Comparison of thyroid hormone-dependent gene responses in vivo and in organ culture of the American bullfrog (Rana (Lithobates) catesbeiana) lung.

Abstract

Postembryonic frog development requires a thyroid hormone (TH)-dependent metamorphic transition from an aquatic larva to a terrestrial frog. Such change in environment involves lung maturation in preparation for breathing air. However, little is known regarding the underlying molecular events and the role of THs in this process. Using quantitative real-time polymerase chain reaction, we evaluated Rana (Lithobates) catesbeiana lung mRNA transcripts representing key elements of TH and oxidative stress signaling pathways during natural and TH-induced precocious metamorphosis. TH induction was evaluated in two ways: 1) in vivo through interperitoneal injection of 10pmol/g body weight of 3,3', 5-triiodothyronine (T3) into premetamorphic tadpoles and analysis after 48h, and 2) in serum-free organ culture in the presence of 10nM T3 after 48h. Abundance of transcripts encoding the transcriptional regulators TH receptors α and β, TH-induced bZip protein, and CCAAT/enhancer binding protein 1 was increased during postembryonic development and following administration of exogenous THs to premetamorphic tadpoles in vivo and culture. In contrast, mRNA representing Krüppel-like factor 9 and cold-inducible RNA binding protein revealed differential effects between natural and precocious metamorphosis. Elevated levels of catalase and Cu/Zn superoxide dismutase mRNA were observed at the end of metamorphosis with transcript levels displaying minimal TH-dependency. No change in stress-responsive heat shock protein 30 mRNA abundance was noted. The results support a role for TH-dependent reprogramming of the lung transcriptome during frog development and reveal a requirement for increased antioxidant capacity following anuran metamorphosis.

• Authors: Nik Veldhoen, Mitchel R Stevenson, Caren C Helbing
• Journal: Comparative biochemistry and physiology. Part D, Genomics & proteomics (Comp Biochem Physiol Part D Genomics Proteomics) Vol. 16 Pg. 99-105 (Dec 2015) ISSN: 1878-0407 [Electronic] Netherlands
• PMID: 26462067 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 Elsevier Inc. All rights reserved.

Chemical References

• Thyroid Hormones

Topics

• Animals
• Gene Expression Regulation, Developmental
• Larva (genetics, growth & development, metabolism)
• Lung (growth & development, metabolism)
• Metamorphosis, Biological
• Organ Culture Techniques
• Oxidative Stress
• Rana catesbeiana (genetics, growth & development, metabolism)
• Thyroid Hormones (metabolism)