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Developmental regulation of molecular signalling in fetal and neonatal diaphragm protein metabolism

journal contribution
posted on 2023-05-20, 08:15 authored by Yong SongYong Song, Pillow, JJ
Structural and functional immaturity of the preterm diaphragm predisposes the preterm baby to respiratory muscle weakness and consequent impaired efficiency of spontaneous respiration, potentially necessitating mechanical respiratory support. The ontogeny of several proteolytic genes (calpain, caspase-3, MAFbx and MuRF-1) changes dynamically with gestational and early postnatal development. We aimed to define the molecular signal cascades and triggers responsible for the dynamic changes in the proteolytic pathways during in utero and early postnatal development. Costal diaphragm was obtained immediately following euthanasia of fetal and newborn lambs from 75 to 200 days postconceptional age (term = 150 days). Gene expression of insulin-like growth factor 1 (IGF-1), tumour necrosis factor α (TNF-α) and myostatin decreased steadily in utero from 75 to 145 days (P < 0.05) and the transcripts increased again after birth except of myostatin. Rapid activation of the fork-head transcriptional factors of the O class (FOXO1) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathways was observed at 24 h of postnatal age. Diaphragm reactive oxygen species (ROS) production increased over 29-fold at 24 h postnatal age, compared with the 145 days fetus (P < 0.01). Local (diaphragmatic) ROS accumulation occurred earlier and was more predominant than systemic (plasma) ROS. There were positive correlations between signalling transduction molecules (FOXO1 and NF-κB) and antioxidant gene expression (superoxide dismutase and glutathione peroxidase 1). We conclude that anabolic (IGF-1) and catabolic (TNF-α and myostatin) factors have a similar developmental pattern with a decreasing trend toward full term. This may reflect in utero integration of cellular events into low protein metabolism as the diaphragm matures in late gestation. On initiation of spontaneous breathing, ROS accumulated and potentially activated cascade of FOXO and NF-κB signal transduction. The finding provides new insights into developmental regulation of protein metabolism within development. The implication of these postnatal events for diaphragm adaptation to the ex utero environment needs further investigation.

History

Publication title

Experimental Biology and Medicine

Volume

238

Issue

8

Article number

913-922

Number

913-922

Pagination

1-10

ISSN

1535-3702

Department/School

Menzies Institute for Medical Research

Publisher

Soc Experimental Biology Medicine

Place of publication

195 West Spring Valley Ave, Maywood, USA, Nj, 07607-1727

Rights statement

Copyright 2013 by the Society for Experimental Biology and Medicine

Repository Status

  • Restricted

Socio-economic Objectives

Clinical health not elsewhere classified

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