Table 1.
Transcription factor (TF) elements used for luciferase TF activity constructs, each of them known to activate relevant chondrocyte signaling pathways.
| Pathway | TF(s) | TF Element (Abbreviation Construct) | Positive Control | References |
|---|---|---|---|---|
| MAPK/JNK | c-FOS:c-JUN | Activator Protein 1 response element (AP1) | FCS (20%) | [36,37,38,39] |
| SOX9 | SOX9 | SRY-box transcription factor 9 response element (SOX9) | Forskolin (10 µM) | [40,41,42] |
| NFκB | NFκB:p65 | Nuclear factor κ B response element (NFκB) | IL-1β (1 ng/mL) | [43,44,45] |
| Notch | CSL | CBF1/RBPJκ/Suppressor of Hairless/Lag-1 response element (CSL) | FCS (20%) | [46,47,48,49] |
| cAMP/PKA | CREB | Cyclic AMP response element (CRE) | Forskolin (10 µM) | [41,50,51] |
| Glucocorticoid signaling | Glucocorticoid receptor | Glucocorticoid receptor response element (GRE) | Dexamethasone (10 µM) | [50,52,53,54] |
| TGF-β | SMAD3:SMAD4 | SMAD binding element (SBE) | TGF-β1 (1 ng/mL) | [8,9,55] |
| Wnt | TCF/LEF | T-cell factor/lymphoid enhancer factor family response element (TCF/LEF) | Wnt3a (200 ng/mL) | [51,56,57] |
| INF-α | STAT1:STAT2 | Interferon-stimulated response element (ISRE) | IFN-α (100 ng/mL) | [58,59] |
| IL-6 | STAT3:STAT3 | Sis-inducible element (SIE) | IL-6 (10 ng/mL) | [55,60,61,62] |
| MAPK/ERK | ELK-1:SRF | Serum response element (SRE) | FCS (20%) | [63,64] |
| RhoA | SRF | Serum response factor (SRF) | FCS (20%) | [63,65] |
| Oxidative stress | NRF2 | Antioxidant response element (ARE) | H2O2 (50 µM) | [66,67,68] |
| Calcium/calcineurin: hyperosmotic signaling | NFAT5 | Nuclear factor of activated T-cells 5 response element (NFAT5) | +100 milliosmole | [69,70,71] |
| PPARγ | PPARγ | Peroxisome Proliferator activated receptor-γ response element (PPRE) | Rosiglitazone (20 µM) | [72,73,74] |