Probes for INS

Spatiotemporal control of Wnt signaling is essential for the development and homeostasis of many tissues. The transmembrane E3 ubiquitin ligases ZNRF3 (zinc and ring finger 3) and RNF43 (ring finger protein 43) antagonize Wnt signaling by promoting degradation of frizzled receptors. ZNRF3 and RNF43 are frequently inactivated in human cancer, but the molecular and therapeutic implications remain unclear. Here, we demonstrate that adrenocortical-specific loss of ZNRF3, but not RNF43, results in adrenal hyperplasia that depends on Porcupine-mediated Wnt ligand secretion. Furthermore, we discovered a Wnt/β-catenin signaling gradient in the adrenal cortex that is disrupted upon loss of ZNRF3. Unlike β-catenin gain-of-function models, which induce high Wnt/β-catenin activation and expansion of the peripheral cortex, ZNRF3 loss triggers activation of moderate-level Wnt/β-catenin signaling that drives proliferative expansion of only the histologically and functionally distinct inner cortex. Genetically reducing β-catenin dosage significantly reverses the ZNRF3-deficient phenotype. Thus, homeostatic maintenance of the adrenal cortex is dependent on varying levels of Wnt/β-catenin activation, which is regulated by ZNRF3.

In mice, implantation always occurs towards the antimesometrial side of the uterus, while the placenta develops at the mesometrial side. What determines this particular orientation of the implanting blastocyst remains unclear. Uterine glands are critical for implantation and pregnancy. In this study, we showed that uterine gland development and active Wnt signalling activity is limited to the antimesometrial side of the uterus. Dkk2, a known antagonist of Wnt signalling, is only present at the mesometrial side of the uterus. Imaging of whole uterus, thick uterine sections (100-1000μm), and individual glands revealed that uterine glands are simple tubes with branches that are directly connected to the luminal epithelium and are only present towards the antimesometrial side of the uterus. By developing a unique mouse model targeting the uterine epithelium, we demonstrated that Wnt/β-catenin signaling is essential for prepubertal gland formation and normal implantation, but dispensable for postpartum gland development and regeneration. Our results for the first time have provided a probable explanation for the antimesometrial bias for implantation.

The periodontal complex is essential for tooth attachment and function and includes the mineralized tissues, cementum and alveolar bone, separated by the unmineralized periodontal ligament (PDL). To gain insights into factors regulating cementum-PDL and bone-PDL borders and protecting against ectopic calcification within the PDL, we employed a proteomic approach to analyze PDL tissue from progressive ankylosis knock-out (Ank−/−) mice, featuring reduced PPi, rapid cementogenesis, and excessive acellular cementum. Using this approach, we identified the matrix protein osteopontin (Spp1/OPN) as an elevated factor of interest in Ank−/− mouse molar PDL. We studied the role of OPN in dental and periodontal development and function. During tooth development in wild-type (WT) mice, Spp1 mRNA was transiently expressed by cementoblasts and strongly by alveolar bone osteoblasts. Developmental analysis from 14 to 240 days postnatal (dpn) indicated normal histological structures in Spp1−/− comparable to WT control mice. Microcomputed tomography (micro-CT) analysis at 30 and 90 dpn revealed significantly increased volumes and tissue mineral densities of Spp1−/− mouse dentin and alveolar bone, while pulp and PDL volumes were decreased and tissue densities were increased. However, acellular cementum growth was unaltered in Spp1−/− mice. Quantitative PCR of periodontal-derived mRNA failed to identify potential local compensators influencing cementum in Spp1−/− vs. WT mice at 26 dpn. We genetically deleted Spp1 on the Ank−/− mouse background to determine whether increased Spp1/OPN was regulating periodontal tissues when the PDL space is challenged by hypercementosis in Ank−/− mice. Ank−/−; Spp1−/−double deficient mice did not exhibit greater hypercementosis than that in Ank−/− mice. Based on these data, we conclude that OPN has a non-redundant role regulating formation and mineralization of dentin and bone, influences tissue properties of PDL and pulp, but does not control acellular cementum apposition. These findings may inform therapies targeted at controlling soft tissue calcification.