Architectural Fragility Of Gene Regulatory Networks Underlies Hematopoietic Stem Cell Aging
Our bodies rely on specialized cells, called hematopoietic stem and progenitor cells (HSPCs), to continuously produce all types of blood and immune cells throughout our lives. As we age, these crucial cells can become less effective, contributing to a weaker immune system and age-related diseases. But what exactly causes this decline?
Recent research has shed light on this mystery by creating the most comprehensive map yet of human HSPCs, analyzing over 380,000 individual cells from 77 donors. This detailed map allowed scientists to observe how the intricate networks that control gene activity within these cells change with age.
The findings reveal a significant “rewiring” of these gene control networks. In older HSPCs, programs that respond to stress and promote the development of certain immune cells (myeloid cells) become more active. At the same time, the networks responsible for the stem cells’ ability to renew themselves and produce other types of immune cells (lymphoid cells) start to break down. This shift explains why older individuals often have a less robust immune system and are more prone to certain blood disorders.
This cellular “disorder” is linked to an increase in what scientists call “cis-regulatory entropy.” Imagine the precise instructions for building and operating a cell becoming noisy and less clear. This includes more random fluctuations in gene activity, weaker connections between control regions and the genes they regulate, and a less defined structure of the cell’s genetic material (chromatin). Essentially, the complex, distant control mechanisms that define a cell’s identity become fragile and erode, while simpler, more robust control systems closer to the genes are maintained or even strengthened. This progressive destabilization of the gene control architecture appears to be a fundamental driver of aging in our blood-forming stem cells.
Source: link to paper