| ALDH1L1 Protein | |
|---|---|
| Protein Name | Aldehyde Dehydrogenase 1 Family Member L1 |
| Gene | ALDH1L1 |
| UniProt ID | O95392 |
| Molecular Weight | ~99 kDa |
| Subcellular Localization | Cytoplasm |
| Protein Family | Aldehyde dehydrogenase family |
| Expression | High in liver, [astrocytes](/entities/astrocytes) in brain |
ALDH1L1 (Aldehyde Dehydrogenase 1 Family Member L1) is a cytosolic enzyme that plays a critical role in folate metabolism and one-carbon unit transfer. It serves as a specific marker for astrocytes in the central nervous system and is involved in converting 10-formyltetrahydrofolate to tetrahydrofolate, thereby regulating intracellular folate pools and one-carbon metabolism.[1]
ALDH1L1 is a multifunctional enzyme comprising three distinct domains:
The enzyme forms a homotetramer in solution, with each subunit containing the three catalytic domains arranged in a modular fashion. The active site contains a conserved catalytic cysteine (Cys-296) essential for dehydrogenase activity.[2]
ALDH1L1 is a central regulator of folate-dependent one-carbon metabolism:
The enzyme catalyzes the irreversible conversion of 10-formyltetrahydrofolate (10-formyl-THF) to tetrahydrofolate (THF) and formate, effectively shuttleing one-carbon units from folate into the formate pool. This reaction is crucial for:
ALDH1L1 is highly expressed in astrocytes throughout the brain and serves as a reliable histological marker for astrocytic populations. Its expression is upregulated during reactive astrocytosis, making it useful in neuropathological studies.[3]
By regulating the 10-formyl-THF/THF balance, ALDH1L1 influences:
ALDH1L1 expression is significantly downregulated in Alzheimer's disease brains, particularly in regions affected by neurodegeneration such as the hippocampus and prefrontal cortex.[4] This reduction may contribute to:
Therapeutic approaches targeting folate metabolism, including supplementation with folate and B vitamins, have shown some promise in slowing cognitive decline in AD patients with elevated homocysteine.[6]
ALDH1L1 is altered in ALS motor cortex and spinal cord, where astrocytic dysfunction plays a key role in disease progression. The enzyme's downregulation may contribute to:
ALDH1L1 functions as a tumor suppressor in several cancers, including hepatocellular carcinoma, pancreatic cancer, and glioblastoma. Its expression is often lost during tumorigenesis, and re-expression can reduce tumor growth through:
ALDH1L1 represents a potential therapeutic target in both neurodegeneration and cancer. In neurodegeneration, enhancing ALDH1L1 activity or folate metabolism may be beneficial, while in cancer, inhibiting the enzyme may selectively target rapidly dividing cells.
ALDH1L1 autoantibodies have been detected in some cancer patients, suggesting potential as a paraneoplastic marker. In the brain, ALDH1L1 expression changes may serve as a biomarker for astrocytic pathology.
[1] ALDH1L1: A folate enzyme with multiple functions (2009)
[2] Crystal structure of human ALDH1L1 (2012)
[3] A transcriptome database for astrocytes, neurons, and oligodendrocytes (2008)
[4] Folate metabolism dysfunction in neurodegenerative disease (2016)
[5] Homocysteine as a risk factor for cognitive impairment (2008)
[6] B vitamins and cognitive decline: HOMAGE study (2019)