Dermatan sulfate synergizes with heparin in murine sperm chromatin decondensation.

SANCHEZ MELISA; ALVAREZ SEDÓ C; JULIANELLI VL; ROMANATO M; CALVO L; CALVO JC; FONTANA VA

SYSTEMS BIOLOGY IN REPRODUCTIVE MEDICINE

INFORMA HEALTHCARE

Lugar: London; Año: 2013 vol. 59 p. 82 - 90

1939-6368

The mammalian sperm nucleus contains an unusually condensed chromatin, due to replacement of the majority of histones by other basic proteins called protamines. However, soon after the spermatozoon penetrates the ooplasm at fertilization, decondensation of this densely packed chromatin must occur to allow formation of the male pronucleus and syngamy. Decondensation is accomplished by protamine disulfide bond reduction by oocyte glutathione and replacement of protamines by oocyte histones with the aid of an acceptor molecule. Previous results from our laboratory have demonstrated that heparan sulfate present in the ooplasm functions as protamine acceptor during human sperm decondensation in vivo. In the present paper, we analyze the role of heparin, structural analogue of heparan sulfate, and dermatan sulfate in murine sperm chromatin decondensation in vitro, including the possibility of a synergistic effect between both glycosaminoglycans. Decondensation was assessed under phase contrast microscopy following incubation of murine spermatozoa with glutathione and either heparin, dermatan sulfate or a combination of both. Ultrastructural changes taking place during decondensation were analyzed by transmission electron microscopy. Both glycosaminoglycans were able to promote the decondensation of murine spermatozoa in vitro but the decondensing ability of heparin was significantly higher. Use of both glycosaminoglycans together revealed the existence of a synergistic effect. Transmission electron microscopy analysis of decondensing spermatozoa supported these findings. Synergism between heparin and dermatan sulfate was observed both in capacitated and non capacitated spermatozoa but decondensation kinetics was faster in the former. The results obtained indicate a new potential role for dermatan sulfate in murine sperm decondensation at fertilization and provide evidence of differences in the degree of chromatin condensation throughout the murine sperm nucleus.