title: Ontogeny of proteolytic signaling and antioxidant capacity in fetal and neonatal diaphragm.
abstract: Although upregulation of protein degradation pathways contributes to the development of muscle weakness in response to muscle injury and inflammation in the adult diaphragm, less is known about the preterm diaphragm. Muscle development during the antenatal and early postnatal periods normally results in net growth. However, the structural and functional immaturity of the preterm diaphragm may predispose it to injury and inflammation induced by adverse antenatal and postnatal exposures. Characterization of the ontogeny of diaphragm protein degradation pathways in early life is essential to recognize altered signaling pathways under pathologic conditions in preterm babies. We assessed the relative role of the major proteolytic pathways and antioxidant capacity during muscle maturation in ovine fetuses and lambs from 75 days to 200 days postconceptual age. Gene expression and protein content of calpain and caspase 3 exhibited a similar profile with advancing gestation, increasing from 75 days to 100 days/128 days and subsequently decreasing gradually toward the end of gestation. In contrast, ubiquitin conjugating and ligase genes did not change during gestation. All proteolytic genes examined (except Ubiquitin) were upregulated rapidly after delivery, with a similar developmental trend observed in calpain II protein content as well as calpain protease activity. In contrast, antioxidant gene expression demonstrated a steady increase from 75 days gestation to 24 hr after birth, followed by a significant reduction at 7 weeks of postnatal age (P ≤ 0.002). The proteolytic signaling and antioxidant capacity patterns reflect the adaptive process to metabolic change and muscle maturity with development.
authors.affiliation: Centre for Neonatal Research and Education, The University of Western Australia, Crawley 6009, Western Australia, Australia.
authors.forename: Yong
authors.initials: Y
authors.lastname: Song
authors.forename: J Jane
authors.initials: JJ
authors.lastname: Pillow
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002154:Calpain / Q000235:genetics; D053148:Caspase 3 / Q000235:genetics; D003964:Diaphragm / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D005865:Gestational Age; D005979:Glutathione Peroxidase / Q000235:genetics; D024510:Muscle Development / Q000235:genetics*; D018384:Oxidative Stress / Q000235:genetics*; D010447:Peptide Hydrolases / Q000235:genetics*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012756:Sheep; D015398:Signal Transduction / Q000235:genetics*; D013482:Superoxide Dismutase / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics; D000094765:Glutathione Peroxidase GPX1
chemical_list: D012333:RNA, Messenger; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D044767:Ubiquitin-Protein Ligases; D010447:Peptide Hydrolases; D002154:Calpain; D053148:Caspase 3; D046988:Proteasome Endopeptidase Complex; D000094765:Glutathione Peroxidase GPX1