XB-ART-36560PLoS One October 10, 2007; 2 (10): e1000.
Membrane type-1 matrix metalloproteinases and tissue inhibitor of metalloproteinases-2 RNA levels mimic each other during Xenopus laevis metamorphosis.
Matrix metalloproteinases (MMPs) and their endogenous inhibitors TIMPs (tissue inhibitors of MMPs), are two protein families that work together to remodel the extracellular matrix (ECM). TIMPs serve not only to inhibit MMP activity, but also aid in the activation of MMPs that are secreted as inactive zymogens. Xenopus laevis metamorphosis is an ideal model for studying MMP and TIMP expression levels because all tissues are remodeled under the control of one molecule, thyroid hormone. Here, using RT-PCR analysis, we examine the metamorphic RNA levels of two membrane-type MMPs (MT1-MMP, MT3-MMP), two TIMPs (TIMP-2, TIMP-3) and a potent gelatinase (Gel-A) that can be activated by the combinatory activity of a MT-MMP and a TIMP. In the metamorphic tail and intestine the RNA levels of TIMP-2 and MT1-MMP mirror each other, and closely resemble that of Gel-A as all three are elevated during periods of cell death and proliferation. Conversely, MT3-MMP and TIMP-3 do not have similar RNA level patterns nor do they mimic the RNA levels of the other genes examined. Intriguingly, TIMP-3, which has been shown to have anti-apoptotic activity, is found at low levels in tissues during periods of apoptosis.
PubMed ID: 17912339
PMC ID: PMC1991586
Article link: PLoS One
Genes referenced: mmp14 mmp16 mt4 mtnr1a timp2 timp3
Article Images: [+] show captions
|Figure 1. Schematic of Intestinal and Tail Cell Death and Cell Proliferation Events During Metamorphosis.Xenopus laevis metamorphosis begins when T3 levels elevate at stage 57 and terminates at stage 66 . Top illustrations are of intestine cross-sections and are not to scale. Distances between stages are also not to scale. In response to T3 the intestine changes from a simple structure with one luminal fold (stage 56) to one with multiple folds in the post-metamorphic froglet following stage 66. As intestine metamorphosis begins ECM remodeling in the connective tissue (C) results in cell death (open circles) and cell proliferation (closed circles) of overlying epithelial cells (E). Bottom illustrations represent tail lengths during metamorphosis. Tail regression due to cell death begins at stage 62/63 and is complete by stage 66. Solid line = cell death, dashed line = cell proliferation. C = connective tissue, E = epithelial, M = muscle|
|Figure 2. Patterns of MMP and TIMP RNA Levels Seen during X. laevis Intestine Metamorphosis Derived From RT-PCR Data.Levels of RNA found during intestine metamorphosis demonstrated that MT1-MMP, TIMP-2 and TIMP-3 shared similar RNA expression patterns, with peaks present at stages 58 and63. MT3-MMP and MMP-2 RNA expression patterns in the intestine did mirror each other, but were not similar to the three other genes. Changes in RNA levels are not quantitative, but instead illustrate patterns of expression.|
|Figure 3. Representative RT-PCR Results of Similar MT1-MMP and TIMP-2 Levels of RNA During Natural and T3 Induced Metamorphosis.PCR products were agarose gel fractionated, stained, and photographed. MT1-MMP and TIMP-2 transcription patterns mimic each other at all stages and conditions. In the intestine, MT1-MMP and TIMP-2 transcripts are poorly detected at stage 56 prior to metamorphosis. Levels of both increase during stages 58, 61 and 63 and then drop to pre-metamorphic levels at stage 65. Conversely, in the tail, transcripts are detectable at stage 56, rise to stage 61, and then begin to drop at stage 63. T3 treatment induces a drop in levels after one day, but an increase after three days for both genes. EF1α RNA levels are shown for all comparable stages and treatments.|
|Figure 4. Patterns of MMP and TIMP RNA Levels Seen During X. laevis Tail Metamorphosis Derived From RT-PCR Data.Levels of RNA found during tail metamorphosis demonstrated that MT1-MMP, TIMP-2 and MMP-2 shared similar RNA expression patterns, peaking at stage 61 and staying elevated at stage 63. MT3-MMP and TIMP-3 expression patterns in the tail were not similar to the three other genes, nor to each other. Changes in RNA levels are not quantitative, but instead illustrate patterns of expression.|
|Figure 5. Patterns of MMP and TIMP RNA Levels Seen During T3 Induced Metamorphosis in X. laevis Intestine and Tail as Derived From RT-PCR Data.Levels of RNA found during induced metamorphosis of the intestine and tail demonstrated that MT1-MMP and TIMP-2 shared similar RNA expression patterns, dipping after 1 day and elevating thereafter. MMP-2 and MT3-MMP also shared similar RNA expression patterns, elevating after 1 day in both the intestine and tail. TIMP-3 expression patterns were not similar between the intestine and tail, nor were they similar to the four other genes. Changes in RNA levels are not quantitative, but instead illustrate patterns of expression.|