DFFA is a human gene whose product the DFFA gene encodes DFF45 (DNA Fragmentation Factor 45 kDa), also known as ICAD (Inhibitor of Caspase-Activated DNase). DFF45 is a 331-amino acid protein that serves as a chaperone and specific inhibitor for DFF40. Variants in DFFA have been implicated in Alzheimer's Disease (AD), Parkinson's Disease (PD), Stroke and Brain Ischemia. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.
Gene Symbol: DFFA
Gene Name: DNA Fragmentation Factor Subunit Alpha
Chromosomal Location: 1p36.22
NCBI Gene ID: 1676
Ensembl ID: ENSG00000164111
UniProt ID: O00273
DFFA encodes the 45 kDa subunit of DNA fragmentation factor (DFF), also known as inhibitor of CAD (ICAD). DFF45 acts as an inhibitor of DFF40 (CAD - Caspase-Activated DNase). Upon caspase-3 cleavage during apoptosis, DFF45 is inactivated, allowing DFF40 to translocate to the nucleus and execute DNA fragmentation 1. While DFF is primarily studied in apoptosis, its regulation is critically relevant to neuronal cell death in neurodegenerative diseases 2.
The DFFA gene encodes DFF45 (DNA Fragmentation Factor 45 kDa), also known as ICAD (Inhibitor of Caspase-Activated DNase). DFF45 is a 331-amino acid protein that serves as a chaperone and specific inhibitor for DFF40.
Mechanism:
- DFF45 binds to DFF40 in the cytoplasm, preventing its nuclease activity
- During apoptosis, caspase-3 cleaves DFF45 at specific aspartic acid residues
- Cleaved DFF45 releases active DFF40, which translocates to the nucleus
- DFF40 exhibits endonuclease activity, producing characteristic DNA ladders 1
Non-Apoptotic Functions:
- ICAD acts as a transcriptional co-activator for certain genes
- The DFF complex may participate in DNA repair pathways
In Alzheimer's disease, DFFA/DFF45 plays a complex role in neuronal death:
- Increased DFF45 cleavage in AD brain tissue correlates with neuronal loss 3
- Caspase-3 activation is elevated in vulnerable brain regions
- DFF-mediated DNA fragmentation contributes to cholinergic neuron death 4
In Parkinson's disease, DFFA contributes to dopaminergic neuron death:
- 6-OHDA and MPTP models show increased DFF45 cleavage in the substantia nigra
- Mitochondrial dysfunction leads to caspase activation and DFF40 activation 5
¶ Stroke and Brain Ischemia
DFFA is particularly relevant to ischemic brain injury:
- Cerebral ischemia rapidly activates caspase-3 and DFF in vulnerable neurons
- DFF45 knockout mice show reduced DNA fragmentation after focal cerebral ischemia 6
In ALS, DFFA contributes to motor neuron death:
- Spinal motor neurons from ALS patients show evidence of DFF activation
- SOD1 mutations enhance caspase activation and DFF-mediated DNA fragmentation
DFFA is expressed throughout the brain:
- Cortex: Pyramidal neurons in layers III and V
- Hippocampus: CA1-CA3 pyramidal neurons
- Basal Ganglia: Striatal medium spiny neurons
- Substantia Nigra: Dopaminergic neurons
- Spinal Cord: Motor neurons in the anterior horn
- Caspase-3 Inhibitors: Prevent DFF45 cleavage indirectly
- Direct DFF40 Inhibitors: Block nuclease activity
- Gene Therapy: Modulate DFFA expression levels
- Neuroprotective Compounds: Preserve DFF45 integrity
- DFF and caspase-activated DNase in apoptosis
- DNA fragmentation in neuronal apoptosis
- Apoptotic DNA degradation in neurodegeneration
- DFF activation in dopaminergic neuron death
- Neuroprotection by DFF inhibition in cerebral ischemia