PARENT SESSION

(T605) EXPRESSION AND POSSIBLE ROLE OF ARYLSULFATASE A (AS-A) IN MOUSE OVARY.

Anupriwan, Araya¹, Costa Santos, Daniela², Schenk, Matthias², Kongmanas, Kessiri², Carmona, Euridice^{2, 4}, Sretarugsa, Prapee¹, Tanphaichitr, Nongnuj^{2, 3}, ¹ Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand² Ottawa Health Research Institue, Ottawa, Canada⁴ Centre de Recherche Guy-Bemier Hospital Maisoneuve-Rosemont, Montreal, Canada³ Departments of Obstetrics/Gynecology and Biochemistry/Microbiology/Immunology, University of Ottawa, Ottawa, Canada

ABSTRACT- AS-A is known as a lysosomal enzyme in somatic cells and an acrosomal enzyme in the sperm. In mature sperm, AS-A is also present on the cell surface and it functions together with its binding ligand, seminolipid, in egg binding. The aim of this study is to determine whether AS-A expresses in the female reproductive tissues such as the ovary. Using an antibody directed monospecifically to AS-A, immunocytochemistry studies revealed selective AS-A staining in the corpora lutea of superovulated mouse ovary sections. Isolated corpora lutea also showed AS-A desulfation activity on an AS-A ′s artificial substrate, p-nitrocatecholsulfate (NCS)- 5.8 U/mg protein, a value twice that of sperm surface AS-A. In order to synchronize development of all corpora lutea in the ovary, pseudopregnant mice were used in subsequent studies. Serum progesterone (P4) and luteal cell morphology were used as parameters for monitoring corpus luteum development. Both immunoblotting and immunocytochemistry revealed increasing expression of AS-A from Day 4 to Day 8 of pseudopregnancy, when the P4 level was rising and reached the maximum, respectively. The extent of AS-A expression continued to increase after the sharp drop of serum P4 and morphological observation of luteolysis. Coincident with AS-A expression in luteal cells was the appearance of 20-hydroxysteroid dehydrogenase, which is responsible for the conversion of progesterone to 20-hydroxyprogesterone, a known mechanism of luteolysis. An increase in AS-A expression was also observed following luteolysis induction in Day 4 pseudopregnant mice with PGF2- injection. Notably, AS-A expression preceded that of active caspace-3, an apoptosis marker. All of these results suggested that AS-A was involved in the luteolysis process. Since cerobroside sulfate and seminolipid, known AS-A ′s natural substrates, were not present in isolated corpora lutea, we suggest that AS-A may function like AS-B or AS-C (due to their similar 3-D structures) in desulfating glycan sulfates or estrone sulfate, respectively. Our structural modeling work indicated that estrone sulfate docked into AS-A ′s active site pocket with minimum energy. Estrone sulfate desulfation would yield estrone, which may then be converted to estradiol, with a possible role in enhancing luteolysis.

KEY WORDS: Arylsulfatase A, Corpus luteum, Luteolysis