Expression of GM-CSF receptors in male germ cells and their role in signaling for increased glucose and vitamin C transport

We studied the expression and function of the granulocyte-macrophage colony stimulating factor (GMCSF) receptor in male germ cells. RT-PCR showed expr ession of mRNAs encoding the alpha- and beta -subunits of the GM-CSF recept or in human testis, and the presence of the alpha- and beta -proteins was c onfirmed by immunoblotting with anti-alpha and anti-beta -antibodies. Immun olocalization studies showed the level of expression of GM-CSF alpha- and b eta -subunits in the germ line in the testis and in ejaculated spermatozoa. Receptor binding studies using radiolabeled GM-CSF revealed that bull sper matozoa have about 105 high-affinity sites with a K-d Of 222 pM and approxi mate to 1100 low-affinity sites with a K-d of 10 nM. GM-CSF signaled, in a time- and dose-dependent manner, for an increased uptake of glucose and vit amin C. J. Cell. Biochem. 80:625-634, 2001. (C) 2001 Wiley-Liss, Inc.