ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Triiodothyronine (T3) dependent growth of GH1 rat pituitary tumor cells in serum-free defined culture requires apotransferrin (apo Tf) (Sirbasku et al.: Mol. Cell. Endocrinol., 77:C47-C55, 1991). Diferric transferrin (2Fe · Tf) also is necessary as an iron source (Eby et al.: Anal. Biochem., 203:317-325, 1992). Further, T3 dependence is prevented by soluble Fe(III) addition to the medium (Sato et al.: In Vitro Cell. Dev. Biol., 27A:599-602, 1991). While our data suggested that apo Tf caused growth by chelation of Fe(III), direct evidence was required. We used urea polyacrylamide gel electrophoresis along with autoradiography and Western immunoblotting to measure the Fe(III) content of growing GH1 cell cultures and identify the apo Tf, mono-metal transferrins and 2Fe · Tf present. We found that apo Tf per se did not cause growth but instead chelated inhibitory levels of Fe(III). In fact, apo Tf need not be present at all provided that Fe(III) is reduced to ≤0.6 μM. In addition, other protein and non-protein Fe(III) chelators were shown to be as effective as apo Tf. Here, we report that pituitary cells are completely inhibited by ≥1.2 μM Fe(III), which are concentrations which might be expected in many culture media and usually are not thought to influence growth. The high sensitivity of pituitary cells to Fe(III) suggests further study to determine what cellular functions are affected and how they interfere with thyroid hormone dependence. © 1993 Wiley-Liss, Inc.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1041560319
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