Cholesterol is an essential component of cell membranes and a key molecule for maintaining metabolic homeostasis. LDL-derived cholesterol is delivered to lysosomes, where NPC1 and NPC2 cooperate to transport free cholesterol to other cellular compartments. When this process is impaired, cholesterol abnormally accumulates in lysosomes, a hallmark of Niemann-Pick disease type C. While NPC1 was known to undergo palmitoylation, a reversible lipid modification regulating protein trafficking, localization, and stability, the enzyme catalyzing this modification and its functional impact on NPC1 remained unknown.
A team led by Professor Zhao Tong-Jin at Fudan University now reports in Life Metabolism that DHHC13 is the palmitoyltransferase responsible for NPC1 palmitoylation. Upon broad inhibition of protein palmitoylation, the researchers observed elevated intracellular cholesterol and impaired lysosomal cholesterol transport. This prompted a screen of the DHHC family, which revealed that loss of DHHC13 led to persistent accumulation of cholesterol in lysosomes, identifying it as a key regulator of lysosomal cholesterol egress (Figure 1).
The researchers next asked how DHHC13 exerts this effect. DHHC13 knockout reduced palmitoylated NPC1 by approximately 90% and total NPC1 by approximately 45%. The NPC1 half-life was shortened from about 24 hours to about 12 hours, and the degradation was blocked by bafilomycin A1, indicating lysosomal degradation. In line with impaired lysosomal delivery, NPC1 colocalization with the lysosomal marker LAMP1 decreased from 75% to 35%. Cys799 and Cys800 were identified as the major palmitoylation sites, with Cys1160 and Cys1167 also contributing to palmitoylation. In vitro , DHHC13 directly catalyzed NPC1 palmitoylation. Notably, the NPC1-C1167Y mutation associated with Niemann-Pick disease type C reduced NPC1 palmitoylation, stability, and lysosomal localization, and abolished NPC1’s ability to correct cholesterol accumulation, thereby connecting the modification directly to disease pathogenesis
To determine whether these findings hold in vivo , the researchers generated Dhhc13 -knockout mice. The cholesterol content was significantly elevated in the brain, liver, spleen, and kidney, with concomitantly decreased NPC1 protein and palmitoylation levels, partially recapitulating features of NPC1 deficiency. The mice also exhibited enlarged hepatocytes, an increased number of splenic hemosiderin-positive cells, and a reduced number of cerebellar Purkinje cells. In separate experiments, two DHHC13 variants linked to neurodegenerative disease traits, Q173H and R451Q, failed to restore NPC1 palmitoylation and cholesterol transport in knockout cells, whereas wild-type DHHC13 did. Q173H weakens the binding of DHHC13 to NPC1, while R451Q impairs its catalytic activity.
Together, these results define a DHHC13-NPC1 regulatory axis: DHHC13 palmitoylates NPC1 to maintain its lysosomal localization and protein stability, thereby enabling cholesterol egress. In the absence of DHHC13, NPC1 undergoes lysosomal degradation and cholesterol accumulates. These findings link protein palmitoylation directly to lysosomal cholesterol homeostasis and provide new insight into the mechanisms of Niemann-Pick disease type C. This work further raises the therapeutic possibility that enhancing DHHC13 activity or interfering with NPC1 depalmitoylation may restore NPC1 function. Whether this approach is effective in more advanced disease remains to be determined.
Life Metabolism
Experimental study
Not applicable
DHHC13 controls lysosomal cholesterol egress through palmitoylating NPC1
10-Sep-2026