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Transformation by oncogenic ras‐p21 alters the processing and subcellular localization of the lysosomal protease cathepsin D
Author(s) -
Démoz Marina,
Castino Roberta,
Dragonetti Antonella,
Raiteri Elisabetta,
Baccino Francesco M.,
Isidoro Ciro
Publication year - 1999
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(19990601)73:3<370::aid-jcb8>3.0.co;2-n
Subject(s) - extracellular , biology , intracellular , microbiology and biotechnology , cell culture , golgi apparatus , cathepsin d , cathepsin b , neoplastic transformation , biochemistry , carcinogenesis , enzyme , endoplasmic reticulum , gene , genetics
The expression, processing, and intracellular localization of cathepsin D (CD), an endosomal‐lysosomal protease involved in malignancy, were studied in rat embryo fibroblasts transformed with an active mutant of c‐Ha‐ ras oncogene. The pattern of the processed molecular forms of CD, comprising two single‐chain mature forms of 45 and 43 kDa and two double‐chain mature forms of 34 + 9 kDa and 30 + 14 kDa, expressed by the parental cell line was similar to that found in normal rat liver cells. By contrast, in the ras ‐transfected counterpart this pattern was profoundly altered in that the 45 kDa species was much less represented and the 30 + 14 kDa species virtually absent. In both untransformed and ras ‐transformed cells the conversion of proCD into mature forms was not inhibited by ammonium chloride, which is known to increase the intravacuolar pH of post‐Golgi compartments. Yet, this drug induced the accumulation of the 43 and 45 kDa molecular forms of mature CD in ras ‐transformed cells and of the 34 kDa molecule in untransformed cells. As compared to controls, in ras ‐transformed fibroblasts vacuolar compartments containing CD were reduced in number and mostly located toward the periphery of the cell. This contrasted with the perinuclear distribution of CD‐positive granules in untransformed cells. Serum deprivation did not affect the growth, nor the intra‐ and extracellular accumulation of CD activity in ras ‐transformed cultures, while it blocked the growth and strongly stimulated the accumulation of CD in the medium in cultures of control fibroblasts. Altogether these data are indicative for a crucial role of ras GTPase in the regulation of the transport between post‐Golgi organelles. J. Cell. Biochem. 73:370–378, 1999. © 1999 Wiley‐Liss, Inc.