Help me please!?

Question

How is the exact mechanism of phytohaemagglutinin (PHA) in stimulating cell cycle of mammals?

Answer 1

Phytohaemagglutinin is a lectin or hemagglutinin, has been used by immunologists for years to trigger DNA synthesis in T lymphocytes, and more recently, to activate latent human immunodeficiency virus type 1 (HIV-1, AIDS virus) from human peripheral lymphocytes. Besides inducing mitosis, lectins are known for their ability to agglutinate many mammalian red blood cell types, alter cell membrane transport systems, alter cell permeability to proteins, and generally interfere with cellular metabolism.

In particular, PHA interferes with glucose metabolism and with Ca2+ uptake, therefore changing the permeability of the lymphocytes membranes. It is believed that it binds to cell surface receptors, thereby activating intra-cellular signaling (mostly through the STAT/MAPK pathwas) that leads to activation of the mitotic processes.

Answer 2

I suppose it would activate molecules which affect the checkpoints of the cell cycle. I don't know the specific molecule or mechanism, but it probably would have some kind of activating affect on checkpoint molecules like Cdk's which would stimulate the cell to divide.