Autotaxin (ATX) Assay Kits​

Autotaxin (ATX) is a 125-kDa glycoprotein that was isolated as a cell motility-stimulating factor from the culture supernatant of human melanoma cells¹⁾. ATX is a phospholipid-metabolizing enzyme that hydrolyzes lysophosphatidylcholine (LPC) to produce lysophosphatidic acid (LPA), which induces organ fibrosis²⁾.

A significant correlation between the histological stages of liver fibrosis and serum ATX activity has been reported³⁾. This correlation is thought to be due to the inhibition of ATX degradation caused by liver damage, such as fibrosis, which leads to the retention of ATX in the bloodstream and an increase in its blood concentration. As ATX levels rise, LPA levels also increase, suggesting that ATX is involved in the progression of fibrosis. While liver biopsy is the most reliable method for assessing fibrosis, it causes significant physical discomfort for patients. Therefore, there is growing interest in less invasive liver fibrosis marker tests, with ATX being considered a promising blood marker for detecting early-stage fibrosis, which is difficult to identify through imaging⁴⁾. However, caution is needed as ATX levels can decrease in patients receiving adrenal corticosteroids due to reduced production by adipose may increase in pregnant women due to placental ATX.

Lysophosphatidylcholine is hydrolyzed by the lysophospholipase D activity of ATX in the sample to form choline. The resultant choline is oxidized by the action of choline oxidase (COD) to form hydrogen peroxide. The resultant hydrogen​ peroxide oxidatively condenses N-Ethyl-N-(3-sulfopropyl)-3-methylaniline (TOPS) and 4-aminoantipyrine quantitatively​ through the action of peroxidase (POD) to produce a blue-violet pigment. The reaction is stopped by addition of the Stop​ Solution and absorbance is measured to determine ATX activity in the sample.

Figure 1. Principle of the ATX assay​

LabAssay™ ATX is a kit used for the determination of ATX in blood (serum and plasma) and cell culture supernatant. With the use of a microplate, this kit provides a convenient method for measuring ATX in ​samples.

Kit performance

1. Stracke, M. L. et al.: J. Biol. Chem., 267(4), 2524(1992).
   Identification, purification, and partial sequence analysis of autotaxin, a novel motility-stimulating protein
2. Umezu-Goto, M. et al.: J. Cell Biol., 158(2), 227(2002).
   Autotaxin has lysophospholipase D activity leading to tumor cell growth and motility by lysophosphatidic acid production
3. Ikeda, H. et al.: The official journal of Japanese Society of Laboratory Medicine, 57(5), 445(2009). (Japanese)​
   Significance of serum autotaxin activity in gastrointestinal disease​
4. “Evidence-based Clinical Guidelines for Nanalcoholic Fatty Liver Disease/Nanalcoholic Steatohepatitis” ed. by The Japanese Society of Gastroenterology, Nankodo, (2014). (Japanese)​