Kinetin
Encyclopedia
Kinetin is a kind of cytokinin
, a class of plant hormone
that promotes cell division
. Kinetin was originally isolated by Miller and Skoog et al. as a compound from autoclaved herring sperm DNA
that had cell division-promoting activity. It was given the name kinetin because of its ability to induce cell division
, provided that auxin
was present in the medium. The story of the discovery of kinetin is a fascinating example of the twists and turns of scientific discovery. Kinetin is often used in plant tissue culture
for inducing formation of callus
(in conjunction with auxin
) and to regenerate shoot
tissues from callus (with lower auxin
concentration).
For a long time, it was believed that kinetin was an artifact produced from the deoxyadenosine residues in DNA
, which degrade on standing for long periods or when heated during the isolation procedure. Therefore, it was thought that kinetin does not occur naturally, but, since 1996, it has been shown by several researchers that kinetin exists naturally in the DNA of cells of almost all organisms tested so far, including human and various plants. The mechanism of production of kinetin in DNA is thought to be via the production of furfural
— an oxidative damage product of deoxyribose sugar in DNA — and its quenching by the adenine base's converting it into N6-furfuryladenine, kinetin.
Since 1994, kinetin has been thoroughly tested for its powerful anti-aging effects in human skin cells and other systems. At present, kinetin is one of the widely used components in numerous skin care cosmetics and cosmeceuticals, such as Valeant products kinerase . There are some reports published on other biological effects of kinetin in human beings, for example its effects as anti-platelet aggregation factor reducing thrombosis formation. In addition, it has been shown to be capable of correcting RNA mis-splicing in the disease of familial dysautonomia
, in which exon 20 of IKBKAP is skipped instead of included in the disease, leading to insufficient levels of IKBKAP protein product as a result of frame-shift-induced nonsense-mediated decay.
. The transplantations occur every three to eight weeks. Callus cultures are not cell cultures, since whole tissue associations are cultivated. Though many cells keep their ability to divide, this is not true for all. One reason for this is the aneuploidy
of the nuclei and the resultant unfavourable chromosome constellations.
J. van Overbeek (Rijksuniversiteit Utrecht) introduced in 1941 coconut milk as a new component of nutrient media for callus cultures. Coconut milk
is liquid endosperm. It stimulates the embryo to grow when it is supplied with food at the same time. Results yielded from callus cultures showed that its active components stimulate the growth of foreign cells, too.
In 1954, F. Skoog
(University of Wisconsin, Madison) developed a technique for the generation and culture of wound tumour tissue from isolated shoot parts of tobacco (Nicotiana tabacum
). The developing callus grows when supplied with yeast
extract, coconut milk, or old DNA preparations. Freshly prepared DNA has no effect but becomes effective after autoclaving. This led to the conclusion that one of its breakdown products is required for cell growth and division. The substance was characterized, was given the name kinetin, and classified as a phytohormone.
Kinetin is also claimed to have dermatologic
effects and is used in some cosmetics.
Cytokinin
Cytokinins are a class of plant growth substances that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence...
, a class of plant hormone
Plant hormone
Plant hormones are chemicals that regulate plant growth, which, in the UK, are termed 'plant growth substances'. Plant hormones are signal molecules produced within the plant, and occur in extremely low concentrations. Hormones regulate cellular processes in targeted cells locally and, when moved...
that promotes cell division
Cell division
Cell division is the process by which a parent cell divides into two or more daughter cells . Cell division is usually a small segment of a larger cell cycle. This type of cell division in eukaryotes is known as mitosis, and leaves the daughter cell capable of dividing again. The corresponding sort...
. Kinetin was originally isolated by Miller and Skoog et al. as a compound from autoclaved herring sperm DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
that had cell division-promoting activity. It was given the name kinetin because of its ability to induce cell division
Cell division
Cell division is the process by which a parent cell divides into two or more daughter cells . Cell division is usually a small segment of a larger cell cycle. This type of cell division in eukaryotes is known as mitosis, and leaves the daughter cell capable of dividing again. The corresponding sort...
, provided that auxin
Auxin
Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...
was present in the medium. The story of the discovery of kinetin is a fascinating example of the twists and turns of scientific discovery. Kinetin is often used in plant tissue culture
Plant tissue culture
Plant tissue culture is a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition. Plant tissue culture is widely used to produce clones of a plant in a method known as micropropagation...
for inducing formation of callus
Callus (cell biology)
Plant callus is a mass of undifferentiated cells derived from plant tissue for use in biological research and biotechnology. In plant biology, callus cells are those cells that cover a plant wound. To induce callus formation, plant tissues are surface sterilized and then plated onto in vitro...
(in conjunction with auxin
Auxin
Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...
) and to regenerate shoot
Shoot
Shoots are new plant growth, they can include stems, flowering stems with flower buds, and leaves. The new growth from seed germination that grows upward is a shoot where leaves will develop...
tissues from callus (with lower auxin
Auxin
Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...
concentration).
For a long time, it was believed that kinetin was an artifact produced from the deoxyadenosine residues in DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
, which degrade on standing for long periods or when heated during the isolation procedure. Therefore, it was thought that kinetin does not occur naturally, but, since 1996, it has been shown by several researchers that kinetin exists naturally in the DNA of cells of almost all organisms tested so far, including human and various plants. The mechanism of production of kinetin in DNA is thought to be via the production of furfural
Furfural
Furfural is an organic compound derived from a variety of agricultural byproducts, including corncobs, oat, wheat bran, and sawdust. The name furfural comes from the Latin word , meaning bran, referring to its usual source....
— an oxidative damage product of deoxyribose sugar in DNA — and its quenching by the adenine base's converting it into N6-furfuryladenine, kinetin.
Since 1994, kinetin has been thoroughly tested for its powerful anti-aging effects in human skin cells and other systems. At present, kinetin is one of the widely used components in numerous skin care cosmetics and cosmeceuticals, such as Valeant products kinerase . There are some reports published on other biological effects of kinetin in human beings, for example its effects as anti-platelet aggregation factor reducing thrombosis formation. In addition, it has been shown to be capable of correcting RNA mis-splicing in the disease of familial dysautonomia
Familial dysautonomia
Familial dysautonomia is a disorder of the autonomic nervous system which affects the development and survival of sensory, sympathetic and some parasympathetic neurons in the autonomic and sensory nervous system resulting in variable symptoms including: insensitivity to pain, inability to produce...
, in which exon 20 of IKBKAP is skipped instead of included in the disease, leading to insufficient levels of IKBKAP protein product as a result of frame-shift-induced nonsense-mediated decay.
History
In 1939 P. A. C. Nobécourt (Paris) began the first permanent callus culture from root explants of carrot (Daucus carota). Such a culture can be kept forever by successive transplantations onto fresh nutrient agarAgar
Agar or agar-agar is a gelatinous substance derived from a polysaccharide that accumulates in the cell walls of agarophyte red algae. Throughout history into modern times, agar has been chiefly used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture medium...
. The transplantations occur every three to eight weeks. Callus cultures are not cell cultures, since whole tissue associations are cultivated. Though many cells keep their ability to divide, this is not true for all. One reason for this is the aneuploidy
Aneuploidy
Aneuploidy is an abnormal number of chromosomes, and is a type of chromosome abnormality. An extra or missing chromosome is a common cause of genetic disorders . Some cancer cells also have abnormal numbers of chromosomes. Aneuploidy occurs during cell division when the chromosomes do not separate...
of the nuclei and the resultant unfavourable chromosome constellations.
J. van Overbeek (Rijksuniversiteit Utrecht) introduced in 1941 coconut milk as a new component of nutrient media for callus cultures. Coconut milk
Coconut milk
Coconut milk is the water that comes from the grated meat of a coconut. The colour and rich taste of the milk can be attributed to the high oil content. In many parts of the world, the term coconut milk is also used to refer to coconut water, the naturally occurring liquid found inside the hollow...
is liquid endosperm. It stimulates the embryo to grow when it is supplied with food at the same time. Results yielded from callus cultures showed that its active components stimulate the growth of foreign cells, too.
In 1954, F. Skoog
Folke K Skoog
Folke Karl Skoog was a Swedish-born American plant physiologist who was a pioneer in the field of plant growth regulators, particularly cytokinins...
(University of Wisconsin, Madison) developed a technique for the generation and culture of wound tumour tissue from isolated shoot parts of tobacco (Nicotiana tabacum
Nicotiana tabacum
Nicotiana tabacum, or cultivated tobacco, is a perennial herbaceous plant. It is found only in cultivation, where it is the most commonly grown of all plants in the Nicotiana genus, and its leaves are commercially grown in many countries to be processed into tobacco. It grows to heights between 1...
). The developing callus grows when supplied with yeast
Yeast
Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...
extract, coconut milk, or old DNA preparations. Freshly prepared DNA has no effect but becomes effective after autoclaving. This led to the conclusion that one of its breakdown products is required for cell growth and division. The substance was characterized, was given the name kinetin, and classified as a phytohormone.
Kinetin is also claimed to have dermatologic
Dermatology
Dermatology is the branch of medicine dealing with the skin and its diseases, a unique specialty with both medical and surgical aspects. A dermatologist takes care of diseases, in the widest sense, and some cosmetic problems of the skin, scalp, hair, and nails....
effects and is used in some cosmetics.