Figure 1.

HL-1 cells express TRs and exhibit T₃-dependent silencing of PLB mRNA and protein expression. A, Total RNA was extracted from HL-1 cells and then assayed by semiquantitative RT-PCR using primers specific for TRα1, TRβ1, or β-actin. As a negative control, reverse transcriptase (RT) was omitted as indicated. B, T₃ inhibits PLB mRNA expression. HL-1 cells cultured with or without T₃ (1 μm) for 24 h were analyzed by RT-PCR using primers specific for PLB or β-actin. The PCR signals were quantitated using by gel documentation, normalized against β-actin expression, and then displayed graphically. Error bars represent the ±sd calculated from three separate experiments. C, Whole-cell lysate was prepared from HL-1 cells cultured with or without T₃ (1 μm) for 72 h and then probed by immunoblot with antibodies against PLB, SERCA2a, or α-tubulin.