Mutations in TUBB8 cause a multiplicity of phenotypes in human oocytes and early embryos.
TUBB8 is a primate-specific β-tubulin isotype whose expression is confined to oocytes and the early embryo. We previously found that mutations in TUBB8 caused oocyte maturation arrest. The objective was to describe newly discovered mutations in TUBB8 and to characterise the accompanying spectrum of phenotypes and modes of inheritance.



Patients with oocyte maturation arrest were sequenced with respect to TUBB8. We investigated the effects of identified mutations in vitro, in cultured cells and in mouse oocytes. Seven heterozygous missense and two homozygous mutations were identified. These mutations cause a range of folding defects in vitro, different degrees of microtubule disruption upon expression in cultured cells and interfere to varying extents in the proper assembly of the meiotic spindle in mouse oocytes. Several of the newly discovered TUBB8 mutations result in phenotypic variability. For example, oocytes harbouring any of three missense mutations (I210V, T238M and N348S) could extrude the first polar body. Moreover, they could be fertilised, although the ensuing embryos became developmentally arrested. Surprisingly, oocytes from patients harbouring homozygous TUBB8 mutations that in either case preclude the expression of a functional TUBB8 polypeptide nonetheless contained identifiable spindles.



Our data substantially expand the range of dysfunctional oocyte phenotypes incurred by mutation in TUBB8, underscore the independent nature of human oocyte meiosis and differentiation, extend the class of genetic diseases known as the tubulinopathies and provide new criteria for the qualitative evaluation of meiosis II (MII) oocytes for in vitro fertilization (IVF).
State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, The People's Republic of China Institutes of Biomedical Sciences, Fudan University, Shanghai, The People's Republic of China.
Ruizhi
R
Feng
Reproductive Medicine Center, Shanghai Ninth hospital, Shanghai Jiao Tong University, Shanghai, The People's Republic of China.
Zheng
Z
Yan
Reproductive Medicine Center, Shanghai Ninth hospital, Shanghai Jiao Tong University, Shanghai, The People's Republic of China.
Bin
B
Li
Shanghai Ji Ai Genetics and IVF Institute, Obstetrics and Gynecology Hospital, Fudan University, Shanghai, The People's Republic of China.
Min
M
Yu
State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, The People's Republic of China Institutes of Biomedical Sciences, Fudan University, Shanghai, The People's Republic of China.
Qing
Q
Sang
Department of Biochemistry and Molecular Pharmacology, New York Langone University Medical Center, New York, USA.
Guoling
G
Tian
State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, The People's Republic of China Institutes of Biomedical Sciences, Fudan University, Shanghai, The People's Republic of China.
Yao
Y
Xu
State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, The People's Republic of China Institutes of Biomedical Sciences, Fudan University, Shanghai, The People's Republic of China.
Biaobang
B
Chen
State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, The People's Republic of China Institutes of Biomedical Sciences, Fudan University, Shanghai, The People's Republic of China.
Ronggui
R
Qu
Shanghai Institute of Planned Parenthood Research, Shanghai, The People's Republic of China.
Zhaogui
Z
Sun
Shanghai Ji Ai Genetics and IVF Institute, Obstetrics and Gynecology Hospital, Fudan University, Shanghai, The People's Republic of China.
Xiaoxi
X
Sun
State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, The People's Republic of China.
Li
L
Jin
Institutes of Biomedical Sciences, Fudan University, Shanghai, The People's Republic of China Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders, Ministry of Education, Shanghai Jiao Tong University, Shanghai, The People's Republic of China.
Lin
L
He
Reproductive Medicine Center, Shanghai Ninth hospital, Shanghai Jiao Tong University, Shanghai, The People's Republic of China Shanghai Key Laboratory of Reproductive Medicine, Shanghai, The People's Republic of China.
Yanping
Y
Kuang
Department of Biochemistry and Molecular Pharmacology, New York Langone University Medical Center, New York, USA.
Nicholas J
NJ
Cowan
State Key Laboratory of Genetic Engineering and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai, The People's Republic of China Institutes of Biomedical Sciences, Fudan University, Shanghai, The People's Republic of China.
Lei
L
Wang
D000818:Animals; D004622:Embryo, Mammalian / Q000378:metabolism; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D009865:Oocytes / Q000378:metabolism*; D010641:Phenotype; D008941:Spindle Apparatus; D014404:Tubulin / Q000235:genetics*
C000604490:TUBB8 protein, human; D014404:Tubulin
TUBB8; female infertility; mutations; oocyte maturation arrest