Fasn Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
FASN (Fatty Acid Synthase) is a large multifunctional enzyme complex that catalyzes the de novo synthesis of long-chain fatty acids, primarily palmitate (C16:0). As a homodimer of 270 kDa subunits, FASN represents one of the largest and most complex enzyme systems in mammalian cells[1]. Each subunit contains seven catalytic domains arranged in a linear array, enabling sequential processing of substrate through each step of fatty acid synthesis.
In the brain, FASN plays crucial roles in maintaining neuronal lipid homeostasis, which is essential for synaptic function, membrane biosynthesis, myelination, and cell signaling. Dysregulation of FASN is increasingly recognized as a significant factor in the pathogenesis of neurodegenerative diseases, particularly Alzheimer's disease and Parkinson's disease[2].
FASN is a symmetrical homodimer with a complex domain organization:
β-Ketoacyl Synthase (KS): The 50 kDa N-terminal domain initiates fatty acid synthesis by condensing acetyl-CoA with malonyl-CoA. This domain contains the active site cysteine essential for acyl group transfer[3].
Malonyl/Acetyl Transferase (MAT): Transfers malonyl-CoA (the 2-carbon donor) and acetyl-CoA (the primer) to the acyl carrier protein (ACP) domain. This domain determines substrate specificity and loading kinetics.
β-Ketoacyl Reductase (KR): Reduces the β-keto group to a hydroxyl group using NADPH as the cofactor. This is the first of two reduction steps in each cycle.
β-Hydroxyacyl Dehydratase (DH): Dehydrates the β-hydroxyacyl intermediate to form a trans-Δ²-enoyl group.
Enoyl Reductase (ER): Uses NADPH to reduce the enoyl group, completing one round of two-carbon elongation.
Acyl Carrier Protein (ACP): The central phosphopantetheine-armed domain that shuttles intermediates between catalytic sites. The 4'-phosphopantetheine arm provides a flexible tether for the growing acyl chain.
Thioesterase (TE): Located at the C-terminus, this domain releases the finished fatty acid (typically palmitate) from the ACP domain when it reaches 16 carbons in length.
FASN is the central enzyme for de novo lipogenesis:
FASN catalyzes the complete synthesis of palmitate from one acetyl-CoA and seven malonyl-CoA molecules:
In the central nervous system, FASN serves critical functions:
FASN dysregulation is a prominent feature of Alzheimer's disease:
In Parkinson's disease, FASN plays complex roles:
FASN is a therapeutic target for several diseases, but CNS applications face challenges:
| Compound | IC₅₀ | Development Stage | CNS Penetration | Notes |
|---|---|---|---|---|
| Orlistat | ~1 μM | Approved (obesity) | Poor | Irreversible inhibitor, GI side effects |
| TVB-2640 | ~0.5 μM | Phase II (cancer) | Limited | First-generation clinical FASN inhibitor |
| Fasnall | ~10 μM | Preclinical | Unknown | Cerulenin analog |
| G28U | ~5 μM | Preclinical | Unknown | Multiple analogs available |
The study of Fasn Protein 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.
Chirala SS, et al.** (2003). Fatty acid synthase: structure and function. (2003). Fatty acid synthase: structure and function. 2003. ↩︎
Pihlajamaki J, et al.** (2009). FASN expression is increased in brains of patients with Alzheimer's disease. (2009). FASN expression is increased in brains of patients with Alzheimer's disease. 2009. ↩︎
Maier T, et al.** (2008). Structure of the human fatty acid synthase. (2008). Structure of the human fatty acid synthase. 2008. ↩︎
Kuhajda FP, et al.** (2000). Fatty acid synthase and cancer: new applications. (2000). Fatty acid synthase and cancer: new applications. 2000. ↩︎