Genes turned on

The field of developmental biology answers the fundamental question of how cells make decisions about what kind of cells they will become.

Scientists from the Sloan Kettering Institute studied the mouse endoderm, the germ layer that forms majority of our internal organs. This paper is published in Nature. Using single-cell RNA sequencing (scRNA-seq), where single cells are isolated and the messenger RNAs in them are fully sequenced, scientists could see a snapshot of the actual genes that are turned on during development.

Their findings were as follows:

Trajectories of endoderm cells were mapped as they acquired embryonic versus extra-embryonic fates, and as they spatially converged within the nascent gut endoderm; revealing them to be globally similar but retaining aspects of their lineage history.

From the MSK website:

They found that cells that come from extra-embryonic tissues and those that come from the embryo are 99% identical regardless of origin, yet there is a set of genes whose activity is different between them. What’s more, the investigators were able to decipher some of the signals that help cells make their earliest fate decision: whether to become part of the embryo or part of the extra-embryonic structures. The team also pinpointed the earliest time when cells with organ-specific endoderm can be identified. It is far earlier than previously believed.

What does this mean?

The study adds to our current understanding of how cells develop. It shows that certain genes are crucial in determining the fate of a cell. This research inevitably leads to more investigations: how are those genes activated, for instance? How do those genes affect the cells, the organ, and the body, in all stages of development? The answers may be useful to our understanding of developmental biology and, hopefully, of cancer.

Reference:

Nowotschin S, et al. The emergent landscape of the mouse gut endoderm at single-cell resolution. Nature (2019). Link here.