The Origination of Cell State Hypothesis and Its Significance to Life Science
This paper was published in Science and Technology Review, 2008, 26(4), 41～46. Requested by readers and permitted by the editor, illustrations and abstract were expanded in English here.
The Origination of Cell State Hypothesis and Its Significance to Life Science
Wang Haibo
Institute of Genetics and Physiology, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang, 050051, China
Abstract Cell is the fundamental unit of life, and yet our understanding of life science remains a fragmented view, despite overwhelming advances in physiology, cell biology, genetics and genomics. To understand the real life, studies should be based on living cells, but most of the experiments are usually conducted with destroyed cells or their isolated elements. Here, a Cell State hypothesis is proposed, which provides a new strategy for studies in life science in a comprehensive, dynamic, multi-level and multi-dimensional way.
The Cell State hypothesis is originated from the studies that aimed to understand the mechanisms of plant tissue and cell culture. It changed the plant tissue and cell culture from illogical experiences to a predictable and inferential level. Of particular note, it also provides a novel insight into the studies of ageing, canceration, animal cloning and stem cell culture, and into the human health care.
The main barrier in plant tissue and cell culture is the difficulty to regenerate plants. Whether any plant can be regenerated or not depends on what type the callus belongs to. The type of callus is determined by its major consisting cells. Through a long-term research of tissue and cell culture in wheat, I have found that different cell types are the various displays of cell state. There are seven highly typical cell types: 1) embryogenic cell (Se), 2) conservative cell (Sa), 3) stimulating cell (Sb), 4) multiplicative cell (St), 5) conservatively degenerated cell (Da), 6) radically degenerated cell (Db), and 7) hyperactively dividing cell (Sc). Among these, the types of Se, Sa, Sb and St cell can be changed into each other with self regulating activities, and can be degenerated to the long curved (Da) or expanded (Db) cells. The Sc cell is similar to the St cell, but has a hyperactive dividing capability. The other cell types are the transitional states of these typical types (Fig.1，Fig.2). The key of plant tissue and cell culture is to regulate the cell state.
The cell state comprehensively reflects the composition, structures, morphology, functions and potentials of a cell. In the Cell State hypothesis, a cell state is abstracted as being controlled by a series of “cell state factors” not only in genetic and physiological aspects, but also from chemical, physical, compositional and structural elements (Fig.3). No matter where the factors come from, their roles can be imagined as having physiological and biochemical effects. Cell state factors can be divided into three categories: 1) stimulating factors (E), 2) conservative factors (I), and 3) degenerative factors (D). E factors mainly promote or maintain the cell at a stimulating state. I factors chiefly make or keep the cell at a conservative state. D factors can show some similar effects as I factors when they are at a low level and especially when the cell is active, but their nature is to destroy the structures and disturb the activities of a cell. All the factors follow the formula of S={[∑E0]+[∑ES]}/{[∑I0]+[∑IS]+[∑D]}, where S represents the cell state coefficient（named as S value）, ∑ denotes the total value of the same type of factors, and [ ] means the level of the composite effects of the same kind factors, while “0” and “S” indicate internal or external factors respectively. The internal factors include the relevant genes, endogenous active substances, the cell structures and their change. The external factors can be considered as exogenous elements. In most cases, auxin and reduced nitrogen can be regarded as E factor- substances; cytokine, oxidized nitrogen can be used as I factor- substances; and harmful metabolites, radicals, heavy metals and others, can be listed as D factor- substances.
The cells of different state distribute in a dolphin-like diagram (Fig.4). According to this diagram and the formula, and the knowledge or experiences about the functions to cells of chemical and physical factors, the cell states of cultures can be successfully regulated towards the desired position.
In the Cell State hypothesis, E and I factors are the basis of living phenomena, and D factors are the tragedy makers in the living processes. In an organism, where D factors heavily accrue, the cell goes to ageing or even death. However, when D factors are accumulated where there are many cells having strong evolutional capability or potential, some of them may be mutated to hyperactively dividing types to dilute the declining substances through cell division in order to maintain the S value to the rang which the living cells should have. The balance of gene expression might be broken with the suppression of D factors, which results in the disorder of cellular activity. The life span might be strongly influenced by the speed and the amount of D factors accumulation in development of an organism. Reducing the accumulation of D factors will lead to a better result of controlling ageing and lesion. An organism will be restored or rejuvenated if the D factor-substances can be eliminated from it (Fig.5).
Although it is in a molecular biological era, cell is still the foundation of life. Without a living cell system, it would be difficult to determine the in vivo functions of bio-substances. The function of gene is determined by its effect on the cell states. For other substances in life system, their functions are also determined by their effects to cell states. An organism can be taken apart to cells, and a cell can further be broken to molecules. Up to date, only the cell can be developed to an organism again, the molecules have not been able to reconstitute to a living cell. This indicates that when a cell is broken to molecules, a large amount of “important or critical things” have been lost or destroyed, and these do not belong to DNA and proteins themselves. Clearly, cell is an extremely complex life system and it needs to be understood at different levels and with different scales. Therefore, the Cell State hypothesis presented in this paper will shed new light on this complex and yet fundamental question.
Keywords cell state; plant tissue and cell culture; ageing; canceration; heath care
发表评论