Question

In only one or two words, how might dysregulation of the cell cycle manifest within an individual?

Answer 1

Dysregulation of the cell cycle manifests in Uncontrolled Cellular Proliferation.

In other words it can lead to Tumorigenesis or Tumor formation.

A very vital mechanism in living organisms is that normal cells with damaged DNA undergo a cell cycle arrest so that the DNA can be repaired and integrity of the genome is preserved.

Dysregulation

Every cell has biochemical pathways that lead to cell cycle arrest in case of DNA damage to allow repair.

These are called checkpoints.

Checkpoints are complex signal transduction pathways that regulate the order of events in the cell cycle and integrate them with DNA repair

By arresting the cell cycle they allow DNA repair so that genomic integrity can be maintained.

In case DNA cannot be repaired some cells undergo a programmed cell death known as Apoptosis

Loss of cell cycle checkpoint integrity DUE TO DEFECTIVE COMPONENTS results in the instability of the genome

Such cells become highly susceptible to uncontrolled proliferation resulting in tumors

For example -

One major type of dysregulation is the dysregulation of the Receptor Tyrosine Kinase (RTK)

RTK is a subclass of tyrosine kinases which mediates inter-cellular communication.

It also controls cellular growth and differentiation along with motility and metabolism

RTK dysregulation occurs when there are alterations in several types of genes coding for RTK.

This dysregulation of RTK signals leads to various cancers (like breast cancer)

There are 4 principle mechanisms by which abnormal RTK activation takes place.

They are -

1. Gain of function mutations

2. Genomic amplification

3. Autocrine activation

4. Chromosomal re-arrangements