Alternative RNA expression of b1-integrin in different stages of mammary gland development

JULIÁN NAIPAUER; ALBANA GATTELLI; ANGELES VINUESA; SOL DEGESE; JONATHAN LAMARRE; OMAR COSO; EDITH KORDON

Cordoba

Congreso; The First South American Spring Symposium in Signal Transduction and Molecular Medicine; 2010

SISTAM

Integrins are heterodimeric cell surface adhesion receptors that play a critical role in the normal development and tumor formation of the mammary gland. In this tissue, we observed that use of alternative polyadenylation sites produces a new b1-integrin (ItgB1) mRNA species, 578bp shorter than the one previously reported. The new species lack two AU-rich elements that might be implicated in mRNA stability. In fact, we observed that the longer 3’UTR, placed downstream of a CMV driven luciferase gene, produced a change in the stability of the corresponding mRNA. In the mouse, we found that different tissues and stages during mammary gland development show specific levels of each ItgB1 mRNA. For example, in this gland  the longer form was up-regulated by estrogenic treatment and lactation. Similarly, in the HC11 mammary cell line, EGF treatment and in vitro differentiation specifically induced this species. On the other hand, post-lactation involution and HC11 cell stretching down-regulated this mRNA. Therefore, our data identify a new regulatory instance for controlling ItgB1 expression during mammary gland development and function, supporting other reports indicating that 3’UTR lengthen can be controlled by proliferation and differentiation states in embryonic and adult tissues.