Genetic and physical interaction between the NPHP5 and NPHP6 gene products.
Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease, caused by mutations of at least nine different genes. Several extrarenal manifestations characterize this disorder, including cerebellar defects, situs inversus and retinitis pigmentosa. While the clinical manifestations vary significantly in NPHP, mutations of NPHP5 and NPHP6 are always associated with progressive blindness. This clinical finding suggests that the gene products, nephrocystin-5 and nephrocystin-6, participate in overlapping signaling pathways to maintain photoreceptor homeostasis. To analyze the genetic interaction between these two proteins in more detail, we studied zebrafish embryos after depletion of NPHP5 and NPHP6. Knockdown of zebrafish zNPHP5 and zNPHP6 produced similar phenotypes, and synergistic effects were observed after the combined knockdown of zNPHP5 and zNPHP6. The N-terminal domain of nephrocystin-6-bound nephrocystin-5, and mapping studies delineated the interacting site from amino acid 696 to 896 of NPHP6. In Xenopus laevis, knockdown of NPHP5 caused substantial neural tube closure defects. This phenotype was copied by expression of the nephrocystin-5-binding fragment of nephrocystin-6, and rescued by co-expression of nephrocystin-5, supporting a physical interaction between both gene products in vivo. Since the N- and C-terminal fragments of nephrocystin-6 engage in the formation of homo- and heteromeric protein complexes, conformational changes seem to regulate the interaction of nephrocystin-6 with its binding partners.
Schäfer
Tobias
T
Renal Division, University Hospital Freiburg, Freiburg, Germany.
Pütz
Michael
M
Lienkamp
Soeren
S
Ganner
Athina
A
Bergbreiter
Astrid
A
Ramachandran
Haribaskar
H
Gieloff
Verena
V
Gerner
Martin
M
Mattonet
Christian
C
Czarnecki
Peter G
PG
Sayer
John A
JA
Otto
Edgar A
EA
Hildebrandt
Friedhelm
F
Kramer-Zucker
Albrecht
A
Walz
Gerd
G
D020816:Amino Acid Motifs; D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D052177:Kidney Diseases, Cystic / Q000150:complications / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008845:Microinjections; D054259:Neural Tube / Q000196:embryology / Q000254:growth & development / Q000378:metabolism; D010641:Phenotype; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
D002148:Calmodulin-Binding Proteins; D029867:Xenopus Proteins