1 Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, Københavns Universitet2 Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, Københavns Universitet3 Division of Nephrology, Boston Children's Hospital, Boston, Massachusetts;4 unknown5 Section I. Center for Healthy Aging, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, Københavns Universitet6 Department of Biochemistry and Molecular Biology, SDU7 Section I. Center for Healthy Aging, Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, Københavns Universitet
Nephronophthisis-related ciliopathies (NPHP-RCs) are developmental and degenerative kidney diseases that are frequently associated with extrarenal pathologies such as retinal degeneration, obesity, and intellectual disability. We recently identified mutations in a gene encoding the centrosomal protein SDCCAG8 as causing NPHP type 10 in humans. To study the role of Sdccag8 in disease pathogenesis, we generated a Sdccag8 gene-trap mouse line. Homozygous Sdccag8(gt/gt) mice lacked the wild-type Sdccag8 transcript and protein, and recapitulated the human phenotypes of NPHP and retinal degeneration. These mice exhibited early onset retinal degeneration that was associated with rhodopsin mislocalization in the photoreceptors and reduced cone cell numbers, and led to progressive loss of vision. By contrast, renal histologic changes occurred later, and no global ciliary defects were observed in the kidneys. Instead, renal pathology was associated with elevated levels of DNA damage response signaling activity. Cell culture studies confirmed the aberrant activation of DNA damage response in Sdccag8(gt/gt)-derived cells, characterized by elevated levels of γH2AX and phosphorylated ATM and cell cycle profile abnormalities. Our analysis of Sdccag8(gt/gt) mice indicates that the pleiotropic phenotypes in these mice may arise through multiple tissue-specific disease mechanisms.
Journal of the American Society of Nephrology:jasn, 2014, Vol 25, Issue 11, p. 2573-83