Paolo Parini (Sweden)
Karolinska Institutet Division of Clinical Chemistry, Department of Laboratory MedicineAuthor Of 3 Presentations
Welcome by Chair Scientific Programme Committee (ID 1517)
Introduction (ID 1589)
O051 - The crosstalk between macroautophagy and chaperone-mediated autophagy (CMA) is influenced by the lipid droplet-associated protein perilipin 2 (PLIN2) during lipophagy (ID 467)
Abstract
Background and Aims
PLIN2 is the most prominent lipid droplet (LD)-associated protein in foam cells. PLIN2 stabilizes LDs and LDs protect PLIN2 from rapid degradation. LD-bound PLIN2 degradation is dependent on AMPK-phosphorylation via chaperone-mediated autophagy (CMA). PLIN2 is vital to maintain certain LD size and number. We have recently shown that the Ser251Pro SNP in PLIN2 influences macroautophagy, cholesterol efflux, cholesterol accumulation and is associated with subclinical atherosclerosis development in humans. Since a direct crosstalk between macroautophagy and CMA has been proposed, we aim to investigate whether the Ser251Pro SNP affects CMA and the degradation of PLIN2, thereby influencing lipophagy.
Methods
We utilized stably transfected HEK293 cells carrying either variant of PLIN2 loaded with oleate, followed by treatment with AMPK modulators: we measured PLIN2 and L2A levels by WB and colocalization of Hsc70/L2A by IHC. We used WT, ATG5-/- and L2A-/- MEF cells transiently transfected with PLIN2 variants: we measured LD number by IHC, PLIN2 levels by WB.
Results
Ser251Pro-dependent differences in lipid accumulation observed in WT MEF cells are abolished in both ATG5-/- and L2A-/- MEF cells. Cells carrying the Pro251 allele show lower L2A expression and less Hsc70/L2A colocalization, indicating fewer CMA-active lysosomes. Further, AMPK inhibition in HEK cells induces PLIN2 expression more in Ser251- than in Pro251-carrying cells.
Conclusions
The effect of the Ser251Pro SNP on lipid accumulation is dependent on both macroautophagy and CMA. The presence of the Pro251 allele reduces CMA-activity and modifies PLIN2 degradation via AMPK. Thus, PLIN2 influences lipophagy via crosstalk between macroautophagy and CMA.