[Study of altered expression of annexin IV and human endometrial receptivity].
OBJECTIVE
To explore the association of altered expression of annexin IV in human endometrium during the implantation window and endometrial receptivity.


METHODS
A comparative proteomic strategy, in a combination of two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), was adopted to search for proteome alternations of pre-receptive (day LH + 2) versus receptive (LH + 7) endometria. The location and abundance of the identified differentially expressed protein- annexin IV were analyzed by immunostaining and western blot.


RESULTS
By comparing protein profiles of LH + 2 and LH + 7 samples, we found a protein up-regulated 2.12 times in LH + 7 samples, with a relative molecular weight of 36,000 and an isoelectric point near pH 5.8. It was characterized using mass spectrometry and was identified as annexin IV. Immunohistochemical analysis revealed an altered localization of annexin IV--in the epithelia on day LH + 2, and both in the epithelia and stroma cells on day LH + 7. Protein levels of annexin IV were up-regulated on day LH + 7 compared with that on day LH + 2 by Western blot. Integrated optical density of the object (OPTDI) was 46.249 +/- 32.376 and 249.507 +/- 31.959, respectively (P = 0.004).


CONCLUSIONS
Our study indicates endometrial samples obtained by microbiopsy are available for proteomics studies. It seems possible that the increased expression of annexin IV during the implantation window plays an important role in the morphological differentiation of the uterus to the receptive state.
Li
Jie
J
Reproductive Medical Center, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China.
Tan
Zhen
Z
Li
Ming-Tao
MT
Liu
Yu-Lin
YL
Liu
Qun
Q
Gu
Xiong-Fei
XF
Zhou
Jian-Zhong
JZ
Zhuang
Guang-Lun
GL
D000328:Adult; D017314:Annexin A4 / Q000096:biosynthesis*; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D010064:Embryo Implantation / Q000502:physiology; D004717:Endometrium / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008597:Menstrual Cycle / Q000502:physiology*; D011247:Pregnancy; D040901:Proteomics; D011960:Receptors, Estrogen / Q000378:metabolism; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013997:Time Factors
D017314:Annexin A4; D011960:Receptors, Estrogen; D016201:Receptors, Lymphocyte Homing; D011980:Receptors, Progesterone