G-quadruplexes are dynamic structures folded in G-rich single-stranded DNA regions. These structures have been recognized as a potential nucleic acid based mechanism for regulating multiple cellular processes such as replication, transcription and genomic maintenance. So far, their transcriptional role in vivo during vertebrate embryonic development has not yet been addressed. Here, we performed an in silico search to find conserved putative G-quadruplex sequences (PQSs) within proximal promoter regions of human, mouse and zebrafish developmental genes. Among the PQSs able to fold in vitro as G-quadruplex, those present in nog3, col2a1 and fzd5 promoters were selected for further studies. In cellulo studies revealed that the selected G-quadruplexes affected the transcription of luciferase controlled by the SV40 nonrelated promoter. G-quadruplex disruption in vivo by microinjection in zebrafish embryos of either small ligands or DNA oligonucleotides complementary to the selected PQSs resulted in lower transcription of the targeted genes. Moreover, zebrafish embryos and larvae phenotypes caused by the presence of complementary oligonucleotides fully resembled those ones reported for nog3, col2a1 and fzd5 morphants. To our knowledge, this is the first work revealing in vivo the role of conserved G-quadruplexes in the embryonic development, one of the most regulated processes of the vertebrates biology.

The transcription factor JUN is highly expressed in pulmonary fibrosis. Its induction in mice drives lung fibrosis, which is abrogated by administration of anti-CD47. Here, we use high-dimensional mass cytometry to profile protein expression and secretome of cells from patients with pulmonary fibrosis. We show that JUN is activated in fibrotic fibroblasts that expressed increased CD47 and PD-L1. Using ATAC-seq and ChIP-seq, we found that activation of JUN rendered promoters and enhancers of CD47 and PD-L1 accessible. We further detect increased IL-6 that amplified JUN-mediated CD47 enhancer activity and protein expression. Using an in vivo mouse model of fibrosis, we found two distinct mechanisms by which blocking IL-6, CD47 and PD-L1 reversed fibrosis, by increasing phagocytosis of profibrotic fibroblasts and by eliminating suppressive effects on adaptive immunity. Our results identify specific immune mechanisms that promote fibrosis and suggest a therapeutic approach that could be used alongside conventional anti-fibrotics for pulmonary fibrosis.

SummaryNeuronal differentiation is characterized by neuritogenesis and neurite outgrowth, processes, which are critically dependent on membrane biosynthesis, and therefore, on the expression and regulation of enzymes involved in phospholipid biosynthesis. During the last decade a great effort was made to clarify where membrane lipids are synthesized, how the newly synthesized membrane components reach the membrane and are inserted during neuritogenesis and to elucidate the mechanism by which the supply of new membrane components is coordinated with the demand for growth. Phosphatidylcholine is the principal and essential component for mammalian membranes. This review updates the mechanism by which phosphatidylcholine biosynthesis takes place and how it is coordinately regulated during neuronal differentiation.