Difference Between Mitogen and Growth Factor

The key difference between mitogen and growth factor is that mitogen is a small protein that induces the cell to begin cell division, while growth factor is a naturally occurring substance that is capable of stimulating cell proliferation, wound healing, and cellular differentiation.

Mitogen and growth factor are two components involved in the cell cycle. The cell cycle is a series of events that take place in a cell. Through this process, a cell grows and divides. The cell cycle consists of two main phases: interphase (G1, S, G2) and mitosis. During interphase, the cell grows and replicates its DNA. In the mitosis phase, the cell undergoes nuclear division.

CONTENTS

1. Overview and Key Difference
2. What is Mitogen 
3. What is Growth Factor
4. Similarities Between Mitogen and Growth Factor
5. Side by Side Comparison – Mitogen vs Growth Factor in Tabular Form
6. Summary

What is Mitogen?

Mitogen is a peptide or a small protein that induces the cell to begin cell division. Mitogenesis is the process of triggering mitosis, typically via mitogen. Normally the function of mitogen is to trigger signal transduction pathways such as mitogen-activated protein kinase (MAPK). This leads to mitosis.

Mitogens primarily influence a set of proteins. These proteins are involved in the restriction of progression through the cell cycle. The G1 checkpoint is directly controlled by mitogens. But further cell cycle progression does not need mitogen to continue. The point in the cell cycle where mitogens are no longer needed to move forward in the cell cycle is called the restriction point. A well-known protein that is activated by mitogens is mitogen-activated kinase.

There are two types of mitogens as endogenous or exogenous factors. An example of endogenous mitogen is endogenous mitogen Nrg1 in Zebrafish. This factor stimulates increasing the cell division rates and producing new layers of heart muscle cells when the heart is damaged. An example of an exogenous mitogen is exogenous PDGF. It is a potent mesangial cell mitogen. Mitogens are very important in cancers due to their effect on the cell cycle. The cancer cells lose their dependence on mitogens.

What is a Growth Factor?

A growth factor is a naturally occurring substance that is capable of stimulating cell proliferation, wound healing, and on occasions, cellular differentiation. It is either a secreted protein or a steroid hormone. The growth factor is a term that is used interchangeably by scientists with the term cytokines. Growth factors were first discovered by Rita Levi-Montalcini, who won Nobel Prize for her discovery in 1986.

Growth factors are highly important for regulating cellular processes. Growth factors act as signalling molecules between cells. Examples include cytokines and hormones. These bind to the specific receptors on the surface of their target cells. They often promote cell differentiation and maturation. For example, the epidermal growth factor (EGF) enhances osteogenic differentiation. Moreover, fibroblast growth factors and vascular endothelial growth factors stimulate blood vessel differentiation.

What are the Similarities Between Mitogen and Growth Factor?

• Mitogen and growth factor are involved in the cell cycle.
• Both can influence checkpoints of the cell cycle.
• Their deregulation causes cancers.
• Both help in the growth of individuals.

What is the Difference Between Mitogen and Growth Factor?

Mitogen is a small protein that induces the cell to begin cell division. On the other hand, the growth factor is a naturally occurring substance that is capable of stimulating cell proliferation, wound healing, and occasionally, cellular differentiation. So, this is the key difference between mitogen and growth factor. Moreover, mitogen is a small protein. In contrast, growth factor is either a secreted protein or a steroid hormone.

The below infographic lists the differences between mitogen and growth factor in tabular form.

Summary – Mitogen vs Growth Factor

The cell cycle is a sequence of events that happen in the cell in order to prepare the cell for division. In interphase, the cell increases in size, and its DNA replicates. The cell divides in the mitosis stage. Certain substances regulate this entire process. Mitogens and growth factors are highly important for cell cycle regulation. Mitogen induces the cell to begin cell division. On the other hand, growth factor is capable of stimulating cell proliferation, wound healing, and cellular differentiation. Thus, this is the summary of the difference between mitogen and growth factor.

Reference:

1. “Mitogen.” An Overview | ScienceDirect Topics, Available here.
2. GW, Gould; Merrall NW; Plevin R. “Growth Factors, Mitogens, Oncogenes and the Regulation of Glucose Transport.” Cellular Signalling, U.S. National Library of Medicine, Available here.

Image Courtesy:

1. “Mitocellcycle” By Aguilar, Victor, and Lluis Fajas. “Cycling through Metabolism.” EMBO Molecular Medicine, vol. 2, no. 9, 2010, pp. 338–348., doi:10.1002/emmm.201000089. – (CC BY-SA 4.0) via Commons Wikimedia

2. “Endothelial receptors and growth factors” By Michael Jeltsch – Own work (CC BY-SA 4.0) via Commons Wikimedia