title: Expression of matrix metalloproteinases (MMP-2, MMP-9) and their inhibitors (TIMP-1, TIMP-2) in canine testis, epididymis and semen.
abstract: This study aims to investigate the role of matrix metalloproteinases (MMPs) in determining semen quality and to evaluate the expression and cellular localization of MMP-2, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 in the testes, epididymis and ejaculated spermatozoa. Gelatinase activities between normal (n = 21) and abnormal (n = 25) semen samples showed a significant, sixfold increase in proMMP-2 and MMP-2 activity in high than low sperm concentration samples (p < 0.001). ProMMP-9 and MMP-9 levels were significantly elevated in samples with low sperm counts compared to those with high sperm density (p < 0.001). High levels of proMMP-2 and MMP-2 were associated with high sperm motility (≥70%, p < 0.001). Sperm-rich fraction showed significantly (eight-fold) higher proMMP-9 enzymatic activity compared with prostatic fraction. The mRNA expressions of MMP-2, MMP-9, TIMP-1 and TIMP-2 were confirmed in testicular and epididymal tissues. Immunohistochemical staining illustrated the MMP-2-specific strong immunoreactivity in the head of mature spermatids during spermatogenesis, whereas MMP-9, TIMP-1 and TIMP-2 were absent in these cells. Matrix metalloproteinase-9 immunoreactivity was observed in the spermatocyte and round spermatid, whereas TIMP-1 was only exhibited in the residual bodies. Immunolabeling of epididymal and ejaculated sperm demonstrated MMP-2 localization along acrosomal region of sperm, while MMP-9, TIMP-1 and TIMP-2 localization was merely limited to the flagella. In conclusion, spermatozoa initially acquire MMP-2 during their formation at testicular level, and the presence of this protein persists through the epididymal transit and up to ejaculate. The enzymatic activity of MMP-2 and MMP-9 may serve as an alternative biomarker in determining semen quality.
authors.affiliation: Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: C
authors.initials: C
authors.lastname: Warinrak
authors.forename: J-T
authors.initials: JT
authors.lastname: Wu
authors.forename: W-L
authors.initials: WL
authors.lastname: Hsu
authors.forename: J-W
authors.initials: JW
authors.lastname: Liao
authors.forename: S-C
authors.initials: SC
authors.lastname: Chang
authors.forename: F-P
authors.initials: FP
authors.lastname: Cheng
mesh_terms: D000818:Animals; D004285:Dogs / Q000378:metabolism*; D004822:Epididymis / Q000201:enzymology*; D015870:Gene Expression; D007150:Immunohistochemistry; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000032:analysis / Q000235:genetics; D020780:Matrix Metalloproteinase 9 / Q000032:analysis / Q000235:genetics; D061965:Matrix Metalloproteinase Inhibitors / Q000032:analysis*; D020782:Matrix Metalloproteinases / Q000235:genetics*; D012661:Semen / Q000201:enzymology*; D013076:Sperm Count; D013091:Spermatogenesis; D013094:Spermatozoa / Q000201:enzymology; D013737:Testis / Q000201:enzymology*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000032:analysis / Q000235:genetics; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000032:analysis / Q000235:genetics
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D019716:Tissue Inhibitor of Metalloproteinase-2; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9