Mice deficient in dual oxidase maturation factors are severely hypothyroid.
Dual oxidases (DUOX1 and DUOX2) are evolutionary conserved reduced nicotinamide adenine dinucleotide phosphate oxidases responsible for regulated hydrogen peroxide (H(2)O(2)) release of epithelial cells. Specific maturation factors (DUOXA1 and DUOXA2) are required for targeting of functional DUOX enzymes to the cell surface. Mutations in the single-copy Duox and Duoxa genes of invertebrates cause developmental defects with reduced survival, whereas knockdown in later life impairs intestinal epithelial immune homeostasis. In humans, mutations in both DUOX2 and DUOXA2 can cause congenital hypothyroidism with partial iodide organification defects compatible with a role of DUOX2-generated H(2)O(2) in driving thyroid peroxidase activity. The DUOX1/DUOXA1 system may account for residual iodide organification in patients with loss of DUOX2, but its physiological function is less clear. To provide a murine model recapitulating complete DUOX deficiency, we simultaneously targeted both Duoxa genes by homologous recombination. Knockout of Duoxa genes (Duoxa(-/-) mice) led to a maturation defect of DUOX proteins lacking Golgi processing of N-glycans and to loss of H(2)O(2) release from thyroid tissue. Postnatally, Duoxa(-/-) mice developed severe goitreous congenital hypothyroidism with undetectable serum T4 and maximally disinhibited TSH levels. Heterozygous mice had normal thyroid function parameters. (125)I uptake and discharge studies and probing of iodinated TG epitopes corroborated the iodide organification defect in Duoxa(-/-) mice. Duoxa(-/-) mice on continuous T4 replacement from P6 showed normal growth without an overt phenotype. Our results confirm in vivo the requirement of DUOXA for functional expression of DUOX-based reduced nicotinamide adenine dinucleotide phosphate oxidases and the role of DUOX isoenzymes as sole source of hormonogenic H(2)O(2).
Biomedical Science Research Building, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA. hgrasber@gmail.com
Helmut
H
Grasberger
Xavier
X
De Deken
Olga Barca
OB
Mayo
Houssam
H
Raad
Mia
M
Weiss
Xiao-Hui
XH
Liao
Samuel
S
Refetoff
D000818:Animals; D004195:Disease Models, Animal; D000074623:Dual Oxidases; D005260:Female; D055786:Gene Knockout Techniques; D006130:Growth Disorders / Q000188:drug therapy / Q000235:genetics; D007037:Hypothyroidism / Q000188:drug therapy / Q000235:genetics*; D007454:Iodides / Q000378:metabolism; D007527:Isoenzymes / Q000172:deficiency; D008297:Male; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019255:NADPH Oxidases / Q000172:deficiency; D009419:Nerve Tissue Proteins / Q000172:deficiency* / Q000235:genetics; D009687:Nuclear Proteins / Q000172:deficiency* / Q000235:genetics; D010641:Phenotype; D013954:Thyroglobulin / Q000378:metabolism; D013961:Thyroid Gland / Q000201:enzymology / Q000473:pathology; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000627:therapeutic use
C560186:DUOXA1 protein, mouse; C572869:DUOXA2 protein, mouse; D007454:Iodides; D007527:Isoenzymes; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D013972:Thyrotropin; D013954:Thyroglobulin; D000074623:Dual Oxidases; D019255:NADPH Oxidases; C519130:Duox1 protein, mouse; D013974:Thyroxine