Manipulation of the nucleoscaffold potentiates cellular reprogramming kinetics

Area of Science:

• Cell Biology
• Nuclear Architecture
• Epigenetics

Background:

• Somatic cell fate is determined by transcription factors and chromatin, maintained by silencing alternate fates via the nuclear scaffold.
• Lamin A/C is a core component of the nuclear scaffold, crucial for maintaining nuclear structure and function.

Purpose of the Study:

• To investigate the role of Lamin A/C as a guardian of cell fate in human fibroblasts.
• To compare the effects of Lamin A/C knockdown versus progerin mutation on nuclear properties and cell fate.

Main Methods:

• Studied human fibroblasts with transient Lamin A/C knockdown and Lamin A/C mutation (progerin).
• Assessed nuclear morphology, heterochromatin levels, DNA accessibility in lamina-associated domains.
• Measured nuclear mechanical properties using a microfluidic cellular squeezing device.
• Evaluated cellular reprogramming kinetics and gene expression.

Main Results:

• Lamin A/C deficiency/mutation disrupted nuclear morphology, reduced heterochromatin, and increased DNA accessibility.
• Altered Lamin A/C impacted nuclear mechanical properties.
• Lamin A/C knockdown accelerated reprogramming by opening heterochromatin.
• Progerin mutation induced senescence, inhibiting reprogramming gene induction.

Conclusions:

• The nuclear scaffold, through Lamin A/C, physically safeguards cellular fate.
• Lamin A/C's structural and mechanical roles are critical for maintaining cell identity and regulating responses to reprogramming stimuli.