ADVERTISEMENTS:
In this article we will discuss about the intercellular communication in multicellular eukaryotes.
In multicellular eukaryotes, the mechanisms that control cell division and cell growth are even more complex because a new dimension intercellular communication must play a major role. Each tissue within an organ and each organ within the body of an organism must grow to the proper size for that particular species.
The growth of bones, muscles, the liver, the pancreas and so on must all be correctly coordinated during the growth and development of a mouse, a rabbit, or a human. Clearly, for this to occur, cell division must be under very precise control within each tissue and must be subject to different regulatory signals in different tissues and organs.
ADVERTISEMENTS:
Because of the intricate interrelationships that exist between the different tissues of a multicellular plant or animal, intercellular communication must play an essential central role in the growth and differentiation of higher plants and animals. How does this intercellular communication occur? What are the mechanisms by which cellular differentiation and cell growth and division are regulated?
At present, we know that there are a host of “factors” that stimulate or inhibit the growth and division of specific types of cells. However, we do not understand how any of these factors influence cell division at the molecular level. Enough information has accumulated to indicate that the total picture will be complex, but at present we are just beginning to understand a few of the pieces of this complex picture.
Cell division, like all other biological processes, is under genetic control. Certain genes must regulate the process of cell division in response to intracellular, intercellular, and environmental signals. These regulatory genes are undoubtedly subject to mutation, like all other genes.
Mutations that abolish the function of these regulatory genes would be expected to lead to abnormal cell division—in the extreme, cither the inability to divide at all or the inability to stop dividing.
ADVERTISEMENTS:
To date, we do not know the details’ of how cell division is controlled for any cell of any higher animal, nor have we identified all of the genes that regulate this process in any higher eukaryote. However, recent studies of viral genes called oncogenes (from the Greek onkos, meaning “tumor”), which can cause a loss of the normal control of cell division, have led to the identification of a set of homologous genes called proto-oncogenes in the genomes of normal animals, including humans.
These normal cellular proto-oncogenes can’ be converted into tumor-causing cellular oncogenes by mutation or by becoming associated with new regulatory sequences through recombination processes. These and related observations indicate that the normal cellular functions of the proto-oncogenes involve specific aspects of the control of cell division.
In fact, it now seems likely that breakthroughs in understanding the normal control of cell division may result from studies on the disruptions of normal control that occur in cancer cells.
