title: NPHP4 is necessary for normal photoreceptor ribbon synapse maintenance and outer segment formation, and for sperm development.
abstract: Nephronophthisis (NPHP) is an autosomal recessive kidney disease that is often associated with vision and/or brain defects. To date, 11 genes are known to cause NPHP. The gene products, while structurally unrelated, all localize to cilia or centrosomes. Although mouse models of NPHP are available for 9 of the 11 genes, none has been described for nephronophthisis 4 (Nphp4). Here we report a novel, chemically induced mutant, nmf192, that bears a nonsense mutation in exon 4 of Nphp4. Homozygous mutant Nphp4(nmf192/nmf192) mice do not exhibit renal defects, phenotypes observed in human patients bearing mutations in NPHP4, but they do develop severe photoreceptor degeneration and extinguished rod and cone ERG responses by 9 weeks of age. Photoreceptor outer segments (OS) fail to develop properly, and some OS markers mislocalize to the inner segments and outer nuclear layer in the Nphp4(nmf192/nmf192) mutant retina. Despite NPHP4 localization to the transition zone in the connecting cilia (CC), the CC appear to be normal in structure and ciliary transport function is partially retained. Likewise, synaptic ribbons develop normally but then rapidly degenerate by P14. Finally, Nphp4(nmf192/nmf192) male mutants are sterile and show reduced sperm motility and epididymal sperm counts. Although Nphp4(nmf192/nmf192) mice fail to recapitulate the kidney phenotype of NPHP, they will provide a valuable tool to further elucidate how NPHP4 functions in the retina and male reproductive organs.
authors.affiliation: The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA.
authors.forename: Jungyeon
authors.initials: J
authors.lastname: Won
authors.forename: Caralina
authors.initials: C
authors.lastname: Marín de Evsikova
authors.forename: Richard S
authors.initials: RS
authors.lastname: Smith
authors.forename: Wanda L
authors.initials: WL
authors.lastname: Hicks
authors.forename: Malia M
authors.initials: MM
authors.lastname: Edwards
authors.forename: Chantal
authors.initials: C
authors.lastname: Longo-Guess
authors.forename: Tiansen
authors.initials: T
authors.lastname: Li
authors.forename: Jürgen K
authors.initials: JK
authors.lastname: Naggert
authors.forename: Patsy M
authors.initials: PM
authors.lastname: Nishina
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002874:Chromosome Mapping; D002923:Cilia / Q000378:metabolism; D018389:Codon, Nonsense; D004596:Electroretinography; D007248:Infertility, Male / Q000235:genetics; D052177:Kidney Diseases, Cystic / Q000235:genetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009607:Nitrosourea Compounds / Q000494:pharmacology; D010641:Phenotype; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology* / Q000648:ultrastructure*; D011506:Proteins / Q000235:genetics* / Q000502:physiology*; D012160:Retina / Q000002:abnormalities; D012162:Retinal Degeneration / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013079:Sperm Maturation / Q000235:genetics*; D013081:Sperm Motility; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure*
chemical_list: D018389:Codon, Nonsense; C559479:NPHP4 protein, mouse; D009607:Nitrosourea Compounds; D011506:Proteins