What is DHFR gene?
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What is DHFR gene?
DHFR is an important folate cycle enzyme required for nucleic acid synthesis as well as homocysteine remethylation, suggesting that DHFR polymorphisms may play a role in cancer susceptibility as well. It is possible that similarly to MTHFR, the DHFR gene variations may play a dual role.
What is DHFR and why is it important?
Dihydrofolate reductase is a small enzyme that plays a supporting role, but an essential role, in the building of DNA and other processes. It manages the state of folate, a snaky organic molecule that shuttles carbon atoms to enzymes that need them in their reactions.
What does DHFR stand for?
Dihydrofolate reductase
Dihydrofolate reductase, or DHFR, is an enzyme that reduces dihydrofolic acid to tetrahydrofolic acid, using NADPH as electron donor, which can be converted to the kinds of tetrahydrofolate cofactors used in 1-carbon transfer chemistry. In humans, the DHFR enzyme is encoded by the DHFR gene.
Is DHFR a protein?
DHFR is a relatively small protein with a large active site in which DHF binds adjacent to the cofactor, NADPH, in a pocket buried deep within the enzyme.
How does the DHFR system work?
The DHFR enzyme catalyzes the conversion of folate to tetrahydrofolate (Figure 1). This precursor is necessary for the de novo synthesis of purines, pyrimidines, and glycine (Goeddel, 1990). Methotrexate is a drug which is similar (i.e., an analog) to folate.
What is the primary inhibitor of DHFR?
Methotrexate inhibits DHFR with a high affinity, thus reducing the amount of tetrahydrofolates required for the synthesis of pyrimidine and purines.
Should I take folic acid with methotrexate?
No. Large doses of MTX are used to treat some cancers, and the drug’s anti-cancer activity results from its interference with folate. So cancer patients taking methotrexate should not take supplemental folic acid.
How does methotrexate interfere with DHFR?
The inhibition of DHFR by folate antagonists (methotrexate) results in a deficiency in the cellular pools of thymidylate and purines and thus in a decrease in nucleic acid synthesis. Therefore, methotrexate interferes with DNA synthesis, repair, and cellular replication.
What is DHFR selection?
DHFR is used as a selection marker for cells that have successfully integrated the vector. Thus, CHO cells that have successfully integrated the expression vector for the drug of interest will have also integrated the dhfr gene, and will survive in medium deficient in GHT.
Why is DHFR important in drug discovery?
From a medicinal chemistry perspective, the ubiquitous enzyme DHFR is of particular interest since it is essential for folate metabolism and purine and thymidylate synthesis in cell proliferation. Poor DHFR activity causes tetrahydrofolate deficiency and cell death [15].
Is MSX toxic?
Methionine sulfoximine is highly toxic to dogs, ferrets, cats, and rabbits.
What happens when DHFR is inhibited?
The synthesis of folates in both eukaryotic and prokaryotic cells is strictly dependent on the activities of two enzymes: DHFR and dihydrofolate synthase (DHFS), whose inhibition leads to cell death.
What are DHFR inhibitors?
A dihydrofolate reductase inhibitor (DHFR inhibitor) is a molecule that inhibits the function of dihydrofolate reductase, and is a type of antifolate. Since folate is needed by rapidly dividing cells to make thymine, this effect may be used to therapeutic advantage.
What is MSX in cell culture?
However, most Chinese Hamster Ovary (CHO) cell production lines contain endogenous GS, and Methionine Sulfoximine (MSX) is required to inhibit excess GS activity resulting from expression of the endogenous gene and achieve adequate selection.
Can methotrexate affect your eyes?
Methotrexate-related ocular toxicities consist of peri-orbital edema, ocular pain, blurred vision, photophobia, conjunctivitis, blepharitis, decreased reflex tear secretion87 and non-arteritic ischemic optic neuropathy.
