| Presenilin-2 (PSEN2) | |
|---|---|
| Gene | PSEN2 |
| UniProt | P49810 |
| PDB | 4UJK, 4UIS |
| Mol. Weight | 44-50 kDa (holoprotein); ~20 kDa (N-terminal fragment); ~22 kDa (C-terminal fragment) |
| Localization | Endoplasmic reticulum, mitochondria, Golgi apparatus, lysosomes |
| Family | Presenilin family; aspartic protease family |
| Chromosome | 1q42.13 |
| Isoforms | Isoform 1 (full-length), Isoform 2, Isoform 3 |
| Diseases | Alzheimer's Disease, Familial AD |
Presenilin-2 (PSEN2) is a homolog of presenilin-1 (PSEN1) and serves as an alternative catalytic subunit of the gamma-secretase complex. Like PSEN1, pathogenic mutations in PSEN2 cause familial Alzheimer's disease (FAD), though with a later age of onset and less aggressive phenotype compared to PSEN1 mutations.
Presenilin-2 (PSEN2) is encoded by the PSEN2 gene located on chromosome 1q42.13. It is a 448-amino acid multipass transmembrane protein with high homology to PSEN1 (~60% amino acid identity). PSEN2 can substitute for PSEN1 in the gamma-secretase complex, though with altered substrate specificity and cleavage efficiency [1].
PSEN2 contains eight transmembrane domains (TMDs) with two essential aspartate residues (D263 and D366) in TMDs 6 and 7 that form the active site of the protease.
| Feature | PSEN1 | PSEN2 |
|---|---|---|
| Amino acids | 467 | 448 |
| Chromosome | 14q24.3 | 1q42.13 |
| Expression | High in neurons | Lower, more widespread |
| Subcellular localization | ER, Golgi | ER, mitochondria |
| Substrate affinity | Higher for APP | Modified specificity |
PSEN2 functions as the catalytic subunit of gamma-secretase, similar to PSEN1. However, PSEN2-containing complexes show:
PSEN2 has unique functions independent of gamma-secretase:
PSEN2 plays important roles in lysosomal proteolysis:
Over 40 pathogenic mutations in PSEN2 have been identified, causing familial AD with:
The PSEN2 N141I mutation (Volga German pedigree) was one of the first identified and remains the most studied [2].
PSEN2 mutations contribute to AD through:
PSEN2 expression and variants may influence sporadic AD risk:
PSEN2-containing complexes respond differently to gamma-secretase modulators (GSMs):
Unique PSEN2 functions suggest therapeutic opportunities:
PSEN2 fragments in cerebrospinal fluid may serve as biomarkers:
PSEN2 interacts with:
| Partner | Function | Reference |
|---|---|---|
| Nicastrin | Gamma-secretase complex | [3] |
| APH1 | Complex stability | [4] |
| PEN2 | Autocleavage | [5] |
| VDAC1 | Mitochondrial channel | [6] |
| Bcl-2 | Apoptosis regulation | [7] |
| Cathepsin D | Lysosomal protease | [8] |
PSEN2 knockout mice show:
PS2APP mice (PSEN2 x APP transgenic):
| Feature | PSEN1 | PSEN2 |
|---|---|---|
| FAD mutations | ~300 | ~40 |
| Age of onset | ~45 years | ~58 years |
| Phenotype severity | More severe | Milder |
| Brain expression | Neuron-enriched | More widespread |
| Substrate specificity | Broader | Narrower |
| Mitochondrial role | Minor | Major |
The study of Presenilin 2 (Psen2) 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.