The Lgr fa
mily of trans
me
mbrane proteins (Lgr4, 5, 6) act as functional receptors for R-spondin proteins (Rspo 1, 2, 3, 4), and potentiate Wnt signaling in different contexts. Lgr5 is arguably the best characterized of the Lgr fa
mily
me
mbers in a nu
mber of adult and e
mbryonic contexts in
mice. However, the function of
m>LGRm> fa
mily
me
mbers in early e
mbryonic develop
ment is unclear, and has not been explored during hu
man develop
ment or tissue differentiation in detail.
Methods
We interrogated the function and expression of LGR family members using human pluripotent stem cell–derived tissues including definitive endoderm, mid/hindgut, and intestinal organoids. We performed embryonic lineage tracing in Lgr5-GFP-IRES-CreERT2 mice.
Results
We show that m>LGR5m> is part of the human definitive endoderm (DE) gene signature, and m>LGR5m> transcripts are induced robustly when human pluripotent stem cells are differentiated into DE. Our results show that m>LGR4m> and m>5m> are functionally required for efficient human endoderm induction. Consistent with data in human DE, we observe m>Lgr5m> reporter (eGFP) activity in the embryonic day 8.5 mouse endoderm, and show the ability to lineage trace these cells into the adult intestine. However, gene expression data also suggest that there are human–mouse species-specific differences at later time points of embryonic development.
Conclusions
Our results show that m>LGR5m> is induced during DE differentiation, LGR receptors are functionally required for DE induction, and that they function to potentiate WNT signaling during this process.