Galectin-3, a soluble 
-galactoside binding lectin, has been implicated in a number of important processes including activation of leukocytes, cell adhesion, tumor metastasis, and tissue remodeling. The recent finding that galectin-3 is expressed in the placenta and decidua, but not between implantation sites or in uteri from nonpregnant animals, indicates that this lectin plays a role in pregnancy as well. It is presumed that the function of galectin-3 is mediated via binding to glycoconjugated partners; therefore, as a first step toward defining the role of galectin-3 in pregnancy, the present work was undertaken to isolate and characterize binding partners for galectin-3 from the utero-placental complex (UPC). Potential binding partners were isolated from murine placenta by affinity purification using immobilized recombinant galectin-3 and elution with the specific disaccharide for the lectin, lactose. Of the several proteins recovered, an Mr 400,000 protein (p400) was the major component and was selected for further study. A rabbit polyclonal antiserum was raised to the protein, and appropriate blocking was accomplished using 3% milk in the absence of detergent. Specificity of the antiserum was demonstrated by Western analysis of placental extracts using chemiluminescence (Pierce). A quantifiable signal could be detected with as little as 4 ng of purified p400 at a 1:25,000 dilution of the antiserum. Extracts from heart, lung, liver, spleen, striated muscle, brain, placenta, and uterus were examined by Western analysis and it was found that p400 was unique to the UPC.
The observation that p400 is expressed only in the UPC is compatible with the hypothesis that galectin-3 interacting with p400 has a role in pregnancy.
This abstract is being presented on Monday, August 2 at 2:00 PM at Todd 133.