Table 4.

Activation of the FXYD2 promoter by HNF1Ba

Cell LineFold Activation
FXYD2Ksp-cadherinKsp-cadherin-mut
HEK293149.20 ± 7.7014.30 ± 3.101.30 ± 0.10
INS-15.00 ± 0.602.30 ± 0.301.30 ± 0.03
INS-1 (endogenous) §15.80bNot expressedNA
  • a The assay measured expression of firefly luciferase under the control of the FXYD2 or Ksp-cadherin promoter. The FXYD2/luciferase contained base pairs −2382 to −1 relative to the ATG of exon γ-a of FXYD2 (Figure 3). Ksp-cadherin contains the promoter of this kidney-specific cadherin gene from −113 to 74. Ksp-cadherin-mut is an established mutant (m3) with inactivated HNF1 binding site, as described previously.41 The fold activation refers to the increase in luciferase activity in cells treated for 24 h with 1 μg/ml tetracycline to induce HNF1B expression versus untreated cells. Data are means ± SD of six measurements involving two independent plasmid preparations. FXYD2/luciferase was activated by HNF1B in both cell lines, and in HEK292 cells the, fold activation was an order of magnitude greater that that found with Ksp-cadherin, an established transcriptional target of HNF1B.41 As expected, expression of HNF1B failed to transactivate the Ksp-cadherin with mutated HNF1B binding sites.

  • b For comparison, these data represent activation of the endogenous FXYD2 gene as assessed by previously published microarray analyses.33