| TP53-Induced Glycolysis and Apoptosis Regulator | |
|---|---|
| Gene Symbol | TIGAR |
| Full Name | TP53 induced glycolysis and apoptosis regulator |
| Chromosome | 12p15 |
| NCBI Gene ID | 2063 |
| OMIM | 610335 |
| Ensembl ID | ENSG00000148231 |
| UniProt ID | Q9Y2H7 |
| Associated Diseases | Amyotrophic Lateral Sclerosis, Parkinson's Disease, Cancer |
TIGAR (TP53-Induced Glycolysis and Apoptosis Regulator) is a gene encoding a bifunctional enzyme with fructose-2,6-bisphosphatase activity. Originally discovered as a p53-regulated gene, TIGAR functions as a metabolic regulator that directs glucose flux between glycolysis and the pentose phosphate pathway (PPP). This dual function makes TIGAR a critical regulator of cellular metabolism, redox balance, and cell survival under stress conditions. In the nervous system, TIGAR plays important roles in neuronal metabolism, stress responses, and has been implicated in the pathogenesis of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS)[1].
TIGAR was identified as a transcriptional target of the tumor suppressor protein p53, linking cellular stress responses to metabolic regulation. The protein possesses enzymatic activity distinct from its name suggests—it is not merely an "apoptosis regulator" but rather a metabolic enzyme whose downstream effects influence cell survival decisions. By controlling the levels of fructose-2,6-bisphosphate (F2,6BP), a potent allosteric activator of glycolysis, TIGAR determines whether glucose is metabolized through glycolysis for energy production or shunted into the pentose phosphate pathway for nucleotide synthesis and NADPH generation[2].
The discovery of TIGAR mutations in patients with amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases has sparked significant research interest in understanding its normal functions in neurons and how dysregulation contributes to disease pathogenesis.
TIGAR belongs to the F2,6BPase family of enzymes, which includes:
TIGAR hydrolyzes fructose-2,6-bisphosphate to fructose-6-phosphate and inorganic phosphate:
This reaction reduces intracellular F2,6BP levels, decreasing PFK-1 activity and glycolytic flux while favoring PPP flux.
By modulating F2,6BP levels, TIGAR controls the balance between:
In neurons, TIGAR functions as a metabolic stress sensor:
TIGAR provides neuroprotection through:
TIGAR influences autophagy through:
TIGAR affects mitochondrial homeostasis:
TIGAR mutations are associated with ALS pathogenesis:
| Variant | Effect | Mechanism |
|---|---|---|
| R192H | Loss of function | Reduced phosphatase activity |
| R234W | Impaired regulation | Altered metabolic response |
| Various rare variants | Variable | Modified enzyme kinetics |
Pathogenic Mechanisms:
TIGAR is implicated in PD through:
In AD pathophysiology:
While TIGAR is protective in neurons, dysregulated expression in cancer:
The study of Tigar Tp53 Induced Glycolysis And Apoptosis Regulator has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.