Human CLEC16A regulates autophagy through modulating mTOR activity.

CLEC16A is genetically linked with multiple autoimmune disorders but its functional relevance in autoimmunity remains obscure. Recent evidence has signposted the emerging role of autophagy in autoimmune disease development. Here, by ectopic expression and siRNA silencing, we show that CLEC16A has an inhibitory role in starvation-induced autophagy in human cells. Combining quantitative proteomics and immunoblotting analyses, we found that CLEC16A likely regulates autophagy by activating mTOR pathway. Overexpression of CLEC16A was found to sensitize cells towards the availability of nutrients, resulting in a heightened mTOR activity, which in turn diminished LC3 autophagic activity following nutrient deprivation. CLEC16A deficiency, on the other hand, delayed mTOR activity in response to nutrient sensing, thereby resulted in an augmented autophagic response. CLEC16A was found residing in cytosolic vesicles and the Golgi, and nutrient removal promoted a stronger clustering within the Golgi, where it was possibly in a vantage position to activate mTOR upon nutrient replenishment. These findings suggest that Golgi-associated CLEC16A negatively regulates autophagy via modulation of mTOR activity, and may provide support for a functional link between CLEC16A and autoimmunity.