Uteroplacental insufficiency decreases p53 serine-15 phosphorylation in term IUGR rat lungs

Area of Science:

• Pulmonary Medicine
• Developmental Biology
• Molecular Biology

Background:

• Intrauterine growth restriction (IUGR) is a known risk factor for chronic lung disease (CLD) in infants.
• The precise molecular mechanisms linking IUGR to acute lung injury and subsequent CLD remain unclear.
• Lung development involves mesenchymal thinning, a process disrupted in CLD, and p53 plays a role in regulating key cellular processes like apoptosis and angiogenesis.

Purpose of the Study:

• To investigate the role of p53, a critical stress-response transcription factor, in IUGR-associated lung alterations.
• To determine if IUGR affects p53 expression or modification in the developing lung, potentially contributing to thickened lung mesenchyme characteristic of CLD.

Main Methods:

• Intrauterine growth restriction was induced in pregnant rats via bilateral uterine artery ligation.
• Lung tissue from IUGR and control rats was analyzed for p53 phosphorylation at serine-15 (serine-15P), an indicator of active p53.
• mRNA levels of p53 target genes involved in apoptosis, cell cycle arrest, and angiogenesis were quantified.

Main Results:

• IUGR significantly decreased serine-15P p53 levels in rat lungs, with reduced phosphorylation localized to thickened distal air space mesenchyme.
• IUGR led to decreased mRNA expression of proapoptotic genes (Bax, Apaf) and angiogenesis-related genes (Tsp-1) downstream of p53.
• Conversely, IUGR increased mRNA expression of the antiapoptotic gene Bcl-2, which is typically downregulated by p53.

Conclusions:

• Uteroplacental insufficiency in IUGR rats is associated with reduced active p53 (serine-15P) in lung mesenchyme, correlating with thickened distal lung air spaces.
• These findings suggest that diminished p53 activity in IUGR lungs may disrupt normal lung development, altering the lung phenotype and increasing vulnerability to injury.