Apoptosis in oral mucosa: lessons from the crypt. A commentary

Area of Science:

• Cell biology
• Gastrointestinal physiology
• Cancer research

Background:

• Programmed cell removal (apoptosis) is vital for tissue homeostasis, balancing cell division and differentiation.
• Apoptosis identification is challenging in stratified epithelia but straightforward in small intestine columnar epithelium due to distinct morphological changes.
• Cell death in the small intestine can be linked to stem cell hierarchy and tissue position.

Purpose of the Study:

• To investigate the role and mechanisms of apoptosis in small intestine stem cells.
• To explore the relationship between apoptosis, stem cell regulation, and genome protection.
• To understand the implications of apoptosis in the low cancer incidence observed in the gastrointestinal tract.

Main Methods:

• Morphological assessment of apoptotic cells in routine paraffin sections of small intestine epithelium.
• Relating cell death to the hierarchical status and tissue position of dying cells.
• Investigating p53-dependent and p53-independent apoptosis in intestinal stem cells following genotoxic stress.

Main Results:

• Apoptosis is readily quantifiable in small intestine columnar epithelium by counting fragmented dying cells.
• A small proportion of stem cells undergo p53-independent apoptosis, suggesting homeostatic regulation of stem cell numbers.
• Intestinal stem cells are susceptible to p53-dependent apoptosis upon exposure to low-level genotoxic agents like radiation.

Conclusions:

• Apoptosis in small intestine stem cells plays a critical role in maintaining tissue homeostasis and regulating stem cell populations.
• p53-dependent apoptosis in intestinal stem cells acts as a genome protective mechanism.
• This apoptotic response likely contributes to the low incidence of cancer in the gastrointestinal tract despite its rapid proliferation.