# The placental effects of trisomy for human chromosome 21 orthologs in four mouse models of Down syndrome

## TL;DR

This study explores how trisomy for human chromosome 21 affects placental function in mouse models of Down syndrome.

## Contribution

The study identifies specific gene and protein expression changes and altered pathways in mouse placental models of Down syndrome.

## Key findings

- Trisomy increased expression of App, Sod1, and Ifnar1 in multiple mouse models.
- Altered extracellular matrix and immune system pathways were observed in some models.
- Ts1Cje showed distinct changes in SOD activity and antioxidant capacity.

## Abstract

Down syndrome (DS) is caused by trisomy for human chromosome 21 (Hsa21) and is associated with atypical neurodevelopment that begins prenatally. The developing human fetus receives nutritional support and gas exchange from the placenta, and normal placental function is essential for proper development. Placentas that sustain fetuses with trisomy 21 contain trisomic cells, but little is known about which Hsa21 genes are overexpressed in the placenta or their downstream molecular, cellular, and functional effects. Although access to human placentas is limited, mouse models of DS provide excellent in vivo systems for investigating the prenatal effects of trisomy. This study examined the placental transcriptome in four mouse models of DS: Dp(16)1/Yey, Ts65Dn, Ts66Yah, and Ts1Cje. Placental gene and protein expression analyses showed that trisomy increased the expression of App, Sod1, and Ifnar1 in Dp(16)1/Yey, Ts65Dn, and Ts66Yah; APP and SOD1 in Dp(16)1/Yey and Ts66Yah; and IFNAR1 in Ts66Yah. Despite modest overlap of trisomy-associated gene dysregulation among these four models, altered extracellular matrix pathways in all four models and upregulation of immune system pathways in Dp(16)1/Yey and Ts66Yah were identified. Altered redox homeostasis was observed for all four models, with Ts1Cje showing distinct changes in SOD activity and antioxidant capacity in comparison to the other three models. Immunofluorescence staining revealed region-specific upregulation of APP, SOD1, and IFNAR1 in Ts66Yah trisomic placentas. This work provides a foundation for understanding the effects of trisomy for Hsa21 orthologs on the mouse placenta and on prenatal development.

Summary: This study identified alterations in RNA expression, protein expression, and redox homeostasis in the placentas of four mouse models of Down syndrome.