Transcriptional regulation of SP-B gene expression by nitric oxide in H441 lung epithelial cells.
Surfactant protein B (SP-B) is essential for the surface tension-lowering function of pulmonary surfactant. Surfactant dysfunction and reduced SP-B levels are associated with elevated nitric oxide (NO) in inflammatory lung diseases, such as acute respiratory distress syndrome. We previously found that NO donors decreased SP-B expression in H441 and MLE-12 lung epithelial cells by reducing SP-B promoter activity. In this study, we determined the roles of DNA elements and interacting transcription factors necessary for NO inhibition of SP-B promoter activity in H441 cells. We found that the NO donor diethylenetriamine-nitric oxide adduct (DETA-NO) decreased SP-B promoter thyroid transcription factor 1 (TTF-1), hepatocyte nuclear factor 3 (HNF-3), and Sp1 binding activities but increased activator protein 1 (AP-1) binding activity. DETA-NO decreased TTF-1, but not Sp1, levels, suggesting that reduced TTF-1 expression contributes to reduced TTF-1 binding activity. Lack of effect on Sp1 levels suggested that DETA-NO inhibits Sp1 binding activity per se. Overexpression of Sp1, but not TTF-1, blocked DETA-NO inhibition of SP-B promoter activity. DETA-NO inhibited SP-B promoter induction by exogenous TTF-1 without altering TTF-1 levels. DETA-NO decreased TTF-1 mRNA levels and gene transcription rate, indicating that DETA-NO inhibits TTF-1 expression at the transcriptional level. We conclude that NO inhibits SP-B promoter by decreasing TTF-1, Sp1, and HNF-3 binding activities and increasing AP-1 binding activity. NO inhibits TTF-1 levels and activity to decrease SP-B expression. NO inhibition of SP-B expression could be a mechanism by which surfactant dysfunction occurs in inflammatory lung diseases.
Boggaram
Vijay
V
Center for Biomedical Research, Univ. of Texas Health Science Center at Tyler, TX 75708-3154, USA. vijay.boggaram@uthct.edu
Chandru
Hemakumar
H
Gottipati
Koteswara Rao
KR
Thakur
Vijayander
V
Das
Aparajita
A
Berhane
Kiflu
K
D002460:Cell Line; D051858:Forkhead Transcription Factors / Q000235:genetics; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D009569:Nitric Oxide / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D037701:Pulmonary Surfactant-Associated Protein B / Q000096:biosynthesis* / Q000235:genetics; D020545:Respiratory Mucosa / Q000187:drug effects / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014226:Triazenes / Q000494:pharmacology
C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; C511144:CCDC59 protein, human; C477894:FOXI1 protein, human; D051858:Forkhead Transcription Factors; D037701:Pulmonary Surfactant-Associated Protein B; D016329:Sp1 Transcription Factor; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D014226:Triazenes; D009569:Nitric Oxide