Nip promotes autophagy through facilitating the interaction of Rab7 and FYCO1

Autophagy is the main degradation pathway to eliminate long-lived and aggregated proteins,aged or malfunctioning organelles,which is essential for the intracellular homeostasis and prevention of malignant transformation.Although the processes of autophagosome biogenesis have been well illuminated,the mechanism of autophagosome transport remains largely unclear.In this study,we demonstrated that the ninein-like protein(Nip),a well-characterized centrosomal associated protein,was able to modulate autophagosome transport and facilitate autophagy.During autophagy,Nip colocalized with autophagosomes and physically interacted with autophagosome marker LC3,autophagosome sorting protein Rab7 and its downstream effector FYCOl.Interestingly,Nip enhanced the interaction between Rab7 and FYC01,thus accelerated autophagic flux and the formation of autophagolysosomes.Furthermore,compared to the wild-type mice,NLP deficient mice treated with chemical agent DMBA were prone to increased incidence of hepatomegaly and liver cancer,which were tight associated with the hepatic autophagic defect.Taken together,our findings provide a new insight for the first time that the well-known centrosomal protein Nip is also a new regulator of autophagy,which promotes the interaction of Rab7 and FYC01 and facilitates the formation of autophagolysosome.