A lactoferrin-receptor, intelectin 1, affects uptake, sub-cellular localization and release of immunochemically detectable lactoferrin by intestinal epithelial Caco-2 cells

Y Akiyama, K Oshima, T Kuhara, K Shin… - The journal of …, 2013 - academic.oup.com
Y Akiyama, K Oshima, T Kuhara, K Shin, F Abe, K Iwatsuki, D Nadano, T Matsuda
The journal of biochemistry, 2013academic.oup.com
Intelectin 1 (IntL) is known as a lectin expressed in intestinal epithelia and also as a receptor
for an iron-binding protein, lactoferrin (LF). Uptake of LF with bound iron by enterocytes via
receptor-mediated endocytosis has been well investigated, whereas subsequent fate of
endocytized LF and LF/IntL complexes remains largely unknown. In the present study, we
examined contribution of IntL to the uptake, sub-cellular localization and subsequent release
of LF by intestinal Caco-2 IntL-transfectants using two-site ELISA and fluorescence confocal …
Abstract
Intelectin 1 (IntL) is known as a lectin expressed in intestinal epithelia and also as a receptor for an iron-binding protein, lactoferrin (LF). Uptake of LF with bound iron by enterocytes via receptor-mediated endocytosis has been well investigated, whereas subsequent fate of endocytized LF and LF/IntL complexes remains largely unknown. In the present study, we examined contribution of IntL to the uptake, sub-cellular localization and subsequent release of LF by intestinal Caco-2 IntL-transfectants using two-site ELISA and fluorescence confocal microscopy. LF taken up by IntL-transfectants was immunochemically detected mostly as intact protein in the cell lysates, and it was a little larger in amount than that of the mock-transfectants. In the IntL-transfectants cultured on porous membrane, LF taken up from the apical side was detected immunochemically as punctate signals in the apical-side cytoplasmic region near nucleus. The LF signals were co-localized with IntL and, in a time-dependent manner, partially with early endosome antigen 1 (EEA1), but not with alkaline phosphatase. LF taken up, retained and subsequently released by the IntL-transfectants was larger in amount than that of mock-transfectants. Moreover, uptake of LF altered sub-cellular localization of IntL and markedly enhanced the IntL signals within the cells.
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