Table 4.
Function of Genes Examined by Real-Time Polymerase Chain Reaction for Changes With Aging
| Name | Symbol | Aliases | Function |
| Phospholipase C–like 1 | Plcl1 | PLC-L (PLC-ϵ), PLDL | Catalyzes hydrolysis of phosphatidylinositol 4,5 biphosphate to diacylglycerol and inositol 1,4,5 triphosphate |
| Keratin, type I cytoskeletal 18 | Krt1-18 | Keratin 18 | Structural constituent of cytoskeleton that dimerizes with KRT8 |
| Cysteine and glycine-rich protein 2 | Csrp2 | Cysteine-rich protein, smooth muscle cell LIM protein | Downregulated in response to platelet-derived growth factor or cell injury, promotes smooth muscle cell proliferation and dedifferentiation |
| Keratin, type II cytoskeletal 8 | Krt2-8 | Keratin 8, cardiac autoantigen 2, 120 kDa | Keratin 8, type II, early embryonic, dimerizes with KRT1 |
| Thyrotropin-releasing hormone | Trh | Thyroliberin precursor | Regulates thyroid stimulating hormone biosynthesis in the anterior pituitary, neurotransmitter/neuromodulator in the central nervous system and peripheral nervous system |
| Endothelial cell–specific molecule 1 | Esm1 | ESM-1 secretory protein | Implications in lung endothelial cell–leukocyte interactions, induction by tumor necrosis factor (TNF)-α and IL-1β |
| Testis-specific histone H2B | Hist1h | Histone 1, H2ba, histone H2B, testis | Histone H2B family protein, nucleosome assembly activity, chromatin organization, and remodeling |
| Insulinlike growth factor–binding protein 2 | Igfbp2 | IBP-2 | Alters interaction of IGF with cell surface receptors, inhibits or stimulates growth promoting effects of IGF |
| Cadherin-22 | Cdh22 | Calcium-dependent cell adhesion proteins, sorting of heterogeneous cell types | |
| Solute carrier family 6 member 15 | Ntt73 | Solute carrier family 6 (neurotransmitter transporter), member 15, orphan transporter v7-3 | Orphan transporter |
| Carbonic anhydrase 3 | Ca3 | Reversible hydration of carbon dioxide | |
| Adiponectin | Adn | Adipocyte, C1q and collagen domain–containing protein, adipose most abundant gene transcript 1, adipocyte complement related protein of 30 kDa | Negative regulator of endothelial nuclear factor-κB and TNF-α signaling, control of fat metabolism and insulin sensitivity |
| Complement component 1, q subcomponent, receptor 1 | C1qr1 | Lymphocyte antigen 68, C1q/MBL/SPA receptor, CD93 antigen | Receptor (or element of a larger receptor complex) for C1q, mannose-binding lectin (MBL2), and pulmonary surfactant protein A (SPA) |
| Chemokine (C-X-C motif) ligand 5 | Cxcl5 | SCYB5, Neutrophil-activating peptide ENA-78 | Neutrophil activation, inflammation/injury |
| Aldehyde oxidase | Aox1 | Enzyme | |
| Signal transducer and activator of transcription 5B | Stat5b | Signal transduction and activation of transcription, activated by interleukin 2 and growth hormone | |
| Tetranectin | TNA | C-type lectin domain family 3, member B, plasminogen kringle 4–binding protein | Binds to plasminogen and isolated kringle 4, may be involved in packaging of molecules destined for exocytosis |
| Lipopolysaccharide-binding protein | LBP | Binds to lipid A moiety of bacterial lipopolysaccharides, LBP/LPS complexes interact with CD14 receptors, inflammation | |
| Chemokine (C-X-C motif) receptor 4 | Cxcr4 | CD184 antigen, leukocyte-derived seven transmembrane domain receptor, neuropeptide Y receptor Y3 | Receptor for the C-X-C chemokine CXCL12/SDF-1, involved in hematopoiesis and vascularization of the gastrointestinal tract, inflammation |
| Proprotein convertase subtilisin/kexin type 2 | Pcsk2 | NEC 2, KEX2-like endoprotease 2, prohormone convertase 2 | Release of protein hormones and neuropeptides from their precursors, generally by hydrolysis of -Lys-Arg- bonds |
| Stathmin-like 2 | Stmn2 | SCG10, superior cervical ganglion-10 protein | Role in neuronal differentiation and modulating membrane interaction with the cytoskeleton during neurite outgrowth |
| Lysozyme | Lys | 1,4-beta-N-acetylmuramidase C, lysozyme C precursor | Bacteriolytic, associated with the monocyte–macrophage system, inflammation |
| Matrix metalloproteinase 12 | MMP12 | Macrophage elastase, macrophage metalloelastase precursor | Involved in tissue injury and remodeling, elastolytic activity |
| Matrix metalloproteinase 3 | MMP3 | Matrix metallopeptidase 3, stromelysin 1, progelatinase | Degrades fibronectin; laminin; gelatins; collagen III, IV, X, and IX; and cartilage proteoglycans; activates procollagenase, inflammation/injury |
| Small inducible cytokine A2 | Scya II | CCL2, monocyte chemotactic protein, monocyte secretory protein | Attracts monocytes and basophils, augments monocyte antitumor activity, inflammation |
Note: Full gene names, abbreviations, and function of transcripts depicted in Figure 2A are shown.