TY - JOUR
T1 - Distinct effects of tubulin isotype mutations on neurite growth in Caenorhabditis elegans
AU - Zheng, Chaogu
AU - Diaz-Cuadros, Margarete
AU - Nguyen, Ken C.Q.
AU - Hall, David H.
AU - Chalfie, Martin
N1 - Funding Information:
The gk alleles of mec-7 and mec-12 listed in Table 1 and tba-7(gk787939) were generated in the million mutation project (Thompson et al., 2013). These gk alleles, as well as mec-17(ok2019), dlk-1(ju476), and dlk-1(km12), were obtained from the Caenorhabditis Genetics Center, which is funded by NIH Office of Research Infrastructure Programs (P40 OD010440). klp-7(tm2143) and mec-12(tm5083) were generated by the National Bioresource Project of Japan, and mec-12(gm379) was kindly provided by Chun-Liang Pan at the National Taiwan University.
Funding Information:
We thank Dan Dickinson, Chun-Liang Pan, and Andrew Chisholm for sharing reagents. This work was supported by National Institutes of Health grants GM30997 (M.C.) and OD 010943 (D.H.H.). Core facilities for electron microscopy were supported by National Institute of Child Health and Human Development P30 HD71593 for the RFK-IDDRC at Albert Einstein College of Medicine.
Publisher Copyright:
© 2017 Schvartz et al.
PY - 2017/10/15
Y1 - 2017/10/15
N2 - Tubulins, the building block of microtubules (MTs), play a critical role in both supporting and regulating neurite growth. Eukaryotic genomes contain multiple tubulin isotypes, and their missense mutations cause a range of neurodevelopmental defects. Using the Caenorhabditis elegans touch receptor neurons, we analyzed the effects of 67 tubulin missense mutations on neurite growth. Three types of mutations emerged: 1) loss-of-function mutations, which cause mild defects in neurite growth; 2) antimorphic mutations, which map to the GTP binding site and intradimer and interdimer interfaces, significantly reduce MT stability, and cause severe neurite growth defects; and 3) neomorphic mutations, which map to the exterior surface, increase MT stability, and cause ectopic neurite growth. Structure-function analysis reveals a causal relationship between tubulin structure and MT stability. This stability affects neuronal morphogenesis. As part of this analysis, we engineered several disease-associated human tubulin mutations into C. Elegans genes and examined their impact on neuronal development at the cellular level. We also discovered an α-tubulin (TBA-7) that appears to destabilize MTs. Loss of TBA-7 led to the formation of hyperstable MTs and the generation of ectopic neurites; the lack of potential sites for polyamination and polyglutamination on TBA- 7 may be responsible for this destabilization.
AB - Tubulins, the building block of microtubules (MTs), play a critical role in both supporting and regulating neurite growth. Eukaryotic genomes contain multiple tubulin isotypes, and their missense mutations cause a range of neurodevelopmental defects. Using the Caenorhabditis elegans touch receptor neurons, we analyzed the effects of 67 tubulin missense mutations on neurite growth. Three types of mutations emerged: 1) loss-of-function mutations, which cause mild defects in neurite growth; 2) antimorphic mutations, which map to the GTP binding site and intradimer and interdimer interfaces, significantly reduce MT stability, and cause severe neurite growth defects; and 3) neomorphic mutations, which map to the exterior surface, increase MT stability, and cause ectopic neurite growth. Structure-function analysis reveals a causal relationship between tubulin structure and MT stability. This stability affects neuronal morphogenesis. As part of this analysis, we engineered several disease-associated human tubulin mutations into C. Elegans genes and examined their impact on neuronal development at the cellular level. We also discovered an α-tubulin (TBA-7) that appears to destabilize MTs. Loss of TBA-7 led to the formation of hyperstable MTs and the generation of ectopic neurites; the lack of potential sites for polyamination and polyglutamination on TBA- 7 may be responsible for this destabilization.
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U2 - 10.1091/mbc.E17-06-0424
DO - 10.1091/mbc.E17-06-0424
M3 - Article
C2 - 28835377
AN - SCOPUS:85031280281
VL - 28
SP - 2786
EP - 2801
JO - Molecular Biology of the Cell
JF - Molecular Biology of the Cell
SN - 1059-1524
IS - 21
ER -