Klotho- and beclin 1-driven autophagy extends life. We examined the role of
beclin 1 in modifying
acute kidney injury (AKI) and whether
beclin 1 mediates Klotho's known renoprotective action in AKI. AKI was induced by
ischemia-reperfusion injury in mice with different levels of autophagy activity by genetic manipulation: wild-type (WT) mice with normal
beclin 1 expression and function, mice with normal
beclin 1 levels but high activity through knockin of gain-of-function mutant
beclin 1 (Becn1F121A), mice with low
beclin 1 levels and activity caused by heterozygous global deletion of
beclin 1 (Becn1+/-), or mice with extremely low
beclin 1 activity from knockin of the mutant constitutively active
beclin 1 inhibitor Bcl-2 (Bcl2AAA). Klotho was increased by transgenic overexpression (Tg-Kl) or recombinant Klotho
protein administration. After
ischemia-reperfusion injury, Becn1F121A mice (high autophagy) had milder AKI and Becn1+/- and Bcl2AAA mice (low autophagy) had more severe AKI than WT mice. Tg-Kl mice had milder AKI, but its renoprotection was partially attenuated in Becn1+/-;Tg-Kl mice and was significantly reduced, although not completely abolished, in Bcl2AAA;Tg-Kl mice. Recombinant Klotho
protein conferred more renoprotection from AKI in WT mice than in Becn1+/- or Bcl2AAA mice. Klotho reduced
beclin 1/Bcl-2
protein complexes and increased autophagy activity, but this effect was less prominent in mice or cells with Bcl2AAA. Transfected Bcl2AAA or Becn1F123A decreased or increased autophagy activity and rendered cells more susceptible or more resistant to oxidative cytotoxicity, respectively. In conclusion,
beclin 1 confers renoprotection by activating autophagy. Klotho protects the kidney partially via disruption of
beclin 1/Bcl-2 interactions and enhancement of autophagy activity.