Identification of novel Nox4 splice variants with impact on ROS levels in A549 cells.
NAD(P)H oxidases (Nox) generate reactive oxygen species (ROS) that function in host defense and cellular signaling. While analyzing the expression of Nox4 at the protein and the mRNA levels, we identified four novel Nox4 splice-variants Nox4B, Nox4C, Nox4D, and Nox4E, which are expressed in human lung A549 cell line and lung tissues. One Nox4 isoform lacks the first NAD(P)H binding site (Nox4B) while another lacks all FADH and NAD(P)H binding sites (Nox4C). Cells over-expressing NoxB or Nox4C exhibited a decrease in ROS levels. Thus, these isoforms have dominant negative characteristics for ROS generation. Two other splice-variants (Nox4D, Nox4E) lack the transmembrane domains, suggesting these as non-membrane associated isoforms. Nox4D contains all FADH and NAD(P)H binding domains and shows the same rate of ROS generation as Nox4 prototype. Taken together, we suggest that Nox4 exists as several isoforms that may have different functions in ROS-related cell signaling.
Goyal
Parag
P
Department of Internal Medicine, Medical School University of Giessen, Klinikstr. 36, D-35392 Giessen, Germany.
Weissmann
Norbert
N
Rose
Frank
F
Grimminger
Friedrich
F
Schäfers
Hans J
HJ
Seeger
Werner
W
Hänze
Jörg
J
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D019295:Computational Biology; D018076:DNA, Complementary / Q000378:metabolism; D005091:Exons; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006031:Glycosylation; D006801:Humans; D007150:Immunohistochemistry; D008168:Lung / Q000473:pathology; D008969:Molecular Sequence Data; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D020033:Protein Isoforms; D012313:RNA / Q000378:metabolism; D017382:Reactive Oxygen Species; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014162:Transfection
D018076:DNA, Complementary; D010455:Peptides; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D012313:RNA; D000074624:NADPH Oxidase 1; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C402799:NOX1 protein, human; C498910:NOX4 protein, human