GSE98715
Protein kinase 7 regulating extracellular matrix assemblies and intracellular RAC1 and myosin II activities in the mesenchyme is important to Wolffian duct morphogenesis.
Wolffian/epididymal duct morphogenesis highly coordinates with its specialized function of providing microenvironment for sperm maturation. Without normal development of Wolffian duct, male infertility will result. Therefore, it is important to understand the cellular and molecular mechanisms that regulated Wolffian duct morphogenesis. Our previous study showed that mediolateral intercalation of epithelial cells was a major driver of ductal elongation. In addition, radial intercalation of mesenchymal cells surrounding the duct also played roles in Wolffian duct morphogenesis, and all of these cell re-arrangements were regulated by protein tyrosine kinase 7 (PTK7), a member of the planar cell polarity (PCP) non-canonical Wnt pathway. In this study, we showed that PTK7 regulated assemblies of extracellular matrix (ECM) at the basement membrane and throughout the mesenchyme. Abnormal assembly of laminin, collagen IV, and nephronectin at the basement membrane and fibrosis-like deposition of fibrilla collagen in the interstitium were observed in Ptk7 knockout Wolffian ducts.  Meanwhile, PTK7 regulated activity levels of small GTPase RAC1 and myosin II in the mesenchyme of the Wolffian duct. Activity levels of RAC1 and myosin II decreased in the Ptk7 knockout mesenchyme compared to controls. When in-vitro-cultured Wolffian ducts were treated with collagenase IV, cross-link of fibrilla collagen was reduced, Wolffian duct elongation and coiling was reduced significantly, and cyst-like bulge was developed in the epithelial duct. When Wolffian ducts were treated with RAC1 inhibitor NSC23766, fibrilla collagen in the mesenchyme was disassembled, and Wolffian duct elongation was suppressed significantly. Our finding suggested that PTK7 regulated ECM assembly in the mesenchyme likely through regulating RAC1 and myosin II activities. Dynamic assembly and remodeling of ECM were important to Wolffian duct morphogenesis. Overall design: Examination of gene expression in PTK7-/- Wolffian ducts