Figure 7.

Signaling and transcription components of Ucp1 regulation. The number below each regulatory factor refers to the ratio of expression in A/J vs. B6 mice. Except for the β3-adrenergic receptor, expression is higher in B6 than A/J at either the mRNA or protein levels; however, these strain-dependent differences all occur downstream of PKA. Most important is that none of the strain-dependent differences for the regulatory factors approaches the difference observed for Ucp1 at either the mRNA or protein levels. This suggests that synergy among the regulatory pathways occurs with a changing cast of factors depending on the genotypes of Iba genes and environmental conditions. NC = No difference in expression between A/J and B6.