title: Non-stringent tissue-source requirements for BMP ligand expression in regulation of body size in Caenorhabditis elegans.
abstract: In Caenorhabditis elegans, the Bone Morphogenetic Protein (BMP)-related ligand Dpp- and BMP-like-1 (DBL-1) regulates body size by promoting the larval and adult growth of the large epidermal syncytium hyp7 without affecting cell division. This system provides an excellent model for dissecting the growth-promoting activities of BMP ligands, since in this context the growth and differentiation functions of DBL-1 are naturally uncoupled. dbl-1 is expressed primarily in neurons and the DBL-1 ligand signals to its receptors and Smad signal transducers in the target tissue of the epidermis. The requirements constraining the source(s) of DBL-1, however, have not previously been investigated. We show here that dbl-1 expression requirements are strikingly relaxed. Expression in non-overlapping subsets of the endogenous expression pattern, as well as ectopic expression, can provide sufficient levels of activity for rescue of the small body size of dbl-1 mutants. By analysing dbl-1 expression levels in transgenic strains with different degrees of rescue, we corroborate the model that DBL-1 is a dose-dependent regulator of growth. We conclude that, for body size regulation, the site of expression of dbl-1 is less important than the level of expression.
authors.affiliation: Department of Biology, Queens College, City University of New York, Flushing, NY 11367, USA. cathy.savagedunn@qc.cuny.edu
authors.forename: Cathy
authors.initials: C
authors.lastname: Savage-Dunn
authors.forename: Ling
authors.initials: L
authors.lastname: Yu
authors.forename: Kwesi
authors.initials: K
authors.lastname: Gill
authors.forename: Muhammad
authors.initials: M
authors.lastname: Awan
authors.forename: Thilini
authors.initials: T
authors.lastname: Fernando
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D049628:Body Size / Q000235:genetics*; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000254:growth & development; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D009154:Mutation; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000235:genetics*; D010614:Pharynx / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics; D040521:Subcutaneous Tissue / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics*
chemical_list: D029742:Caenorhabditis elegans Proteins; C117509:Dbl-1 protein, C elegans; D009479:Neuropeptides; D016212:Transforming Growth Factor beta