AP2A1 modulates cell states between senescence and rejuvenation

Area of Science:

• Cell Biology
• Aging Research
• Molecular Mechanisms

Background:

• Aging is characterized by senescent cell accumulation, which are larger than young cells and contribute to age-related diseases.
• The molecular basis for maintaining the enlarged architecture of senescent cells is not well understood.
• Actin stress fiber reorganization is a key feature of senescent human fibroblasts.

Purpose of the Study:

• To investigate the molecular mechanisms underlying the maintenance of large cell size in senescent cells.
• To identify key proteins involved in actin stress fiber reorganization during senescence.
• To explore the role of AP2A1 in cellular senescence and rejuvenation.

Main Methods:

• Studied replicative senescence in human fibroblasts.
• Utilized proteomic analysis to identify upregulated proteins in senescent cells.
• Performed AP2A1 knockdown and overexpression experiments.
• Investigated the colocalization and movement of AP2A1 and integrin β1 along stress fibers.
• Examined focal adhesions and cell adhesion strength.

Main Results:

• AP2A1 (alpha 1 adaptin subunit of the adaptor protein 2) is upregulated along enlarged stress fibers in senescent cells.
• AP2A1 knockdown reversed senescence phenotypes, promoting cellular rejuvenation.
• AP2A1 overexpression in young cells induced senescence phenotypes.
• AP2A1 colocalized and moved linearly with integrin β1 along stress fibers.
• Senescent cells exhibit enlarged focal adhesions and strengthened substrate adhesion via integrin β1 translocation.

Conclusions:

• Senescent cells maintain their large size by reinforcing anchorage through integrin β1 translocation along stress fibers.
• AP2A1 plays a crucial role in regulating senescent cell size and architecture.
• This mechanism may be particularly efficient in senescent cells due to their enlarged size and altered transport dynamics.