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Wang et al. J Transl Genet Genom 2023;7:126-40 https://dx.doi.org/10.20517/jtgg.2023.07 Page 136

Figure 5. Western blots of ECM-A proteins. Protein samples were isolated from two unrelated human fetal membrane samples (1, 2),
which were delivered from various outcomes of pregnancies, including (a) pPROM, (b) FTB, (c) sPTL, and (d) PROM. Antibodies
against the ECM-A pathway were used to probe ECM-A proteins. GAPDH was used as an internal control for protein loading.

functional domain, the metalloproteinase domain, of ADAMs is similar to the matrix metalloproteases
(MMPs), which include MMP-1, MMP-8, and MMP-9 and have been reported to be involved in the fetal
membrane rupture [37-40] . The proteases MMP-8 and MMP-9 involved in ECM degradation were elevated in
the amniotic fluid, which may reduce the mechanical support of the membrane. MMPs are the major
proteases involved in ECM degradation . They can degrade ECM protein substrates, including collagens,
[41]
fibronectin, laminin, and vitronectin, by breaking the cell-to-cell and cell-to-ECM adhesion. In fact, the
amount of ADAM8 was found to be elevated in the amniotic fluid of women who gave birth prematurely,
[42]
which is thought to be a possible risk factor for preterm birth . Therefore, it is likely that ADAM9 is
involved in the metabolism of the ECM and thus in preterm birth.

ECM-A and sPTB
The ECM plays an active and dynamic role that both reflects and facilitates the functional requirements of a
tissue. Our earlier study determined that ECM proteins COL4A1, LAMA2, FBLN2, and APMAP were
downregulated in the premature tissues of human placentas, including fetal membranes in spontaneous
preterm births . Applying experimental models may further address the contribution of the interaction
[43]
between the intrauterine environment and gene expression on the pathogenic mechanism(s) of sPTB [22,23] .
Studies on mice deficient in the proteoglycan decorin have demonstrated that progesterone and estrogen
may regulate ECM organization and turnover, expressions of factors required for assembly and synthesis of
collagen and elastic fibers are temporally regulated, and the ultrastructure of collagen fibrils and elastic
fibers is markedly altered during pregnancy in wild-type mice .
[44]
Our results in this study certainly supported that any possible environmental factors that result in the
alteration of lnc-ADAM9 may epigenetically regulate mRNA-ADAM9 and consequently has an impact on
the ECM-A pathway in the sPTB. In the current study, to better understand the epigenetic regulation of
lncADAM9 on its overlapped mRNAs, lncRNA-TG HTR8 cells were constructed, in which the in vivo
expression pattern of lncADAM9 and its mRNA simulated in vitro, with lncADAM9 up-regulated and
mRNA-ADAM9 down-regulated. Many transcripts were impacted by overexpressed lncADAM9 in the