Expression of fatty acid elongases in cells of the seminiferous epithelium

Abstract

Fatty acid elongases play a crucial role in the biosynthesis of long-chain polyunsaturated fatty acids (PUFA) and in their further elongation to very long chain (VLC) PUFA. Male rat germ cell membranes contain glycerophospholipids with C18-C24 PUFA and sphingolipids with C26 to C32 PUFA. In the present study, the expression of seven members of the Elovl (elongation of very long chain fatty acids) gene family that encode elongases was surveyed in pachytene spermatocytes, round spermatids and Sertoli cells. The mRNAs of Elovl1, Elovl2, Elovl4, Elovl5, and Elovl6 were detected in all of these cells , all of them lacked Elovl3 expression, and Elovl7 was expressed only in the latter. As the ELOVL4 protein was previously shown to be responsible for the elongation of >C24 PUFA in the retina, the expression of this protein was also evaluated. During postnatal development, ELOVL4 was not detectable in testis up to P21, i.e., its time of appearance concurred with that of the first spermatocytes. Thereafter, the protein was evidently present in spermatocytes and spermatids, and was also faintly detected in Sertoli cells. As Elovl2 and Elovl5 are essential to form PUFA, and Elovl4 is required to elongate them, the joint expression of these elongases in spermatocytes and spermatids implies that they are functionally related, probably acting in sequence to produce the VLCPUFA of sphingolipids.