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Loss of PDK1 Induces Meiotic Defects in Oocytes From Diabetic Mice
Juan Ge1, Na Zhang1, Shoubin Tang1
1State Key Laboratory of Reproductive Medicine, Suzhou Municipal Hospital, Nanjing Medical University, Nanjing, China.
Abstract:
Maternal diabetes has been shown to impair oocyte quality; however, the underlying mechanisms remain unclear. Here, using a streptozotocin (STZ)-induced diabetic mouse model, we first detected and reduced expression of pyruvate dehydrogenase kinase 1 (PDK1) in diabetic oocytes, accompanying with the lowered phosphorylation of serine residue 232 on α subunit of the pyruvate dehydrogenase (PDH) complex (Ser232-PDHE1α). Importantly, forced expression of PDK1 not only elevated the phosphorylation level of Ser232-PDHE1α, but also partly prevented the spindle disorganization and chromosome misalignment in oocytes from diabetic mice, with no beneficial effects on metabolic dysfunction. Moreover, a phospho-mimetic S232D-PDHE1α mutant is also capable of ameliorating the maternal diabetes-associated meiotic defects. In sum, our data indicate that PDK1-controlled Ser232-PDHE1α phosphorylation pathway mediates the effects of diabetic environment on oocyte competence.
Insights
Maternal diabetes impairs egg quality by reducing pyruvate dehydrogenase kinase 1 (PDK1) expression, affecting oocyte competence. Restoring PDK1 or its downstream pathway can mitigate these diabetes-induced meiotic defects.
Area of Science:
- Reproductive Biology
- Molecular Endocrinology
- Cellular Metabolism
Background:
- Maternal diabetes negatively impacts oocyte quality, but the molecular mechanisms are not fully understood.
- Pyruvate dehydrogenase kinase 1 (PDK1) and its regulation of the pyruvate dehydrogenase complex (PDH) are crucial for cellular energy metabolism and function.
- Oocyte quality is essential for successful fertilization and embryonic development.
Purpose of the Study:
- To investigate the role of pyruvate dehydrogenase kinase 1 (PDK1) in mediating the detrimental effects of maternal diabetes on oocyte quality.
- To elucidate the specific pathway involving PDK1 and the phosphorylation of the α subunit of the pyruvate dehydrogenase (PDH) complex (PDHE1α) at serine residue 232 (Ser232-PDHE1α).
Main Methods:
- Utilized a streptozotocin (STZ)-induced diabetic mouse model to study oocytes.
- Assessed the expression levels of PDK1 and the phosphorylation status of Ser232-PDHE1α in oocytes from diabetic and control mice.
- Experimentally manipulated PDK1 expression and PDHE1α phosphorylation to evaluate their impact on meiotic defects.
Main Results:
- Diabetic oocytes exhibited reduced PDK1 expression and decreased phosphorylation of Ser232-PDHE1α.
- Forced expression of PDK1 partially rescued spindle disorganization and chromosome misalignment in diabetic oocytes, without improving metabolic dysfunction.
- A phospho-mimetic S232D-PDHE1α mutant also ameliorated maternal diabetes-associated meiotic defects.
Conclusions:
- The PDK1-controlled Ser232-PDHE1α phosphorylation pathway is a key mediator of diabetic environment-induced impairments in oocyte competence.
- Targeting this specific pathway may offer a therapeutic strategy to improve oocyte quality in diabetic individuals.
- Further research is warranted to fully understand the implications of metabolic dysfunction on oocyte meiotic progression.
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