Rat Amnion Type IV Collagen Composition and Metabolism: RESULTS(2)

6 May

RESULTS(2)Loss of Type IV Collagen from Rat Amnions Before Labor and Increased MMP Expression

Western blot analyses of extracts of rat amnions collected on Days 18-21 of pregnancy using an antibody recognizing a1(IV)/a2(IV) chains of type IV collagen demonstrated a marked reduction in the content of type IV col-lagens per unit protein by Day 21 (Fig. 3). Immunoreactive bands of 180 kDa and 120 kDa predominated on Days 18 and 19, with some NC1 dimer evident at 45 kDa. By Day 20, these immunoreactive bands were reduced in intensity, and they were markedly depleted by Day 21 when approximately 75% of the immunoreactive type IV collagen had been depleted as assessed by densitometric analysis of Western blots. Brilliant Blue G staining of the polyacrylamide gels demonstrated that equal amounts of amnion extract protein had been loaded in each lane but that the relative abundance of some of the protein components changed between Day 18 and Day 21 (Fig. 3B). antibiotic levaquin

Western blot analysis of extracts for the gelatinases MMP-2 and MMP-9 demonstrated increased expression of these enzymes by Day 20, with substantial increases on Day 21 (Fig. 3C).
Fig3Rat Amnion TypeFIG. 3. Loss of type IV collagen from the rat amnion as the time of delivery approaches, and the up-regulation of MMP-2 and MMP-9. Amnion extracts were subjected to Western blot analysis or zymog-raphy as described in the text. A) Western blot of type IV collagen (bracket). B) Brilliant Blue G-stained gel of amnion extracts before transfer, demonstrating protein loading of each lane. C) Western blot analysis of MMP-2 and MMP-9. D) Zymo-graphic analysis of Day 19 and Day 21 amnion extracts. Arrows indicate MMP-9 monomer and dimers; arrowhead identifies MMP-2; bar indicates 68-kDa activity possibly representing activated MMP-9.