scholarly journals Functional characterization of recombinant human ClC‐4 chloride channels in cultured mammalian cells

2002 ◽  
Vol 539 (2) ◽  
pp. 373-383 ◽  
Author(s):  
Carlos G. Vanoye ◽  
Alfred L. George Jr
Author(s):  
Christoph Gstöttner ◽  
Tao Zhang ◽  
Anja Resemann ◽  
Sophia Ruben ◽  
Stuart Pengelley ◽  
...  

1998 ◽  
Vol 111 (10) ◽  
pp. 1341-1349 ◽  
Author(s):  
M. Imoto ◽  
I. Tachibana ◽  
R. Urrutia

Dynamin proteins containing a GTPase domain, a pleckstrin homology motif and a proline-rich tail participate in receptor-mediated endocytosis in organisms ranging from insects to vertebrates. In addition, dynamin-related GTPases, such as the yeast Golgi protein Vps1p, which lack both the pleckstrin homology motif and the proline-rich region, participate in vesicular transport within the secretory pathway in lower eukaryotes. However, no data is available on the existence of Vps1p-like proteins in mammalian cells. In this study, we report the identification and characterization of a novel gene encoding a human dynamin-related protein, DRP1, displaying high similarity to the Golgi dynamin-like protein Vps1p from yeast and to a Caenorhabditis elegans protein deposited in the databank. These proteins are highly conserved in their N-terminal tripartite GTPase domain but lack the pleckstrin homology motif and proline-rich region. Northern blot analysis reveals that the DRP1 mRNA is detected at high levels in human muscle, heart, kidney and brain. Immunolocalization studies in Chinese hamster ovary (CHO) cells using an epitope-tagged form of DRP1 and confocal microscopy show that this protein is concentrated in a perinuclear region that labels with the endoplasmic reticulum marker DiOC6(3) and the Golgi marker C5-DMB-Cer. In addition, the localization of DRP1 is highly similar to the localization of the endoplasmic reticulum and cis-Golgi GTPase Rab1A, but not to the staining for the trans-Golgi GTPase Rab6. Furthermore, overexpression of a cDNA encoding a GTP binding site mutant of DRP1 (DRP1(K38E)) in CHO cells decreases the amount of a secreted luciferase reporter protein, whereas the overexpression of wild-type DRP1 increases the secretion of this marker. Together, these results constitute the first structural and functional characterization of a mammalian protein similar to the yeast dynamin-related GTPase Vps1p and indicate that the participation of these proteins in secretion has been conserved throughout evolution.


FEBS Journal ◽  
2006 ◽  
Vol 273 (24) ◽  
pp. 5550-5563 ◽  
Author(s):  
Siva K. Panguluri ◽  
Prasanna Kumar ◽  
Subba R. Palli

2010 ◽  
Vol 5 ◽  
pp. 2 ◽  
Author(s):  
Vanessa González-Pérez ◽  
David J Reiner ◽  
Jamie K Alan ◽  
Cicely Mitchell ◽  
Lloyd J Edwards ◽  
...  

2008 ◽  
Vol 200 (3) ◽  
pp. 357-365 ◽  
Author(s):  
Sabine Lindenthal ◽  
Nathalie Lecat-Guillet ◽  
Alejandro Ondo-Mendez ◽  
Yves Ambroise ◽  
Bernard Rousseau ◽  
...  

The sodium/iodide symporter (NIS) mediates the active transport of iodide from the bloodstream into thyrocytes. NIS function is strategic for the diagnosis and treatment of various thyroid diseases. In addition, a promising anti-cancer strategy based on targeted NIS gene transfer in non-thyroidal cells is currently developed. However, only little information is available concerning the molecular mechanism of NIS-mediated iodide translocation. Ten small molecules have recently been identified using a high-throughput screening method for their inhibitory effect on iodide uptake of NIS-expressing mammalian cells. In the present study, we analyzed these compounds for their rapid and reversible effects on the iodide-induced current in NIS-expressing Xenopus oocytes. Four molecules almost completely inhibited the iodide-induced current; for three of them the effect was irreversible, for one compound the initial current could be fully re-established after washout. Three molecules showed a rapid inhibitory effect of about 75%, half of which was reversible. Another three compounds inhibited the iodide-induced current from 10 to 50%. Some molecules altered the membrane conductance by themselves, i.e. in the absence of iodide. For one of these molecules the observed effect was also found in water-injected oocytes whereas for some others the iodide-independent effect was associated with NIS expression. The tested molecules show a surprisingly high variability in their possible mode of action, and thus are promising tools for further functional characterization of NIS on a molecular level, and they could be useful for medical applications.


2010 ◽  
Vol 285 (18) ◽  
pp. 13918-13929 ◽  
Author(s):  
Sumitra Miriyala ◽  
Thangaiah Subramanian ◽  
Manikandan Panchatcharam ◽  
Hongmei Ren ◽  
Mark I. McDermott ◽  
...  

2018 ◽  
Vol 7 (2) ◽  
pp. 412-418 ◽  
Author(s):  
Weixi Liao ◽  
Bing Liu ◽  
Chih-Chun Chang ◽  
Ling-Jun Lin ◽  
Che Lin ◽  
...  

2007 ◽  
Vol 293 (3) ◽  
pp. F761-F766 ◽  
Author(s):  
Jianning Zhang ◽  
Ion Alexandru Bobulescu ◽  
Sunita Goyal ◽  
Peter S. Aronson ◽  
Michel G. Baum ◽  
...  

NHE8 is expressed in the apical membrane of the proximal tubule and is predicted to be a Na+/H+ exchanger on the basis of its primary amino acid sequence. Functional characterization of native NHE8 in mammalian cells has not been possible to date. We screened a number of polarized renal cell lines for the plasma membrane Na+/H+ exchangers (NHE1, 2, 3, 4, and 8) and found only NHE1 and NHE8 transcripts in NRK cells by RT-PCR. NHE8 protein is expressed in the apical membrane of NRK cells as demonstrated by immunoblots, confocal fluorescent immunocytochemistry, and immunoelectron microscopy. NHE1, on the other hand, is expressed primarily in the basolateral membrane. Bilateral perfusion of NRK cells grown on permeable supports shows Na+/H+ exchange activity on both the apical and basolateral membranes. NHE8-specific small interfering RNA knocks down NHE8 protein expression but does not affect NHE1 protein levels. Knockdown of NHE8 protein is accompanied by a commensurate reduction in apical NHE activity, without altered basolateral NHE activity. Conversely, transfection of NHE1-specific small interfering RNA knocks down NHE1 protein expression without affecting NHE8 protein levels and reduces basolateral NHE activity without affecting apical NHE activity. NHE8 is the only apical membrane Na+/H+ exchanger in NRK cells. NHE8 activity is Na+ dependent, displaying a cooperative sigmoidal relationship, and is highly sensitive to 5-( N-ethyl- n-isopropyl)-amiloride (EIPA). NRK cells provide a useful system where NHE8 can be studied in its native environment.


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