Regulation of Gamma-Glutamyl INTRODUCTION

Gamma-glutamyl transpeptidase (GGT; EC 23.2.2) is an important enzyme involved in glutathione metabolism . Previous studies have shown that GGT is present in epididymal epithelial cells and luminal fluids . Even though the function of epididymal GGT is unclear, a recent transgenic study showed that a hypoplastic epididymal epithelium was present in GGTml/GGTml mice. It has been proposed that epididymal GGT may function to protect spermatozoa from oxidative stress in the epididymal duct and/or to recover extracellular cysteine for the synthesis of epididymal proteins.

Molecular studies have shown that in the rat, multiple forms of mRNA are encoded by a single GGT gene using different promoters.  Three forms of GGT mRNAs (II, III, and IV) are expressed in the rat epididymis . GGT mRNA-И and GGT mRNA-III are mainly expressed in the caput region, while GGT mRNA-IV is highly expressed in the initial segment. After unilateral efferent duct ligation (EDL) to prevent the influx of rete testis fluid (RTF) into the initial segment, the level of GGT mRNA-IV, not GGT mRNA-II and GGT mRNA-III, in the initial segment decreased remarkably compared to that in the sham control ; however, whether GGT catalytic activity and GGT protein are present and affected by EDL in the initial segment remains unclear. buy levaquin online

Testicular factors are required for the maintenance of cellular structure in the initial segment of the rat epididymis . It has been reported that testicular factors including spermatozoa may be involved in the regulation of the expression of GGT, polyomavirus enhancer activator 3 (PEA3), A-raf, C-raf-1, proenkephalin, and 5a-reductase genes in the initial segment of the rat epididymis.