EPYC (Epiphycan) Gene Review Notes
Gene Overview
- Gene: EPYC (also known as DSPG3, PG-Lb, SLRR3B)
- Protein: Epiphycan (dermatan sulfate proteoglycan 3)
- UniProt: Q99645
- Classification: Small Leucine-Rich Proteoglycan (SLRP), Class III subfamily
- Structure: 322 amino acids, ~36.6 kDa, contains 6 leucine-rich repeats (LRRs)
Core Function Summary
Epiphycan is a secreted extracellular matrix proteoglycan that functions primarily to:
1. Regulate collagen fibrillogenesis - particularly type II collagen in cartilage [PMID:8975717, deep-research-perplexity lines 139-146]
2. Organize extracellular matrix architecture - maintains ordered structure of cartilage and other connective tissues [deep-research-perplexity lines 139-146, UniProt]
3. Modulate growth factor signaling - binds and sequesters TGF-β and BMPs [deep-research-perplexity lines 154-157]
Molecular Function
- Glycosaminoglycan binding: Carries dermatan sulfate GAG chains that mediate interactions PMID:8975717
- Collagen binding: Direct binding to collagen fibrils via LRR domains regulates fibril assembly [deep-research-perplexity lines 214-219]
- Growth factor binding: Binds TGF-β isoforms and BMPs, modulating their bioavailability [deep-research-perplexity lines 154-157]
Biological Processes
- Collagen fibril organization: Controls kinetics of collagen fibril formation and limits lateral growth [deep-research-perplexity lines 139-146, 214-219]
- Bone development: Influences endochondral ossification and osteoblast function [deep-research-perplexity lines 148-151, UniProt]
- Cartilage development: Essential for articular cartilage development and growth plate organization [deep-research-perplexity lines 135-138, 161-165]
- ECM organization: Creates matrix architecture through interactions with collagen, hyaluronan, and other proteoglycans [deep-research-perplexity lines 145-146]
Cellular Localization
- Extracellular matrix: Secreted protein with N-terminal signal peptide [UniProt lines 181-182]
- Tissue distribution: Primarily cartilage, ligament, and placenta [PMID:8975717 lines 49-50, UniProt line 82]
- Developmental expression: Epiphyseal cartilage, growth plate, articular cartilage [deep-research-perplexity lines 135-138]
Structural Features
- Signal peptide: Amino acids 1-19 for secretion [UniProt lines 181-182]
- LRRNT domain: Amino acids 106-143 [UniProt lines 186-187]
- Six LRRs: Leucine-rich repeats at positions 144-310 [UniProt lines 188-199]
- GAG attachment sites: Dermatan sulfate chain at Ser-64; O-linked glycans at Thr-60 and Ser-96 [UniProt lines 203-211]
- Disulfide bonds: Two disulfide bridges (Cys118-Cys130, Cys279-Cys312) [UniProt lines 218-221]
Disease Associations
- Osteoarthritis: EPYC-deficient mice develop progressive osteoarthritis; enhanced phenotype in EPYC/biglycan double knockouts [deep-research-perplexity lines 161-169]
- Corneal dystrophies: Candidate gene for posterior amorphous corneal dystrophy (PACD) and cornea plana [deep-research-perplexity lines 168-171]
- Cancer: Upregulated in pancreatic and ovarian cancers; promotes tumor progression via PI3K/AKT signaling [deep-research-perplexity lines 174-179]
Protein Interactions
- Collagen II: Primary binding partner in cartilage [deep-research-perplexity lines 141-143]
- TGF-β family: Binds and sequesters TGF-β and BMPs [deep-research-perplexity lines 154-157]
- PLCG2 and CRK: Signaling molecules identified as interacting partners [deep-research-perplexity line 157]
Signaling Pathways
- PI3K/AKT pathway: Activated by EPYC in cancer and normal contexts [deep-research-perplexity lines 181-185]
- Focal adhesion signaling: Engages integrin-mediated signaling cascades [deep-research-perplexity lines 185-186]
- TGF-β signaling: Modulates TGF-β bioavailability and signaling activity [deep-research-perplexity lines 154-157]
Functional Redundancy
- Shows partial functional redundancy with other SLRPs (particularly biglycan)
- Double EPYC/biglycan knockouts have more severe osteoarthritis than single knockouts [deep-research-perplexity lines 161-165, 194-199]
- Tissues upregulate other SLRPs (asporin, fibromodulin, lumican) when EPYC is deleted [deep-research-perplexity lines 163-164]
PANTHER Family
- Family: PTHR46269 - EPIPHYCAN-RELATED
- Subfamily: PTHR46269:SF3 - EPIPHYCAN
- 15 reviewed protein members across species [fetch-gene output]
Key References
- PMID:8975717 - Original characterization of human DSPG3/EPYC PMID:8975717
- Deep research file contains 46 citations covering structure, function, disease associations