Alternative titles; symbols
HGNC Approved Gene Symbol: NOX4
Cytogenetic location: 11q14.3 Genomic coordinates (GRCh38) : 11:89,324,353-89,589,557 (from NCBI)
Oxygen sensing is essential for homeostasis in all aerobic organisms. A phagocyte-type oxidase, similar to that responsible for the production of large amounts of reactive oxygen species (ROS) in neutrophil granulocytes, with resultant antimicrobial activity, has been postulated to function in the kidney as an oxygen sensor that regulates the synthesis of erythropoietin (EPO; 133170) in the renal cortex (summary by Geiszt et al., 2000).
The NOX4 gene encodes a protein expressed in many tissues, including vascular endothelial cells, that is a major source of ROS (summary by Ago et al., 2004).
By EST database searching for sequences corresponding to the conserved C-terminal region of gp91-phox (see 300481), followed by 5-prime and 3-prime RACE, Geiszt et al. (2000) identified a novel kidney cDNA in both human and mouse, which they designated renal NADPH oxidase (RENOX). The human RENOX cDNA encodes a deduced 578-amino acid protein with 90% sequence identity to its mouse counterpart. The protein contains conserved features considered critical for NADPH oxidase function, namely 6 hydrophobic segments within the N-terminal segment, proposed as membrane-embedded domains involved in transmembrane electron transport, and sequence motifs corresponding to proposed binding sites for heme, flavin, and NADPH. RENOX also contains a nucleotide-binding sequence motif in the C-terminal region, often referred to as the 'P-loop,' that is present in various ATP- or GTP-binding proteins. Northern blot and in situ hybridization analyses showed that RENOX mRNA is highly expressed in the kidney, particularly in the proximal convoluted tubule cells of the renal cortex.
Shiose et al. (2001) cloned NOX4 from a human kidney cDNA library. Northern blot analysis detected a 2.4-kb transcript expressed almost exclusively in adult and fetal kidney. Weak expression was also found in heart, skeletal muscle, and brain. In contrast to the findings of Geiszt et al. (2000), their immunohistochemical analysis of kidney cortex revealed strongest staining of epithelial cells of distal tubules and only faint staining of proximal tubules. Western blot analysis of transfected COS-7 and HeLa cells revealed a protein with an apparent molecular mass of 66 kD. Shiose et al. (2001) suggested that 2 minor bands of higher molecular mass could indicate oligomerization and that a membrane-associated protein of about 75 kD could represent glycosylation at one of the 4 putative N-glycosylation sites. Shiose et al. (2001) also found strong endogenous expression of NOX4 mRNA and protein in renal carcinoma cell lines.
Geiszt et al. (2000) found that NIH 3T3 fibroblasts overexpressing transfected RENOX showed increased production of superoxide and developed signs of cellular senescence. They suggested that RENOX, as a renal source of ROS, may fulfill the function of the putative oxygen sensor in the kidney.
By biochemical analysis of endogenous renal NOX4, Shiose et al. (2001) determined that the enzyme can use either NADH or NADPH as an electron donor for superoxide production.
Using Northern blot analysis, Ago et al. (2004) found high levels of NOX4 in cultured human umbilical vein endothelial cells and rat aortic endothelial cells. Expression of NOX4 further increased with serum withdrawal. Rat aortic endothelial cell membranes produced both superoxide and a hydroxyl radical derived from superoxide in an NADPH-dependent manner. Antisense Nox4 reduced superoxide production and Nox4 mRNA levels in a dose-dependent manner. Ago et al. (2004) concluded that NOX4 may function as the major catalytic component of an endothelial NADPH oxidase.
By Western blot analysis, Majumder et al. (2021) showed that levels of GRB2 (108355) and NOX4 were elevated in tissues from mouse models for Alzheimer disease (AD; see 104300) and type 2 diabetes (T2D; 125853), as well as in tissues from AD and T2D patients. Knockdown analysis in SHSY-5Y and HepG2 cells revealed that miRNA1271 targeted and restricted expression of ALK (105590) and RYK (600524), which elevated expression of GRB2 and NOX4. Moreover, PAX4 (167413), a transcription factor for both GRB2 and NOX4, was overexpressed during ALK and RYK knockdown due to reduced expression of the PAX4 suppressor ARX (300382) via beta-catenin (see 116806) signaling. In addition, expression of various cytoskeletal proteins was downregulated in liver tissue of T2D patients and in ALK/RYK knockdown cells, but overexpression of GRB2 reversed the cytoskeletal degradation through interaction with NOX4.
Shiose et al. (2001) determined that the NOX4 gene contains 18 exons and spans at least 160 kb.
Geiszt et al. (2000) stated that the nucleotide sequence of RENOX matches that found in a genomic clone on chromosome 15. In a note added in proof, they stated that genomic clones assigned to chromosome 11 also contain sequence corresponding to RENOX. By FISH, Shiose et al. (2001) mapped the NOX4 gene to chromosome 11q14.2-q21.
Ago, T., Kitazono, T., Ooboshi, H., Iyama, T., Han, Y. H., Takada, J., Wakisaka, M., Ibayashi, S., Utsumi, H., Iida, M. Nox4 as the major catalytic component of an endothelial NAD(P)H oxidase. Circulation 109: 227-233, 2004. [PubMed: 14718399] [Full Text: https://doi.org/10.1161/01.CIR.0000105680.92873.70]
Geiszt, M., Kopp, J. B., Varnai, P., Leto, T. L. Identification of Renox, an NAD(P)H oxidase in kidney. Proc. Nat. Acad. Sci. 97: 8010-8014, 2000. [PubMed: 10869423] [Full Text: https://doi.org/10.1073/pnas.130135897]
Majumder, P., Chanda, K., Das, D., Singh, B. K., Chakrabarti, P., Jana, N. R., Mukhopadhyay, D. A nexus of miR-1271, PAX4 and ALK/RYK influences the cytoskeletal architectures in Alzheimer's disease and type 2 diabetes. Biochem. J. 478: 3297-3317, 2021. [PubMed: 34409981] [Full Text: https://doi.org/10.1042/BCJ20210175]
Shiose, A., Kuroda, J., Tsuruya, K., Hirai, M., Hirakata, H., Naito, S., Hattori, M., Sakaki Y., Sumimoto, H. A novel superoxide-producing NAD(P)H oxidase in kidney. J. Biol. Chem. 276: 1417-1423, 2001. [PubMed: 11032835] [Full Text: https://doi.org/10.1074/jbc.M007597200]