RESUMEN
BACKGROUND Lung alveolar epithelial type II cells (AEC II) are the most important stem cells in lung tissues, which are critical for wound repair of bronchopulmonary dysplasia (BPD). This study investigated the effects of calcitonin gene-related peptide (CGRP) on AEC II cells exposed to hyperoxia. MATERIAL AND METHODS Neonatal rat AEC II cells were isolated and identified by detecting surfactant protein C (SP-C). Three small interfering RNAs targeting Notch 1 were synthesized and transfected into AEC II. A hyperoxia-exposed AEC II cell injury model was established and was divided into 8 groups. MDA levels and SOD activity were examined using lipid peroxidation assay kits. Apoptosis and reactive oxygen species (ROS) production were evaluated using flow cytometry. Notch 1 mRNA expression was examined using RT-PCR. Homocysteine-induced endoplasmic reticulum protein (HERP) was examined using Western blot analysis. RESULTS CGRP treatment significantly enhanced MDA levels and decreased SOD activity compared to hyperoxia-treated AEC II cells (P<0.05). CGRP treatment significantly inhibited hyperoxia-induced AEC II cell apoptosis, and significantly suppressed hyperoxia-induced ROS production compared to hyperoxia-treated AEC II cells (P<0.05) either undergoing g secretase inhibitor or Notch RNA interference. CGRP significantly triggered Notch 1 mRNA expression and significantly enhanced HERP expression compared to hyperoxia-treated AEC II cells (P<0.05) either undergoing g secretase inhibitor or Notch RNA interference. CONCLUSIONS In AEC II cells, extrinsic peptide CGRP suppressed hyperoxia-induced apoptosis, oxidative stress, and ROS production, which may be triggered by Notch 1 and HERP signaling pathway.
Asunto(s)
Péptido Relacionado con Gen de Calcitonina/farmacología , Células Epiteliales Alveolares/metabolismo , Animales , Animales Recién Nacidos/metabolismo , Apoptosis/efectos de los fármacos , Péptido Relacionado con Gen de Calcitonina/metabolismo , Proliferación Celular/efectos de los fármacos , Células Cultivadas/metabolismo , Retículo Endoplásmico/metabolismo , Células Epiteliales/metabolismo , Hiperoxia/tratamiento farmacológico , Hiperoxia/metabolismo , Pulmón/metabolismo , Proteínas de la Membrana/efectos de los fármacos , Proteínas de la Membrana/metabolismo , Estrés Oxidativo/efectos de los fármacos , Oxígeno/metabolismo , Ratas , Ratas Sprague-Dawley , Especies Reactivas de Oxígeno/metabolismo , Receptor Notch1/efectos de los fármacos , Receptor Notch1/metabolismo , Transducción de Señal/efectos de los fármacosRESUMEN
OBJECTIVE: The aim of this study was to investigate the regulatory mechanism of endothelin-1 (ET-1), an endothelium-derived vasoconstrictor, on adipogenesis in vitro and in vivo. METHODS: 3T3-L1 preadipocytes were used to explore the mechanisms mediating ET-1 actions on preadipocyte proliferation and adipocyte differentiation. To investigate the in vivo effect of ET-1, male Sprague-Dawley rats were infused with ET-1 or saline for 4 weeks via intraperitoneally implanted osmotic pumps, and the fat pad weight and adipocyte size of adipose tissues were measured. RESULTS: ET-1 stimulated preadipocyte proliferation and increased the cell number at the mitotic clonal expansion stage of adipocyte differentiation via the endothelin A receptor (ETAR) and activation of the protein kinase C (PKC) pathway. ET-1, via ETAR, inhibited adipocyte differentiation partially through an ERK-dependent pathway. Furthermore, no significant difference in the body weight and fat pad weight was observed in either ET-1- or saline-infused rats. Compared with saline-infused rats, the adipocyte cell number was significantly increased but the adipocyte size was significantly decreased in ET-1-infused rats. CONCLUSIONS: Chronic ET-1 infusion increased the number of small adipocytes without the change of white adipose tissue mass in rats, which were associated with ET-1-stimulated preadipocyte proliferation, but not ET-1-suppressed adipocyte differentiation.