TY - JOUR
T1 - SNX14 mutations affect endoplasmic reticulumassociated neutral lipid metabolism in autosomal recessive spinocerebellar ataxia 20
AU - Bryant, Dale
AU - Liu, Yang
AU - Datta, Sanchari
AU - Hariri, Hanaa
AU - Seda, Marian
AU - Anderson, Glenn
AU - Peskett, Emma
AU - Demetriou, Charalambos
AU - Sousa, Sergio
AU - Jenkins, Dagan
AU - Clayton, Peter
AU - Bitner-Glindzicz, Maria
AU - Moore, Gudrun E.
AU - Henne, W. Mike
AU - Stanier, Philip
N1 - Funding Information:
We would like to thank the families with SCAR20 who provided biological samples and clinical information. This work was funded by a grant from Great Ormond Street Hospital Children's Charity (V4215 to P.S.) and supported by the National Institute for Health Biomedical Research Centre at Great Ormond Street Hospital for Children NHS Foundation and University College London. This work was also sponsored by grants to W.M.H. from the Welch Foundation (I-1873), the National Institute of General Medical Sciences (R35/MIRA R350821601), the Searle Scholars Foundation (SSP-2016-1482) and the University of Texas South Western Endowed Scholars Program.
Funding Information:
This work was funded by a grant from Great Ormond Street Hospital Children’s Charity (V4215 to P.S.) and supported by the National Institute for Health Biomedical Research Centre at Great Ormond Street Hospital for Children NHS Foundation and University College London. This work was also sponsored by grants to W.M.H. from the Welch Foundation (I-1873), the National Institute of General Medical Sciences (R35/MIRA R350821601), the Searle Scholars Foundation (SSP-2016-1482) and the University of Texas South Western Endowed Scholars Program.
Publisher Copyright:
© The Author(s) 2018. Published by Oxford University Press. All rights reserved.
PY - 2018/6/1
Y1 - 2018/6/1
N2 - Mutations in SNX14 cause the autosomal recessive cerebellar ataxia 20 (SCAR20). Mutations generally result in loss of protein although several coding region deletions have also been reported. Patient-derived fibroblasts show disrupted autophagy, but the precise function of SNX14 is unknown. The yeast homolog, Mdm1, functions in endoplasmic reticulum (ER)-lysosome/ vacuole inter-organelle tethering, but functional conservation in mammals is still required. Here, we show that loss of SNX14 alters but does not block autophagic flux. In addition, we find that SNX14 is an ER-associated protein that functions in neutral lipid homeostasis and inter-organelle crosstalk. SNX14 requires its N-terminal transmembrane helices for ER localization, while the Phox homology (PX) domain is dispensable for subcellular localization. Both SNX14-mutant fibroblasts and SNX14KO HEK293 cells accumulate aberrant cytoplasmic vacuoles, suggesting defects in endolysosomal homeostasis. However, ER-late endosome/lysosome contact sites are maintained in SNX14KO cells, indicating that it is not a prerequisite for ER-endolysosomal tethering. Further investigation of SNX14- deficiency indicates general defects in neutral lipid metabolism. SNX14KO cells display distinct perinuclear accumulation of filipin in LAMP1-positive lysosomal structures indicating cholesterol accumulation. Consistent with this, SNX14KO cells display a slight but detectable decrease in cholesterol ester levels, which is exacerbated with U18666A. Finally, SNX14 associates with ER-derived lipid droplets (LD) following oleate treatment, indicating a role in ER-LD crosstalk. We therefore identify an important role for SNX14 in neutral lipid homeostasis between the ER, lysosomes and LDs that may provide an early intervention target to alleviate the clinical symptoms of SCAR20.
AB - Mutations in SNX14 cause the autosomal recessive cerebellar ataxia 20 (SCAR20). Mutations generally result in loss of protein although several coding region deletions have also been reported. Patient-derived fibroblasts show disrupted autophagy, but the precise function of SNX14 is unknown. The yeast homolog, Mdm1, functions in endoplasmic reticulum (ER)-lysosome/ vacuole inter-organelle tethering, but functional conservation in mammals is still required. Here, we show that loss of SNX14 alters but does not block autophagic flux. In addition, we find that SNX14 is an ER-associated protein that functions in neutral lipid homeostasis and inter-organelle crosstalk. SNX14 requires its N-terminal transmembrane helices for ER localization, while the Phox homology (PX) domain is dispensable for subcellular localization. Both SNX14-mutant fibroblasts and SNX14KO HEK293 cells accumulate aberrant cytoplasmic vacuoles, suggesting defects in endolysosomal homeostasis. However, ER-late endosome/lysosome contact sites are maintained in SNX14KO cells, indicating that it is not a prerequisite for ER-endolysosomal tethering. Further investigation of SNX14- deficiency indicates general defects in neutral lipid metabolism. SNX14KO cells display distinct perinuclear accumulation of filipin in LAMP1-positive lysosomal structures indicating cholesterol accumulation. Consistent with this, SNX14KO cells display a slight but detectable decrease in cholesterol ester levels, which is exacerbated with U18666A. Finally, SNX14 associates with ER-derived lipid droplets (LD) following oleate treatment, indicating a role in ER-LD crosstalk. We therefore identify an important role for SNX14 in neutral lipid homeostasis between the ER, lysosomes and LDs that may provide an early intervention target to alleviate the clinical symptoms of SCAR20.
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U2 - 10.1093/hmg/ddy101
DO - 10.1093/hmg/ddy101
M3 - Article
C2 - 29635513
AN - SCOPUS:85048135282
SN - 0964-6906
VL - 27
SP - 1927
EP - 1940
JO - Human molecular genetics
JF - Human molecular genetics
IS - 11
ER -