scholarly journals β3-adrenoceptor agonist-induced down-regulation of Gsα and functional desensitization in a Chinese hamster ovary cell line expressing a β3-adrenoceptor refractory to down-regulation

1994 ◽  
Vol 303 (3) ◽  
pp. 973-978 ◽  
Author(s):  
J Chambers ◽  
J Park ◽  
D Cronk ◽  
C Chapman ◽  
F R Kennedy ◽  
...  

Chinese hamster ovary (CHO) cells transfected to express human beta 2- or beta 3-adrenoceptors (beta 2-CHO and beta 3-CHO cells) were exposed to the beta-adrenoceptor agonist isoprenaline at various concentrations and for differing times. Sustained exposure of the beta 2-CHO but not beta 3-CHO cells to isoprenaline resulted in a time- and concentration-dependent down-regulation of the receptor as measured by a reduction in specific binding of [125I]cyanopindolol. Such maintained exposure of cells expressing either receptor to the agonist produced a marked down-regulation of immunologically detectable levels of the alpha subunit of the stimulatory guanine-nucleotide-binding protein Gs. This effect was specific for Gs because levels of both G12 alpha and Gq alpha/G11 alpha were unaltered by isoprenaline treatment of both beta 2-CHO and beta 3-CHO cells. The effect of isoprenaline on Gs alpha down-regulation was some 30-fold more potent in the beta 2-CHO than in the beta 3-CHO cells. Time courses of isoprenaline-induced down-regulation of Gs alpha were not different, however, in the two cell lines. Isoprenaline treatment of the beta 3-CHO cells produced a desensitization of agonist-mediated regulation of adenylyl cyclase, manifested by a 4-fold reduction in the potency and a 30% reduction in maximal effect of the agonist, whereas desensitization of the beta 2-CHO cells was considerably greater (25-fold reduction in potency and 70% reduction in maximal effect). These results demonstrate that agonist-induced down-regulation of the G-protein which interacts with a receptor can be produced by both beta 2- and beta 3-adrenoceptors. Despite apparent concurrence of down-regulation of receptors and G-proteins in other systems [e.g. Adie, Mullaney, McKenzie and Milligan (1992) Biochem. J. 285, 529-536], agonist-induced receptor down-regulation does not appear to be a prerequisite for down-regulation of the G-protein. Furthermore, the results suggest that agonist-induced down-regulation of a G-protein may be sufficient, in the absence of receptor regulation, to induce some agonist desensitization of effector function.

2002 ◽  
Vol 79 (5) ◽  
pp. 580-585 ◽  
Author(s):  
Elisabetta G. P. Prati ◽  
Mattia Matasci ◽  
Tobias B. Suter ◽  
Andre Dinter ◽  
Adriana R. Sburlati ◽  
...  

1999 ◽  
Vol 73 (10) ◽  
pp. 8019-8026 ◽  
Author(s):  
Ralf Nixdorf ◽  
Jerg Schmidt ◽  
Axel Karger ◽  
Thomas C. Mettenleiter

ABSTRACT Chinese hamster ovary (CHO) cells have recently been used for identification of receptors for several alphaherpesviruses, including pseudorabies virus (PrV) (R. J. Geraghty, C. Krummenacher, G. H. Cohen, R. J. Eisenberg, and P. G. Spear, Science 280:1618–1620, 1998). The experiments were based on the fact that CHO cells are inefficient target cells for PrV. However, a detailed analysis of the interaction between PrV and CHO wild-type and recombinant PrV-receptor bearing cells has not been performed. We show here that PrV has a growth defect on CHO cells which leads to a ca. 100-fold reduction in plating efficiency, strongly delayed penetration kinetics, and a 104-fold reduction in one-step growth. Entry of PrV into CHO cells is significantly delayed but is not affected by inhibitors of endocytosis, suggesting that the mechanism of penetration resembles that on permissive cells. The defects in plating efficiency and penetration could be corrected by expression of herpesvirus entry mediators B (HveB), HveC, or HveD, with HveC being the most effective. However, the defects in one-step growth and plaque formation were not corrected by expression of PrV receptors, indicating an additional restriction in viral replication after entry. Surprisingly, PrV infection of CHO cells was sensitive to neutralization by a gB-specific monoclonal antibody, which does not inhibit PrV infection of other host cells. Moreover, the same monoclonal antibody neutralized PrV infectivity on cells displaying the interference phenomenon by overexpression of gD and subsequent intracellular sequestration of gD receptors. Thus, absence of gD receptors on two different host cells leads to an increased sensitivity of PrV toward gB neutralization. We hypothesize that this is due to the increased requirement for interaction of gB with a cellular surface protein in the absence of the gD-gD receptor interaction. As expected, CHO cells are as susceptible as other host cells to infection by PrV gD− Pass, an infectious gD-negative PrV mutant. However, PrV gD− Pass was also not able to form plaques on CHO cells.


Author(s):  
Shazid Md. Sharker ◽  
Md. Atiqur Rahman

Most of clinical approved protein-based drugs or under in clinical trial have a profound impact in the treatment of critical diseases. The mammalian eukaryotic cells culture approaches, particularly the CHO (Chinese Hamster Ovary) cells are mainly used in the biopharmaceutical industry for the mass-production of therapeutic protein. Recent advances in CHO cell bioprocessing to yield recombinant proteins and monoclonal antibodies have enabled the expression of quality protein. The developments of cell lines are possible to upgrade specific productivity. As a result, it holds an interesting area for academic as well as industrial researchers around the world. This review will concentrate on the recent progress of the mammalian CHO cells culture technology and the future scope of further development for the mass-production of protein therapeutics.


2021 ◽  
pp. 2100098
Author(s):  
Benjamin F. Synoground ◽  
Claire E. McGraw ◽  
Kathryn S. Elliott ◽  
Christina Leuze ◽  
Jada R. Roth ◽  
...  

2008 ◽  
Vol 369 (2) ◽  
pp. 712-717 ◽  
Author(s):  
Oleg V. Yarishkin ◽  
Eun-Mi Hwang ◽  
Jae-Yong Park ◽  
Dawon Kang ◽  
Jaehee Han ◽  
...  

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