Expression and phenotype analysis of the nephrocystin-1 and nephrocystin-4 homologs in Caenorhabditis elegans.
Nephronophthisis (NPHP), an autosomal-recessive cystic kidney disease, is the most frequent genetic cause of end-stage renal failure in children. NPHP types 1 and 4 are caused by mutations in NPHP1 and NPHP4, encoding the proteins nephrocystin-1 and nephrocystin-4, respectively. Nephrocystin-1 and nephrocystin-4 are expressed in primary cilia of renal epithelial cells. NPHP1 and NPHP4 are highly conserved in Caenorhabditis elegans. However, this species does not have a kidney but an excretory system that consists of an excretory cell, an excretory gland cell, a duct cell, and a pore cell. Therefore, cell type-specific expression pattern and function of the nephrocystin homologs in C. elegans were of interest. Expression of green fluorescence protein fusion constructs that contain the C. elegans promoter regions for nph-1 and nph-4 was not found in the excretory system but in ciliated sensory neurons of the head (amphid neurons) and the tail in hermaphrodites (phasmid neurons) and males (sensory ray neurons). As the knockout phenotype for the PKD homologs lov-1 and pkd-2 shows impaired male mating behavior, RNAi knockdown animals were analyzed for this phenotype. A similar phenotype was found in the nph-1 and nph-4 RNAi knockdown animals compared with the lov-1 and pkd-2 knockout phenotype. Thus, it is suggested that renal cyst-causing genes may be part of a shared functional module, highly conserved in evolution. The NPHP homologs may be necessary for initial assembly of the cilium, whereas the polycystic kidney disease homologs may function as sensory transducers.
Wolf
Matthias T F
MT
Department of Pediatrics and Communicable Diseases, University of Michigan, 8220C MSRB III, 1150 West Medical Center Drive, Ann Arbor, MI 48109-0646, USA.
Lee
Jeeyong
J
Panther
Franziska
F
Otto
Edgar A
EA
Guan
Kun-Liang
KL
Hildebrandt
Friedhelm
F
D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D012734:Disorders of Sex Development; D019143:Evolution, Molecular; D015870:Gene Expression; D008297:Male; D016296:Mutagenesis; D010641:Phenotype; D012726:Sexual Behavior, Animal / Q000502:physiology*
D029742:Caenorhabditis elegans Proteins; C501204:nephrocystin 1, C elegans; C501205:nephrocystin 4, C elegans