title: Myeloid ecotropic viral integration site 1 (MEIS) 1 involvement in embryonic implantation.
abstract: BACKGROUND
  The HOXA10 homeobox gene controls embryonic uterine development and adult endometrial receptivity. The three-amino-acid loop extension (TALE) family homeobox genes like myeloid ecotropic viral integration site 1 (MEIS) provide enhanced target gene activation and specificity in HOX-regulated cellular processes by acting as HOX cofactors.
  
  
  RESULTS
  Analysis of an Affymetrix data set in the public domain showed high expression of MEIS1 in human endometrium. MEIS1 expression was confirmed during the human menstrual cycle by RT-PCR and in situ hybridization and was increased during the secretory compared with proliferative phase of the cycle (P = 0.0001), the time of implantation. To assess the importance of maternal Meis1 expression in a mouse model, the uteri of Day 2 pregnant mice were injected with Meis1 over-expression or small interfering RNA (siRNA) constructs. Blocking Meis1 expression by siRNA before implantation significantly reduced average implantation rates (P = 0.00001). Increased or decreased Meis1 expression significantly increased or decreased the expression of integrin beta3, a transcriptional target of HOXA10 and an important factor in early embryo-endometrium interactions (P = 0.006). Manipulating Meis1 expression before implantation also dramatically affected the number of pinopodes, uterine endometrial epithelial projections that develop at the time of endometrial receptivity.
  
  
  CONCLUSIONS
  The results suggest that in mouse, meis1 contributes to regulating endometrial development during the menstrual cycle and establishing the conditions necessary for implantation.
authors.affiliation: Reproductive Medicine Center, Tongji Hospital, Tongji Medicine College, Huazhong, University of Science and Technology, 1095 JieFang Avenue, Wuhan 430030, People's Republic of China.
authors.forename: Bei
authors.initials: B
authors.lastname: Xu
authors.forename: Dirk
authors.initials: D
authors.lastname: Geerts
authors.forename: Kun
authors.initials: K
authors.lastname: Qian
authors.forename: Hanwang
authors.initials: H
authors.lastname: Zhang
authors.forename: Guijin
authors.initials: G
authors.lastname: Zhu
mesh_terms: D000328:Adult; D000818:Animals; D010064:Embryo Implantation; D004717:Endometrium / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000096:biosynthesis*; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D008597:Menstrual Cycle / Q000378:metabolism*; D051379:Mice; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation
chemical_list: D018398:Homeodomain Proteins; C000616391:MEIS1 protein, human; C000616392:Meis1 protein, mouse; D000075064:Myeloid Ecotropic Viral Integration Site 1 Protein; D009363:Neoplasm Proteins