Localization and distribution of wolframin in human tissues.

Wolframin is a transmembrane glycoprotein of 890 aminoacids, encoded by WFS1 gene. WFS1 mutations are responsible for Wolfram syndrome, an autosomal recessive disorder. In the present paper, we first characterized the polyclonal wolframin antibody by dot blot. Secondly, we verified antibody specificity by western blotting using different human cell lines. Thirdly, we studied wolframin localization in human foetal (14-35 weeks) and adult tissues by immunohistochemistry. Wolframin expression was distributed in many organs, with different tissue and cell localization and expression levels. In foetal systems, wolframin expression was faint at 14-16 weeks and increased when development proceeded. In adult human tissues a variable positive staining was observed in both simple and stratified epithelia. A moderate wolframin expression was observed in liver and in the endocrine portion of the pancreas. In conclusion, our data suggest that this protein may have important roles in a number of different tissues, including many that are not known to be affected by WFS1-linked diseases. The immunopositivity in adult human tissues suggests that it may function maintaining physiological cellular homeostasis.