Did You Know?
Sometimes, cell differentiation is also known to take place in reverse. This happens in species like starfish and worms whose specialized, differentiated cells convert back to their original embryonic cell when their body parts get detached.
Our body consists of millions and millions of cells of different types. They are all formed from the genome of a single fertilized egg. The process by which a less specialized cell becomes a more specialized cell type is called cell differentiation. This is a process which is seen in multicellular organisms. Here, right from the time after fertilization, the zygote begins to differentiate into a specialized network of cells. Differentiation is a common process in adult stem cells that divide and differentiate into specialized daughter cells. There are many different types of cells in the human body. A cell that can differentiate into all types of cells that make up the body is known as pluripotent cell. These cells are known as embryonic stem cells in animals and mammals. A cell that can differentiate into almost any kind of cell type, including placental cells is known as totipotent cell.
Why is Cell Differentiation Important?
We all know that it is a process in which cells become specialized in respective functions as well as structures. This is when the cells decide the type of cell they are going to be. It is especially important for the development of multicellular organisms. As mentioned above, we all begin with being a single-celled zygote, after which it is decided whether the cell is going to be muscle cell or a nerve cell, what structure it will take up, and what function it will perform.
Cell Differentiation Process
Each specialized cell type in an organism expresses a subset of all the genes that constitute the genome of that specific species. Each type of cell is defined by its pattern of regulated gene expression. Cell differentiation is thus, simply a transition of a cell from one type of cell to another and involves a switch from one pattern of gene expression to another. During development, it can be understood to be the result of a gene regulatory network. A regulatory gene and its regulatory modules are nodes in a gene regulatory network, i.e., they receive input and create output elsewhere in the network.
A few evolutionarily-conserved molecular processes are often involved in the cellular mechanisms that control this process. The main types of molecular processes that control this process involve cell signaling. Many of the signal molecules that convey information from one cell to another during the control of cell differentiation are known as growth factors. Although the details of specific signal transduction pathways vary, these pathways often share certain general steps. A ligand produced by one cell binds to a receptor in the extracellular region of another cell, thus, inducing a conformational change in the receptor. Due to the shape of the cytoplasmic domain of the receptor, changing the receptor acquires enzymatic activity. The receptor then catalyzes reactions that phosphorylate other proteins which activate them. A cascade of phosphorylation reactions eventually activate a dormant transcription factor or a cytoskeletal protein, which contributes to the differentiation process in the target cell.
Embryonic induction refers to cascades of signaling events, during which a cell or a tissue signals to another cell or tissue, thus, influencing its eventual developmental fate. These tissues help in controlling the differentiation of neighboring cells. Other important mechanisms fall under the category of asymmetric cell divisions. These divisions give rise to daughter cells, which have distinct developmental fates. They can occur due to segregation of cytoplasmic determinants or because of signaling. In the former process, distinct daughter cells are created during cytokinesis because of an uneven distribution of regulatory molecules in the parent cell. The distinct cytoplasm that each daughter cell inherits results in a distinct pattern of differentiation for each of the daughter cells produced. An important type of intracellular differentiation control signal would include RNA molecules. The size of the cell at the end of all cell divisions is what determines whether it becomes a specialized germ cell or a somatic cell.
This is a complicated, yet regular process that goes on in our body. It holds a lot of importance for two basic reasons. Firstly, it helps to identify stem cells, which could be used in the future to deal with conditions that require transplant and form the basis of embryonic stem cell research. Also, in cytopathology, the level of cellular differentiation is used as a measure of cancer progression, where the term 'grade' is used as a marker to determine how differentiated a cell in a tumor is. Thus, the importance of this process cannot be underestimated as it could hold the key to future treatments for fatal diseases.