Biology subjects

Stottmann, R. W.

Publications and source records attributed to Stottmann, R. W..

2 recordsLinked to original sources

bioRxiv2019

Nubp2 is required for cranial neural crest survival in the mouse.

The N-ethyl-N-nitrosourea (ENU) forward genetic screen is a useful tool for the unbiased discovery of novel mechanisms regulating developmental processes. We recovered the dorothy mutation in such a screen designed to recover recessive mutations affecting craniofacial development in the mouse. Dorothy embryos die prenatally and exhibit many striking phenotypes commonly associated with ciliopathies, including a severe midfacial clefting phenotype. We used exome sequencing to discover a missense mutation in Nucleotide Binding Protein 2 (Nubp2) to be causative. This finding was confirmed with a complementation analysis between the dorothy allele and a Nubp2 null allele (Nubp2Null). We demonstrate that Nubp2 is indispensable for embryogenesis. NUBP2 is implicated in both the Cytosolic Iron/Sulfur cluster Assembly (CIA) pathway and in the negative regulation of ciliogenesis. Conditional ablation of Nubp2 in the neural crest lineage with Wnt1-cre recapitulates the dorothy craniofacial phenotype. Using this model, we found that the proportion of ciliated cells in the craniofacial mesenchyme was unchanged, and that markers of the Shh, Fgf, and Bmp signaling pathways are unaltered. Finally, we show that the phenotype results from a marked increase in apoptosis within the craniofacial mesenchyme.\n\nSummary StatementAn ENU screen identifies a novel allele of Nubp2 which is then demonstrated to be required for cranial neural crest survival and proper midfacial development.

developmental biology↗

bioRxiv2019

Severe Biallelic Loss-of-function Mutations in Nicotinamide Mononucleotide Adenylyltransferase 2 (NMNAT2) in Two Fetuses with Fetal Akinesia Deformation Sequence

The three nicotinamide mononucleotide adenylyltransferase (NMNAT) family members synthesize the electron carrier nicotinamide adenine dinucleotide (NAD+) and are essential for cellular metabolism. In mammalian axons, NMNAT activity appears to be required for axon survival and is predominantly provided by NMNAT2. NMNAT2 has recently been shown to also function as a chaperone to aid in the refolding of misfolded proteins. Nmnat2 deficiency in mice, or in its ortholog dNmnat in Drosophila, results in axon outgrowth and survival defects. Peripheral nerve axons in NMNAT2-deficient mice fail to extend and innervate targets, and skeletal muscle is severely underdeveloped. In addition, removing NMNAT2 from established axons initiates axon death by Wallerian degeneration. We report here on two stillborn siblings with fetal akinesia deformation sequence (FADS), severely reduced skeletal muscle mass and hydrops fetalis. Clinical exome sequencing identified compound heterozygous NMNAT2 variant alleles in both cases. Both protein variants are incapable of supporting axon survival in mouse primary neuron cultures when overexpressed. In vitro assays demonstrate altered protein stability and/or defects in NAD+ synthesis and chaperone functions. Thus, both patient NMNAT2 alleles are null or severely hypo-morphic. These data indicate a previously unknown role for NMNAT2 in human neurological development and provide the first direct molecular evidence to support the involvement of Wallerian degeneration in a human axonal disorder.

genetics↗