Ciliary abnormalities in senescent human fibroblasts impair proliferative capacity

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Somatic cells undergo senescence, a state of irreversible cell cycle arrest, after a finite number of divisions.
• Senescence and DNA damage increase centrosome number, crucial for mitotic spindle formation.
• Centrosomes also serve as basal bodies for primary cilia, which are involved in sensing extracellular signals like Hedgehog.

Purpose of the Study:

• To investigate the impact of senescence on primary cilia.
• To explore the relationship between primary cilia, Hedgehog signaling, and cell proliferation in senescence.

Main Methods:

• Analysis of primary cilia frequency and length in senescent human fibroblasts.
• Quantification of CP110 levels and Hedgehog pathway components in senescent cells.
• Experimental manipulation of Hedgehog signaling and CP110 levels in young cells.

Main Results:

• Senescent human fibroblasts showed increased primary cilia frequency and length.
• Reduced levels of the ciliary regulator CP110 and Hedgehog pathway elements were observed in senescent cells.
• Hedgehog inhibition in young cells led to cell cycle arrest and increased cilium length.
• CP110 depletion in young cells increased ciliation and reduced proliferation.

Conclusions:

• Primary cilia are elongated and more frequent in senescent cells.
• Reduced CP110 and altered Hedgehog pathway signaling are associated with senescence-induced ciliation changes.
• Hedgehog signaling may regulate primary ciliation, and primary cilia could be novel determinants of senescence-induced proliferation reduction.