Figure 7.

Loss of CLEC16A-Hrs interaction in Clec16a KO mice splenocytes and schematic diagram depicting multifaceted CLEC16A: receptor recycling and critical regulator of autophagy/mitophagy. (A) CLEC16A IP-pull down and representative immunoblot depicting expression of CLEC16A and Hrs from control (Oil) and Clec16a KO (TAM) mice. Membranes were stripped and re-probed for β-actin as a loading control. (B) Quantitation graph depicting CLEC16A and Hrs expression (n = 3 repeats). ^***P < 0.001 (unpaired two-tailed Student's t-test). (C) NK cell requires a fine balance in the amount of CLEC16A protein. On the left side of figure (1), there is a normal level of endogenous CLEC16A that controls receptor trafficking by participating in endosome recycling. Binding of CLEC16A to the Hrs/Actinin-4/BERP/Myosin V [CART(cytoskeleton associated recycling or transport)] complex supports transport of receptor enriched endosomes to the cell surface membrane. The amount of this protein could be a checkpoint for the NK cell. When overexpressed [middle panel (2)], CLEC16A itself is getting ubiquitinated. There is an increased association of the ubiquitinated CLEC16A with the CART complex and the efficient receptor recycling is interrupted. In this situation the receptors will be targeted for degradation via autophagy. Thus, receptor signaling will be attenuated when CLEC16A is overexpressed. On other hand, CLEC16A is known to stabilize and prevents the proteosomal degradation of Nrdp1 limiting recruitment of Parkin to the mitochondrial surface and also promotes autophagosome-lysosome fusion during the terminal steps of mitophagy. Loss of CLEC16A will lead to an accumulation of unhealthy mitochondria due to disrupted mitophagy [right (3)].