Macrophage-stimulating protein and calcium homeostasis in zebrafish.
To systematically identify novel gene functions essential for osteogenesis and skeletal mineralization, we performed a forward genetic mutagenesis screen in zebrafish and isolated a mutant that showed delayed skeletal mineralization. Analysis of the mutant phenotype in an osterix:nuclear-GFP transgenic background demonstrated that mutants contain osterix-expressing osteoblasts comparable to wild-type embryos. Positional cloning revealed a premature stop mutation in the macrophage-stimulating protein (msp) gene, predicted to result in a biologically inactive protein. Analysis of the embryonic expression pattern for the receptor for Msp, Ron, shows specific expression in the corpuscles of Stannius, a teleost-specific organ that produces stanniocalcin, a pivotal hormone in fish calcium homeostasis. Knockdown of Ron resulted in identical phenotypes as observed in msp mutants. Msp mutant embryos could be rescued by excess calcium. Consistent with a role for Msp/Ron in calcium homeostasis, calcium-regulating factors, such as pth1, pth2, stc1l, and trpv5/6 were significantly affected in msp mutant larvae. While Msp and Ron have previously been shown to play a critical role in a wide variety of biological processes, we introduce here the Msp/Ron signaling axis as a previously unappreciated player in calcium homeostasis and embryonic skeletal mineralization.
Hubrecht Institute, KNAW and University Medical Centre Utrecht, Uppsalalaan 8, 3584CT Utrecht, The Netherlands.
Leonie F A
LF
Huitema
Jörg
J
Renn
Ive
I
Logister
Jerilyn K
JK
Gray
Susan E
SE
Waltz
Gert
G
Flik
Stefan
S
Schulte-Merker
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis / Q000235:genetics / Q000502:physiology; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
D006023:Glycoproteins; D011518:Proto-Oncogene Proteins; D029961:Zebrafish Proteins; C082332:macrophage stimulating protein; D017228:Hepatocyte Growth Factor; C051795:teleocalcin; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases; D002118:Calcium