HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 38, 27640-27646, September 21, 2007

This Article Full Text Full Text (PDF) All Versions of this Article: 282/38/27640    most recent M702240200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Leich, F. Articles by Arnold, U. Search for Related Content PubMed PubMed Citation Articles by Leich, F. Articles by Arnold, U. Social Bookmarking                      What's this?

Endocytotic Internalization as a Crucial Factor for the Cytotoxicity of Ribonucleases^*

Franziska Leich, Nadine Stöhr, Anne Rietz, Renate Ulbrich-Hofmann, and Ulrich Arnold¹

From the Institute of Biochemistry and Biotechnology, and the Interdisciplinary Center for Applied Medical and Human Biological Research, Martin Luther University Halle-Wittenberg, D-06120 Halle, Germany

The cytotoxic action of ribonucleases (RNases) requires the interaction of the enzyme with the cellular membrane, its internalization, translocation to the cytosol, and the degradation of ribonucleic acid. The interplay of these processes as well as the role of the thermodynamic and proteolytic stability, the catalytic activity, and the evasion from the intracellular ribonuclease inhibitor (RI) has not yet been fully elucidated. As cytosolic internalization is indispensable for the cytotoxicity of extracellular ribonucleases, we investigated the extent of cytosolic internalization of a cytotoxic, RI-evasive RNase A variant (G88R-RNase A) and of various similarly cytotoxic but RI-sensitive RNase A tandem enzyme variants in comparison to the internalization of the non-cytotoxic and RI-sensitive RNase A. After incubation of K-562 cells with the RNase A variants for 36 h, the internalized amount of RNases was analyzed by rapid cell disruption followed by subcellular fractionation and semiquantitative immunoblotting. The data indicate that an enhanced cellular uptake and an increased entry of the RNases into the cytosol can outweigh the abolishment of catalytic activity by RI. As all RNase A variants proved to be resistant to the proteases present in the different subcellular fractions for more than 100 h, our results suggest that the cytotoxic potency of RNases is determined by an efficient internalization into the cytosol.

Received for publication, March 15, 2007 , and in revised form, July 16, 2007.

^* This work was supported by a grant from the Land Saxony-Anhalt (3537C/0903T). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: Dept. of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 3, 06120 Halle, Germany. Tel.: 49-345-5524865; Fax: 49-345-5527303; E-mail: ulrich.arnold{at}biochemtech.uni-halle.de.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				S. S. Singhal, S. Yadav, K. Drake, J. Singhal, and S. Awasthi Hsf-1 and POB1 Induce Drug Sensitivity and Apoptosis by Inhibiting Ralbp1 J. Biol. Chem., July 11, 2008; 283(28): 19714 - 19729. [Abstract] [Full Text] [PDF]