Identification and androgen regulation of egasyn in the mouse epididymis

• Published in: Biochimica et biophysica acta Vol. 1401; no. 2; pp. 177 - 186
• Main Authors: Abou-Haila, Aida, Orgebin-Crist, Marie-Claire, Skudlarek, Marjorie D, Tulsiani, Daulat R.P
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 04.02.1998
• Subjects: Androgen regulation; Androgens - pharmacology; Animals; Antineoplastic Agents, Hormonal - administration & dosage; Carboxylic Ester Hydrolases - analysis; Carboxylic Ester Hydrolases - deficiency; Carboxylic Ester Hydrolases - drug effects; Castration; Egasyn; Epididymis; Epididymis - drug effects; Epididymis - enzymology; Esterase; Esterases - chemistry; Male; Membrane Glycoproteins - analysis; Membrane Glycoproteins - deficiency; Membrane Glycoproteins - drug effects; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Mouse; Precipitin Tests; Testosterone - administration & dosage; Two-dimensional electrophoresis; Androgen regulation; Epididymis; Two-dimensional electrophoresis; Esterase; Mouse; Egasyn
• ISSN: 0167-4889; 0006-3002; 1879-2596
• DOI: 10.1016/S0167-4889(97)00117-1

The expression and androgen regulation of egasyn, the endoplasmic reticulum-targeting protein of β- d-glucuronidase, was examined in the mouse-epididymis. The proximal (caput) and distal (corpus & cauda) epididymal tissue extracts were prepared by homogenization and sonication in buffered Triton X-100 solution, and high speed centrifugation. The supernatant when resolved by 2D-PAGE under non-denaturing conditions and stained for esterase activity showed that the distal (but not proximal) epididymis of the normal mouse contain several specific forms of esterases. These forms include a series of four variants (p I 5.2–5.75) with high mobility (HM) and esterase activity, and three faintly staining variants (beginning at p I 6.0) with low mobility (LM). Several lines of evidence indicate that the specific esterases seen in the corpus/cauda epididymidis are egasyn-esterases. Firstly, these molecular forms were not seen in the distal epididymal extracts from the egasyn-deficient mouse. Secondly, the HM forms can be immunoprecipitated with anti-egasyn antibody, suggesting the presence of free egasyn. Finally, the LM forms disappeared after heat treatment (56°C for 8 min), a condition known to dissociate egasyn:β- d-glucuronidase complex. This result indicates that a small amount of egasyn is complexed with β- d-glucuronidase. Immunoblotting (Western blot) studies (using anti-egasyn antibody) following resolution of egasyn released from the egasyn:β- d-glucuronidase complex revealed a single band of an apparent molecular weight 64 kDa in the distal (but not proximal) epididymis, indicating that the mouse epididymal egasyn is identical or very similar to the liver egasyn. Castration of mice lead to the appearance of free and complexed egasyn forms in the proximal epididymis. Testosterone supplementation to the castrated mice resulted in the disappearance of the induced egasyn forms from the caput epididymidis. Taken together, these results indicate that the expression of egasyn in the epididymis is region-specific and is differentially regulated by androgens.