Regulation of Ion Transport by the NHERF Family of PDZ Proteins

Physiology ◽  
2004 ◽  
Vol 19 (6) ◽  
pp. 362-369 ◽  
Author(s):  
Shirish Shenolikar ◽  
James W. Voltz ◽  
Rochelle Cunningham ◽  
Edward J. Weinman
Keyword(s):  
Membrane Proteins ◽  
Epithelial Cells ◽  
Ion Transport ◽  
Ion Homeostasis ◽  
Ion Transporters ◽  
Pdz Proteins ◽  
The Past

NHERFs are the best-studied apical PDZ proteins that are highly expressed in epithelial cells. Molecular and cellular studies over the past decade show that NHERFs regulate the targeting or trafficking of ion transporters and other membrane proteins and transduce physiological and pathophysiological signals that regulate ion homeostasis in mammals.

scholarly journals Physiological Significance of Ion Transporters and Channels in the Stomach and Pathophysiological Relevance in Gastric Cancer

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Dumin Yuan ◽  
Zhiyuan Ma ◽  
Biguang Tuo ◽  
Taolang Li ◽  
Xuemei Liu
Keyword(s):  
Gastric Cancer ◽  
Epithelial Cells ◽  
Ion Transport ◽  
Gastric Acid ◽  
Malignant Disease ◽  
Chronic Atrophic Gastritis ◽  
Ion Transporters ◽  
Barrier Dysfunction ◽  
Acid Base ◽  
Plasma Membrane Permeability

Gastric cancer (GC) is a highly invasive and fatal malignant disease that accounts for 5.7% of new global cancer cases and is the third leading cause of cancer-related death. Acid/base homeostasis is critical for organisms because protein and enzyme function, cellular structure, and plasma membrane permeability change with pH. Various ion transporters are expressed in normal gastric mucosal epithelial cells and regulate gastric acid secretion, ion transport, and fluid absorption, thereby stabilizing the differentiation and homeostasis of gastric mucosal epithelial cells. Ion transporter dysfunction results in disordered ion transport, mucosa barrier dysfunction, and acid/base disturbances, causing gastric acid-related diseases such as chronic atrophic gastritis (CAG) and GC. This review summarizes the physiological functions of multiple ion transporters and channels in the stomach, including Cl− channels, Cl−/HCO3− exchangers, sodium/hydrogen exchangers (NHEs), and potassium (K+) channels, and their pathophysiological relevance in GC.

scholarly journals Lentiviral CRISPR-guided RNA library screening identified Adam17 as an upstream negative regulator of Procr in mammary epithelium

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ting Wu ◽  
Yinghua Wang ◽  
Tianxiong Xiao ◽  
Yirui Ai ◽  
Jinsong Li ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Membrane Proteins ◽  
Epithelial Cells ◽  
Adult Stem Cells ◽  
Vascular System ◽  
Negative Regulator ◽  
Breast Cancer Cell Lines ◽  
Screening System ◽  
Membrane Expression ◽  
Sorting Technique

Abstract Background Protein C receptor (Procr) has recently been shown to mark resident adult stem cells in the mammary gland, vascular system, and pancreatic islets. More so, high Procr expression was also detected and used as indicator for subsets of triple-negative breast cancers (TNBCs). Previous study has revealed Procr as a target of Wnt/β-catenin signaling; however, direct upstream regulatory mechanism of Procr remains unknown. To comprehend the molecular role of Procr during physiology and pathology, elucidating the upstream effectors of Procr is necessary. Here, we provide a system for screening negative regulators of Procr, which could be adapted for broad molecular analysis on membrane proteins. Results We established a screening system which combines CRISPR-Cas9 guided gene disruption with fluorescence activated cell sorting technique (FACS). CommaDβ (murine epithelial cells line) was used for the initial Procr upstream effector screening using lentiviral CRISPR-gRNA library. Shortlisted genes were further validated through individual lentiviral gRNA infection followed by Procr expression evaluation. Adam17 was identified as a specific negative inhibitor of Procr expression. In addition, MDA-MB-231 cells and Hs578T cells (human breast cancer cell lines) were used to verify the conserved regulation of ADAM17 over PROCR expression. Conclusion We established an efficient CRISPR-Cas9/FACS screening system, which identifies the regulators of membrane proteins. Through this system, we identified Adam17 as the negative regulator of Procr membrane expression both in mammary epithelial cells and breast cancer cells.

β-Barrel outer membrane proteins suppress mTORC2 activation and induce autophagic responses

2018 ◽  
Vol 11 (558) ◽  
pp. eaat7493 ◽  
Author(s):  
Anu Chaudhary ◽  
Cassandra Kamischke ◽  
Mara Leite ◽  
Melissa A. Altura ◽  
Loren Kinman ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Epithelial Cells ◽  
Outer Membrane ◽  
Cellular Response ◽  
Tertiary Structure ◽  
Inflammatory Responses ◽  
Outer Membrane Proteins ◽  
Cell Surface Receptor ◽  
Mouse Bone Marrow ◽  
Endosomal Acidification

The outer membranes of Gram-negative bacteria and mitochondria contain proteins with a distinct β-barrel tertiary structure that could function as a molecular pattern recognized by the innate immune system. Here, we report that purified outer membrane proteins (OMPs) from different bacterial and mitochondrial sources triggered the induction of autophagy-related endosomal acidification, LC3B lipidation, and p62 degradation. Furthermore, OMPs reduced the phosphorylation and therefore activation of the multiprotein complex mTORC2 and its substrate Akt in macrophages and epithelial cells. The cell surface receptor SlamF8 and the DNA-protein kinase subunit XRCC6 were required for these OMP-specific responses in macrophages and epithelial cells, respectively. The addition of OMPs to mouse bone marrow–derived macrophages infected withSalmonellaTyphimurium facilitated bacterial clearance. These data identify a specific cellular response mediated by bacterial and mitochondrial OMPs that can alter inflammatory responses and influence the killing of pathogens.

Effects of oviductal proteins, including heat shock 70 kDa protein 8, on survival of ram spermatozoa over 48 h in vitro

2009 ◽  
Vol 21 (3) ◽  
pp. 408 ◽  
Author(s):  
R. E. Lloyd ◽  
R. M. A. Elliott ◽  
A. Fazeli ◽  
P. F. Watson ◽  
W. V. Holt
Keyword(s):  
Plasma Membrane ◽  
Heat Shock ◽  
Membrane Proteins ◽  
Epithelial Cells ◽  
Beneficial Effect ◽  
Active Component ◽  
Apical Plasma Membrane ◽  
Series Of Experiments ◽  
Dose Dependent

Following insemination, ram spermatozoa are transported to the isthmus region of the oviduct where they bind to the oviductal epithelial cells (OEC), remaining viable for several hours. The aim of the present study was to begin to decipher which component(s) of the ewe oviduct actively participates in maintaining the viability of ram spermatozoa. A series of experiments was conducted to investigate whether: (1) soluble OEC apical plasma membrane proteins (sAPM) isolated from ewes prolong survival of ram spermatozoa over an extended (48 h) coincubation period at 39°C; (2) a recombinant form of one of these oviductal proteins, namely heat shock 70 kDa protein 8 (HSPA8), prolongs survival of ram spermatozoa; and (3) pretreatment with HSPA8 antibody compromises the ability of sAPM to prolong the survival of ram spermatozoa. Both sAPM and recombinant HSPA8 had a beneficial effect on the viability of ram spermatozoa during coincubation, although both these effects were dose dependent. In contrast, pretreatment with HSPA8 antibody significantly negated the ability of sAPM to maintain the viability of ram spermatozoa. These findings suggest that HSPA8 is an active component of the ewe oviduct that participates in maintaining the viability of ram spermatozoa. This is a potentially valuable observation given that there is a great deal of room for improving existing diluents for storing fresh ram semen.

scholarly journals Cold-induced microtubule disruption and relocalization of membrane proteins in kidney epithelial cells.

1998 ◽  
Vol 9 (2) ◽  
pp. 155-166
Author(s):  
S Breton ◽  
D Brown
Keyword(s):  
Membrane Proteins ◽  
Epithelial Cells ◽  
Cultured Cells ◽  
Cold Treatment ◽  
Partial Recovery ◽  
Solution Ph ◽  
Microtubule Network ◽  
Cold Preservation ◽  
Aquaporin 2 ◽  
Microtubule Disruption

Cold preservation of kidneys is commonly used in human transplantation and in vitro studies. However, although disruption of the cytoskeleton by cold has been demonstrated in cultured cells, the effect of cold treatment on intact kidney is poorly understood. In this study, specific antibodies were used to examine the effect of hypothermia on the cytoskeletal network and the trafficking of some membrane proteins in the urinary tubule. Rat kidneys were cut into thin slices (approximately 0.5 mm) that were divided into several groups: (1) some were immediately fixed in paraformaldehyde, sodium periodate, and lysine (PLP); (2) some were stored at 4 degrees C for 15 min or 4 h before being fixed in cold PLP; or (3) after 4 h cold treatment, some slices were rewarmed to 37 degrees C for 15, 30, and 60 min in a physiologic solution, pH 7.4, and were then fixed in warm PLP. Immunofluorescence staining revealed an almost complete disruption of the microtubule network in proximal tubules after 15 min cold treatment, whereas microtubules in other segments were affected after 4 h. A partial recovery of the microtubule network was observed after 60 min rewarming. In contrast, actin filaments seemed to be resistant to cold treatment. gp330, aquaporin-2, H+ ATPase, and the AE1 anion exchanger were all relocated into numerous vesicles that were distributed throughout the cytoplasm after hypothermia followed by rewarming, whereas Na-K-ATPase retained its basolateral localization. The vasopressin-stimulated insertion of aquaporin-2 water channels into the apical membrane was inhibited during the initial rewarming period after cold exposure. Thus, cold preservation of tissues might impair, at least transiently, the polarized membrane expression and function of some transport proteins in renal epithelial cells.

scholarly journals Activation of TRPV1 channels leads to stimulation of NKCC1 cotransport in the lens

2018 ◽  
Vol 315 (6) ◽  
pp. C793-C802 ◽  
Author(s):  
Mohammad Shahidullah ◽  
Amritlal Mandal ◽  
Nicholas A. Delamere
Keyword(s):  
Ion Transport ◽  
Transient Receptor Potential ◽  
Ion Homeostasis ◽  
Receptor Potential ◽  
Transient Receptor Potential Vanilloid ◽  
Signaling Mechanism ◽  
Trpv1 Channels ◽  
Trpv1 Antagonist ◽  
Transient Receptor ◽  
Stimulation Of

Lens ion homeostasis is crucial in maintaining water content and, in turn, refractive index and transparency of the multicellular syncytium-like structure. New information is emerging on the regulation of ion transport in the lens by mechanisms that rely on transient receptor potential vanilloid (TRPV) ion channels. We found recently that TRPV1 activation leads to Ca2+/PKC-dependent ERK1/2 signaling. Here, we show that the TRPV1 agonist capsaicin (100 nM) and hyperosmotic solution (350 vs. 300 mosM) each caused an increase of bumetanide-inhibitable Rb uptake by intact porcine lenses and Na-K-2Cl cotransporter 1 (NKCC1) phosphorylation in the lens epithelium. The TRPV1 antagonist A889425 (1 µM) abolished the increases of Rb uptake and NKCC1 phosphorylation in response to hyperosmotic solution. Exposing lenses to hyperosmotic solution in the presence of MEK/ERK inhibitor U0126 (10 µM) or the with-no-lysine kinase (WNK) inhibitor WNK463 (1 µM) also prevented NKCC1 phosphorylation and the Rb uptake responses to hyperosmotic solution. WNK463 did not prevent the increase in ERK1/2 phosphorylation that occurs in response to capsaicin or hyperosmotic solution, suggesting that ERK1/2 activation occurs before WNK activation in the sequence of signaling events. Taken together, the evidence indicates that activation of TRPV1 is a critical early step in a signaling mechanism that responds to a hyperosmotic stimulus, possibly lens shrinkage. By activating ERK1/2 and WNK, TRPV1 activation leads to NKCC1 phosphorylation and stimulation of NKCC1-mediated ion transport.

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