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General Comment |
NCBI Summary:
This gene encodes a member of the SLC39 family of solute-carrier genes, which show structural characteristics of zinc transporters. The encoded protein is glycosylated and found in the plasma membrane and mitochondria, and functions in the cellular import of zinc at the onset of inflammation. It is also thought to be the primary transporter of the toxic cation cadmium, which is found in cigarette smoke. Multiple transcript variants encoding different isoforms have been found for this gene. Additional alternatively spliced transcript variants of this gene have been described, but their full-length nature is not known. [provided by RefSeq, Oct 2008]
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Comment |
Oocyte-cumulus cell interactions regulate free intracellular zinc in mouse oocytes. Lisle RS et al. Zinc increases in the oocyte during maturation and is required for progression and completion of meiosis. The objective of this study was to determine whether cumulus cells regulate the levels of free intracellular zinc in the oocyte during maturation. In the cumulus-oocyte complex (COC), the relative level of free intracellular zinc was almost 4-fold higher in cumulus cells compared to the resident germinal vesicle (GV) stage oocyte. Removal of cumulus cells caused a 4-fold increase in intracellular zinc in the oocyte by one hour after cumulus cell removal, but subsequent co-culture of denuded oocytes with COC decreased free intracellular zinc in the oocyte by 65%. Thus, cumulus cells suppress free intracellular zinc in the oocyte. The zinc transporter proteins Zip6, Zip8, Zip9, Zip10, Zip12, Znt2, Znt4, Znt5 and Znt8 mRNA was higher in oocytes, while Zip1, Zip7, Zip13, Zip14, Znt6, Znt7 and Znt9 mRNA was higher in cumulus cells. Thus a complex zinc transport network is present in the COC. Pretreatment with EGF for 4 hours abolished the ability of cumulus-oocyte complexes to restrict free intracellular zinc in denuded oocytes. Co-culture of denuded MII oocytes with COC lowers free intracellular zinc in mature oocytes. Oocytes matured in vivo or oocytes from older mice had lower levels of free intracellular zinc than oocytes matured in vitro or from younger mice. Thus, a precise mechanism for regulating oocyte zinc homeostasis has been uncovered in the cumulus-oocyte complex that is disrupted with increasing age or by removal of cumulus cells.
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