Molecular Program That Controls The Cells

The study revealing that the molecular program; that controls cells capacity for division. Cells in the body proliferate at different rates. Some divide constantly and throughout life, like the ones that line the gut. Others divide only rarely, sometimes resting for several years in a non-dividing state. The molecular mechanisms that help control this cellular hibernation; termed quiescence, revealing how cells can purposefully choose to retain the capacity to divide.

This explaining cell division and cell state; but also the dynamics of the cellular machinery that supports these processes; including a group of proteins at a critical structure called the centromere; that ensure that chromosomes are properly inheriting every time a cell divides. During cell division, each resident chromosome gets duplicating and then equally apportioning; ensuring that both cells receive a complete set of genetic instructions.

The molecular program

The unsung hero of this careful choreography is the centromere, a small chromosomal region that anchors the rope-like fibers that separate chromosomes during cell division. Chromosomes that lack a centromere cannot be transporting to their rightful places. That leaves cells with a jumbled mess of DNA a steppingstone toward disordered growth and, potentially, cancer.

The key centromere protein, named CENP-A; was widely thought to be static, but is in fact replenishing at a slow, yet continuous, rate. This serves not only to refresh and maintain the apparatus requiring for cell division but also to provide a marker of the cells’ future capacity for proliferation. Centromeres are not defined by DNA sequence; but instead by the assortment of proteins that gather upon them. That is to say, centromeres are spelled out in epigenetic terms.

Epigenetic lexicon of the centromere

But within the epigenetic lexicon of the centromere; a protein called CENP-A is particularly indispensable. Oocytes, the female reproductive cells; first form in humans during embryonic development and remain dormant until after puberty representing a decade or more of inactivity.  But when they studying mature muscle cells; a cell type that has lost its capacity to divide and is therefore at the end of its developmental journey they uncovering a very different scenario.

In these cells, the levels of CENP-A at the centromeres are drastically reducing; particularly when compared to the cells’ younger brethren. The researchers hypothesize that this difference reflects distinct needs to maintain their centromeres; which in turn signals disparate capacities for cell division. As an epigenetic mark, the CENP-A protein forms part of a nucleosome; the unit of bobbin-like histone proteins around which DNA is tightly wound, like thread on a spool.