Submitted May 25, 2007
Returned for revision June 22, 2007
Accepted December 6, 2007
Testis
Dimeric Transferrin Inhibits Phagocytosis of Residual Bodies by Testicular Rat Sertoli Cells
Marina G. Yefimova ,
Amina Sow ,
Isabelle Fontaine ,
Vincent Guilleminot ,
Nadine Martinat ,
Pascale Crepieux ,
Sylvie Canepa ,
Marie-Christine Maurel ,
Sophie Fouchécourt ,
Eric Reiter ,
Omar Benzakour ,
and
Florian Guillou *
* To whom correspondence should be addressed. E-mail: guillou{at}tours.inra.fr.
Abstract
Transferrin is well known as an iron transport glycoprotein. Dimeric or tetrameric transferrin forms have recently been reported to modulate phagocytosis by human leukocytes. It is mainly synthesized by the liver, and also by other sources such as Sertoli cells of the testis. Sertoli cells show a strong phagocytic activity towards apoptotic germ cells and residual bodies. Here, we provide evidence that purified human dimeric transferrin from commercial source decreased residual body phagocytosis, unlike monomeric transferrin. The presence of iron appeared essential for dimeric transferrin inhibitory activity. Importantly, dimeric transferrin could be visualized by immunoblotting in Sertoli cell lysates as well as in culture media, indicating that dimeric transferrin could be physiologically secreted by Sertoli cells. By siRNA-mediated knock-down, we show that endogenous transferrin significantly inhibited residual body ingestion by Sertoli cells. These results are the first to identify dimeric transferrin in Sertoli cells, and to demonstrate its implication as a physiological modulator of residual body phagocytosis by Sertoli cells.
Key words:
Testis •
Sertoli cells •
Phagocytosis •
Residual bodies •
Transferrin
