Journal Article

Molecular Guardians of Oocyte Maturation: A Systematic Review on TUBB8, KIF11, and CKAP5 in IVF Outcomes

Mazis Kourakos, Dimitris, Voros, Charalampos, Athanasiou, Aikaterini, Papadimas, Georgios, Daskalakis, Georgios, Varthaliti, Antonia, Vaitsis, Dimitrios, Bananis, Kyriakos, Sapantzoglou, Ioakeim, Athanasiou, Diamantis, Koulakmanidis, Aristotelis-Marios, Gkirgkinoudis, Athanasios, Loutradis, Dimitrios, Papapanagiotou, Ioannis, Daskalaki, Maria Anastasia, Mavrogianni, Despoina, Migklis, Kyriaki, Antsaklis, Panagiotis, Athanasiou, Antonia, Ivanidou, Sofia, Theodora, Marianna

2025

Overview

The efficacy of in vitro fertilization (IVF) is significantly hindered by early embryonic developmental failure and oocyte maturation arrest. Recent findings in reproductive genetics have identified several oocyte-specific genes—TUBB8, KIF11, and CKAP5—as essential regulators of meiotic spindle formation and cytoskeletal dynamics. Mutations in these genes can lead to significant meiotic defects, fertilization failure, and embryo arrest. The links between genotype and phenotype, along with the underlying biological mechanisms, remain inadequately characterized despite the increasing number of identified variations. This systematic review was conducted in accordance with PRISMA 2020 guidelines. Relevant papers were retrieved from the PubMed and Embase databases using combinations of the keywords “TUBB8,” “KIF11,” “CKAP5,” “oocyte maturation arrest,” “embryonic arrest,” and “IVF failure.” Studies were included if they contained clinical, genomic, and functional data on TUBB8, KIF11, or CKAP5 mutations in women undergoing IVF. Molecular data, including gene variant classifications, inheritance models, in vitro tests (such as microtubule network analysis in HeLa cells), and assisted reproductive technology (ART) outcomes, were obtained. Eighteen trials including 35 women with primary infertility were included. Over fifty different variants were identified, the majority of which can be attributed to TUBB8 mutations. TUBB8 disrupted α/β-tubulin heterodimer assembly due to homozygous missense mutations, hence hindering meiotic spindle formation and leading to early embryo fragmentation or the creation of many pronuclei and cleavage failure. KIF11 mutations resulted in spindle disorganization and chromosomal misalignment via disrupting tubulin acetylation and microtubule transport. Mutations in CKAP5 impaired bipolar spindle assembly and microtubule stabilization. In vitro validation studies showed cytoskeletal disturbances, protein instability, and dominant negative effects in transfected animals. Donor egg IVF was the sole effective treatment; however, no viable pregnancies were documented in patients with pathogenic mutations of TUBB8 or KIF11. TUBB8, KIF11, and CKAP5 are essential for safeguarding oocyte meiotic competence and early embryonic development at the molecular level. Genetic differences in these genes disrupt microtubule dynamics and spindle assembly, resulting in various aspects of oocyte maturation and fertilization. Functional validation underscores the necessity of routine genetic screening for women experiencing unresolved IVF failure, as it substantiates their causal role in infertility. Future therapeutic avenues in ART may be enhanced by tailored counseling and innovative rescue methodologies like as gene therapy.

• Publisher: MDPI AG
• Subject: Boolean / Cell cycle / Cell division / Chromosomes / Cytoskeletal Proteins - genetics / Cytoskeletal Proteins - metabolism / Embryonic development / Embryos / Female / Fertilization in Vitro / Genetic aspects / Genetic screening / Genomics / Humans / In vitro fertilization / Kinases / Kinesins - genetics / Kinesins - metabolism / Mutation / Oocytes - metabolism / Phosphorylation / Polymerization / Proteins / Reactive oxygen species / Systematic review / Tubulin - genetics / Tubulin - metabolism / Tubulins