Abstract
Sphingomyelinases generate ceramide from sphingomyelin as a second messenger in intracellular signaling pathways involved in cell proliferation, differentiation, or apoptosis. Children from 12 unrelated families presented with microcephaly, simplified gyral pattern of the cortex, hypomyelination, cerebellar hypoplasia, congenital arthrogryposis, and early fetal/postnatal demise. Genomic analysis revealed bi-allelic loss-of-function variants in SMPD4, coding for the neutral sphingomyelinase-3 (nSMase-3/SMPD4). Overexpression of human Myc-tagged SMPD4 showed localization both to the outer nuclear envelope and the ER and additionally revealed interactions with several nuclear pore complex proteins by proteomics analysis. Fibroblasts from affected individuals showed ER cisternae abnormalities, suspected for increased autophagy, and were more susceptible to apoptosis under stress conditions, while treatment with siSMPD4 caused delayed cell cycle progression. Our data show that SMPD4 links homeostasis of membrane sphingolipids to cell fate by regulating the cross-talk between the ER and the outer nuclear envelope, while its loss reveals a pathogenic mechanism in microcephaly.
Original language | English (US) |
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Pages (from-to) | 689-705 |
Number of pages | 17 |
Journal | American Journal of Human Genetics |
Volume | 105 |
Issue number | 4 |
DOIs | |
State | Published - Oct 3 2019 |
Externally published | Yes |
Bibliographical note
Funding Information:We thank Mark Nellist, Niels Galjart, Danny Huylebroeck, Robert W. Hofstra, and Andreas Kremer for fruitful discussions and continuous support. G.M.S.M. is supported by ZonMW Top grant # 91217045 and by private donations. Research reported in this publication was supported by the National Institute of Neurological Disorders and Stroke (NINDS) under award number K08NS092898 and Jordan’s Guardian Angels (to G.M.M.). We thank the Broad Institute ( U54HG003067 to E. Lander and UM1HG008900 to D. MacArthur). R.W.S. is supported by the NIH ( R01NS085023 ). We thank Lauren Blizzard with assistance in Sanger Sequence verification of affected individuals in family 8. We also thank Luisa Iommarini, Department of Pharmacy and Biotechnology-FABIT, University of Bologna, Bologna, Italy, for help with the LC3B western blots. W.W. was supported by a grant from National Science Centre, Poland 2015/19/B/NZ2/01824 . A.C.J. is supported by a fellowship from FWO . A.C.J., G.M.M., G.M.S.M., M.W., M.S.Z., and W.B.D. are members of the European Network on Brain malformations (COST Action CA16118, https://www.cost.eu/actions/CA16118/ ).
Funding Information:
We thank Mark Nellist, Niels Galjart, Danny Huylebroeck, Robert W. Hofstra, and Andreas Kremer for fruitful discussions and continuous support. G.M.S.M. is supported by ZonMW Top grant #91217045 and by private donations. Research reported in this publication was supported by the National Institute of Neurological Disorders and Stroke (NINDS) under award number K08NS092898 and Jordan's Guardian Angels (to G.M.M.). We thank the Broad Institute (U54HG003067 to E. Lander and UM1HG008900 to D. MacArthur). R.W.S. is supported by the NIH (R01NS085023). We thank Lauren Blizzard with assistance in Sanger Sequence verification of affected individuals in family 8. We also thank Luisa Iommarini, Department of Pharmacy and Biotechnology-FABIT, University of Bologna, Bologna, Italy, for help with the LC3B western blots. W.W. was supported by a grant from National Science Centre, Poland 2015/19/B/NZ2/01824. A.C.J. is supported by a fellowship from FWO. A.C.J. G.M.M. G.M.S.M. M.W. M.S.Z. and W.B.D. are members of the European Network on Brain malformations (COST Action CA16118, https://www.cost.eu/actions/CA16118/).
Publisher Copyright:
© 2019 American Society of Human Genetics
Keywords
- NET13
- SMPD4
- arthrogryposis
- microcephaly
- neutral-sphingomyelinase