Accumulation of ubiquitin and sequestosome-1 implicate protein damage in diacetyl-induced cytotoxicity

Details

• Personal Author:
  Barnabei JL ; Battelli LA ; Bucklew-Moyers W ; Cumpston AM ; Edwards RJ ; Fedan, Jeffery S. ; Fluharty KL ; Friend S ; Goldsmith WT ; Goravanahally MP ; Grantham JT ; Honaker JC ; Hubbs, Ann F. ; Jackson MC ; Kashon ML ; Kelly F ; Knepp AK ; McKinney W ; McKinstry K ; Mercer RR ; Munro T ; Palmer SM ; Reynolds SH ; Sargent LM ; Schwegler-Berry D ; Smith SL ; Sriram K
• Description:
  Inhaled diacetyl vapors are associated with flavorings-related lung disease, a potentially fatal airways disease. The reactive a-dicarbonyl group in diacetyl causes protein damage in vitro. Dicarbonyl/L- xylulose reductase (DCXR) metabolizes diacetyl to acetoin, which lacks this a-dicarbonyl group. To investigate the hypothesis that flavorings-related lung disease is caused by in vivo protein damage, we correlated diacetyl-induced airway damage in mice with immunofluorescence for markers of protein turnover and autophagy. Western immunoblots identified shifts in ubiquitin pools. Diacetyl inhalation caused dose-dependent increases in bronchial epithelial cells with puncta of total ubiquitin and K63-8 ubiquitin, central mediators of protein turnover. This response was greater in Dcxr knockout than in wild type mice inhaling 200 ppm diacetyl, further implicating the a-dicarbonyl group in the protein damage. Western immunoblots demonstrated decreased free ubiquitin in airway-enriched fractions. Transmission electron microscopy and co-localization of ubiquitin-positive puncta with lysosomal 12 markers LAMP1 and LAMP2 and with the multifunctional scaffolding protein, sequestosome-1 (SQSTM1/p62), confirmed autophagy. Surprisingly, immunoreactive SQSTM1 also accumulated in the olfactory bulb of the brain. Olfactory bulb SQSTM1 often congregated in activated microglial cells which also contained olfactory marker protein, indicating neuronophagia within the olfactory bulb. This suggests the possibility that SQSTM1 or damaged proteins may be transported from the nose to the brain. Together, these findings strongly implicate widespread protein damage in the etiology of flavorings-related lung disease. [Description provided by NIOSH]
• Subjects:
  Diacetyl Flavoring Agents Immune System Laboratories Lung Diseases Occupational Health Respiratory System Respiratory Tract Diseases Safety
• Keywords:
  Cell Biology Etiology Flavorings Immune Reaction Inhalation Laboratory Animals Lung Disease
• ISSN:
  0002-9440
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  Georgia ; North Carolina ; OSHA Region 3 ; OSHA Region 4 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  186
• Issue:
  11
• NIOSHTIC Number:
  nn:20048662
• Citation:
  Am J Pathol 2016 Nov; 186(11):2887-2908
• Contact Point Address:
  Ann F. Hubbs, DVM, PhD, DACVP, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1095 Willowdale Rd., Morgantown, WV 26505
• Email:
  ahubbs@cdc.gov
• CAS Registry Number:
  Butanedione (CAS RN 431-03-8)
• Federal Fiscal Year:
  2017
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  True
• Source Full Name:
  The American Journal of Pathology
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:5b5db0076f069bc751b25f7ac738ac6a4228d8e6049696264f0955776db57b7e44488f6317e08427fda735a8ac107642389a8813e99f2ac6699e36d5c0c41623
• Download URL:
  https://stacks.cdc.gov/view/cdc/203369/cdc_203369_DS1.pdf
• File Type:
  [PDF - 4.07 MB ]