(72) HAND1 controls epithelial morphogenesis and fate specification in a human pluripotent stem cell-based amnion model

AURTHORS: Lauren N. Juga^1,*, Jenna C. Wettstein^1,*, Chari L. Cortez^2,*, Nikola Sekulovski¹, Amber E. Carleton¹, Linnea L. Taniguchi¹, Anusha Rengarajan¹, Jenna K. Schmidt³, Thaddeus G. Golos^3,4,5, Deborah L. Gumucio^2,6, Chien-Wei Lin⁷ and Kenichiro Taniguchi^1,2,8,9,†

AFFILIATIONS:

¹Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI 53226, USA

²Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA

³Wisconsin National Primate Research Center (WNPRC), Madison, WI, USA

⁴Department of Obstetrics and Gynecology, University of Wisconsin - Madison School of Medicine, Madison, WI USA

⁵Department of Comparative Biosciences, University of Wisconsin - Madison School of Veterinary Medicine, Madison, WI, USA

⁶Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA

⁷Division of Biostatistics, Institute for Health and Equity, Medical College of Wisconsin, Milwaukee, WI 53226, USA

⁸Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI 53226, USA

⁹Cancer Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA

^*Co-first authors

^†Corresponding author

 


Abstract Text: Amniogenesis is triggered in a collection of pluripotent epiblast cells as the human embryo implants. While recent studies identified transcriptomes of developing amnion in early primate embryos as well as in amnion models based on human pluripotent stem cells, key transcriptional machineries governing amnion fate specification is not well understood. Recently, we showed that the expression of HAND1, a basic helix-loop-helix transcription factor, is seen at an intermediate stage of amnion formation, when cells initiate squamous morphogenesis and adapt an amnion fate. Here, we explored the role of HAND1 during human amnion formation in Gel-3D, a three-dimensional model of amnion formation based on human pluripotent stem cells. Consistent with the previous studies, prominent HAND1 transcript expression is seen by day 2, and nuclear HAND1 protein is abundantly seen by d3. Strikingly, while the expression of ISL1, a marker of specified amnion cells is seen, loss-of-function mutation of HAND1 results in reduced expression of several amnion markers and in impaired epithelial polarization. Our time-course bulk transcriptomic analysis in control and HAND1-KO Gel-3D cysts reveals SOX7, a SoxF transcription factor, as one of the downstream targets of HAND1 activity. Moreover, we show that the HAND1-SOX7 transcriptional axis is critical for maintaining epithelial characteristics of developing Gel-3D amnion cysts, and identify several downstream targets of the HAND1-SOX7 axis. Together, this study reveals key roles for HAND1 and SOX7 transcription factors in promoting amniogenic differentiation as well as in maintaining amniotic epithelial structure.