Homeobox (HOX) genes are evolutionarily conserved genes encoding transcription factors that regulate mammalian embryonic growth and development of the urogenital tract.
In both humans and mice, HOXA11 persists in the adult reproductive tract and is thought to play an important role in maintaining tissue developmental plasticity by regulating the expression of genes involved in extracellular matrix metabolism in the reproductive organs. Previously, we have shown that HOXA11 is necessary for development of the uterosacral ligaments in mice and deficient in women with pelvic organ prolapse. Therefore, we hypothesized that Hoxa11 regulates the synthesis and/or metabolism of collagens in the uterosacral ligaments and uterus and tested this by establishing an in utero and peritoneal Hoxa11 gene knockdown system in C57/BL6 mice using vectors bearing Hoxa11 short-hairpin RNA. Specific knockdown of Hoxa11 transcripts and protein levels were confirmed versus control vectors. Protein and mRNA expression of collagen type I and III exhibited significant decreases following Hoxa11 KD according to Western blot and real-time PCR. Tissue inhibitor of matrix metalloproteinase1 expression also exhibited a significant decrease. Gelatinase zymography confirmed increases in pro-MMP2 and MMP9, and activated MMP2 following Hoxa11 knockdown. These results reveal that Hoxa11 knockdown in the uterosacral ligaments and uterus increases extracellular matrix degradation. More importantly, it suggests a mechanism in the weakening of the pelvic floor support in women, since decreased HOXA11 gene expression has been reported to be associated with decreased collagen and increased MMP2 expression in the uterosacral ligaments of women with pelvic organ prolapse.
Written by:
Ma Y, Guess M, Datar A, Hennessey A, Cardenas I, Johnson J, Connell KA. Are you the author?
Reference: Biol Reprod. 2011 Dec 21. [Epub ahead of print]
PubMed Abstract
PMID: 22190701
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