AIMS: Chaperone-mediated autophagy (CMA) is a selective mechanism for the 
degradation of soluble cytosolic proteins bearing the sequence KFERQ. These 
proteins are targeted by chaperones and delivered to lysosomes where they are 
translocated into the lysosomal lumen and degraded via the lysosome-associated 
membrane protein type 2A (LAMP-2A). Mutations in LAMP2 that inhibit autophagy 
result in Danon disease characterized by hypertrophic cardiomyopathy. The 
ryanodine receptor type 2 (RyR2) plays a key role in cardiomyocyte 
excitation-contraction and its dysfunction can lead to cardiac failure. Whether 
RyR2 is degraded by CMA is unknown.
METHODS AND RESULTS: To induce CMA, cultured neonatal rat cardiomyocytes were 
treated with geldanamycin (GA) to promote protein degradation through this 
pathway. GA increased LAMP-2A levels together with its redistribution and 
colocalization with Hsc70 in the perinuclear region, changes indicative of CMA 
activation. The inhibition of lysosomes but not proteasomes prevented the loss 
of RyR2. The recovery of RyR2 content after incubation with GA by siRNA 
targeting LAMP-2A suggests that RyR2 is degraded via CMA. In silico analysis 
also revealed that the RyR2 sequence harbours six KFERQ motifs which are 
required for the recognition Hsc70 and its degradation via CMA. Our data suggest 
that presenilins are involved in RyR2 degradation by CMA.
CONCLUSION: These findings are consistent with a model in which oxidative damage 
of the RyR2 targets it for turnover by presenilins and CMA, which could lead to 
removal of damaged or leaky RyR2 channels.