DIFFERENTIAL REGULATION OF UBIQUITOUSLY EXPRESSED ZINC TRANSPORTERS IN HUMAN COLON ADENO CARCINOMA CELLS (CACO-2) TO ZINC DEPLETION AND SUPPLEMENTATION

Zinc inadequacy is a major nutrition concern in public health globally. The lack of precise and sensitive biomarkers of zinc impedes large-scale public health intervention strategies. The existing marker, plasma zinc concentration, is stringently regulated by the tissues involved in zinc homeostasis. The tissue zinc homeostasis is regulated by several zinc transporters (ZnTs) and importers (ZIPs). Intestine plays an important role in zinc homeostasis but the expression dynamics with respect to zinc status is not well understood. Therefore, using a representative cell line of enterocyte cells (Caco-2) zinc deficiency was induced by an intracellular zinc chelator (TPEN) and zinc sulphate was used to make the cells sufficient, respectively. The expression of various transcripts levels of ubiquitously expressed zinc transporters was measured by Real Time-PCR. Among the zinc exporters (ZnT1, 5, and 9), it was observed that ZnT9 was down-regulated and subsequently up-regulated when the cells were exposed to zinc deficiency and zinc sufficiency, respectively. The present study reveals that although most of the ubiquitously expressed transporters show a different level of expression, ZnT9, ZIP7, and MT2 play major roles in maintaining zinc homeostasis in enterocyte cells.