Loss of Fnip1 synergizes with loss of TSC1 resulting in accelerated PKD and mTOR activation.

<p>(A) Kidney-to-brain ratio graph comparing double null (<i>Tsc1</i>^<i>fl/fl</i><i>Mb1</i>Cre⁺<i>Fnip1</i>^<i>-/-</i>), <i>Fnip1</i>^<i>-/-</i> (<i>Fnip1</i>^<i>-/-</i><i>Tsc1</i>^<i>fl/+</i> <i>Mb1</i>Cre-), <i>Tsc1</i> null (<i>Fnip1</i>^<i>-/+</i> <i>Tsc1</i>^<i>fl/fl</i><i>Mb1</i>Cre⁺), and heterozygous (<i>Fnip1</i>^<i>-/+</i> <i>Tsc1</i>^<i>fl/+</i> <i>Mb1Cre</i>^-) mice at 5 weeks of age, showing an increase in kidney size of double null mice at an early age. (B) Representative histology image of <i>Tsc1</i>^<i>fl/fl</i> <i>Mb1</i>Cre⁺<i>Fnip1</i>^<i>-/-</i> double null mice showing the development of severe polycystic kidney disease at 5 weeks of age. (C) Kaplan Meier survival graph of <i>Tsc1</i>^<i>fl/fl</i><i>Mb1</i>Cre⁺<i>Fnip1</i>^<i>-/-</i> double null and <i>Tsc1</i>^<i>fl/+</i><i>Mb1</i>Cre⁺<i>Fnip1</i>^<i>-/-</i> mice. Double-null mice develop PKD very early in life, indicating that loss of <i>Fnip1</i> in <i>Tsc1</i> null mice greatly accelerates the onset of PKD relative to <i>Tsc1</i> loss alone. (D) Immunoblots of proteins isolated from whole kidney lysates derived from 5 week-old wildtype, <i>Tsc1</i>^<i>-/-</i>, and <i>Tsc1</i>^<i>-/-</i><i>Fnip1</i>^<i>-/-</i> blots showing increased p-Erk, p-S6R, and p-4E-BP in <i>Tsc1</i>^<i>-/-</i> <i>Fnip1</i>^<i>-/-</i> kidney tissue compared to <i>Tsc1</i>^<i>-/-</i> and WT mice indicating hyperactivation of the mTORC1 and Erk pathways. p-AMPK is decreased in double null mice relative to <i>Tsc1</i>^<i>-/-</i> and WT mice, suggesting decreased AMPK activation. (n = 3 each genotype, p-values are shown).