The Transcription Factor PU.1 Mediates Multi-Walled Carbon Nanotubes-Induced Arachidonate 5-Lipoxygenase Expression and Proinflammatory Responses in Macrophages

Details

• Personal Author:
  Lim, C. ; Gu, Ja K. ; Ma, Qiang
• Description:
  Background and Purpose: Exposure to fibrogenic multi-walled carbon nanotubes (MWCNTs) induces the production of proinflammatory lipid mediators (LMs) in myeloid cells to instigate inflammation. The molecular underpinnings of LM production in nanotoxicity remain unclear. Methods: Murine (J774A.1 cells) or human monocyte derived macrophages were treated with MWCNTs (Mitsui-7) or Carbon black (CB, Printex90), an amorphous carbon material control, at 2.5 or 10 µg/mL for 24 hours. The molecular induction of arachidonate 5-lypoxygenase (Alox5) and production of LMs were assessed by quantitative RT-PCR or ELISA assay, respectively, and the key transcription factor was identified by a series of luciferase reporter assay and chromatin immunoprecipitation assay after the exposure in macrophages. Results: MWCNTs induced the expression of Alox5 at both mRNA and protein levels in murine and human macrophages, accompanied by marked elevation of chemotactic LM leukotriene B4 (LTB4). Induction is comparable to those by potent M1 inducers. CB did not increase Alox5 expression or LTB4 production at equivalent doses. MWCNTs induced the expression of a heterologous luciferase reporter under the control of the murine Alox5 promoter. Deletional analysis for the 5' upstream regulatory region of Alox5 promoter uncovered multiple activation regions of which the activities were further increased by MWCNTs. We also found that the Alox5 promoter contains four binding sites for PU.1, a ETS domain-containing master regulator of hematopoiesis, which was further increased by MWCNTs. Knockdown of PU.1 using specific small hairpin-RNA blocked the basal and induced expression of Alox5 mRNA and the production of LTB4 as well as prostaglandin E2. Conclusions: The results demonstrate a critical role of PU.1 in mediating MWCNTs-induced expression of Alox5 and production of proinflammatory LMs, revealing a molecular framework where the hematopoietic transcription factor PU.1 is activated to orchestrate multiple proinflammatory responses to sterile particulate stimuli. Description provided by NIOSH
• Subjects:
  • Immune System
  • Nanotubes, Carbon
  • Occupational Health
  • Safety
• Keywords:
  • MWCNT; Multi-walled carbon nanotubes; Nanotoxicology; Macrophages; Gene expression; Immune reaction
• Source:
  Toxicologist 2025 Mar; 204(S1):466
• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Philadelphia Region OSHA ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  2 pdf pages
• Volume:
  204
• NIOSHTIC Number:
  nn:20071585
• CAS Registry Number:
  • Carbon nanotubes (CAS RN 308068-56-6)
• Federal Fiscal Year:
  2025
• NORA Priority Area:
  Construction ; Manufacturing
• Peer Reviewed:
  False
• Download URL:
  https://stacks.cdc.gov/view/cdc/259360/cdc_259360_DS1.pdf
• File Type:
  [PDF - 260.17 KB]
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:5ff4cb9686e0e0c06b641843f6204fd9f6f6d618cfc90413443b4972a778814daf23d7e402db7e48306f1f5fa8db34ba62d15c6cbee456e1d846cdb1e09d1caf