Kunjithapatham R, Ganapathy-Kanniappan S. GAPDH with NAD
+-binding site mutation competitively inhibits the wild-type and affects glucose metabolism in cancer.
Biochim Biophys Acta Gen Subj 2018;
1862:2555-2563. [PMID:
30077773 DOI:
10.1016/j.bbagen.2018.08.001]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/26/2018] [Accepted: 08/01/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND
Rapid utilization of glucose is a metabolic signature of majority of cancers, hence enzymes of the glycolytic pathway remain attractive therapeutic targets. Recent reports have shown that targeting the glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), an abundant, ubiquitous multifunctional protein frequently upregulated in cancer, affects cancer progression. Here, we report that a catalytically-deficient mutant-GAPDH competitively inhibits the wild-type, and disrupts glucose metabolism in cancer cells.
METHODS
Using site-directed mutagenesis, the human GAPDH clone was mutated at one of the NAD+-binding sites, (i.e.) arginine (R13) and isoleucine (I14) to glutamine (Q13) and phenylalanine (F14), respectively. The inhibitory role of the mutant-GAPDH, and its effect on energy metabolism and cancer phenotype was determined using in vitro and in vivo models of cancer.
RESULTS
The enzymatically-dysfunctional mutant-GAPDH competitively inhibited the wild-type GAPDH in a cell-free system. In cancer cells, ectopic expression of the mutant-GAPDH, but not the wild-type, inhibited the glycolytic capacity of cellular-GAPDH, and led to the induction of metabolic stress accompanied by a sharp decline in glucose-uptake. Furthermore, expression of mutant-GAPDH affected cancer growth in vitro and in vivo. Mechanistically, structural analysis by bioinformatics revealed that the mutations at the NAD+-binding site altered the solvent-accessibility that perhaps affected the functionality of mutant-GAPDH.
CONCLUSION
Mutant-GAPDH affects the enzymatic function of cellular-GAPDH and disrupts energy metabolism.
GENERAL SIGNIFICANCE
Our findings demonstrate that a minimal mutation at the NAD+-binding site is sufficient to generate a competitive but dysfunctional GAPDH, and its ectopic expression inhibits the wild-type to disrupt glycolysis.
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