Iodide concentration in milk by mammals is a necessary step for thyroid hormone synthesis by the newborn. With the purpose of using the mouse as an animal model to analyse the role of the sodium iodide symporter (NIS) in iodide transport and its regulation in the mammary gland, mouse NIS (mNIS) cDNA was isolated from lactating mice. The cloned sequence shows an open reading frame of 1854 nucleotides encoding a protein of 618 amino acids highly homologous to the rat and human NIS (95% and 81% identity respectively). Expression of mNIS in cultured mammalian cells induced cellular iodide accumulation. This iodide uptake process is sodium dependent and inhibited by thiocyanate and perchlorate. Tissue distribution analysis revealed that mNIS mRNAs are predominantly expressed in thyroid, stomach and in the lactating mammary gland and are present to a lower extent in several other tissues. Our data show for the first time that the level of mNIS mRNA is upregulated in the mammary gland during lactation.

Although senescent cells can be eliminated by the immune system, they tend to accumulate with age in various tissues. Here we show that senescent cells can evade immune clearance by natural killer (NK) cells by upregulating the expression of the disialylated ganglioside GD3 at their surface. The increased level of GD3 expression on senescent cells that naturally occurs upon aging in liver, lung, kidney or bones leads to a strong suppression of NK-cell-mediated immunosurveillance. In mice, we found that targeting GD3⁺ senescent cells with anti-GD3 immunotherapy attenuated the development of experimentally induced or age-related lung and liver fibrosis and age-related bone remodeling. These results demonstrate that GD3 upregulation confers immune privilege to senescent cells. We propose that GD3 acts as a senescence immune checkpoint (SIC) that allows senescent cells to escape immunosurveillance and to trigger immune anergy during aging.