Hormonal regulation of protein synthesis in the rat epididymis. Characterization of androgen-dependent and testicular fluid-dependent proteins

Abstract

1. Protein synthesis has been investigated in different regions of the rat epididymis by measuring incorporation of [35S]methionine in tissue minces incubated in vitro followed by analysis of labelled proteins on polyacrylamide gels containing sodium dodecyl sulphate. Rates of synthesis were highest in the proximal cauda > distal cauda > initial segment > ductuli efferentes > corpus > distal caput > proximal caput. One protein (mol.wt. 23 000) characterized the initial segment, three proteins (mol.wts. 18 500, 19 000 and 32 000) the caput and one protein (mol.wt. 47 000) the cauda. 2. After castration, [35S]methionine incorporation in all regions of the epididymis was reduced to < 10% of that in normal animals but could be restored to control levels within 5 days by testosterone treatment. Other steroids (corticosterone, oestrogen or progesterone) were ineffective. 3. The synthesis of the 18 500, 19 000, and 32 000 mol.wt. proteins in the caput and the 47 000 mol.wt. protein in the cauda were preferentially regulated by androgens, whilst the synthesis of 23 000 and approx. 80 000 mol.wt. proteins in the initial segment was dependent upon factors present in testicular fluid. 4. The androgen-dependent and testicular fluid-dependent proteins were major components of epididymal secretion. Purification and characterization of the 18 500, 19 000, 23 000 and 32 000 mol.wt. proteins showed them to be acidic glycoproteins with a carbohydrate content of 7.6-13.2%. The 47 000 mol.wt. protein, on the other hand, is highly basic. 5. A possible role for these proteins in the acquisition of motility, fertilizing capacity and storage of spermatozoa in the epididymis is discussed.

Quantification of epididymal retinoic acid‐binding protein (ERABP) mRNA in different anatomical regions of the adult rat epididymis

“…While ample evidence exists indicating that the synthesis and secretion of certain proteins is controlled by androgens in the rat epididymis (3,17), little is known about how the induction of androgen-dependent genes is controlled during the development of the rat epididymis.…”

“…Since previous studies (17,18) have shown that ERABP is synthesized exclusively in a restricted anatomical area of the caput epididymis, the caput epididymis was further subdivided into the proximal and distal regions and the level of ERABP mRNAs was determined (Fig 4). The amount of ERABP mRNAs measured in the proximal and distal regions of the caput epididymis and estimated from the standard curve (Fig.…”

Purification of mouse sperm acrosin, its activation from proacrosin and effect on homologous egg investments

“…Electrophoresis on 12% polyacrylamide gels containing SDS was carried out under reducing and non-reducing conditions according to Jones, Brown, Von Glos & Parker (1980 (Brown & Hartree, 1978). The design of subsequent egg-acrosin tests required that buffers used for binding and elution of acrosin were modified from those previously described.…”

Characterization and hormonal regulation of tissue and fluid proteins in the mouse epididymis

“…Identification of androgen-responsive proteins in epididymal fluid has been performed by electrophoresis in the rat (Brooks and Higgins, 1980 ;Jones et al, 1980 ;Brooks, 1981 ;1983), the rabbit (Jones et al, 1981 ), the monkey (Arslan et al, 1986) and man (Tez6n et al, 1985), but in the mouse, only 15 to 20 cauda luminal peptides have been detected without any mention of their androgen-dependence (Flickinger et al, 1986). Although radioautographic studies have evidenced the pathway and kinetics of protein secretion in the various segments of the mouse epididymis (Fain-Maurel et al, 1981 ;Flickinger, 1981 ) (Brooks and Higgins, 1980) and the ram (Dacheux and Voglmayr, 1983) because of its expression in all the epididymal segments.…”