Testican is a type of
proteoglycan. Testican-1 is a highly conserved, multidomain proteoglycan that is most prominently expressed in the
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
of the brain, and is upregulated in activated
astroglial cells of the cerebrum. Several functions of this gene product have now been demonstrated in
vitro
Vitro is the largest glass producer in Mexico and one of the world's largest organizations in the glass industry. Founded in 1909 in Monterrey, Mexico, this corporation has 30 subsidiaries in Mexico, United States, Brazil, Colombia, Bolivia, Cos ...
including membrane-type matrix
metalloproteinase
A metalloproteinase, or metalloprotease, is any protease enzyme whose catalytic mechanism involves a metal. An example is ADAM12 which plays a significant role in the fusion of muscle cells during embryo development, in a process known as myo ...
inhibition,
cathepsin L inhibition, and low-affinity calcium binding. The purified gene product has been shown to inhibit cell attachment and neurite extensions in culture. Functions of testican in vivo have yet to be demonstrated in knockout mice or other models. Testican has been shown to carry substantial amounts of
chondroitin
A chondroitin is a chondrin derivative.
Types include:
* Chondroitin sulfate
* Dermatan sulfate
Chondroitin as a supplement is now commonly used (often in combination with glucosamine) in treating the joint disease of osteoarthritis. In contrast ...
sulfate as well as other
oligosaccharides
An oligosaccharide (/ˌɑlɪgoʊˈsækəˌɹaɪd/; from the Greek ὀλίγος ''olígos'', "a few", and σάκχαρ ''sácchar'', "sugar") is a saccharide polymer containing a small number (typically two to ten) of monosaccharides (simple suga ...
, but the biological significance of these embellishments is not yet known.
In humans there are three testicans:
*
SPOCK1 (Testican 1)
*
SPOCK2 (Testican 2)
*
SPOCK3 (Testican 3)
Medicinal Roles
Testican-1 is known to play a role in lapatinib resistance, which is a drug used to treat HER2-positive gastric cancer.
Testican-1 is involved in the pathway for this drug, and leads to drug resistance when upregulated.
When testican-1 levels are artificially reduced, sensitivity towards lapatinib was once again increased.
This shows the potential for future use in combatting drug resistance.
Testican-1 has also shown to be useful when studying
sepsis
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
in patients.
A study revealed that patients with more advanced sepsis exhibited higher levels of testican-1.
This is useful in determining the severity of sepsis in a clinical setting and could allow healthcare professionals to formulate a better treatment plan.
References
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