Publications

• Yeast and human P4-ATPases transport glycosphingolipids using conserved structural motifs.

  Roland B.P., Naito T., Best J.T., Arnaiz-Yepez C., Takatsu H., Yu R.J., Shin H.W., Graham T.R.

  Lipid transport is an essential process with manifest importance to human health and disease. Phospholipid flippases (P4-ATPases) transport lipids across the membrane bilayer and are involved in signal transduction, cell division, and vesicular transport. Mutations in flippase genes cause or contr ... >> More

  Lipid transport is an essential process with manifest importance to human health and disease. Phospholipid flippases (P4-ATPases) transport lipids across the membrane bilayer and are involved in signal transduction, cell division, and vesicular transport. Mutations in flippase genes cause or contribute to a host of diseases, such as cholestasis, neurological deficits, immunological dysfunction, and metabolic disorders. Genome-wide association studies have shown that <i>ATP10A</i> and <i>ATP10D</i> variants are associated with an increased risk of diabetes, obesity, myocardial infarction, and atherosclerosis. Moreover, <i>ATP10D</i> SNPs are associated with elevated levels of glucosylceramide (GlcCer) in plasma from diverse European populations. Although sphingolipids strongly contribute to metabolic disease, little is known about how GlcCer is transported across cell membranes. Here, we identify a conserved clade of P4-ATPases from <i>Saccharomyces cerevisiae</i> (Dnf1, Dnf2), <i>Schizosaccharomyces pombe</i> (Dnf2), and <i>Homo sapiens</i> (ATP10A, ATP10D) that transport GlcCer bearing an <i>sn2</i> acyl-linked fluorescent tag. Further, we establish structural determinants necessary for recognition of this sphingolipid substrate. Using enzyme chimeras and site-directed mutagenesis, we observed that residues in transmembrane (TM) segments 1, 4, and 6 contribute to GlcCer selection, with a conserved glutamine in the center of TM4 playing an essential role. Our molecular observations help refine models for substrate translocation by P4-ATPases, clarify the relationship between these flippases and human disease, and have fundamental implications for membrane organization and sphingolipid homeostasis. << Less

  J. Biol. Chem. 294:1794-1806(2019) [PubMed] [EuropePMC]

• Mutated ATP10B increases Parkinson's disease risk by compromising lysosomal glucosylceramide export.

  BELNEU consortium, Martin S., Smolders S., Van den Haute C., Heeman B., van Veen S., Crosiers D., Beletchi I., Verstraeten A., Gossye H., Gelders G., Pals P., Hamouda N.N., Engelborghs S., Martin J.J., Eggermont J., De Deyn P.P., Cras P., Baekelandt V., Vangheluwe P., Van Broeckhoven C.

  Parkinson's disease (PD) is a progressive neurodegenerative brain disease presenting with a variety of motor and non-motor symptoms, loss of midbrain dopaminergic neurons in the substantia nigra pars compacta and the occurrence of α-synuclein-positive Lewy bodies in surviving neurons. Here, we per ... >> More

  Parkinson's disease (PD) is a progressive neurodegenerative brain disease presenting with a variety of motor and non-motor symptoms, loss of midbrain dopaminergic neurons in the substantia nigra pars compacta and the occurrence of α-synuclein-positive Lewy bodies in surviving neurons. Here, we performed whole exome sequencing in 52 early-onset PD patients and identified 3 carriers of compound heterozygous mutations in the ATP10B P4-type ATPase gene. Genetic screening of a Belgian PD and dementia with Lewy bodies (DLB) cohort identified 4 additional compound heterozygous mutation carriers (6/617 PD patients, 0.97%; 1/226 DLB patients, 0.44%). We established that ATP10B encodes a late endo-lysosomal lipid flippase that translocates the lipids glucosylceramide (GluCer) and phosphatidylcholine (PC) towards the cytosolic membrane leaflet. The PD associated ATP10B mutants are catalytically inactive and fail to provide cellular protection against the environmental PD risk factors rotenone and manganese. In isolated cortical neurons, loss of ATP10B leads to general lysosomal dysfunction and cell death. Impaired lysosomal functionality and integrity is well known to be implicated in PD pathology and linked to multiple causal PD genes and genetic risk factors. Our results indicate that recessive loss of function mutations in ATP10B increase risk for PD by disturbed lysosomal export of GluCer and PC. Both ATP10B and glucocerebrosidase 1, encoded by the PD risk gene GBA1, reduce lysosomal GluCer levels, emerging lysosomal GluCer accumulation as a potential PD driver. << Less

  Acta Neuropathol. 139:1001-1024(2020) [PubMed] [EuropePMC]