title: ZO-1 and -2 Are Required for TRPV1-Modulated Paracellular Permeability.
abstract: The tight junction-based paracellular pathway plays an important role in saliva secretion. Zonula occludens (ZO) proteins are submembranous proteins of tight junction complex; however, their function in salivary epithelium is poorly understood. Here, we found that activation of transient receptor potential vanilloid subtype 1 (TRPV1) by capsaicin increased rat saliva secretion both in vivo and ex vivo. Meanwhile, TRPV1 activation enlarged the width of tight junctions between neighboring acinar cells, increased the paracellular ﬂux of 4-kDa fluorescein isothiocyanate (FITC)-dextran in submandibular gland (SMG) tissues, and decreased transepithelial electric resistance (TER) in SMG-C6 cells. ZO-1, -2, and -3 were distributed principally to the apical lateral region of acinar cells in SMG tissues and continuously encircled the peripheries of SMG-C6 cells in the untreated condition. TRPV1 activation obviously diminished ZO-1 and -2 staining, but not ZO-3 or β-catenin, at the cell-cell contacts ex vivo and in vitro. Moreover, in untreated SMG-C6 cells, ZO-1 and -2 single or double knockdown by small interfering RNA (siRNA) increased the paracellular ﬂux of 4-kDa FITC-dextran. In capsaicin-treated cells, ZO-1 and -2 single or double knockdown abolished, whereas their re-expression restored, the capsaicin-induced increase in paracellular permeability. Furthermore, TRPV1 activation increased RhoA activity, and inhibition of either RhoA or Rho kinase (ROCK) abolished the capsaicin-induced TER decrease as well as ZO-1 and -2 redistribution. These results indicate that ZO-1 and -2 play crucial roles in both basal salivary epithelial barrier function and TRPV1-modulated paracellular transport. RhoA-ROCK signaling pathway is responsible for TRPV1-modulated paracellular permeability as well as ZO-1 and -2 redistribution.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China.
authors.forename: X
authors.initials: X
authors.lastname: Cong
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China.
authors.forename: R L
authors.initials: RL
authors.lastname: Xiang
authors.affiliation: Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: M
authors.initials: M
authors.lastname: Mei
authors.affiliation: Department of Pediatric Dentistry, Beijing Stomatological Hospital, Capital Medical University, Beijing, China.
authors.forename: N Y
authors.initials: NY
authors.lastname: Yang
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China.
authors.forename: Y C
authors.initials: YC
authors.lastname: Su
authors.affiliation: Department of Physiology, School of Dentistry, Seoul National University, Seoul, South Korea.
authors.forename: S
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Physiology, School of Dentistry, Seoul National University, Seoul, South Korea.
authors.forename: K
authors.initials: K
authors.lastname: Park
authors.affiliation: Department of Oral Medicine, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: L W
authors.initials: LW
authors.lastname: Zhang
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education and Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China pathophy@bjmu.edu.cn.
authors.forename: L L
authors.initials: LL
authors.lastname: Wu
authors.affiliation: Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing, China.
authors.forename: G Y
authors.initials: GY
authors.lastname: Yu
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002463:Cell Membrane Permeability / Q000502:physiology; D004848:Epithelium; D055785:Gene Knockdown Techniques; D008297:Male; D046529:Microscopy, Electron, Transmission; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012472:Salivation / Q000502:physiology; D013363:Submandibular Gland / Q000502:physiology*; D050916:TRPV Cation Channels / Q000502:physiology*; D019108:Tight Junctions / Q000502:physiology*; D062826:Zonula Occludens-1 Protein / Q000502:physiology*; D062827:Zonula Occludens-2 Protein / Q000502:physiology*
chemical_list: D050916:TRPV Cation Channels; C569044:Tjp1 protein, rat; C000606525:Tjp2 protein, rat; C493922:Trpv1 protein, rat; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
keywords: capsaicin; salivary cells; salivation; tight junction; transient receptor potential vanilloid subtype 1; zonula occludens