Cyclic changes in the expression of endometrial proteins of the mouse during the normal estrus cycle

Cellular proteins extracted from the endometrial tissue of normal sexually mature outbred mice were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) to define the changes in protein expression that occur during the normal estrus cycle. Using one dimensional gradient SDS-PAGE it was possible to resolve approximately 80 protein bands, 8 of which showed cyclic changes. Five protein bands (Mr 28, 40, 135, 150 and 220 kD) were most prominent in the estrus phase and were barely detectable or not visible at all in the diestrus phase. Since the estrus phase is under the influence of estrogen, these five proteins were considered to be estrogen-induced. Two protein bands (Mr 35, and 37 kD) were more prominent in the diestrus phase. The 116 kD protein band was found only in the diestrus phase. These three proteins were considered to be induced by progesterone, the hormone that governs the diestrus phase of the cycle. None of the protein bands was found to be typical of the proestrus and metestrus phases of the cycle, although the 28 kD band appeared more prominent in proestrus than in other phases. These data show that the mouse estrus cycle is associated with phase-specific changes which can be reproducibly and reliably detected by SDS-PAGE.