Aplnra/b Sequentially Regulate Organ Left-Right Patterning via Distinct Mechanisms

Abstract

The G protein-coupled receptor APJ/Aplnr has been widely reported to be involved in heart and vascular development and disease, but whether it contributes to organ left-right patterning is largely unknown. Here, we show that in zebrafish, aplnra/b coordinates organ LR patterning in an apela/apln ligand-dependent manner using distinct mechanisms at different stages. During gastrulation and early somitogenesis, aplnra/b loss of function results in heart and liver LR asymmetry defects, accompanied by disturbed KV/cilia morphogenesis and disrupted left-sided Nodal/spaw expression in the LPM. In this process, only aplnra loss of function results in KV/cilia morphogenesis defect. In addition, only apela works as the early endogenous ligand to regulate KV morphogenesis, which then contributes to left-sided Nodal/spaw expression and subsequent organ LR patterning. The aplnra-apela cascade regulates KV morphogenesis by enhancing the expression of foxj1a , but not fgf8 or dnh9 , during KV development. At the late somite stage, both aplnra and aplnrb contribute to the expression of lft1 in the trunk midline but do not regulate KV formation, and this role is possibly mediated by both endogenous ligands, apela and apln . In conclusion, our study is the first to identify a role for aplnra/b and their endogenous ligands apela/apln in LR patterning, and it clarifies the distinct roles of aplnra-apela and aplnra/b-apela/apln in orchestrating organ LR patterning.

Mcm5 Represses Endodermal Migration through Cxcr4a-itgb1b Cascade Instead of Cell Cycle Control

“…During gastrulation, the liver progenitors migrate to the dorsal midline under the mesoderm and are then established as the left-sided liver at a late stage [ 18 ]. Any disturbance to the endodermal migration [ 11 ] or left–right asymmetric cascade [ 17 , 19 ] will cause randomized endodermal organ location, including liver bifida and liver reversal. To identify why liver bifida occurs in embryos overexpressing mcm5 mRNA, the KV morphogenesis, midline, Nodal/spaw , and endodermal progenitor migration were examined.…”

“…In situ hybridization was performed as described previously [ 17 ]. The probes sox17 , spaw , lft1 , fabp10 , and papc were used [ 17 ].…”

“…In situ hybridization was performed as described previously [ 17 ]. The probes sox17 , spaw , lft1 , fabp10 , and papc were used [ 17 ]. The CDs of vmhc and mcm5 were amplified via PCR and cloned into the pGEM-T easy vector system; then the plasmid was linearized, and the vmhc antisense probe and the mcm5 antisense probe were synthesized.…”

“…The CDs of vmhc and mcm5 were amplified via PCR and cloned into the pGEM-T easy vector system; then the plasmid was linearized, and the vmhc antisense probe and the mcm5 antisense probe were synthesized. To synthesize probes yap1 , wwtri , itgb1b , itgb1a , cxcr4a , and cxcl12b , the CDs for individual genes were amplified via PCR (an additional T7/Sp6 promoter was added to the start end of the Reverse Primer for each gene); part of the PCR product was used for sequencing to evaluate whether the right PCR product was obtained, while the remainder was used as a template to synthesize the probes [ 17 ].…”

MCM5 mutation leads to silence of Stat1-bcl2 and accelerates the apoptosis of immature T lymphocytes with DNA damage

“…Wild type (AB), transgenic line Tg(c-myb:EGFP) 31 , Tg(coro1a:EGFP) 32 , Tg(gata1:desRed) 33 , Tg(lyz:desRed) 32 , Δ113p53 M/M 34 , mcm5 +/-35 , mcm3 +/-, Tg(HSP70l:MCM5-t2a-mCherry) and Tg(Rag2:desRed) 36 shes were maintained in standard conditions at about 28.5℃. The developmental stages were characterized as previously described 37 .…”