TY - JOUR
T1 - Mutations in TMEM260 Cause a Pediatric Neurodevelopmental, Cardiac, and Renal Syndrome
AU - Ta-Shma, Asaf
AU - Khan, Tahir N.
AU - Vivante, Asaf
AU - Willer, Jason R.
AU - Matak, Pavle
AU - Jalas, Chaim
AU - Pode-Shakked, Ben
AU - Salem, Yishay
AU - Anikster, Yair
AU - Hildebrandt, Friedhelm
AU - Katsanis, Nicholas
AU - Elpeleg, Orly
AU - Davis, Erica E.
PY - 2017/4/6
Y1 - 2017/4/6
N2 - Despite the accelerated discovery of genes associated with syndromic traits, the majority of families affected by such conditions remain undiagnosed. Here, we employed whole-exome sequencing in two unrelated consanguineous kindreds with central nervous system (CNS), cardiac, renal, and digit abnormalities. We identified homozygous truncating mutations in TMEM260, a locus predicted to encode numerous splice isoforms. Systematic expression analyses across tissues and developmental stages validated two such isoforms, which differ in the utilization of an internal exon. The mutations in both families map uniquely to the long isoform, raising the possibility of an isoform-specific disorder. Consistent with this notion, RT-PCR of lymphocyte cell lines from one of the kindreds showed reduced levels of only the long isoform, which could be ameliorated by emetine, suggesting that the mutation induces nonsense-mediated decay. Subsequent in vivo testing supported this hypothesis. First, either transient suppression or CRISPR/Cas9 genome editing of zebrafish tmem260 recapitulated key neurological phenotypes. Second, co-injection of morphants with the long human TMEM260 mRNA rescued CNS pathology, whereas the short isoform was significantly less efficient. Finally, immunocytochemical and biochemical studies showed preferential enrichment of the long TMEM260 isoform to the plasma membrane. Together, our data suggest that there is overall reduced, but not ablated, functionality of TMEM260 and that attenuation of the membrane-associated functions of this protein is a principal driver of pathology. These observations contribute to an appreciation of the roles of splice isoforms in genetic disorders and suggest that dissection of the functions of these transcripts will most likely inform pathomechanism.
AB - Despite the accelerated discovery of genes associated with syndromic traits, the majority of families affected by such conditions remain undiagnosed. Here, we employed whole-exome sequencing in two unrelated consanguineous kindreds with central nervous system (CNS), cardiac, renal, and digit abnormalities. We identified homozygous truncating mutations in TMEM260, a locus predicted to encode numerous splice isoforms. Systematic expression analyses across tissues and developmental stages validated two such isoforms, which differ in the utilization of an internal exon. The mutations in both families map uniquely to the long isoform, raising the possibility of an isoform-specific disorder. Consistent with this notion, RT-PCR of lymphocyte cell lines from one of the kindreds showed reduced levels of only the long isoform, which could be ameliorated by emetine, suggesting that the mutation induces nonsense-mediated decay. Subsequent in vivo testing supported this hypothesis. First, either transient suppression or CRISPR/Cas9 genome editing of zebrafish tmem260 recapitulated key neurological phenotypes. Second, co-injection of morphants with the long human TMEM260 mRNA rescued CNS pathology, whereas the short isoform was significantly less efficient. Finally, immunocytochemical and biochemical studies showed preferential enrichment of the long TMEM260 isoform to the plasma membrane. Together, our data suggest that there is overall reduced, but not ablated, functionality of TMEM260 and that attenuation of the membrane-associated functions of this protein is a principal driver of pathology. These observations contribute to an appreciation of the roles of splice isoforms in genetic disorders and suggest that dissection of the functions of these transcripts will most likely inform pathomechanism.
KW - neurodevelopmental syndrome
KW - splice isoforms
KW - whole-exome sequencing
UR - http://www.scopus.com/inward/record.url?scp=85015277673&partnerID=8YFLogxK
U2 - 10.1016/j.ajhg.2017.02.007
DO - 10.1016/j.ajhg.2017.02.007
M3 - Article
C2 - 28318500
AN - SCOPUS:85015277673
VL - 100
SP - 666
EP - 675
JO - American Journal of Human Genetics
JF - American Journal of Human Genetics
SN - 0002-9297
IS - 4
ER -