Parallel waves of inductive signaling and mesenchyme maturation regulate differentiation of the chick mesonephros

• Published in: Developmental biology 2014-01, Vol.385 (1), p.122-135
• Main Authors: Soueid-Baumgarten, Sharon, Yelin, Ronit, Davila, Etty K., Schultheiss, Thomas M.
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Cell Differentiation; Chick Embryo; Embryo Culture Techniques; Gene Expression Regulation, Developmental; Induction; Intracellular Signaling Peptides and Proteins - metabolism; Kidney; Kidney - embryology; Kidney - metabolism; LIM-Homeodomain Proteins - biosynthesis; Mesoderm - embryology; Mesoderm - growth & development; Mesonephros; Mesonephros - embryology; PAX2 Transcription Factor - metabolism; Protein-Serine-Threonine Kinases - metabolism; Somites - embryology; Somites - metabolism; Wnt signaling; Wnt Signaling Pathway - physiology; Wnt4 Protein - biosynthesis
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2013.09.026

The mesonephros is a linear kidney that, in chicken embryos, stretches between the axial levels of the 15th to the 30th somites. Mesonephros differentiation proceeds from anterior to posterior and is dependent on signals from the nephric duct, which migrates from anterior to posterior through the mesonephric region. If migration of the nephric duct is blocked, markers of tubule differentiation, including Lhx1 and Wnt4, are not activated posterior to the blockade. However, activation and maintenance of the early mesonephric mesenchyme markers Osr1, Eya1 and Pax2 proceeds normally in an anterior-to-posterior wave, indicating that these genes are not dependent on inductive signals from the duct. The expression of Lhx1 and Wnt4 can be rescued in duct-blocked embryos by supplying a source of canonical Wnt signaling, although epithelial structures are not obtained, suggesting that the duct may express other tubule-inducing signals in addition to Wnts. In the absence of the nephric duct, anterior mesonephric mesenchyme adjacent to somites exhibits greater competence to initiate tubular differentiation in response to Wnt signaling than more posterior mesonephric mesenchyme adjacent to unsegmented paraxial mesoderm. It is proposed that mesonephric tubule differentiation is regulated by two independent parallel waves, one of inductive signaling from the nephric duct and the other of competence of the mesonephric mesenchyme to undergo tubular differentiation, both of which travel from anterior to posterior in parallel with the formation of new somites. •Chick mesonephros differentiation regulated by duct-dependent and independent events.•Expression of early mesonephric genes Osr1, Pax2, and Eya1 is duct-independent.•Activation of tubule markers Wnt4 and Lhx1 is duct-dependent.•Duct-independent maturation of mesonephric mesenchyme required for differentiation.•Wnt signaling partially rescues absence of nephric duct.