[Transcriptome analysis in fetal lungs of SRC1/SRC2 double-knockout mice].

Steroid receptor coactivators (SRCs) significantly increase the transcriptional activity of various steroid hormone receptors, and play an important regulatory role in a variety of physiological functions such as food intake, sleep, stress response and reproduction. Previous studies have found that pregnant mice carrying fetuses with SRC1/2 double-knockout (dKO) manifested delayed labor, partly due to the hypoplasia of fetal lungs and the decreased secretion of pulmonary surfactant protein-A (SP-A) and platelet activating factor (PAF). However, there is still a lack of systematic analysis of the changes in gene expression at the whole transcriptome level in the fetal lungs of SRC1/2 dKO mice. In this study, the SRC1KO, SRC2KO, SRC1/2 dKO and wild-type (WT) mouse fetal lung samples were collected at 18.5 days post coitus. The Illumina platform was employed for transcriptome mRNA sequencing, and then the differentially expressed genes (DEGs) were annotated and analyzed by GO and KEGG analysis. The results showed that the proportion of quality score of the sequencing data above Q30 in all samples was more than 92% and passed the quality control. Compared with WT fetal lungs, SRC1KO and SRC2KO fetal lungs had 61 and 32 DEGs, respectively; SRC1/2 dKO fetal lungs had 480, 11 and 901 DEGs compared with WT, SRC1KO and SRC2KO fetal lungs, respectively. Among these genes, Aspg, Crispld2, Eln, Ntsr2, Slc10a6 and Vgll3 were the unique DEGs of SRC1/2 dKO fetal lungs compared with other genotype mice. Real-time PCR and Western blotting verified the reliability of transcriptome sequencing results. The GO analysis of the DEGs between SRC1/2 dKO and WT mouse fetal lungs showed that the DEGs were significantly enriched in the extracellular space, extracellular region, and extracellular matrix in terms of cellular component. In the biological process, they were significantly enriched in the term of development of multiple organs. KEGG pathway analysis showed that the DEGs were mainly enriched in signaling pathways such as the complement system, extracellular matrix-receptor interactions, and protein digestion and absorption. In summary, this study comprehensively revealed the changes of gene expression in the fetal lungs of SRC1/2 dKO mice at the transcriptome level, which provides a new theoretical basis for the study of the developmental regulatory mechanism of the fetal lung during pregnancy, and the fetus-derived signals that affect the initiation of labor.

Decrease in SHP-1 enhances myometrium remodeling via FAK activation leading to labor.

Preterm birth is one of the most common complications during human pregnancy and is associated with a dramatic switch within the uterus from quiescence to contractility. However, the mechanisms underlying uterine remodeling are largely unknown. Protein kinases and phosphatases play critical roles in regulating the phosphorylation of proteins involved in the smooth muscle cell functions. In the present study, we found that Src-homology phosphatase type-1 (SHP-1, PTPN6) was significantly decreased in human myometrium in labor compared with that not in labor. Timed-pregnant mice injected intraperitoneally with the specific SHP-1 inhibitor protein tyrosine phosphatase inhibitor I (PTPI-1) manifested significantly preterm labor, with enriched plasmalemmal dense plaques between myometrial cells and increased phosphorylation at Tyr397 and Tyr576/577 sites of focal adhesion kinase (FAK) in myometrial cells, which remained to the time of labor, whereas the phosphorylation levels of ERK1/2 and phosphatidylinositol 3 kinase (PI3K) showed a rapid increase upon PTPI-1 injection but fell back to normal at the time of labor. The Tyr576/577 in FAK played an important role in the interaction between FAK and SHP-1. Knockdown of SHP-1 dramatically increased the spontaneous contraction of human uterine smooth muscle cells (HUSMCs), which was reversed by coinfection of a FAK-knockdown lentivirus. PGF2α downregulated SHP-1 via PLCß-PKC-NF-κB or PI3K-NF-κB pathways, suggesting the regenerative downregulation of SHP-1 enhances the uterine remodeling and plasticity by activating FAK and subsequent focal adhesion pathway, which eventually facilitates myometrium contraction and leads to labor. The study sheds new light on understanding of mechanisms that underlie the initiation of labor, and interventions for modulation of SHP-1 may provide a potential strategy for preventing preterm birth.