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Hypoxia‐Induced Changes in the Ubiquitin Proteasome System in a Mouse Model of Pulmonary Hypertension
Author(s) -
Wade Brandy E,
Zhao Jingru,
Ma Jing,
Hart C. Michael,
Sutliff Roy L.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1016.17
Subject(s) - ubiquitin , proteasome , hypoxia (environmental) , pulmonary hypertension , chemistry , microbiology and biotechnology , biology , endocrinology , medicine , biochemistry , oxygen , gene , organic chemistry
Pulmonary hypertension( PH ) involves a sustained increase in pulmonary arterial pressure and resistance that result in right ventricular( RV ) hypertrophy and can ultimately lead to RV failure and death. The mechanisms leading to vascular cell proliferation and vascular remodeling in PH are incompletely defined. The majority of therapeutic approaches target vasodilation but do not address the cellular proliferation and vascular remodeling that underlie PH pathogenesis. The objective of this study is to examine the role of the ubiquitin proteasome system ( UPS ), an important regulator of protein stability, inhypoxia‐induced PH. Current evidence demonstrates changes in UPS activity in PH; however, the pathways and proteins influenced by these changes are poorly defined. Mice exposed to normoxic or hypoxic (10% O 2 ) conditions for 3 weeks were used to identify proteins with altered ubiquitination in response to hypoxia exposure. Lungs were collected, and the PTMScan ® Ubiquitin Remnant Motif (K‐ɛ‐GG) Kit was used to precipitate ubiquitinated proteins for analysis by mass spectrometry ( MS ). This unbiased MS technique allows identification of changes in ubiquitination of individual peptides as well as global changes in ubiquitin linkage. 198uniquely modified peptides with significant changes in ubiquitination were identified using a fold change threshold of ≥±1.5 (p<0.05). Further analysis revealed a significant decrease in total available ubiquitin though no significant change in total number of ubiquitinated substrates was observed. Hypoxia significantly decreases K11 ubiquitination indicating changes in UPS‐mediated cellcycle regulation. Hypoxia significantly increases K48 ubiquitination suggesting changes in UPS‐mediated protein stability. Increased K48 ubiquitination combined with hypoxia‐induced increases in proteasome and autophagy activity also suggest that ubiquitin‐mediated protein stability may play an important role in PH. These data point to a hypoxia‐induced shift in activity or expression of ubiquitin ligases, the proteins responsible for covalent addition of a ubiquitin moiety to a protein target, and indicate that other shifts in UPS activity may play a significant role in PH pathogenesis. Support or Funding Information NIH RO1HL102167 (CMH and RLS), Merit Review from VA Office of Research and Development (1I01BX001910 to CMH), and AHA postdoctoral fellowship (16POST30930007 to BEW), SIRE (to JZ)