Open AccessEnhanced suicidal erythrocyte death in mice carrying a loss‐of‐function mutation of the adenomatous polyposis coli gene
Author(s) -
Qadri Syed M.,
Mahmud Hasan,
Lang Elisabeth,
Gu Shuchen,
Bobbala Diwakar,
Zelenak Christine,
Jilani Kashif,
Siegfried Alexandra,
Föller Michael,
Lang Florian
Publication year - 2012
Publication title -
journal of cellular and molecular medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.44
H-Index - 130
eISSN - 1582-4934
pISSN - 1582-1838
DOI - 10.1111/j.1582-4934.2011.01387.x
Subject(s) - adenomatous polyposis coli , ionomycin , annexin , microbiology and biotechnology , annexin a5 , biology , red blood cell , cytosol , reticulocytosis , chemistry , intracellular , medicine , biochemistry , flow cytometry , cancer , genetics , colorectal cancer , enzyme , anemia
Loss‐of‐function mutations in human adenomatous polyposis coli (APC) lead to multiple colonic adenomatous polyps eventually resulting in colonic carcinoma. Similarly, heterozygous mice carrying defective APC ( apc Min/+ ) suffer from intestinal tumours. The animals further suffer from anaemia, which in theory could result from accelerated eryptosis, a suicidal erythrocyte death triggered by enhanced cytosolic Ca 2+ activity and characterized by cell membrane scrambling and cell shrinkage. To explore, whether APC‐deficiency enhances eryptosis, we estimated cell membrane scrambling from annexin V binding, cell size from forward scatter and cytosolic ATP utilizing luciferin–luciferase in isolated erythrocytes from apc Min/+ mice and wild‐type mice ( apc +/+ ). Clearance of circulating erythrocytes was estimated by carboxyfluorescein‐diacetate‐succinimidyl‐ester labelling. As a result, apc Min/+ mice were anaemic despite reticulocytosis. Cytosolic ATP was significantly lower and annexin V binding significantly higher in apc Min/+ erythrocytes than in apc +/+ erythrocytes. Glucose depletion enhanced annexin V binding, an effect significantly more pronounced in apc Min/+ erythrocytes than in apc +/+ erythrocytes. Extracellular Ca 2+ removal or inhibition of Ca 2+ entry with amiloride (1 mM) blunted the increase but did not abrogate the genotype differences of annexin V binding following glucose depletion. Stimulation of Ca 2+ ‐entry by treatment with Ca 2+ ‐ionophore ionomycin (10 μM) increased annexin V binding, an effect again significantly more pronounced in apc Min/+ erythrocytes than in apc +/+ erythrocytes. Following retrieval and injection into the circulation of the same mice, apc Min/+ erythrocytes were more rapidly cleared from circulating blood than apc +/+ erythrocytes. Most labelled erythrocytes were trapped in the spleen, which was significantly enlarged in apc Min/+ mice. The observations point to accelerated eryptosis and subsequent clearance of apc Min/+ erythrocytes, which contributes to or even accounts for the enhanced erythrocyte turnover, anaemia and splenomegaly in those mice.