SLC30A9 mutation affecting intracellular zinc homeostasis causes a novel cerebro-renal syndrome.
A novel autosomal recessive cerebro-renal syndrome was identified in consanguineous Bedouin kindred: neurological deterioration was evident as of early age, progressing into severe intellectual disability, profound ataxia, camptocormia and oculomotor apraxia. Brain MRI was normal. Four of the six affected individuals also had early-onset nephropathy with features of tubulo-interstitial nephritis, hypertension and tendency for hyperkalemia, though none had rapid deterioration of renal function. Genome wide linkage analysis identified an ∼18 Mb disease-associated locus on chromosome 4 (maximal logarithm of odds score 4.4 at D4S2971; θ = 0). Whole exome sequencing identified a single mutation in SLC30A9 within this locus, segregating as expected within the kindred and not found in a homozygous state in 300 Bedouin controls. We showed that SLC30A9 (solute carrier family 30 member 9; also known as ZnT-9) is ubiquitously expressed with high levels in cerebellum, skeletal muscle, thymus and kidney. Confocal analysis of SH-SY5Y cells overexpressing SLC30A9 fused to enhanced green fluorescent protein demonstrated vesicular cytosolic localization associated with the endoplasmic reticulum, not co-localizing with endosomal or Golgi markers. SLC30A9 encodes a putative zinc transporter (by similarity) previously associated with Wnt signalling. However, using dual-luciferase reporter assay in SH-SY5Y cells we showed that Wnt signalling was not affected by the mutation. Based on protein modelling, the identified mutation is expected to affect SLC30A9's highly conserved cation efflux domain, putatively disrupting its transmembrane helix structure. Cytosolic Zn2+ measurements in HEK293 cells overexpressing wild-type and mutant SLC30A9 showed lower zinc concentration within mutant rather than wild-type SLC30A9 cells. This suggests that SLC30A9 has zinc transport properties affecting intracellular zinc homeostasis, and that the molecular mechanism of the disease is through defective function of this novel activity of SLC30A9 rather than by a defect in its previously described role in transcriptional activation of Wnt signalling.
The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
Yonatan
Y
Perez
Pediatric Neurology unit, Division of Pediatrics, Soroka University Medical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84101, Israel.
Zamir
Z
Shorer
The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
Keren
K
Liani-Leibson
Section of Cell Biology and Functional Genomics, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London W12 0NN, UK.
Pauline
P
Chabosseau
The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
Rotem
R
Kadir
The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
Michael
M
Volodarsky
The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.
Daniel
D
Halperin
Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, 8410501, Israel.
Shiran
S
Barber-Zucker
Pediatric Nephology unit, Division of Pediatrics, Soroka University Medical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84101, Israel.
Hanna
H
Shalev
Pediatric Nephology unit, Division of Pediatrics, Soroka University Medical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84101, Israel.
Ruth
R
Schreiber
Department of Ophthalmolgy, Soroka Medical Center and Clalit Health Services, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer-Sheva, BeerSheva 84105, Israel.
Libe
L
Gradstein
Pediatric Nephology unit, Division of Pediatrics, Soroka University Medical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84101, Israel.
Evgenia
E
Gurevich
Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer Sheva, 8410501, Israel.
Raz
R
Zarivach
Section of Cell Biology and Functional Genomics, Division of Diabetes Endocrinology and Metabolism, Department of Medicine, Imperial College London, London W12 0NN, UK.
Guy A
GA
Rutter
Pediatric Nephology unit, Division of Pediatrics, Soroka University Medical Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84101, Israel.
Daniel
D
Landau
The Morris Kahn Laboratory of Human Genetics, National Institute for Biotechnology in the Negev and Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel.|Genetics Institute, Soroka University Medical Center, Ben Gurion University of the Negev, Beer Sheva 84101, Israel.
Ohad S
OS
Birk
D017668:Age of Onset; D018912:Arabs; D027682:Cation Transport Proteins / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics*; D002874:Chromosome Mapping; D003241:Consanguinity; D003600:Cytosol / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D055106:Genome-Wide Association Study; D057809:HEK293 Cells; D015417:Hereditary Sensory and Motor Neuropathy / Q000235:genetics*; D006706:Homeostasis / Q000235:genetics*; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000235:genetics*; D007674:Kidney Diseases / Q000235:genetics*; D008297:Male; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics*; D010375:Pedigree; D013577:Syndrome; D014157:Transcription Factors; D060449:Wnt Signaling Pathway / Q000235:genetics; D015032:Zinc / Q000378:metabolism*
D027682:Cation Transport Proteins; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; C120900:SLC30A9 protein, human; D014157:Transcription Factors; D015032:Zinc
Cerebro-renal syndrome; SLC30A9; ZnT9; neurodevelopmental regression; zinc homeostasis