Distinct patterns of HSP30 and HSP70 degradation in Xenopus laevis A6 cells recovering from thermal stress

2014 ◽  
Vol 168 ◽  
pp. 1-10 ◽  
Author(s):  
Saad Khan ◽  
John J. Heikkila
Keyword(s):  
Thermal Stress ◽  
Xenopus Laevis ◽  
A6 Cells

scholarly journals Expression of cell adhesion molecule E-cadherin in Xenopus embryos begins at gastrulation and predominates in the ectoderm.

1989 ◽  
Vol 108 (6) ◽  
pp. 2449-2458 ◽  
Author(s):  
Y S Choi ◽  
B Gumbiner
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cell ◽  
Xenopus Laevis ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Cell Layer ◽  
Outer Cell ◽  
A6 Cells ◽  
Xenopus Embryos ◽  
E Cadherin

The expression of the Ca2+-dependent epithelial cell adhesion molecule E-cadherin (also known as uvomorulin and L-CAM) in the early stages of embryonic development of Xenopus laevis was examined. E-Cadherin was identified in the Xenopus A6 epithelial cell line by antibody cross-reactivity and several biochemical characteristics. Four independent mAbs were generated against purified Xenopus E-cadherin. All four mAbs recognized the same polypeptides in A6 cells, adult epithelial tissues, and embryos. These mAbs inhibited the formation of cell contacts between A6 cells and stained the basolateral plasma membranes of A6 cells, hepatocytes, and alveolar epithelial cells. The time of E-cadherin expression in early Xenopus embryos was determined by immunoblotting. Unlike its expression in early mouse embryos, E-cadherin was not present in the eggs or early blastula of Xenopus laevis. These findings indicate that a different Ca2+-dependent cell adhesion molecule, perhaps another member of the cadherin gene family, is responsible for the Ca2+-dependent adhesion between cleavage stage Xenopus blastomeres. Detectable accumulation of E-cadherin started just before gastrulation at stage 9 1/2 and increased rapidly up to the end of gastrulation at stage 15. In stage 15 embryos, specific immunofluorescence staining of E-cadherin was discernible only in ectoderm, but not in mesoderm and endoderm. The ectoderm at this stage consists of two cell layers. The outer cell layer of ectoderm was stained intensely, and staining was localized to the basolateral plasma membrane of these cells. Lower levels of staining were observed in the inner cell layer of ectoderm. The coincidence of E-cadherin expression with the process of gastrulation and its restriction to the ectoderm indicate that it may play a role in the morphogenetic movements of gastrulation and resulting segregation of embryonic germ layers.

Heat shock-induced acquisition of thermotolerance at the levels of cell survival and translation in Xenopus A6 kidney epithelial cells

1999 ◽  
Vol 77 (2) ◽  
pp. 141-151 ◽  
Author(s):  
Donna Phang ◽  
Elizabeth M Joyce ◽  
John J Heikkila
Keyword(s):  
Heat Shock ◽  
Xenopus Laevis ◽  
Cell Survival ◽  
Recovery Period ◽  
Epithelial Cell Line ◽  
Amino Acid Incorporation ◽  
A6 Cells ◽  
Acid Incorporation ◽  
Survival Studies ◽  
Shock Proteins

In this study we have investigated the acquisition of thermotolerance in a Xenopus laevis kidney A6 epithelial cell line at both the level of cell survival and translation. In cell survival studies, A6 cells were incubated at temperatures ranging from 22 to 35°C for 2 h followed by a thermal challenge at 39°C for 2 h and a recovery period at 22°C for 24 h. Optimal acquisition of thermotolerance occurred at 33°C. For example, exposure of A6 cells to 39°C for 2 h resulted in only 3.4% survival of the cells whereas prior exposure to 33°C for 2 h enhanced the survival rate to 69%. This state of thermotolerance in A6 cells was detectable after 1 h at 33°C and was maintained even after 18 h of incubation. Cycloheximide inhibited the acquisition of thermotolerance at 33°C suggesting the requirement for ongoing protein synthesis. The optimal temperature for the acquisition of translational thermotolerance also occurred at 33°C. Treatment of A6 cells at 39°C for 2 h resulted in an inhibition of labeled amino acid incorporation into protein which recovered to approximately 14% of control after 19 h at 22°C whereas cells treated at 33°C for 2 h prior to the thermal challenge recovered to 58% of control levels. These translationally thermotolerant cells displayed relatively high levels of the heat shock proteins hsp30, hsp70, and hsp90 compared to pretreatment at 22, 28, 30, or 35°C. These studies demonstrate that Xenopus A6 cells can acquire a state of thermotolerance and that it is correlated with the synthesis of heat shock proteins.Key words: Xenopus laevis, heat shock protein, hsps, A6 cells, chaperone, thermotolerance.

Cloning of the Xenopus laevis aldolase C gene and analysis of its promoter function in developing Xenopus embryos and A6 cells

1998 ◽  
Vol 1442 (2-3) ◽  
pp. 199-217 ◽  
Author(s):  
Hitomi Yatsuki ◽  
Mamoru Outida ◽  
Yasuo Atsuchi ◽  
Tunehiro Mukai ◽  
Koichiro Shiokawa ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
A6 Cells ◽  
Promoter Function ◽  
Aldolase C ◽  
Xenopus Embryos

scholarly journals Nuclear proteins of quiescent Xenopus laevis cells inhibit DNA replication in intact and permeabilized nuclei.

1996 ◽  
Vol 133 (5) ◽  
pp. 955-969 ◽  
Author(s):  
J Fang ◽  
R M Benbow
Keyword(s):  
Dna Replication ◽  
Xenopus Laevis ◽  
Nuclear Dna ◽  
Cultured Cells ◽  
Sperm Chromatin ◽  
Quiescent State ◽  
Cell Nuclei ◽  
A6 Cells ◽  
Egg Extracts ◽  
Liver Nuclei

Quiescent cells from adult vertebrate liver and contact-inhibited or serum-deprived tissue cultures are active metabolically but do not carry out nuclear DNA replication and cell division. Replication of intact nuclei isolated from either quiescent Xenopus liver or cultured Xenopus A6 cells in quiescence was barely detectable in interphase extracts of Xenopus laevis eggs, although Xenopus sperm chromatin was replicated with approximately 100% efficiency in the same extracts. Permeabilization of nuclei from quiescent Xenopus liver or cultured Xenopus epithelial A6 cells did not facilitate efficient replication in egg extracts. Moreover, replication of Xenopus sperm chromatin in egg extracts was strongly inhibited by a soluble extract of isolated Xenopus liver nuclei; in contrast, complementary-strand synthesis on single-stranded DNA templates in egg extracts was not affected. Inhibition was specific to endogenous molecules localized preferentially in quiescent as opposed to proliferating cell nuclei, and was not due to suppression of cdk2 kinase activity. Extracts of Xenopus liver nuclei also inhibited growth of sperm nuclei formed in egg extracts. However, the rate and extent of decondensation of sperm chromatin in egg extracts were not affected. The formation of prereplication centers detected by anti-RP-A antibody was not affected by extracts of liver nuclei, but formation of active replication foci was blocked by the same extracts. Inhibition of DNA replication was alleviated when liver nuclear extracts were added to metaphase egg extracts before or immediately after Ca++ ion-induced transition to interphase. A plausible interpretation of our data is that endogenous inhibitors of DNA replication play an important role in establishing and maintaining a quiescent state in Xenopus cells, both in vivo and in cultured cells, perhaps by negatively regulating positive modulators of the replication machinery.

scholarly journals Primary structure of an apical protein from Xenopus laevis that participates in amiloride-sensitive sodium channel activity.

1992 ◽  
Vol 119 (6) ◽  
pp. 1497-1506 ◽  
Author(s):  
O Staub ◽  
F Verrey ◽  
T R Kleyman ◽  
D J Benos ◽  
B C Rossier ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Sodium Channel ◽  
Signal Sequence ◽  
Sodium Current ◽  
Regulatory Protein ◽  
Epithelial Sodium Channel ◽  
Apical Plasma Membrane ◽  
Sodium Reabsorption ◽  
A6 Cells ◽  
Apical Side

High resistance epithelia express on their apical side an amiloride-sensitive sodium channel that controls sodium reabsorption. A cDNA was found to encode a 1,420-amino acid long polypeptide with no signal sequence, a putative transmembrane segment, and three predicted amphipathic alpha helices. A corresponding 5.2-kb mRNA was detected in Xenopus laevis kidney, intestine, and oocytes, with weak expression in stomach and eyes. An antibody directed against a fusion protein containing a COOH-terminus segment of the protein and an antiidiotypic antibody known to recognize the amiloride binding site of the epithelial sodium channel (Kleyman, T. R., J.-P. Kraehenbuhl, and S. A. Ernst. 1991. J. Biol. Chem. 266:3907-3915) immunoprecipitated a similar protein complex from [35S]methionine-labeled and from apically radioiodinated Xenopus laevis kidney-derived A6 cells. A single integral of 130-kD protein was recovered from samples reduced with DTT. The antibody also cross-reacted by ELISA with the putative amiloride-sensitive sodium channel isolated from A6 cells (Benos, D. J., G. Saccomani, and S. Sariban-Sohraby. 1987. J. Biol. Chem. 262:10613-10618). Although the protein is translated, cRNA injected into oocytes did not reconstitute amiloride-sensitive sodium transport, while antisense RNA or antisense oligodeoxynucleotides specific for two distinct sequences of the cloned cDNA inhibited amiloride-sensitive sodium current induced by injection of A6 cell mRNA. We propose that the cDNA encodes an apical plasma membrane protein that plays a role in the functional expression of the amiloride-sensitive epithelial sodium channel. It may represent a subunit of the Xenopus laevis sodium channel or a regulatory protein essential for sodium channel function.

Knockdown of Pex11β reveals its pivotal role in regulating peroxisomal genes, numbers, and ROS levels in Xenopus laevis A6 cells

2013 ◽  
Vol 50 (4) ◽  
pp. 340-349 ◽  
Author(s):  
Mark A. Fox ◽  
Michelle A. Nieuwesteeg ◽  
Jessica A. Willson ◽  
Mario Cepeda ◽  
Sashko Damjanovski
Keyword(s):  
Xenopus Laevis ◽  
Pivotal Role ◽  
A6 Cells
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