Table 4.
Summary of functions of 21 genes with significant differential expression in IBS-D rectosigmoid mucosa
| Gene Symbol | Aliases and Descriptions | Gene ID | Summary of Gene Function or Product |
|---|---|---|---|
| Neurotransmitters | |||
| P2RY4 | purinergic receptor P2Y | 5030 | G protein-coupled receptor responsive to uridine nucleotides, partially responsive to ATP, and not responsive to ADP |
| VIP | vasoactive intestinal peptide | 7432 | Encodes G protein-coupled receptor, relaxes smooth muscle, stimulates cAMP to produce intestinal secretion |
| Ion Channels | |||
| GUCA2B | guanylate cyclase activator 2B (uroguanylin) | 2981 | Gene encodes uroguanylin expressed in the stomach and intestine, functions as endogenous ligand for guanylate cyclase-C receptor increasing cyclic GMP, chloride, and water secretion |
| PDZD3 | PDZ domain-containing protein 3; alias IKEPP; PDZK2; NHERF4 | 79849 | Encodes protein-protein interaction molecules of structural proteins and the tight junction protein, zonula occludens 1; functions in sodium-hydrogen exchange (NHE3) as well as guanylyl cyclase C (GCC, or GUCY2C)-induced chloride and water secretion (through cGMP signaling that leads to cystic fibrosis transmembrane conductance regulator phosphorylation) |
| Mucosal repair, apoptosis, and cell adhesion | |||
| FN1 | fibronectin 1 | 2335 | Encodes fibronectin, a glycoprotein at the cell surface and in extracellular matrix, is involved in cell adhesion and migration processes including wound healing and host defense |
| TFF1 | trefoil factor 1 | 7031 | Gene on chromosome 21 for stable secretory proteins expressed in GI mucosa and likely protect the mucosa from insults, stabilizes mucus layer, and affects healing of epithelium. |
| RBP2 | retinol-binding protein 2 | 5948 | RBP2 is present in the small intestinal epithelium and involved in the uptake and/or intracellular metabolism of vitamin A, necessary for growth, differentiation of epithelial tissues |
| BIRC5 | baculoviral IAP repeat-containing 5 | 332 | Inhibitor of apoptosis (IAP) gene family, expression is high during fetal development, low in adult tissues. |
| Glucose metabolism | |||
| IGFBP2 | insulin-like growth factor-binding protein 2 | 3485 | Metabolism of proteins; regulation of insulin-like growth factor (IGF) transport and uptake by insulin-like growth factor binding proteins (IGFBPs) |
| ALDOB | aldolase B and C, fructose-bisphosphatases | 229 | Catalyzes the conversion of hexose (fructose-1,6-bisphosphate) to 2 trioses (glyceraldehyde 3-phosphate and dihydroxyacetone phosphate). Vertebrates have 3 aldolase isozymes A, B, and C |
| Defects in ALDOB cause hereditary fructose intolerance. | |||
| ALDOC | 230 | Gene encodes aldolase expressed specifically in the hippocampus and Purkinje cells of the brain | |
| Stress protein-related genes | |||
| HSPA1A | heat shock 70-kDa protein 1A | 3303 | Intronless genes located in the major histocompatibility complex class III region; encodes a 70-kDa heat shock protein that stabilizes existing proteins against aggregation and mediates the folding of newly translated proteins in the cytosol and in organelles |
| HSPA1B | heat shock 70-kDa protein 1B | 3304 | |
| Chemokine-related genes | |||
| CCL20 | chemokine (C-C motif) ligand 20 | 6364 | Encodes gene for protein that provides key homing signals for cells of the adaptive immune system, both proinflammatory and suppressive T cell subsets |
| C4BPA | complement component 4-binding protein α | 722 | Gene on human chromosome 1 encodes C4b-binding protein that controls activation of the complement cascade through the classical pathway |
| Immune function, defense against infections | |||
| IFI44L | interferon-induced protein 44-like | 10964 | A type I interferon-stimulated gene that encodes a protein that has modest activity against hepatitis C virus |
| IFIT3 | interferon-induced protein with tetra-tricopeptide repeats 3 | 3437 | Genes involved in expression of INF-induced genes, hallmark of host antiviral immunity |
| MX1 | myxovirus resistance protein 1 | 4599 | Encodes interferon-inducible Mx protein responsible for protection against influenza virus infection and a member of both the dynamin family and the family of large GTPases |
| Absorptive mechanisms | |||
| LCN15 | lipocalin 15 | 389812 | Gene encodes proteins with high affinity to small lipophilic molecules |
| Other functions | |||
| DUSP27 | dual specificity phosphatase 27 | 92235 | Encodes protein with role in MAPK signaling cascades |
| WDR72 | WD repeat-containing protein 72 | 256764 | Encodes a protein with seven WD40 domains. WD or β-transducin repeats typically fold together to form a circular solenoid protein domain called the WD40 domain. Mutations in amelogenesis imperfecta type IIA3 |