Furthermore, our findings showed that acetic acid could maintain the intestinal barrier function by increasing the expression of tight junction proteins and rearranging the tight junction structure by regulating F-actin in mid-intestine epithelial cells. Thus, our results provide insights into the effects of the gut microbiome and SCFAs on intestine barrier homeostasis and provide essential knowledge for intervening in SUS by targeting metabolites or the gut microbiota.
Collapse
Affiliation(s)
- Mingshan Song
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
| | - Zhen Zhang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
| | - Yanan Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
| | - Yangxi Xiang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
| | - Chenghua Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Ningbo University, Ningbo, China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| |
Collapse
|
3
|
Laaker CJ, Cantelon C, Davis AB, Lloyd KR, Agyeman N, Hiltz AR, Smith BL, Konsman JP, Reyes TM. Early life cancer and chemotherapy lead to cognitive deficits related to alterations in microglial-associated gene expression in prefrontal cortex. Brain Behav Immun 2023; 113:176-188. [PMID: 37468114 PMCID: PMC10529696 DOI: 10.1016/j.bbi.2023.07.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 06/24/2023] [Accepted: 07/15/2023] [Indexed: 07/21/2023] Open
Abstract
Children that survive leukemia are at an increased risk for cognitive difficulties. A better understanding of the neurobiological changes in response to early life chemotherapy will help develop therapeutic strategies to improve quality of life for leukemia survivors. To that end, we used a translationally-relevant mouse model consisting of leukemic cell line (L1210) injection into postnatal day (P)19 mice followed by methotrexate, vincristine, and leucovorin chemotherapy. Beginning one week after the end of chemotherapy, social behavior, recognition memory and executive function (using the 5 choice serial reaction time task (5CSRTT)) were tested in male and female mice. Prefrontal cortex (PFC) and hippocampus (HPC) were collected at the conclusion of behavioral assays for gene expression analysis. Mice exposed to early life cancer + chemotherapy were slower to progress through increasingly difficult stages of the 5CSRTT and showed an increase in premature errors, indicating impulsive action. A cluster of microglial-related genes in the PFC were found to be associated with performance in the 5CSRTT and acquisition of the operant response, and long-term changes in gene expression were evident in both PFC and HPC. This work identifies gene expression changes in PFC and HPC that may underlie cognitive deficits in survivors of early life exposure to cancer + chemotherapy.
Collapse
Affiliation(s)
- Collin J Laaker
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Claire Cantelon
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Alyshia B Davis
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Kelsey R Lloyd
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Nana Agyeman
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Adam R Hiltz
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Brittany L Smith
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Jan Pieter Konsman
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA
| | - Teresa M Reyes
- University of Cincinnati, College of Medicine, Department of Pharmacology and Systems Physiology, Cincinnati, OH, USA.
| |
Collapse
|
4
|
Li C, Zhang Y, Liu R, Mai Y. Anagliptin Protected against Hypoxia/Reperfusion-Induced Brain Vascular Endothelial Permeability by Increasing ZO-1. ACS OMEGA 2021; 6:7771-7777. [PMID: 33778288 PMCID: PMC7992143 DOI: 10.1021/acsomega.1c00242] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/22/2021] [Indexed: 05/17/2023]
Abstract
BACKGROUND AND PURPOSE Cerebral ischemia-reperfusion injury is commonly induced during the treatment of ischemic stroke and is reported to be related to the blood-brain barrier destruction and brain vascular endothelial cell dysfunction. Anagliptin is a novel antidiabetic agent recently reported to protect neurons from oxidative stress. In the present study, we aim to investigate the protective property of anagliptin against oxygen-glucose deprivation and reperfusion (OGD/R)-induced injury on endothelial cells and clarify the potential underlying mechanism. METHODS OGD/R modeling was established on bEnd.3 brain endothelial cells. Cell viability was detected using the MTT assay, and the mitochondrial reactive oxygen species (ROS) level was measured using the mitoses red staining assay. The endothelial monolayer permeability was determined using an FITC-dextran permeation assay. The expression levels of NOX-4 and ZO-1 were evaluated using qRT-PCR and Western blot assays. The expressions of MLC-2, p-MLC-2, and myosin light chain kinase (MLCK) were determined using Western blot. RESULTS First, the decreased cell viability, upregulated NOX-4, and elevated mitochondrial ROS level in the endothelial cells induced by OGD/R were reversed by treatment with anagliptin. Second, the enlarged endothelial permeability and the decreased expression level of ZO-1 in the endothelial cells induced by OGD/R were alleviated by anagliptin. Third, the downregulation of ZO-1 and enlarged brain endothelial monolayer permeability induced by OGD/R were ameliorated by an MLCK inhibitor, ML-7. Lastly, the elevated expressions of MLCK and p-MLC-2 induced by OGD/R were suppressed by anagliptin. CONCLUSION Anagliptin protected against hypoxia/reperfusion-induced brain vascular endothelial permeability by increasing the expression ZO-1, mediated by inhibition of the MLCK/MLC-2 signaling pathway.
Collapse
Affiliation(s)
- Chuo Li
- Department
of Neurology, Guangzhou Eighth People’s
Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510440, China
- . Phone/Fax: +86-020-36473145
| | - Yusheng Zhang
- Department
of Neurology and Stroke Center, The First
Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510632, China
| | - Rongrong Liu
- Department
of Neurology and Stroke Center, The First
Affiliated Hospital of Jinan University, Guangzhou, Guangdong 510632, China
| | - Yuzhen Mai
- Department
of Neurology, Guangzhou Eighth People’s
Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510440, China
| |
Collapse
|
5
|
Contributions of Myosin Light Chain Kinase to Regulation of Epithelial Paracellular Permeability and Mucosal Homeostasis. Int J Mol Sci 2020; 21:ijms21030993. [PMID: 32028590 PMCID: PMC7037368 DOI: 10.3390/ijms21030993] [Citation(s) in RCA: 75] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 01/30/2020] [Accepted: 01/30/2020] [Indexed: 12/20/2022] Open
Abstract
Intestinal barrier function is required for the maintenance of mucosal homeostasis. Barrier dysfunction is thought to promote progression of both intestinal and systemic diseases. In many cases, this barrier loss reflects increased permeability of the paracellular tight junction as a consequence of myosin light chain kinase (MLCK) activation and myosin II regulatory light chain (MLC) phosphorylation. Although some details about MLCK activation remain to be defined, it is clear that this triggers perijunctional actomyosin ring (PAMR) contraction that leads to molecular reorganization of tight junction structure and composition, including occludin endocytosis. In disease states, this process can be triggered by pro-inflammatory cytokines including tumor necrosis factor-α (TNF), interleukin-1β (IL-1β), and several related molecules. Of these, TNF has been studied in the greatest detail and is known to activate long MLCK transcription, expression, enzymatic activity, and recruitment to the PAMR. Unfortunately, toxicities associated with inhibition of MLCK expression or enzymatic activity make these unsuitable as therapeutic targets. Recent work has, however, identified a small molecule that prevents MLCK1 recruitment to the PAMR without inhibiting enzymatic function. This small molecule, termed Divertin, restores barrier function after TNF-induced barrier loss and prevents disease progression in experimental chronic inflammatory bowel disease.
Collapse
|
6
|
Stuettgen V, Brayden DJ. Investigations of Piperazine Derivatives as Intestinal Permeation Enhancers in Isolated Rat Intestinal Tissue Mucosae. AAPS JOURNAL 2020; 22:33. [PMID: 31989362 DOI: 10.1208/s12248-020-0416-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 12/24/2019] [Indexed: 12/31/2022]
Abstract
A limiting factor for oral delivery of macromolecules is low intestinal epithelial permeability. 1-Phenylpiperazine (PPZ), 1-(4-methylphenyl) piperazine (1-4-MPPZ) and 1-methyl-4-phenylpiperazine (1-M-4-PPZ) have emerged as potential permeation enhancers (PEs) from a screen carried out by others in Caco-2 monolayers. Here, their efficacy, mechanism of action and potential for epithelial toxicity were further examined in Caco-2 cells and isolated rat intestinal mucosae. Using high-content analysis, PPZ and 1-4-MPPZ decreased mitochondrial membrane potential and increased plasma membrane potential in Caco-2 cells to a greater extent than 1-M-4-PPZ. The Papp of the paracellular marker, [14C]-mannitol, and of the peptide, [3H]-octreotide, was measured across rat colonic mucosae following apical addition of the three piperazines. PPZ and 1-4-MPPZ induced a concentration-dependent decrease in transepithelial electrical resistance (TEER) and an increase in the Papp of [14C]-mannitol without causing histological damage. 1-M-4-PPZ was without effect. The piperazines caused the Krebs-Henseleit buffer pH to become alkaline, which partially attenuated the increase in Papp of [14C]-mannitol caused by PPZ and 1-4-MPPZ. Only addition of 1-4-MPPZ increased the Papp of [3H]-octreotide. Pre-incubation of mucosae with two 5-HT4 receptor antagonists, a loop diuretic and a myosin light chain kinase inhibitor, reduced the permeation enhancement capacity of PPZ and 1-4-MPP for [14C]-mannitol. 1-4-MPPZ holds most promise as a PE, but intestinal physiology may also be impacted due to multiple mechanisms of action.
Collapse
Affiliation(s)
- V Stuettgen
- School of Veterinary Medicine and Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - D J Brayden
- School of Veterinary Medicine and Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland.
| |
Collapse
|
7
|
Chen T, Yin XL, Kang N, Wang XG, Li BS, Ji HJ, Zhang YQ, Bian LQ, Zhang BH, Wang FY, Tang XD. Chang'an II Decoction ( II )-Containing Serum Ameliorates Tumor Necrosis Factor-α-Induced Intestinal Epithelial Barrier Dysfunction via MLCK-MLC Signaling Pathway in Rats. Chin J Integr Med 2019; 26:745-753. [PMID: 31768870 DOI: 10.1007/s11655-019-3034-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2018] [Indexed: 12/17/2022]
Abstract
OBJECTIVE To investigate the effect of Chang'an II Decoction ( II ))-containing serum on intestinal epithelial barrier dysfunction in rats. METHODS Tumor necrosis factor (TNF)-α-induced injury of Caco-2 monolayers were established as an inflammatory model of human intestinal epithelium. Caco-2 monolayers were treated with blank serum and Chang'an II Decoction-containing serum that obtained from the rats which were treated with distilled water and Chang'an II Decoction intragastrically at doses of 0.49, 0.98, 1.96 g/(kg·d) for 1 week, respectively. After preparation of containing serum, cells were divided into the normal group, the model group, the Chang'an II-H, M, and L groups (treated with 30 ng/mL TNF-α and medium plus 10% high, middle-, and low-doses Chang'an II serum, respectively). Epithelial barrier function was assessed by transepithelial electrical resistance (TER) and permeability of fluorescein isothiocyanate (FITC)-labeled dextran. Transmission electron microscopy was used to observe the ultrastructure of tight junctions (TJs). Immunofluorescence of zonula occludens-1 (ZO-1), claudin-1 and nuclear transcription factor-kappa p65 (NF-κ Bp65) were measured to determine the protein distribution. The mRNA expression of myosin light chain kinase (MLCK) was measured by real-time polymerase chain reaction. The expression levels of MLCK, myosin light chain (MLC) and p-MLC were determined by Western blot. RESULTS Chang'an II Decoction-containing serum significantly attenuated the TER and paracellular permeability induced by TNF-α. It alleviated TNF-α-induced morphological alterations in TJ proteins. The increases in MLCK mRNA and MLCK, MLC and p-MLC protein expressions induced by TNF-α were significantly inhibited in the Chang'an II-H group. Additionally, Chang'an II Decoction significantly attenuated translocation of NF-κ Bp65 into the nucleus. CONCLUSION High-dose Chang'an II-containing serum attenuates TNF-α-induced intestinal barrier dysfunction. The underlying mechanism may be involved in inhibiting the MLCK-MLC phosphorylation signaling pathway mediated by NF-κ Bp65.
Collapse
Affiliation(s)
- Ting Chen
- Department of Gastroenterology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China
| | - Xiao-Lan Yin
- Graduate School of China Academy of Chinese Medical Sciences, Beijing, 100700, China
| | - Nan Kang
- Department of Internal Medicine, Jining Medical College Affiliated Hospital, Jining, 272029, Shandong Province, China
| | - Xiao-Ge Wang
- Department of Gastroenterology, Henan University of Chinese Medicine Affiliated Hospital, Zhengzhou, 136300, China
| | - Bao-Shuang Li
- Department of Gastroenterology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China
| | - Hai-Jie Ji
- Department of Gastroenterology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China
| | - Yin-Qiang Zhang
- Department of Liver Diseases, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China
| | - Li-Qun Bian
- Department of Gastroenterology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China
| | - Bei-Hua Zhang
- Department of Gastroenterology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China
| | - Feng-Yun Wang
- Department of Gastroenterology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China
| | - Xu-Dong Tang
- Department of Gastroenterology, Xiyuan Hospital, China Academy of Chinese Medical Sciences, Beijing, 100091, China.
| |
Collapse
|
8
|
Wang Y, Li Y, Zou J, Polster SP, Lightle R, Moore T, Dimaano M, He TC, Weber CR, Awad IA, Shen L. The cerebral cavernous malformation disease causing gene KRIT1 participates in intestinal epithelial barrier maintenance and regulation. FASEB J 2019; 33:2132-2143. [PMID: 30252535 PMCID: PMC6338648 DOI: 10.1096/fj.201800343r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 08/27/2018] [Indexed: 01/15/2023]
Abstract
Epithelial barrier maintenance and regulation requires an intact perijunctional actomyosin ring underneath the cell-cell junctions. By searching for known factors affecting the actin cytoskeleton, we identified Krev interaction trapped protein 1 (KRIT1) as a major regulator for epithelial barrier function through multiple mechanisms. KRIT1 is expressed in both small intestinal and colonic epithelium, and KRIT1 knockdown in differentiated Caco-2 intestinal epithelium decreases epithelial barrier function and increases cation selectivity. KRIT1 knockdown abolished Rho-associated protein kinase-induced and myosin II motor inhibitor-induced barrier loss by limiting both small and large molecule permeability but did not affect myosin light chain kinase-induced increases in epithelial barrier function. These data suggest that KRIT1 participates in Rho-associated protein kinase- and myosin II motor-dependent (but not myosin light chain kinase-dependent) epithelial barrier regulation. KRIT1 knockdown exacerbated low-dose TNF-induced barrier loss, along with increased cleaved caspase-3 production. Both events are blocked by pan-caspase inhibition, indicating that KRIT1 regulates TNF-induced barrier loss through limiting epithelial apoptosis. These data indicate that KRIT1 controls epithelial barrier maintenance and regulation through multiple pathways, suggesting that KRIT1 mutation in cerebral cavernous malformation disease may alter epithelial function and affect human health.-Wang, Y., Li, Y., Zou, J., Polster, S. P., Lightle, R., Moore, T., Dimaano, M., He, T.-C., Weber, C. R., Awad, I. A., Shen, L. The cerebral cavernous malformation disease causing gene KRIT1 participates in intestinal epithelial barrier maintenance and regulation.
Collapse
Affiliation(s)
- Yitang Wang
- Section of Neurosurgery, Department of Surgery, The University of Chicago, Chicago, Illinois, USA
- Department of Pathology, The University of Chicago, Chicago, Illinois, USA
| | - Ye Li
- Section of Neurosurgery, Department of Surgery, The University of Chicago, Chicago, Illinois, USA
- Department of Pathology, The University of Chicago, Chicago, Illinois, USA
| | - Jinjing Zou
- Department of Pathology, The University of Chicago, Chicago, Illinois, USA
- Department of Pulmonary and Critical Care Medicine, Renmin Hospital of Wuhan University, Wuhan, China
| | - Sean P. Polster
- Section of Neurosurgery, Department of Surgery, The University of Chicago, Chicago, Illinois, USA
| | - Rhonda Lightle
- Section of Neurosurgery, Department of Surgery, The University of Chicago, Chicago, Illinois, USA
| | - Thomas Moore
- Section of Neurosurgery, Department of Surgery, The University of Chicago, Chicago, Illinois, USA
| | - Matthew Dimaano
- Department of Medicine, The University of Chicago, Chicago, Illinois, USA; and
| | - Tong-Chuan He
- Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago, Chicago, Illinois, USA
| | | | - Issam A. Awad
- Section of Neurosurgery, Department of Surgery, The University of Chicago, Chicago, Illinois, USA
| | - Le Shen
- Section of Neurosurgery, Department of Surgery, The University of Chicago, Chicago, Illinois, USA
- Department of Pathology, The University of Chicago, Chicago, Illinois, USA
| |
Collapse
|
9
|
Blebbistatin modulates prostatic cell growth and contrapctility through myosin II signaling. Clin Sci (Lond) 2018; 132:2189-2205. [PMID: 30279228 DOI: 10.1042/cs20180294] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 09/13/2018] [Accepted: 10/01/2018] [Indexed: 01/07/2023]
Abstract
To investigate the effect of blebbistatin (BLEB, a selective myosin inhibitor) on regulating contractility and growth of prostate cells and to provide insight into possible mechanisms associated with these actions. BLEB was incubated with cell lines of BPH-1 and WPMY-1, and intraprostatically injected into rats. Cell growth was determined by flow cytometry, and in vitro organ bath studies were performed to explore muscle contractility. Smooth muscle (SM) myosin isoform (SM1/2, SM-A/B, and LC17a/b) expression was determined via competitive reverse transcriptase PCR. SM myosin heavy chain (MHC), non-muscle (NM) MHC isoforms (NMMHC-A and NMMHC-B), and proteins related to cell apoptosis were further analyzed via Western blotting. Masson's trichrome staining was applied to tissue sections. BLEB could dose-dependently trigger apoptosis and retard the growth of BPH-1 and WPMY-1. Consistent with in vitro effect, administration of BLEB to the prostate could decrease rat prostatic epithelial and SM cells via increased apoptosis. Western blotting confirmed the effects of BLEB on inducing apoptosis through a mechanism involving MLC20 dephosphorylation with down-regulation of Bcl-2 and up-regulation of BAX and cleaved caspase 3. Meanwhile, NMMHC-A and NMMHC-B, the downstream proteins of MLC20, were found significantly attenuated in BPH-1 and WPMY-1 cells, as well as rat prostate tissues. Additionally, BLEB decreased SM cell number and SM MHC expression, along with attenuated phenylephrine-induced contraction and altered prostate SMM isoform composition with up-regulation of SM-B and down-regulation of LC17a, favoring a faster contraction. Our novel data demonstrate BLEB regulated myosin expression and functional activity. The mechanism involved MLC20 dephosphorylation and altered SMM isoform composition.
Collapse
|
10
|
Listeria Adhesion Protein Induces Intestinal Epithelial Barrier Dysfunction for Bacterial Translocation. Cell Host Microbe 2018; 23:470-484.e7. [PMID: 29606495 DOI: 10.1016/j.chom.2018.03.004] [Citation(s) in RCA: 120] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 12/30/2017] [Accepted: 03/09/2018] [Indexed: 12/24/2022]
Abstract
Intestinal epithelial cells are the first line of defense against enteric pathogens, yet bacterial pathogens, such as Listeria monocytogenes, can breach this barrier. We show that Listeria adhesion protein (LAP) induces intestinal epithelial barrier dysfunction to promote bacterial translocation. These disruptions are attributed to the production of pro-inflammatory cytokines TNF-α and IL-6, which is observed in mice challenged with WT and isogenic strains lacking the surface invasion protein Internalin A (ΔinlA), but not a lap- mutant. Additionally, upon engagement of its surface receptor Hsp60, LAP activates canonical NF-κB signaling, facilitating myosin light-chain kinase (MLCK)-mediated opening of the epithelial barrier via cellular redistribution of the epithelial junctional proteins claudin-1, occludin, and E-cadherin. Pharmacological inhibition of MLCK or NF-κB in cells or genetic ablation of MLCK in mice prevents mislocalization of junctional proteins and L. monocytogenes translocation. Thus, L. monocytogenes uses LAP to exploit epithelial defenses and cross the intestinal epithelial barrier.
Collapse
|
11
|
Garcia MA, Nelson WJ, Chavez N. Cell-Cell Junctions Organize Structural and Signaling Networks. Cold Spring Harb Perspect Biol 2018; 10:a029181. [PMID: 28600395 PMCID: PMC5773398 DOI: 10.1101/cshperspect.a029181] [Citation(s) in RCA: 273] [Impact Index Per Article: 45.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cell-cell junctions link cells to each other in tissues, and regulate tissue homeostasis in critical cell processes that include tissue barrier function, cell proliferation, and migration. Defects in cell-cell junctions give rise to a wide range of tissue abnormalities that disrupt homeostasis and are common in genetic abnormalities and cancers. Here, we discuss the organization and function of cell-cell junctions primarily involved in adhesion (tight junction, adherens junction, and desmosomes) in two different epithelial tissues: a simple epithelium (intestine) and a stratified epithelium (epidermis). Studies in these tissues reveal similarities and differences in the organization and functions of different cell-cell junctions that meet the requirements for the specialized functions of each tissue. We discuss cell-cell junction responses to genetic and environmental perturbations that provide further insights into their roles in maintaining tissue homeostasis.
Collapse
Affiliation(s)
- Miguel A Garcia
- Department of Biology, Stanford University, Stanford, California 94305
| | - W James Nelson
- Department of Biology, Stanford University, Stanford, California 94305
- Departments of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305
| | - Natalie Chavez
- Department of Biology, Stanford University, Stanford, California 94305
| |
Collapse
|
12
|
Complementary Roles of Nod2 in Hematopoietic and Nonhematopoietic Cells in Preventing Gut Barrier Dysfunction Dependent on MLCK Activity. Inflamm Bowel Dis 2017; 23:1109-1119. [PMID: 28520587 DOI: 10.1097/mib.0000000000001135] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Crohn's disease (CD) pathogenesis is multifactorial involving genetic and environmental factors. Loss of function mutations in the nucleotide oligomerization domain 2 (NOD2) gene are the main genetic risk factor for CD. Like patients with CD, Nod2 mice are characterized by an enhanced Th1 immune response and a defective mucosal barrier function evidenced by increased intestinal permeability. We previously showed that the latter is related to hematopoietic Nod2 deficiency. Our aim was to explore the mechanisms by which Nod2 expressed in the hematopoietic and in the nonhematopoietic compartments interplay to control epithelial paracellular permeability. METHODS Depletion of CD4 T cells in Nod2 mice and treatments with inhibitors were conducted in chimeric mice transplanted with bone marrow cells from Nod2-deficient donors into Nod2-sufficient recipients or vice versa. Caco-2 cells overexpressing a NOD2 gene which did or did not include a CD-associated polymorphism were treated with inhibitors or siRNAs and cocultured with hematopoietic cells from Peyer's patches. RESULTS In vivo and in vitro Nod2 in hematopoietic cells regulates epithelial paracellular permeability through cytokine production influencing myosin light chain kinase (MLCK) activity. Indeed, tumor necrosis factor-α and interferon-γ secretion by CD4 T cells upregulated expression and activity of epithelial MLCK leading to increased epithelial tight junction opening. When stimulated by muramyl dipeptide, Nod2 in the nonhematopoietic compartment normalized the permeability and T-cell cytokine secretion and regulated MLCK activity. This MLCK regulation is mediated by TAK1 and RICK-dependent mechanisms. CONCLUSIONS Our study demonstrates how hematopoietic and nonhematopoietic Nod2 regulate intestinal barrier function, improving our knowledge on the mechanisms involved in CD pathogenesis.
Collapse
|
13
|
Cong X, Zhang Y, He QH, Wei T, Zhang XM, Zhang JZ, Xiang RL, Yu GY, Wu LL. Endothelial Tight Junctions Are Opened in Cholinergic-Evoked Salivation In Vivo. J Dent Res 2017; 96:562-570. [PMID: 28118553 DOI: 10.1177/0022034516685048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Blood vessels provide the original supplies for the formation of primary saliva, which is regulated by the tight junctions (TJs) between endothelial cells. Previous studies have shown that blood flow increases with vasodilatation during cholinergic-evoked salivation. However, changes in vascular paracellular permeability and the role of endothelial TJs in salivation are unknown. Here, we established an in vivo paracellular permeability detection system and observed that the endothelial TJs were permeable to 4-kDa fluorescein isothiocyanate (FITC)-dextran while impermeable to 40- and 70-kDa FITC-dextran under an unstimulated condition in mouse submandibular glands (SMGs). Pilocarpine increased the flux of 4- and 40-kDa FITC-dextran out of blood vessels but did not affect 70-kDa FITC-dextran. Claudin 5, a TJ protein specifically localized in salivary endothelial cells, was redistributed from the apicolateral membranes to the lateral and basolateral membranes and cytoplasm in cholinergic-stimulated mouse SMGs and freshly cultured human SMG tissues. In the transplanted SMGs from epiphora patients, we found that claudin 5 was present in the basolateral membranes and cytoplasm, instead of the apical region in control SMGs. Moreover, the level of phospho-myosin light chain 2 increased within the blood vessels of the pilocarpine-stimulated mouse SMGs and transplanted human SMGs, while the downstream molecule F-actin was reorganized in the endothelial cells of the transplanted human SMGs. Taken together, our findings provide direct visual evidence that the opening of endothelial TJs and the redistribution of claudin 5 are essential events contributing to cholinergic-evoked salivation, thus enriching our understanding of the secretory mechanisms that link blood flow to primary saliva formation by regulating the endothelial paracellular permeability.
Collapse
Affiliation(s)
- X Cong
- 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China
| | - Y Zhang
- 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China
| | - Q H He
- 2 Center of Medical and Health Analysis, Peking University Health Science Center, Beijing, P.R. China
| | - T Wei
- 3 Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - X M Zhang
- 3 Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - J Z Zhang
- 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China
| | - R L Xiang
- 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China
| | - G Y Yu
- 3 Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, P.R. China
| | - L L Wu
- 1 Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University School of Basic Medical Sciences, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, P.R. China
| |
Collapse
|
14
|
Abstract
Mucosal barriers separate self from non-self and are essential for life. These barriers, which are the first line of defense against external pathogens, are formed by epithelial cells and the substances they secrete. Rather than an absolute barrier, epithelia at mucosal surfaces must allow selective paracellular flux that discriminates between solutes and water while preventing the passage of bacteria and toxins. In vertebrates, tight junctions seal the paracellular space; flux across the tight junction can occur through two distinct routes that differ in selectivity, capacity, molecular composition and regulation. Dysregulation of either pathway can accompany disease. A third, tight-junction-independent route that reflects epithelial damage can also contribute to barrier loss during disease. In this Cell Science at a Glance article and accompanying poster, we present current knowledge on the molecular components and pathways that establish this selectively permeable barrier and the interactions that lead to barrier dysfunction during disease.
Collapse
Affiliation(s)
- Marion M France
- Department of Medicine (Gastroenterology, Hepatology, and Endoscopy), Brigham and Women's Hospital and Harvard Medical School, 20 Shattuck St, TH1428, Boston, MA 02115, USA
| | - Jerrold R Turner
- Department of Medicine (Gastroenterology, Hepatology, and Endoscopy), Brigham and Women's Hospital and Harvard Medical School, 20 Shattuck St, TH1428, Boston, MA 02115, USA
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, 20 Shattuck St, TH1428, Boston, MA 02115, USA
| |
Collapse
|
15
|
Mokkala K, Laitinen K, Röytiö H. Bifidobacterium lactis 420 and fish oil enhance intestinal epithelial integrity in Caco-2 cells. Nutr Res 2016; 36:246-52. [DOI: 10.1016/j.nutres.2015.11.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 11/17/2015] [Accepted: 11/24/2015] [Indexed: 12/28/2022]
|
16
|
|
17
|
Paschoud S, Jond L, Guerrera D, Citi S. PLEKHA7 modulates epithelial tight junction barrier function. Tissue Barriers 2014; 2:e28755. [PMID: 24843844 PMCID: PMC4022608 DOI: 10.4161/tisb.28755] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 03/21/2014] [Indexed: 12/13/2022] Open
Abstract
PLEKHA7 is a recently identified protein of the epithelial zonula adhaerens (ZA), and is part of a protein complex that stabilizes the ZA, by linking it to microtubules. Since the ZA is important in the assembly and disassembly of tight junctions (TJ), we asked whether PLEKHA7 is involved in modulating epithelial TJ barrier function. We generated clonal MDCK cell lines in which one of four different constructs of PLEKHA7 was inducibly expressed. All constructs were localized at junctions, but constructs lacking the C-terminal region were also distributed diffusely in the cytoplasm. Inducible expression of PLEKHA7 constructs did not affect the expression and localization of TJ proteins, the steady-state value of transepithelial resistance (TER), the development of TER during the calcium switch, and the flux of large molecules across confluent monolayers. In contrast, expression of three out of four constructs resulted both in enhanced recruitment of E-cadherin and associated proteins at the apical ZA and at lateral puncta adherentia (PA), a decreased TER at 18 h after assembly at normal calcium, and an attenuation in the fall in TER after extracellular calcium removal. This latter effect was inhibited when cells were treated with nocodazole. Immunoprecipitation analysis showed that PLEKHA7 forms a complex with the cytoplasmic TJ proteins ZO-1 and cingulin, and this association does not depend on the integrity of microtubules. These results suggest that PLEKHA7 modulates the dynamics of assembly and disassembly of the TJ barrier, through E-cadherin protein complex- and microtubule-dependent mechanisms.
Collapse
Affiliation(s)
- Serge Paschoud
- Departments of Cell Biology and Molecular Biology; University of Geneva; Geneva ; Switzerland Institute of Genetics and Genomics of Geneva; University of Geneva; Geneva, Switzerland
| | - Lionel Jond
- Departments of Cell Biology and Molecular Biology; University of Geneva; Geneva ; Switzerland Institute of Genetics and Genomics of Geneva; University of Geneva; Geneva, Switzerland
| | - Diego Guerrera
- Departments of Cell Biology and Molecular Biology; University of Geneva; Geneva ; Switzerland Institute of Genetics and Genomics of Geneva; University of Geneva; Geneva, Switzerland
| | - Sandra Citi
- Departments of Cell Biology and Molecular Biology; University of Geneva; Geneva ; Switzerland Institute of Genetics and Genomics of Geneva; University of Geneva; Geneva, Switzerland
| |
Collapse
|
18
|
Luo HM, Du MH, Lin ZL, Zhang L, Ma L, Wang H, Yu W, Lv Y, Lu JY, Pi YL, Hu S, Sheng ZY. Valproic acid treatment inhibits hypoxia-inducible factor 1α accumulation and protects against burn-induced gut barrier dysfunction in a rodent model. PLoS One 2013; 8:e77523. [PMID: 24147016 PMCID: PMC3798300 DOI: 10.1371/journal.pone.0077523] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 09/09/2013] [Indexed: 01/30/2023] Open
Abstract
Objective Burn-induced gut dysfunction plays an important role in the development of sepsis and multiple organ dysfunction. Emerging evidence suggests that hypoxia-inducible factor-1α (HIF-1α) is critical in paracelluar barrier functions via regulating vascular endothelial growth factor (VEGF) and myosin light chain kinase (MLCK) expression. Previous studies have also demonstrated that histone deacetylase inhibitors (HDACIs) can repress HIF-1α. This study aims to examine whether valproic acid (VPA), a HDACI, protects against burn-induced gut barrier dysfunction via repressing HIF-1α-dependent upregulation of VEGF and MLCK expression. Methods Rats were subjected to third degree 55% TBSA burns and treated with/ without VPA (300mg/kg). Intestinal barrier dysfunction was evaluated by permeability of intestinal mucosa to fluorescein isothiocyanate (FITC)-dextran and histologic evaluation. Histone acetylation, tight junction protein zonula occludens 1 (ZO-1), VEGF, MLCK and HIF-1α were measured. In addition, CaCO2 cells were transfected with siRNA directed against HIF-1α and were stimulated with CoCl2 (1mM) for 24 hours with/without VPA (2mM) followed by analysis of HIF-1α, MLCK, VEGF and ZO-1. Results Burn insults resulted in a significant increase in intestinal permeability and mucosal damage, accompanied by a significant reduction in histone acetylation, ZO-1, upregulation of VEGF, MLCK expression, and an increase in HIF-1α accumulation. VPA significantly attenuated the increase in intestinal permeability, mucosa damage, histone deacetylation and changes in ZO-1 expression. VPA also attenuated the increased VEGF, MLCK and HIF-1α protein levels. VPA reduced HIF-1α, MLCK and VEGF production and prevented ZO-1 loss in CoCl2-stimulated Caco-2 cells. Moreover, transfection of siRNA directed against HIF-1α led to inhibition of MLCK and VEGF production, accompanied by upregulation of ZO-1. Conclusions These results indicate that VPA can protect against burn-induced gut barrier dysfunction. These protective effects may be due to its inhibitory action on HIF-1α, leading to a reduction in intestinal VEGF and MLCK expression and minimizing ZO-1 degradation.
Collapse
Affiliation(s)
- Hong-Min Luo
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Ming-Hua Du
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Zhi-Long Lin
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Lin Zhang
- Obstetrics and Gynecology Department, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Li Ma
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Huan Wang
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Wen Yu
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Yi Lv
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Jiang-Yang Lu
- Department of Pathology, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Yu-Li Pi
- Department of Ophtalmology, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
| | - Sen Hu
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
- * E-mail: (SH); (ZYS)
| | - Zhi-Yong Sheng
- Laboratory of Shock and Organ Dysfunction, Burns Institute, the First Hospital Affiliated to the People’s Liberation Army General Hospital, Beijing, China
- * E-mail: (SH); (ZYS)
| |
Collapse
|
19
|
Cong X, Zhang Y, Yang NY, Li J, Ding C, Ding QW, Su YC, Mei M, Guo XH, Wu LL, Yu GY. Occludin is required for TRPV1-modulated paracellular permeability in the submandibular gland. J Cell Sci 2013; 126:1109-21. [PMID: 23345400 DOI: 10.1242/jcs.111781] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Occludin plays an important role in maintaining tight junction barrier function in many types of epithelia. We previously reported that activation of transient receptor potential vanilloid subtype 1 (TRPV1) in rabbit submandibular gland promoted salivary secretion, partly by an increase in paracellular permeability. We have now explored the role of occludin in TRPV1-modulated paracellular permeability in a rat submandibular gland cell line SMG-C6. Both TRPV1 and occludin were expressed in SMG-C6 cells, and capsaicin induced redistribution of occludin, but not claudin-3, claudin-4 or E-cadherin, from the cell membrane into the cytoplasm. Capsaicin also decreased transepithelial electrical resistance (TER) and increased the Trypan Blue and FITC-dextran flux. Capsazepine (CPZ), a TRPV1 antagonist, inhibited the capsaicin-induced occludin redistribution and TER decrease. Moreover, occludin knockdown by shRNA suppressed, whereas occludin re-expression restored, the TER response to capsaicin. Mechanistically, TRPV1 activation increased ERK1/2 and MLC2 phosphorylation. PD98059, an ERK1/2 kinase inhibitor, abolished the capsaicin-induced MLC2 phosphorylation, whereas ML-7, an MLC2 kinase inhibitor, did not affect ERK1/2 phosphorylation, suggesting that ERK1/2 is the upstream signaling molecule of MLC2. Capsaicin also induced F-actin reorganization, which was abolished by CPZ, PD98059 and ML-7, indicating that TRPV1 activation altered F-actin organization in an ERK1/2- and MLC2-dependent manner. Furthermore, either PD98059 or ML-7 could abolish the capsaicin-induced TER response and occludin redistribution, whereas knockdown of ERK1/2 further confirmed that the TRPV1-modulated paracellular permeability was ERK1/2 dependent. Taken together, these results identified a crucial role of occludin in submandibular epithelial cells, and more importantly, demonstrated that occludin was required to mediate TRPV1-modulated paracellular permeability.
Collapse
Affiliation(s)
- Xin Cong
- Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Zuhl M, Schneider S, Lanphere K, Conn C, Dokladny K, Moseley P. Exercise regulation of intestinal tight junction proteins. Br J Sports Med 2012; 48:980-6. [PMID: 23134759 DOI: 10.1136/bjsports-2012-091585] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Gastrointestinal distress, such as diarrhoea, cramping, vomiting, nausea and gastric pain are common among athletes during training and competition. The mechanisms that cause these symptoms are not fully understood. The stress of heat and oxidative damage during exercise causes disruption to intestinal epithelial cell tight junction proteins resulting in increased permeability to luminal endotoxins. The endotoxin moves into the blood stream leading to a systemic immune response. Tight junction integrity is altered by the phosphoylation state of the proteins occludin and claudins, and may be regulated by the type of exercise performed. Prolonged exercise and high-intensity exercise lead to an increase in key phosphorylation enzymes that ultimately cause tight junction dysfunction, but the mechanisms are different. The purpose of this review is to (1) explain the function and physiology of tight junction regulation, (2) discuss the effects of prolonged and high-intensity exercise on tight junction permeability leading to gastrointestinal distress and (3) review agents that may increase or decrease tight junction integrity during exercise.
Collapse
Affiliation(s)
- Micah Zuhl
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, New Mexico, USA
| | - Suzanne Schneider
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, New Mexico, USA
| | - Katherine Lanphere
- Department of Health, Exercise, and Sport Sciences, University of New Mexico, Albuquerque, New Mexico, USA
| | - Carole Conn
- Department of Nutrition/Dietetics, University of New Mexico, Albuquerque, New Mexico, USA
| | - Karol Dokladny
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico, USA
| | - Pope Moseley
- Department of Internal Medicine, University of New Mexico, Albuquerque, New Mexico, USA
| |
Collapse
|
21
|
Cong X, Zhang Y, Shi L, Yang NY, Ding C, Li J, Ding QW, Su YC, Xiang RL, Wu LL, Yu GY. Activation of transient receptor potential vanilloid subtype 1 increases expression and permeability of tight junction in normal and hyposecretory submandibular gland. J Transl Med 2012; 92:753-68. [PMID: 22391958 DOI: 10.1038/labinvest.2012.12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Tight junction (TJ) is an important structure that regulates material transport through the paracellular pathway across the epithelium, but its significance in salivary physiology and pathogenesis of salivary dysfunctional diseases is not fully understood. We previously demonstrated that a functional transient receptor potential vanilloid subtype 1 (TRPV1) expresses in submandibular gland (SMG). However, association of TRPV1-induced saliva secretion with TJ remains unknown. Here we explored the effect of TRPV1 activation on expression and function of TJ of rabbit SMG in vitro and in vivo. RT-PCR and western blot analysis revealed that capsaicin upregulated expression of zonula occludin-1 (ZO-1), claudin (Cldn)-3, and -11, but not Cldn-1, -2, -4, -5, and -7 in cultured SMG cells. Capsaicin also increased the entering of 4 kDa FITC-dextran into the acinar lumen, induced redistribution of cytoskeleton F-actin under confocal microscope, and these effects were abolished by preincubation of capsazepine, a TRPV1 antagonist, indicating that activation of TRPV1 increases expression and permeability of TJ in SMG. Additionally, in a hyposecretory model induced by rabbit SMG transplantation, the expression of ZO-1, Cldn-3, and -11 was decreased, whereas other TJs remained unaltered. The structure of TJ was impaired and the width of apical TJs was reduced under transmission electron microscope, concomitant with diminished immunofluorescence of F-actin in peri-apicolateral region, indicating impaired TJ expression and decreased paracellular permeability in the transplanted SMG. Moreover, topical capsaicin cream increased secretion, decreased TJ structural injury, reversed TJ expression levels, and protected F-actin morphology from disarrangement in transplanted SMGs. These data provide the first evidence to demonstrate that TJ components, particularly ZO-1, Cldn-3, and -11 have important roles in secretion of SMG under both physiological and pathophysiological conditions. The injury in TJ integrity was involved in the hypofunctional SMGs, and TRPV1 might be a potential target to improve saliva secretion through modulating expression and function of TJs.
Collapse
Affiliation(s)
- Xin Cong
- Center for Salivary Gland Diseases of Peking University School and Hospital of Stomatology, Department of Physiology and Pathophysiology, Peking University HealthScience Center and Key Laboratory of Molecular Cardiovascular Sciences, Beijing, China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
22
|
DiPaolo BC, Margulies SS. Rho kinase signaling pathways during stretch in primary alveolar epithelia. Am J Physiol Lung Cell Mol Physiol 2012; 302:L992-1002. [PMID: 22287611 DOI: 10.1152/ajplung.00175.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Alveolar epithelial cells (AECs) maintain integrity of the blood-gas barrier with actin-anchored intercellular tight junctions. Stretched type I-like AECs undergo magnitude- and frequency-dependent actin cytoskeletal remodeling into perijunctional actin rings. On the basis of published studies in human pulmonary artery endothelial cells (HPAECs), we hypothesize that RhoA activity, Rho kinase (ROCK) activity, and phosphorylation of myosin light chain II (MLC2) increase in stretched type I-like AECs in a manner that is dependent on stretch magnitude, and that RhoA, ROCK, or MLC2 activity inhibition will attenuate stretch-induced actin remodeling and preserve barrier properties. Primary type I-like AEC monolayers were stretched biaxially to create a change in surface area (ΔSA) of 12%, 25%, or 37% in a cyclic manner at 0.25 Hz for up to 60 min or left unstretched. Type I-like AECs were also treated with Rho pathway inhibitors (ML-7, Y-27632, or blebbistatin) and stained for F-actin or treated with the myosin phosphatase inhibitor calyculin-A and quantified for monolayer permeability. Counter to our hypothesis, ROCK activity and MLC2 phosphorylation decreased in type I-like AECs stretched to 25% and 37% ΔSA and did not change in monolayers stretched to 12% ΔSA. Furthermore, RhoA activity decreased in type I-like AECs stretched to 37% ΔSA. In contrast, MLC2 phosphorylation in HPAECs increased when HPAECs were stretched to 12% ΔSA but then decreased when they were stretched to 37% ΔSA, similar to type I-like AECs. Perijunctional actin rings were observed in unstretched type I-like AECs treated with the Rho pathway inhibitor blebbistatin. Myosin phosphatase inhibition increased MLC2 phosphorylation in stretched type I-like AECs but had no effect on monolayer permeability. In summary, stretch alters RhoA activity, ROCK activity, and MLC2 phosphorylation in a manner dependent on stretch magnitude and cell type.
Collapse
Affiliation(s)
- Brian C DiPaolo
- Department of Bioengineering, University of Pennsylvania, 210 South 33rd St., Philadelphia, PA 19104-6321, USA
| | | |
Collapse
|
23
|
Rodgers LS, Fanning AS. Regulation of epithelial permeability by the actin cytoskeleton. Cytoskeleton (Hoboken) 2011; 68:653-60. [PMID: 22083950 DOI: 10.1002/cm.20547] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 01/06/2023]
Abstract
The actin cytoskeleton is a dynamic structure necessary for cell and tissue organization, including the maintenance of epithelial barriers. The epithelial barrier regulates the movement of ions, macromolecules, immune cells, and pathogens, and is thus essential for normal organ function. Disruption in the epithelial barrier has been shown to coincide with alterations of the actin cytoskeleton in several disease states. These disruptions primarily manifest as increased movement through the paracellular space, which is normally regulated by tight junctions (TJ). Despite extensive research demonstrating a direct link between the actin cytoskeleton and epithelial permeability, our understanding of the physiological mechanisms that link permeability and tight junction structure are still limited. In this review, we explore the role of the actin cytoskeleton at TJ and present several areas for future study.
Collapse
Affiliation(s)
- Laurel S Rodgers
- Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, 27599-7545, USA
| | | |
Collapse
|
24
|
Vojdani A, Lambert J. The Role of Th17 in Neuroimmune Disorders: Target for CAM Therapy. Part II. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2011; 2011:984965. [PMID: 19622601 PMCID: PMC3137879 DOI: 10.1093/ecam/nep063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 05/22/2009] [Indexed: 12/23/2022]
Abstract
Decades of research went into understanding the role that Th1 autoreactive T-cells play in neuroinflammation. Here we describe another effector population, the IL-17-producing T-helper lineage (Th17), which drives the inflammatory process. Through the recruitment of inflammatory infiltration neutrophils and the activation of matrix metalloproteinases, IL-17, a cytokine secreted by Th17 cells, contributes to blood-brain barrier breakdown and the subsequent attraction of macrophages and monocytes into the nervous system. The entry of cells along with the local production of inflammatory cytokines leads to myelin and axonal damage. This activation of the inflammatory response system is induced by different pathogenic factors, such as gut bacterial endotoxins resulting in progressive neurodegeneration by Th17 cells. Through the understanding of the role of bacterial endotoxins and other pathogenic factors in the induction of autoimmune diseases by Th17 cells, CAM practitioners will be able to design CAM therapies targeting IL-17 activity. Targeted therapy can restore the integrity of the intestinal and blood-brain barriers using probiotics, N-acetyl-cysteine, α-lipoic acid, resveratrol and others for their patients with autoimmunities, in particular those with neuroinflammation and neurodegeneration.
Collapse
|
25
|
Goguen BN, Hoffman BD, Sellers JR, Schwartz MA, Imperiali B. Light-Triggered Myosin Activation for Probing Dynamic Cellular Processes. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201100674] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
26
|
Goguen BN, Hoffman BD, Sellers JR, Schwartz MA, Imperiali B. Light-triggered myosin activation for probing dynamic cellular processes. Angew Chem Int Ed Engl 2011; 50:5667-70. [PMID: 21542072 DOI: 10.1002/anie.201100674] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Indexed: 11/05/2022]
Affiliation(s)
- Brenda N Goguen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | | | | | | |
Collapse
|
27
|
KSR1 is a functional protein kinase capable of serine autophosphorylation and direct phosphorylation of MEK1. Exp Cell Res 2010; 317:452-63. [PMID: 21144847 DOI: 10.1016/j.yexcr.2010.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 11/29/2010] [Accepted: 11/29/2010] [Indexed: 11/20/2022]
Abstract
The extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathway is a highly conserved signaling pathway that regulates diverse cellular processes including differentiation, proliferation, and survival. Kinase suppressor of Ras-1 (KSR1) binds each of the three ERK cascade components to facilitate pathway activation. Even though KSR1 contains a C-terminal kinase domain, evidence supporting the catalytic function of KSR1 remains controversial. In this study, we produced recombinant wild-type or kinase-inactive (D683A/D700A) KSR1 proteins in Escherichia coli to test the hypothesis that KSR1 is a functional protein kinase. Recombinant wild-type KSR1, but not recombinant kinase-inactive KSR1, underwent autophosphorylation on serine residue(s), phosphorylated myelin basic protein (MBP) as a generic substrate, and phosphorylated recombinant kinase-inactive MAPK/ERK kinase-1 (MEK1). Furthermore, FLAG immunoprecipitates from KSR1(-/-) colon epithelial cells stably expressing FLAG-tagged wild-type KSR1 (+KSR1), but not vector (+vector) or FLAG-tagged kinase-inactive KSR1 (+D683A/D700A), were able to phosphorylate kinase-inactive MEK1. Since TNF activates the ERK pathway in colon epithelial cells, we tested the biological effects of KSR1 in the survival response downstream of TNF. We found that +vector and +D683A/D700A cells underwent apoptosis when treated with TNF, whereas +KSR1 cells were resistant. However, +KSR1 cells were sensitized to TNF-induced cell loss in the absence of MEK kinase activity. These data provide clear evidence that KSR1 is a functional protein kinase, MEK1 is an in vitro substrate of KSR1, and the catalytic activities of both proteins are required for eliciting cell survival responses downstream of TNF.
Collapse
|
28
|
Snoek SA, Verstege MI, Boeckxstaens GE, van den Wijngaard RM, de Jonge WJ. The enteric nervous system as a regulator of intestinal epithelial barrier function in health and disease. Expert Rev Gastroenterol Hepatol 2010; 4:637-51. [PMID: 20932148 DOI: 10.1586/egh.10.51] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The intestinal epithelia proliferate and differentiate along the crypt villus axis to constitute a barrier cell layer separating some 10¹³ potentially harmful bacteria from a sterile mucosal compartment. Strict regulatory mechanisms are required to maintain a balance between the appropriate uptake of luminal food components and proteins, while constraining the exposure of the mucosal compartment to luminal antigens and microbes. The enteric nervous system is increasingly recognized as such a regulatory housekeeper of the epithelial barrier integrity, in addition to its ascribed immunomodulatory potential. Inflammation affects both epithelial integrity and barrier function and, in turn, loss of barrier function perpetuates inflammatory conditions. The observation that inflammatory conditions affect enteric neurons may add to the dysregulated barrier function in chronic disease. Here, we review the current understanding of the regulatory role of the nervous system in the maintenance of barrier function in healthy state, or during pathological conditions of, for instance, stress-induced colitis, surgical trauma or inflammation. We will discuss the clinical potential for advances in understanding the role of the enteric nervous system in this important phenomenon.
Collapse
Affiliation(s)
- Susanne A Snoek
- Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands
| | | | | | | | | |
Collapse
|
29
|
DiPaolo BC, Lenormand G, Fredberg JJ, Margulies SS. Stretch magnitude and frequency-dependent actin cytoskeleton remodeling in alveolar epithelia. Am J Physiol Cell Physiol 2010; 299:C345-53. [PMID: 20519449 DOI: 10.1152/ajpcell.00379.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Alveolar epithelial cells (AEC) maintain integrity of the blood-gas barrier with gasket-like intercellular tight junctions (TJ) that are anchored internally to the actin cytoskeleton. We hypothesize that stretch rapidly reorganizes actin (<10 min) into a perijunctional actin ring (PJAR) in a manner that is dependent on magnitude and frequency of the stretch, accompanied by spontaneous movement of actin-anchored receptors at the plasma membrane. Primary AEC monolayers were stretched biaxially to create a change in surface area (DeltaSA) of 12%, 25%, or 37% in a cyclic manner at 0.25 Hz for up to 60 min, or held tonic at 25% DeltaSA for up to 60 min, or left unstretched. By 10 min of stretch PJARs were evident in 25% and 37% DeltaSA at 0.25 Hz, but not for 12% DeltaSA at 0.25 Hz, or at tonic 25% DeltaSA, or with no stretch. Treatment with 1 muM jasplakinolide abolished stretch-induced PJAR formation, however. As a rough index of remodeling rate, we measured spontaneous motions of 5-mum microbeads bound to actin focal adhesion complexes on the apical membrane surfaces; within 1 min of exposure to DeltaSA of 25% and 37%, these motions increased substantially, increased with increasing stretch frequency, and were consistent with our mechanistic hypothesis. With a tonic stretch, however, the spontaneous motion of microbeads attenuated back to unstretched levels, whereas PJAR remained unchanged. Stretch did not increase spontaneous microbead motion in human alveolar epithelial adenocarcinoma A549 monolayers, confirming that this actin remodeling response to stretch was a cell-type specific response. In summary, stretch of primary rat AEC monolayers forms PJARs and rapidly reorganized actin binding sites at the plasma membrane in a manner dependent on stretch magnitude and frequency.
Collapse
Affiliation(s)
- Brian C DiPaolo
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania19104-6321, USA
| | | | | | | |
Collapse
|
30
|
Hours MC, Mery L. The N-terminal domain of the type 1 Ins(1,4,5)P3 receptor stably expressed in MDCK cells interacts with myosin IIA and alters epithelial cell morphology. J Cell Sci 2010; 123:1449-59. [PMID: 20375063 DOI: 10.1242/jcs.057687] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cytosolic Ca(2+) controls a wide range of cellular events. The versatility of this second messenger depends on its ability to form diverse spatial and temporal patterns, including waves and oscillations. Ca(2+)-signaling patterns are thought to be determined in part by the subcellular distribution of inositol (1,4,5)-trisphosphate receptors [Ins(1,4,5)P(3)Rs] but little is currently known about how the localization of the Ins(1,4,5)P(3)R itself is regulated. Here, we report that the recruitment of GFP-tagged Ins(1,4,5)P(3)Rs in the vicinity of tight junctions in Madin-Darby canine kidney (MDCK) cells requires the N-terminal domain. Stable expression of this domain in polarized MDCK cells induced a flattened morphology, affected cytokinesis, accelerated cell migration in response to monolayer wounding and interfered with the cortical targeting of myosin IIA. In addition, downregulation of myosin IIA in polarized MDCK cells was found to mimic the effects of stable expression of the N-terminal part of Ins(1,4,5)P(3)R on cell shape and to alter localization of endogenous Ins(1,4,5)P(3)Rs. Taken together, these results support a model in which the recruitment of Ins(1,4,5)P(3)Rs at the apex of the lateral membrane in polarized MDCK cells, involves myosin IIA and might be important for the regulation of cortical actin dynamics.
Collapse
|
31
|
Abouhamed M, Grobe K, San IVLC, Thelen S, Honnert U, Balda MS, Matter K, Bähler M. Myosin IXa regulates epithelial differentiation and its deficiency results in hydrocephalus. Mol Biol Cell 2010; 20:5074-85. [PMID: 19828736 DOI: 10.1091/mbc.e09-04-0291] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The ependymal multiciliated epithelium in the brain restricts the cerebrospinal fluid to the cerebral ventricles and regulates its flow. We report here that mice deficient for myosin IXa (Myo9a), an actin-dependent motor molecule with a Rho GTPase-activating (GAP) domain, develop severe hydrocephalus with stenosis and closure of the ventral caudal 3rd ventricle and the aqueduct. Myo9a is expressed in maturing ependymal epithelial cells, and its absence leads to impaired maturation of ependymal cells. The Myo9a deficiency further resulted in a distorted ependyma due to irregular epithelial cell morphology and altered organization of intercellular junctions. Ependymal cells occasionally delaminated, forming multilayered structures that bridged the CSF-filled ventricular space. Hydrocephalus formation could be significantly attenuated by the inhibition of the Rho-effector Rho-kinase (ROCK). Administration of ROCK-inhibitor restored maturation of ependymal cells, but not the morphological distortions of the ependyma. Similarly, down-regulation of Myo9a by siRNA in Caco-2 adenocarcinoma cells increased Rho-signaling and induced alterations in differentiation, cell morphology, junction assembly, junctional signaling, and gene expression. Our results demonstrate that Myo9a is a critical regulator of Rho-dependent and -independent signaling mechanisms that guide epithelial differentiation. Moreover, Rho-kinases may represent a new target for therapeutic intervention in some forms of hydrocephalus.
Collapse
Affiliation(s)
- Marouan Abouhamed
- Institute of General Zoology and Genetics, Westfalian Wilhelms University, 48149 Münster, Germany
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Steed E, Balda MS, Matter K. Dynamics and functions of tight junctions. Trends Cell Biol 2010; 20:142-9. [PMID: 20061152 DOI: 10.1016/j.tcb.2009.12.002] [Citation(s) in RCA: 299] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 12/02/2009] [Accepted: 12/02/2009] [Indexed: 12/13/2022]
Abstract
Tight junctions are intercellular adhesion complexes in vertebrates that are required for the formation of functional epithelial and endothelial barriers. Their morphological appearance and biochemical composition, that includes large multimeric protein complexes, have long fostered the belief that they are relatively rigid, non-dynamic structures. Recent observations now suggest that at least some junctional elements and proteins can be very dynamic, and that such dynamic properties are important for different tight junction functions ranging from the regulation of paracellular permeability to junction-associated signalling mechanisms that guide cell behaviour. Combining such dynamic properties with existing tight junction models will help us to advance our understanding of the molecular mechanisms that underlie the functional properties of tight junctions.
Collapse
Affiliation(s)
- Emily Steed
- Department of Cell Biology, UCL Institute of Ophthalmology, University College London, Bath Street, London EC1V 9EL, UK
| | | | | |
Collapse
|
33
|
Mullin JM, Skrovanek SM, Valenzano MC. Modification of Tight Junction Structure and Permeability by Nutritional Means. Ann N Y Acad Sci 2009; 1165:99-112. [DOI: 10.1111/j.1749-6632.2009.04028.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
34
|
Al-Sadi R, Ye D, Dokladny K, Ma TY. Mechanism of IL-1beta-induced increase in intestinal epithelial tight junction permeability. THE JOURNAL OF IMMUNOLOGY 2008; 180:5653-61. [PMID: 18390750 DOI: 10.4049/jimmunol.180.8.5653] [Citation(s) in RCA: 308] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The IL-1beta-induced increase in intestinal epithelial tight junction (TJ) permeability has been postulated to be an important mechanism contributing to intestinal inflammation of Crohn's disease and other inflammatory conditions of the gut. The intracellular and molecular mechanisms that mediate the IL-1beta-induced increase in intestinal TJ permeability remain unclear. The purpose of this study was to elucidate the mechanisms that mediate the IL-1beta-induced increase in intestinal TJ permeability. Specifically, the role of myosin L chain kinase (MLCK) was investigated. IL-1beta caused a progressive increase in MLCK protein expression. The time course of IL-1beta-induced increase in MLCK level correlated linearly with increase in Caco-2 TJ permeability. Inhibition of the IL-1beta-induced increase in MLCK protein expression prevented the increase in Caco-2 TJ permeability. Inhibition of the IL-1beta-induced increase in MLCK activity also prevented the increase in Caco-2 TJ permeability. Additionally, knock-down of MLCK protein expression by small interference RNA prevented the IL-1beta-induced increase in Caco-2 TJ permeability. The IL-1beta-induced increase in MLCK protein expression was preceded by an increase in MLCK mRNA expression. The IL-1beta-induced increase in MLCK mRNA transcription and subsequent increase in MLCK protein expression and Caco-2 TJ permeability was mediated by activation of NF-kappaB. In conclusion, our data indicate that the IL-1beta increase in Caco-2 TJ permeability was mediated by an increase in MLCK expression and activity. Our findings also indicate that the IL-1beta-induced increase in MLCK protein expression and Caco-2 TJ permeability was mediated by an NF-kappaB-dependent increase in MLCK gene transcription.
Collapse
Affiliation(s)
- Rana Al-Sadi
- Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
| | | | | | | |
Collapse
|
35
|
Crosstalk of tight junction components with signaling pathways. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:729-56. [PMID: 17950242 DOI: 10.1016/j.bbamem.2007.08.018] [Citation(s) in RCA: 565] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 08/03/2007] [Accepted: 08/16/2007] [Indexed: 12/28/2022]
Abstract
Tight junctions (TJs) regulate the passage of ions and molecules through the paracellular pathway in epithelial and endothelial cells. TJs are highly dynamic structures whose degree of sealing varies according to external stimuli, physiological and pathological conditions. In this review we analyze how the crosstalk of protein kinase C, protein kinase A, myosin light chain kinase, mitogen-activated protein kinases, phosphoinositide 3-kinase and Rho signaling pathways is involved in TJ regulation triggered by diverse stimuli. We also report how the phosphorylation of the main TJ components, claudins, occludin and ZO proteins, impacts epithelial and endothelial cell function.
Collapse
|
36
|
Ivanov AI, Bachar M, Babbin BA, Adelstein RS, Nusrat A, Parkos CA. A unique role for nonmuscle myosin heavy chain IIA in regulation of epithelial apical junctions. PLoS One 2007; 2:e658. [PMID: 17668046 PMCID: PMC1920554 DOI: 10.1371/journal.pone.0000658] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2007] [Accepted: 06/25/2007] [Indexed: 01/21/2023] Open
Abstract
The integrity and function of the epithelial barrier is dependent on the apical junctional complex (AJC) composed of tight and adherens junctions and regulated by the underlying actin filaments. A major F-actin motor, myosin II, was previously implicated in regulation of the AJC, however direct evidence of the involvement of myosin II in AJC dynamics are lacking and the molecular identity of the myosin II motor that regulates formation and disassembly of apical junctions in mammalian epithelia is unknown. We investigated the role of nonmuscle myosin II (NMMII) heavy chain isoforms, A, B, and C in regulation of epithelial AJC dynamics and function. Expression of the three NMMII isoforms was observed in model intestinal epithelial cell lines, where all isoforms accumulated within the perijunctional F-actin belt. siRNA-mediated downregulation of NMMIIA, but not NMMIIB or NMMIIC expression in SK-CO15 colonic epithelial cells resulted in profound changes of cell morphology and cell-cell adhesions. These changes included acquisition of a fibroblast-like cell shape, defective paracellular barrier, and substantial attenuation of the assembly and disassembly of both adherens and tight junctions. Impaired assembly of the AJC observed after NMMIIA knock-down involved dramatic disorganization of perijunctional actin filaments. These findings provide the first direct non-pharmacological evidence of myosin II-dependent regulation of AJC dynamics in mammalian epithelia and highlight a unique role of NMMIIA in junctional biogenesis.
Collapse
Affiliation(s)
- Andrei I Ivanov
- Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia, United States of America.
| | | | | | | | | | | |
Collapse
|
37
|
Samarin SN, Ivanov AI, Flatau G, Parkos CA, Nusrat A. Rho/Rho-associated kinase-II signaling mediates disassembly of epithelial apical junctions. Mol Biol Cell 2007; 18:3429-39. [PMID: 17596509 PMCID: PMC1951751 DOI: 10.1091/mbc.e07-04-0315] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Apical junctional complex (AJC) plays a vital role in regulation of epithelial barrier function. Disassembly of the AJC is observed in diverse physiological and pathological states; however, mechanisms governing this process are not well understood. We previously reported that the AJC disassembly is driven by the formation of apical contractile acto-myosin rings. In the present study, we analyzed the signaling pathways regulating acto-myosin-dependent disruption of AJC by using a model of extracellular calcium depletion. Pharmacological inhibition analysis revealed a critical role of Rho-associated kinase (ROCK) in AJC disassembly in calcium-depleted epithelial cells. Furthermore, small interfering RNA (siRNA)-mediated knockdown of ROCK-II, but not ROCK-I, attenuated the disruption of the AJC. Interestingly, AJC disassembly was not dependent on myosin light chain kinase and myosin phosphatase. Calcium depletion resulted in activation of Rho GTPase and transient colocalization of Rho with internalized AJC proteins. Pharmacological inhibition of Rho prevented AJC disassembly. Additionally, Rho guanine nucleotide exchange factor (GEF)-H1 translocated to contractile F-actin rings after calcium depletion, and siRNA-mediated depletion of GEF-H1 inhibited AJC disassembly. Thus, our findings demonstrate a central role of the GEF-H1/Rho/ROCK-II signaling pathway in the disassembly of AJC in epithelial cells.
Collapse
Affiliation(s)
- Stanislav N. Samarin
- *Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322; and
| | - Andrei I. Ivanov
- *Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322; and
| | - Gilles Flatau
- Institut National de la Santé et de la Recherche Médicale, U627, Université de Nice-Sophia Antipolis, Faculté de Médecine, 06107 Nice, France
| | - Charles A. Parkos
- *Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322; and
| | - Asma Nusrat
- *Epithelial Pathobiology Research Unit, Department of Pathology and Laboratory Medicine, Emory University, Atlanta, GA 30322; and
| |
Collapse
|
38
|
Abstract
Transcellular transport affects the paracellular flux through 2 distinct mechanisms: by determining the driving force and by altering the permeability of the paracellular pathway. Such coordination ensures efficient transepithelial transport by preventing the build-up of large electrical and osmotic gradients. The regulation of paracellular permeability was originally recognized as increased paracellular flux of water and solutes upon the activation of the intestinal Na+-coupled glucose uptake. Despite great advances in the molecular characterization of the tight junctions that form the structural basis of epithelial barrier functions, the mechanisms whereby apical transporters alter the paracellular pathways remains unresolved. Recent studies suggest that myosin-based contractility is central to this coupling. In this minireview, we summarize our current knowledge of paracellular permeability, its regulation by contractility, and the various signaling events that link apical Na+-glucose cotransport to myosin phosphorylation. While the role of myosin phosphorylation appears to be universal, the mechanism(s) whereby apical transport triggers this process is likely cell specific. The current model suggests that in intestinal cells, a key factor is a p38 MAP kinase-induced Na+/H+-exchanger-mediated alkalinization. We propose an alternative, nonexclusive mechanism in kidney tubular cells, in which the key event may be a Na+-cotransport-triggered plasma membrane depolarization, which in turn leads to Rho-mediated myosin phosphorylation.
Collapse
Affiliation(s)
- András Kapus
- The St. Michael's Hospital Research Institute and Department of Surgery, University of Toronto, 30 Bond Street, Queen Wing 7009, Toronto, ON M5B 1W8, Canada
| | | |
Collapse
|
39
|
Maher S, Feighery L, Brayden DJ, McClean S. Melittin as an epithelial permeability enhancer I: investigation of its mechanism of action in Caco-2 monolayers. Pharm Res 2007; 24:1336-45. [PMID: 17373574 DOI: 10.1007/s11095-007-9288-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Accepted: 01/19/2007] [Indexed: 02/07/2023]
Abstract
PURPOSE Melittin is an amphipathic antimicrobial peptide which has been shown to enhance the permeability of mannitol and reduce transepithelial electrical resistance (TER) across Caco-2 monolayers. The aim of this work was to further examine the potential of melittin as a paracellular permeability enhancer and to investigate the mechanism of interaction with tight junction proteins in Caco-2. MATERIALS AND METHODS The permeability of a range of fluorescent markers of differing molecular weights across monolayers was examined and immunofluorescence and western blotting analysis of tight junction proteins were also carried out. The mechanism of TER reduction was also examined using cell signalling inhibitors. RESULTS Apical but not basolateral addition of melittin increased the permeability of a range FITC-dextrans (4-70 kDa) across monolayers. Melittin effects were reversible and no cytotoxicity was evident in polarized Caco-2 epithelia at the concentrations used. Altered expression of ZO-1, E-cadherin and F-actin was also detected. The phospholipase A2 inhibitors, aristolochic acid and indomethacin and the cyclooxygenase inhibitor, piroxicam, partially attenuated melittin-induced TER reduction, suggesting that part of the mechanism by which melittin opens tight junctions involves prostaglandin signalling. CONCLUSIONS Apically-added melittin opens tight junctions, causing dramatic TER reductions with significant increases in flux of dextrans. These effects appear mediated in part via PLA2 and involve alterations in specific tight junction proteins.
Collapse
Affiliation(s)
- Sam Maher
- Institute of Technology Tallaght Dublin, Belgard Road, Tallaght, Dublin, Ireland
| | | | | | | |
Collapse
|
40
|
Olivera DS, Boggs SE, Beenhouwer C, Aden J, Knall C. Cellular mechanisms of mainstream cigarette smoke-induced lung epithelial tight junction permeability changes in vitro. Inhal Toxicol 2007; 19:13-22. [PMID: 17127639 DOI: 10.1080/08958370600985768] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Mainstream cigarette smoke increases the permeability of human airways; however, the mechanism for this increased permeability is poorly defined. Tight junctions between adjacent epithelial cells constitute the physiological barrier to fluid and macromolecules in epithelium. These structures are highly regulated by phosphorylation and their association with the cytoskeleton. The goal of these studies was to identify the signal transduction pathways that regulate smoke-induced permeability. Using a physiologically relevant air-liquid interface exposure system, electrically tight monolayers of the human bronchial epithelial cell-line Calu-3 were exposed to fresh, whole mainstream cigarette smoke. This exposure results in a regulated, dose-dependent loss of epithelial barrier function in the lung epithelial monolayers. With cigarette smoke exposure, transepithelial electrical resistance (TER) is decreased and albumin flux is increased, indicating a loss in barrier function to ions and macromolecules, respectively; however, both largely recover in 30 min. Smoke-induced losses of macromolecular barrier function are the result of multicellular junctional reorganization, resulting in increased leak volume rather than leak frequency. Inhibiting Rho kinase (ROCK) significantly reduces the smoke-induced permeability to both ions and macromolecules, while inhibiting protein tyrosine kinases (PTK) only reduces smoke-induced macromolecular permeability. Interestingly, inhibiting myosin light chain kinase (MLCK) exacerbates smoke-induced permeability, indicating that MLCK and ROCK have opposing regulatory roles. Our results demonstrate that the smoke-induced loss of epithelial barrier function in human bronchial epithelium is a regulated process rather than a cytotoxic response. Additionally, our results indicate that activation of PTK and ROCK and inactivation of MLCK contribute to the increased airway permeability caused by mainstream cigarette smoke.
Collapse
Affiliation(s)
- Dorian S Olivera
- Program in Toxicology, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
| | | | | | | | | |
Collapse
|
41
|
Li X, Gorodeski G. Non-muscle myosin-II-B filament regulation of paracellular resistance in cervical epithelial cells is associated with modulation of the cortical acto-myosin. ACTA ACUST UNITED AC 2006; 13:579-91. [PMID: 17088080 PMCID: PMC1850386 DOI: 10.1016/j.jsgi.2006.09.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Indexed: 12/29/2022]
Abstract
OBJECTIVE To understand myosin regulation of epithelial permeability. METHODS This was an experimental study, using human cervical epithelial cells CaSki. End points were paracellular permeability (determined in terms of transepithelial electrical resistance); non-muscle myosin-II-B (NMM-II-B) cellular localization; NMM-II-B phosphorylation status; NMM-II-B-actin interaction (determined in vitro by the immunoprecipitation-immunoreactivity method); and NMM-II-B filamentation (determined in vitro using purified NMM-II-B filaments in terms of filaments disassembly/assembly ratios. RESULTS Treatment of cells with the Rho-associated kinase (ROCK) inhibitor Y-27632 or with the phosphatase inhibitor okadaic acid decreased the resistance of the lateral intercellular space (R(LIS)), and increased phosphorylation of NMM-II-B on threonine and serine residues. Y-27632 induced disorganization of the cortical acto-myosin and decreased co-immunoprecipitation of actin with NMM-II-B. Homodimerization assays using NMM-II-B filaments from cells treated with Y-27632 or okadaic acid revealed decreased filamentation compared to control cells. However, okadaic acid blocked Y-27632 decreased filamentation. Treatment with DRB, a casein kinase-II (CK2) inhibitor, induced opposing effects to those of Y-27632 and okadaic acid. Treatment with 5,6-dichloro-1-beta-(D)-ribofuranosylbenzimidazole (DRB) did not involve modulation of actin depolymerization, suggesting that NMM-II-B regulation of the R(LIS) was independent of actin polymerization status. Exposure of NMM-II-B filaments to CK2 increased filamentation, regardless of prior treatments in vivo with Y-27632, okadaic acid, or DRB. CONCLUSIONS The results suggest that NMM-II-B filaments are in steady-state equilibrium of phosphorylation-dephosphorylation mediated by CK2 and by ROCK-regulated myosin heavy chain phosphatase, respectively. Increased phosphorylation would tend to inhibit assembly of NMM-II-B filaments and lead to decreased actin-myosin interaction, which would tend to decrease the R(LIS) and increase the paracellular permeability.
Collapse
Affiliation(s)
- Xin Li
- Departments of Reproductive Biology, Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, USA
| | | |
Collapse
|
42
|
Li X, Zhou L, Gorodeski GI. Estrogen regulates epithelial cell deformability by modulation of cortical actomyosin through phosphorylation of nonmuscle myosin heavy-chain II-B filaments. Endocrinology 2006; 147:5236-48. [PMID: 16901965 PMCID: PMC2398684 DOI: 10.1210/en.2006-0779] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The objective of the study was to understand how estrogen modulates the rigidity of the cytoskeleton in epithelial cells. Estrogen depletion decreased, and treatment with 17beta-estradiol increased deformability of cervical-vaginal epithelial cells. Estrogen also induced redistribution of nonmuscle myosin II-B (NMM-II-B); lesser interaction of NMM-II-B with actin; increased phosphorylation of NMM-II-B-heavy chains at threonine and serine residues; and decreased filamentation of NMM-II-B in vitro. The effects of 17beta-estradiol were time and dose related and could be mimicked by diethylstilbestrol. The effects of estrogen were blocked by cotreatment with antisense oligonucleotide for the estrogen receptor-alpha and inhibited by ICI-182,780 and tamoxifen; omission of epithelial growth factor (EGF) from the culture medium; and cotreatments with the EGF receptor inhibitor AG1478, the ERK-MAPK inhibitor PD98059, the casein kinase-II (CK2) inhibitor 5,6-dichloro-1-beta-(D)-ribofuranosylbenzimidazole, the Rho-associated kinase inhibitor Y-27632, and the nonspecific phosphatase inhibitor okadaic acid. Coadministration of 5,6-dichloro-1-beta-(D)-ribofuranosylbenzimidazole plus okadaic acid blocked the 17beta-estradiol effect. H-89 or LY294002 did not significantly affect estrogen effects. Treatment with estrogen increased activation of ERK1/2 and CK2 activity. These data suggest a novel pathway of estrogen regulation of the cytoskeleton in epithelial cells. The effect is mediated by estrogen receptor-alpha and involves in part the EGF-EGF receptor and ERK-MAPK cascades as proximal signaling networks and the CK2 and Rho-associated kinase-regulated myosin heavy chain phosphatase as terminal effectors. Augmented phosphorylation of NMM-II-B can block filamentation and induce disassociation of the myosin from the cortical actin, and disruption of the actomyosin ring can increase cell deformability. This mechanism can explain estrogen regulation of paracellular permeability in cervical-vaginal epithelia in vivo.
Collapse
Affiliation(s)
- Xin Li
- Department of Reproductive Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | | | | |
Collapse
|
43
|
Graham WV, Wang F, Clayburgh DR, Cheng JX, Yoon B, Wang Y, Lin A, Turner JR. Tumor Necrosis Factor-induced Long Myosin Light Chain Kinase Transcription Is Regulated by Differentiation-dependent Signaling Events. J Biol Chem 2006; 281:26205-15. [PMID: 16835238 DOI: 10.1074/jbc.m602164200] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Myosin light chain kinase (MLCK) is expressed as long and short isoforms from unique transcriptional start sites within a single gene. Tumor necrosis factor (TNF) augments intestinal epithelial long MLCK expression, which is critical to cytoskeletal regulation. We found that TNF increases long MLCK mRNA transcription, both in human enterocytes in vitro and murine enterocytes in vivo.5'-RACE identified two novel exons, 1A and 1B, which encode alternative long MLCK transcriptional start sites. Chromatin immunoprecipitation (ChIP) and site-directed mutagenesis identified two essential Sp1 sites upstream of the exon 1A long MLCK transcriptional start site. Analysis of deletion and truncation mutants showed that a 102-bp region including these Sp1 sites was necessary for basal transcription. A promoter construct including 4-kb upstream of exon 1A was responsive to TNF, AP-1, or NFkappaB, but all except NFkappaB responses were absent in a shorter 2-kb construct, and all responses were absent in a 1-kb construct. Electrophoretic mobility shift assays, ChIP, and site-directed mutagenesis explained these data by identifying three functional AP-1 sites between 2- and 4-kb upstream of exon 1A and two NFkappaB sites between 1- and 2-kb upstream of exon 1A. Analysis of differentiating epithelia showed that only well differentiated enterocytes activated the 4-kb long MLCK promoter in response to TNF, and consensus promoter reporters demonstrated that TNF-induced NFkappaB activation decreased during differentiation while TNF-induced AP-1 activation increased. Thus either AP-1 or NFkappaB can up-regulate long MLCK transcription, but the mechanisms by which TNF up-regulates intestinal epithelial long MLCK transcription from exon 1A are differentiation-dependent.
Collapse
Affiliation(s)
- W Vallen Graham
- Department of Pathology, University of Chicago, Chicago, Illinois 60637, USA
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Jöns T, Wittschieber D, Beyer A, Meier C, Brune A, Thomzig A, Ahnert-Hilger G, Veh RW. K+-ATP-channel-related protein complexes: potential transducers in the regulation of epithelial tight junction permeability. J Cell Sci 2006; 119:3087-97. [PMID: 16820413 DOI: 10.1242/jcs.03041] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
K+-ATP channels are composed of an inwardly rectifying Kir6 subunit and an auxiliary sulfonylurea receptor (SUR) protein. The SUR subunits of Kir6 channels have been recognized as an ATPase, which appears to work as a mechanochemical device like other members of the ABC protein family. Thus, in spite of just gating ions, Kir6/Sur might, in addition, regulate completely different cellular systems. However, so far no model system was available to directly investigate this possibility. Using highly specific antibodies against Kir6.1-SUR2A and an in vitro model system of the rat small intestine, we describe a new function of the Kir6.1-SUR2A complex, namely the regulation of paracellular permeability. The Kir6.1-SUR2A complex localizes to regulated tight junctions in a variety of gastrointestinal, renal and liver tissues of rat, pig and human, whereas it is absent in the urothelium. Changes in paracellular permeability following food intake was investigated by incubating the lumen of morphological well-defined segments of rat small intestine with various amounts of glucose. Variations in the lumenal glucose concentrations and regulators of Kir6.1/SUR2A activity, such as tolbutamide or diazoxide, specifically modulate paracellular permeability. The data presented here shed new light on the physiological and pathophysiological role K+-ATP channels might have for the regulation of tight junctions.
Collapse
Affiliation(s)
- Thomas Jöns
- Charité-Universitätsmedizin Berlin, Centrum für Anatomie, Institut für Integrative Neuroanatomie, Philippstr. 12, 10115 Berlin, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
45
|
Fiandra L, Casartelli M, Giordana B. The paracellular pathway in the lepidopteran larval midgut: modulation by intracellular mediators. Comp Biochem Physiol A Mol Integr Physiol 2006; 144:464-73. [PMID: 16765075 DOI: 10.1016/j.cbpa.2006.04.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2005] [Revised: 03/23/2006] [Accepted: 04/11/2006] [Indexed: 11/18/2022]
Abstract
The features of the paracellular pathway, an important route for the transfer of ions and molecules in epithelia, are in insects still poorly investigated and it has not yet been elucidated how the septate junction (SJ) acts as a transepithelial barrier. In this study, some properties of the paracellular pathway of Bombyx mori larval midgut, isolated in Ussing chambers, were determined and the modulation of SJ permeability by intracellular events disclosed. Diffusion potentials evoked by transepithelial gradients of different salts indicated that the junction bore weak negative charges and that the paracellular pathway was selective with respect to ion charge and size. In standard conditions, the transepithelial resistance was 28.2+/-2.1 Omega cm(2), a value indicating that the midgut is a low resistance epithelium. The modulation of midgut SJ by typical enhancers of mammalian tight junction permeability known to act on the cytoskeleton was studied by measuring the shunt resistance and the lumen-to-haemolymph flux of sucrose. An increase of the intracellular level of cAMP and Ca(2+) caused a significant decrease of the shunt resistance and an increase of SJ permeability. The attenuation of Ca(2+) effect in the presence of the calcium channel blocker nifedipine indicated that the influx of external Ca(2+) into the cytoplasm was important for the opening of the SJ, as well as the release of Ca(2+) from the intracellular stores.
Collapse
Affiliation(s)
- L Fiandra
- Department of Biology, University of Milan, Via Celoria 26, 20133 Milano, Italy.
| | | | | |
Collapse
|
46
|
Shen L, Black ED, Witkowski ED, Lencer WI, Guerriero V, Schneeberger EE, Turner JR. Myosin light chain phosphorylation regulates barrier function by remodeling tight junction structure. J Cell Sci 2006; 119:2095-106. [PMID: 16638813 DOI: 10.1242/jcs.02915] [Citation(s) in RCA: 336] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Epithelial tight junctions form a barrier against passive paracellular flux. This barrier is regulated by complex physiologic and pathophysiologic signals that acutely fine-tune tight junction permeability. Although actomyosin contraction and myosin light chain phosphorylation are clearly involved in some forms of tight junction regulation, the contributions of other signaling events and the role of myosin light chain phosphorylation in this response are poorly understood. Here we ask if activation of myosin light chain kinase alone is sufficient to induce downstream tight junction regulation. We use a confluent polarized intestinal epithelial cell model system in which constitutively active myosin light chain kinase, tMLCK, is expressed using an inducible promoter. tMLCK expression increases myosin light chain phosphorylation, reorganizes perijunctional F-actin, and increases tight junction permeability. TJ proteins ZO-1 and occludin are markedly redistributed, morphologically and biochemically, but effects on claudin-1 and claudin-2 are limited. tMLCK inhibition prevents changes in barrier function and tight junction organization induced by tMLCK expression, suggesting that these events both require myosin light chain phosphorylation. We conclude that myosin light chain phosphorylation alone is sufficient to induce tight junction regulation and provide new insights into the molecular mechanisms that mediate this regulation.
Collapse
Affiliation(s)
- Le Shen
- Department of Pathology, The University of Chicago, 5841 South Maryland Avenue, MC 1089,Chicago, IL 60637, USA
| | | | | | | | | | | | | |
Collapse
|
47
|
Shen L, Turner JR. Role of epithelial cells in initiation and propagation of intestinal inflammation. Eliminating the static: tight junction dynamics exposed. Am J Physiol Gastrointest Liver Physiol 2006; 290:G577-82. [PMID: 16537969 DOI: 10.1152/ajpgi.00439.2005] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Like all mucosal surfaces, the intestine forms a barrier that separates the external environment, i.e., the gut lumen, from the protected internal milieu. The intestinal barrier is formed by the epithelial cells that line the luminal surface. Plasma membranes of these cells prevent free passage of hydrophilic molecules across this barrier but do not seal the space between cells. This function is provided by the tight junction. Each cell is encircled at the apicolateral boundary by the tight junction, which seals the paracellular space. The tight junction does not form a completely impermeant seal, however, because that would prevent paracellular absorption of essential nutrients and ions; intestinal tight junctions are "leaky" and allow solutes to be transported paracellularly according to size and charge. Abundant data are available to demonstrate that barrier properties of tight junctions can be modulated in response to physiological, pharmacological, and pathophysiological stimuli, but the structural modifications responsible for these responses are poorly defined. Recent advances in understanding the role of tight junction dynamics in response to such stimuli are the focus of this review.
Collapse
Affiliation(s)
- Le Shen
- Department of Pathology, The University of Chicago, Illnois, USA
| | | |
Collapse
|
48
|
Ye D, Ma I, Ma TY. Molecular mechanism of tumor necrosis factor-alpha modulation of intestinal epithelial tight junction barrier. Am J Physiol Gastrointest Liver Physiol 2006; 290:G496-504. [PMID: 16474009 DOI: 10.1152/ajpgi.00318.2005] [Citation(s) in RCA: 290] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A TNF-alpha-induced increase in intestinal epithelial tight junction (TJ) permeability has been proposed to be an important proinflammatory mechanism contributing to intestinal inflammation in Crohn's disease and other inflammatory conditions. Previous studies from our laboratory suggested that the TNF-alpha-induced increase in intestinal TJ permeability was mediated by an increase in myosin light chain kinase (MLCK) protein expression. However, the molecular mechanisms that mediate the TNF-alpha increase in intestinal TJ permeability and MLCK protein expression remain unknown. The purpose of this study was to delineate the intracellular and molecular mechanisms that mediate the TNF-alpha-induced increase in intestinal TJ permeability; using an in vitro intestinal epithelial model system consisting of filter-grown Caco-2 intestinal epithelial monolayers. To examine the molecular mechanisms involved in the TNF-alpha regulation of intestinal TJ barrier, we identified and cloned for the first time a functionally active MLCK promoter region. TNF-alpha treatment of filter-grown Caco-2 monolayers transfected with plasmid vector containing the MLCK promoter region produced an increase in MLCK promoter activity and MLCK transcription. The TNF-alpha-induced increase in MLCK transcription corresponded to a sequential increase in MLCK protein expression, MLCK activity, and Caco-2 TJ permeability. The TNF-alpha-induced increase in MLCK promoter activity was mediated by NF-kappaB activation, and the inhibition of NF-kappaB activation prevented the TNF-alpha-induced increase in promoter activity and the subsequent increase in MLCK protein expression and Caco-2 TJ permeability. The TNF-alpha-induced activation of MLCK promoter was mediated by binding of the activated NF-kappaB p50/p65 dimer to the downstream kappaB binding site (-84 to -75) on the MLCK promoter region; deletion of the kappaB binding site prevented the TNF-alpha increase in promoter activity. Additionally, siRNA silencing of NF-kappaB p65 also prevented the TNF-alpha increase in MLCK promoter activity. In conclusion, our findings indicated that the TNF-alpha-induced increase in intestinal epithelial TJ permeability was mediated by NF-kappaB p50/p65 binding and activation of the MLCK promoter. NF-kappaB p50/p65 activation of the MLCK promoter then leads to a stepwise increase in MLCK transcription, expression and activity, and MLCK-mediated opening of the intestinal TJ barrier.
Collapse
Affiliation(s)
- Dongmei Ye
- Department of Internal Medicine-Gastroenterology, MSC10 5550, University of New Mexico, Albuquerque, NM 87131-0001, USA
| | | | | |
Collapse
|
49
|
Aijaz S, Balda MS, Matter K. Tight junctions: molecular architecture and function. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 248:261-98. [PMID: 16487793 DOI: 10.1016/s0074-7696(06)48005-0] [Citation(s) in RCA: 223] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tight junctions are the most apical component of the epithelial junctional complex and are crucial for the formation and functioning of epithelial and endothelial barriers. They regulate selective diffusion of ions and solutes along the paracellular pathway and restrict apical/basolateral intramembrane diffusion of lipids. Research over the past years provided much insight into the molecular composition of tight junctions, and we are starting to understand the mechanisms that permit selective paracellular diffusion. Moreover, a complex network of proteins has been identified at tight junctions that is based on cytoskeleton-linked adaptors that recruit and thereby often regulate different types of signaling components that regulate epithelial proliferation, differentiation, and polarization.
Collapse
Affiliation(s)
- Saima Aijaz
- Division of Cell Biology, Institute of Ophthalmology, University College London, London, United Kingdom
| | | | | |
Collapse
|
50
|
Araki Y, Katoh T, Ogawa A, Bamba S, Andoh A, Koyama S, Fujiyama Y, Bamba T. Bile acid modulates transepithelial permeability via the generation of reactive oxygen species in the Caco-2 cell line. Free Radic Biol Med 2005; 39:769-80. [PMID: 16109307 DOI: 10.1016/j.freeradbiomed.2005.04.026] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Revised: 04/29/2005] [Accepted: 04/29/2005] [Indexed: 02/06/2023]
Abstract
The barrier functions in epithelial and endothelial cells seem to be very important for maintaining normal biological homeostasis. However, it is unclear whether or how bile acids affect the epithelial barrier. We examined the bile acid-induced disruption of the epithelial barrier. We measured the transepithelial electrical resistance (TEER) of Caco-2 cells as a marker of disruption of the epithelial barrier. Reactive oxygen species (ROS) generation was also measured. Cholic acid (CA) decreased the TEER and increased intracellular ROS generation. PLA2 (phospholipase A2), COX (cyclooxygenase), PKC (protein kinase), ERK 1/2 (extracellular signal-regulated kinase 1/2), PI 3 K (phosphatidylinositol 3-kinase), p38 MAPK (p38 mitogen-activated protein kinase), MLCK (myosin light-chain kinase), NADH dehydrogenase, and XO (xanthine oxidase) inhibitors or ROS scavengers prevented the CA-induced TEER decrease. PLA2, COX, PKC, NADH dehydrogenase, and XO inhibitors prevented the CA-induced ROS generation but not ERK 1/2, PI 3 K, p38 MAPK, and MLCK inhibitors. If the cells were treated with ROS generators such as superoxide dismutase, the TEER decreased. ERK 1/2, PI 3 K, p38 MAPK, and MLCK inhibitors prevent these ROS generators from inducing the TEER decrease. These results suggest that ROS play an important role. In addition, PLA2, COX, PKC, NADH dehydrogenase, and XO are located upstream of the ROS generation, but ERK 1/2, PI 3 K, p38 MAPK, and MLCK are downstream during the signaling of CA-induced TEER alterations.
Collapse
Affiliation(s)
- Yoshio Araki
- Department of Internal Medicine, Biwako Youikuin Hospital, 7-7-2 Ohgaya, Otsu 520-2144 Shiga, Japan.
| | | | | | | | | | | | | | | |
Collapse
|