TP53-inducible glycolysis and apoptosis regulator

Protein involved in cellular metabolism and apoptosis

Diagram of the human TP53-inducible glycolysis and apoptosis regulator (TIGAR) protein.

The TP53-inducible glycolysis and apoptosis regulator (TIGAR) is a protein that plays a crucial role in cellular metabolism and the regulation of apoptosis. It is encoded by the C12orf5 gene in humans and is a target of the tumor protein p53 (TP53), a well-known tumor suppressor protein. TIGAR functions primarily by modulating the levels of fructose-2,6-bisphosphate in cells, thereby influencing the glycolytic pathway and protecting cells from oxidative stress.

Function

TIGAR acts as a fructose-2,6-bisphosphatase, which reduces the levels of fructose-2,6-bisphosphate, a potent activator of phosphofructokinase-1 (PFK-1), a key enzyme in the glycolytic pathway. By decreasing fructose-2,6-bisphosphate levels, TIGAR effectively downregulates glycolysis and shifts cellular metabolism towards the pentose phosphate pathway (PPP). This shift enhances the production of NADPH, a critical reducing agent that helps in detoxifying reactive oxygen species (ROS) and thus protects cells from oxidative damage.

Role in Apoptosis

TIGAR's ability to modulate cellular metabolism has significant implications for apoptosis, the programmed cell death process. By reducing oxidative stress, TIGAR can inhibit apoptosis, thereby promoting cell survival under conditions of stress. This function is particularly important in the context of cancer, where TIGAR expression can contribute to the survival of cancer cells by protecting them from oxidative damage and apoptosis.

Regulation

The expression of TIGAR is directly regulated by the tumor suppressor protein p53. Under conditions of cellular stress, such as DNA damage, p53 is activated and can induce the expression of TIGAR. This induction is part of the broader role of p53 in maintaining cellular homeostasis and preventing tumorigenesis by regulating various genes involved in cell cycle arrest, DNA repair, and apoptosis.

Clinical Significance

Given its role in modulating metabolism and apoptosis, TIGAR has been implicated in various diseases, particularly cancer. Overexpression of TIGAR has been observed in several types of cancer, where it may contribute to tumor progression by enhancing cell survival and resistance to chemotherapy. As such, TIGAR represents a potential target for therapeutic intervention in cancer treatment.

Related pages

• Tumor protein p53
• Apoptosis
• Glycolysis
• Pentose phosphate pathway
• Reactive oxygen species