Hyaluronan synthase
Encyclopedia
Hyaluronan synthases are membrane-bound enzymes which use UDP-α-N-acetyl-D-glucosamine and UDP-α-D-glucuronate as substrates to produce the glycosaminoglycan
hyaluronan
at the cell surface and extrude it through the membrane into the extracellular
space.
, HAS2
and HAS3
. Each of these isoforms resides at a different chromosome location and has been cloned. Two of the main differences between the isoforms are the chain length of the hyaluronan
molecules that they produce and the ease with which they can be released from the cell surface. When mammalian cells are stimulated by changes in their immediate environment (cytokines, extracellular matrix
proximities), the HAS isoforms respond differently and appear to be under different control mechanisms.
During the development of the embryo
, each isoform is uniquely expressed, both spatially and temporally.
of the cancer cells. During the processes of intravasation or extravasation, the interaction of HAS produced HA with receptors such as CD44 or RHAMM promote the cell changes that allow for the cancer cells to infiltrate the vascular or lymphatic systems. While traveling in these systems, HA produced by HAS protects the cancer cell from physical damage. Finally, in the formation of a metastatic lesion, HAS produces HA to allow the cancer cell to interact with native cells at the secondary site and to produce a tumor for itself.
Increased HA production by cancer cells increases invasive capacity. HA's interaction with CD44 activates focal adhesion kinase (FAK), an important molecule in the process of cell motility by coordinating dissolution of the focal adhesions at the leading edge of the cell and formation at the lagging edge. Another signaling pathway activated by HA's interaction with CD44 is the Akt pathway which leads to expression of osteopontin, a molecule which can stimulate cell migration. The HA produced by HAS also has been suggested to protect the cancer cell from physical damage while in the circulatory or lymphatic systems. This role of HA has been shown in other cell types, but has not yet been researched in cancer cells. The HA produced by HAS up-regulates secretion of various MMPs, proteolytic enzymes that are involved in many stages of the metastatic cascade. Research has shown that the different HASs may impact the metastatic steps in different ways based on the molecular weight and amount of HA they produce.
Glycosaminoglycan
Glycosaminoglycans or mucopolysaccharides are long unbranched polysaccharides consisting of a repeating disaccharide unit. The repeating unit consists of a hexose or a hexuronic acid, linked to a hexosamine .-Production:Protein cores made in the rough endoplasmic reticulum are posttranslationally...
hyaluronan
Hyaluronan
Hyaluronan is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues...
at the cell surface and extrude it through the membrane into the extracellular
Extracellular
In cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...
space.
Isoforms
There are three mammalian hyaluronan synthases described to date - HAS1HAS1
Hyaluronan synthase 1 is an enzyme that in humans is encoded by the HAS1 gene.-Structure:Hyaluronan or hyaluronic acid is a high molecular weight unbranched polysaccharide synthesized by a wide variety of organisms from bacteria to mammals, and is a constituent of the extracellular matrix...
, HAS2
HAS2
Hyaluronan synthase 2 is an enzyme that in humans is encoded by the HAS2 gene.-Further reading:...
and HAS3
HAS3
Hyaluronan synthase 3 is an enzyme that in humans is encoded by the HAS3 gene.-Further reading:...
. Each of these isoforms resides at a different chromosome location and has been cloned. Two of the main differences between the isoforms are the chain length of the hyaluronan
Hyaluronan
Hyaluronan is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues...
molecules that they produce and the ease with which they can be released from the cell surface. When mammalian cells are stimulated by changes in their immediate environment (cytokines, extracellular matrix
Extracellular matrix
In biology, the extracellular matrix is the extracellular part of animal tissue that usually provides structural support to the animal cells in addition to performing various other important functions. The extracellular matrix is the defining feature of connective tissue in animals.Extracellular...
proximities), the HAS isoforms respond differently and appear to be under different control mechanisms.
During the development of the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
, each isoform is uniquely expressed, both spatially and temporally.
- HAS2 is probably the most important synthase at this time as mice lacking the ability to express HAS2 (knock-out mice) die at mid-gestationGestationGestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
, - HAS1 or HAS3 knock-out mice show no effect on foetal development,.
Role in Cancer Metastasis
HAS can play roles in all of the stages of cancer metastasis. By producing anti-adhesive HA, HAS can allow tumor cells to release from the primary tumor mass and if HA associates with receptors such as CD44, the activation of Rho GTPases can promote EMTEpithelial-mesenchymal transition
Epithelial-mesenchymal transition or transformation is a hypothesized program of development of biological cells characterized by loss of cell adhesion, repression of E-cadherin expression, and increased cell mobility...
of the cancer cells. During the processes of intravasation or extravasation, the interaction of HAS produced HA with receptors such as CD44 or RHAMM promote the cell changes that allow for the cancer cells to infiltrate the vascular or lymphatic systems. While traveling in these systems, HA produced by HAS protects the cancer cell from physical damage. Finally, in the formation of a metastatic lesion, HAS produces HA to allow the cancer cell to interact with native cells at the secondary site and to produce a tumor for itself.
Increased HA production by cancer cells increases invasive capacity. HA's interaction with CD44 activates focal adhesion kinase (FAK), an important molecule in the process of cell motility by coordinating dissolution of the focal adhesions at the leading edge of the cell and formation at the lagging edge. Another signaling pathway activated by HA's interaction with CD44 is the Akt pathway which leads to expression of osteopontin, a molecule which can stimulate cell migration. The HA produced by HAS also has been suggested to protect the cancer cell from physical damage while in the circulatory or lymphatic systems. This role of HA has been shown in other cell types, but has not yet been researched in cancer cells. The HA produced by HAS up-regulates secretion of various MMPs, proteolytic enzymes that are involved in many stages of the metastatic cascade. Research has shown that the different HASs may impact the metastatic steps in different ways based on the molecular weight and amount of HA they produce.