Sprouty genes control diastema tooth development via bidirectional antagonism of epithelial-mesenchymal FGF signaling
DEVELOPMENTAL CELL
Authors: Klein, Ophir D.; Minowada, George; Peterkova, Renata; Kangas, Aapo; Yu, Benjamin D.; Lesot, Herve; Peterka, Miroslav; Jernvall, Jukka; Martin, Gail R.
Abstract
Unlike humans, who have a continuous row of teeth, mice have only molars and incisors separated by a toothless region called a diastema. Although tooth buds form in the embryonic diastema, they regress and do not develop into teeth. Here, we identify members of the Sprouty (Spry) family, which encode negative feedback regulators of fibroblast growth factor (FGF) and other receptor tyrosine kinase signaling, as genes that repress diastema tooth development. We show that different Sprouty genes are deployed in different tissue compartments-Spry2 in epithelium and Spry4 in mesenchyme-to prevent diastema tooth formation. We provide genetic evidence that they function to ensure that diastema tooth buds are refractory to signaling via FGF ligands that are present in the region and thus prevent these buds from engaging in the FGF-mediated bidirectional signaling between epithelium and mesenchyme that normally sustains tooth development.
Sprouty2, PTEN, and PP2A interact to regulate prostate cancer progression
JOURNAL OF CLINICAL INVESTIGATION
Authors: Patel, Rachana; Gao, Meiling; Ahmad, Imran; Fleming, Janis; Singh, Lukram B.; Rai, Taranjit Singh; McKie, Arthur B.; Seywright, Morag; Barnetson, Robert J.; Edwards, Joanne; Sansom, Owen J.; Leung, Hing Y.
Abstract
Concurrent activation of RAS/ERK and PI3K/AKT pathways is implicated in prostate cancer progression. The negative regulators of these pathways, including sprouty2 (SPRY2), protein phosphatase 2A (PP2A), and phosphatase and tensin homolog (PTEN), are commonly inactivated in prostate cancer. The molecular basis of cooperation between these genetic alterations is unknown. Here, we show that SPRY2 deficiency alone triggers activation of AKT and ERK, but this is insufficient to drive tumorigenesis. In addition to AKT and ERK activation, SPRY2 loss also activates a PP2A-dependent tumor suppressor checkpoint. Mechanistically, the PP2A-mediated growth arrest depends on GSK3 beta and is ultimately mediated by nuclear PTEN. In murine prostate cancer models, Pten haploinsufficiency synergized with Spry2 deficiency to drive tumorigenesis, including metastasis. Together, these results show that loss of Pten cooperates with Spry2 deficiency by bypassing a novel tumor suppressor checkpoint. Furthermore, loss of SPRY2 expression correlates strongly with loss of PTEN and/or PP2A subunits in human prostate cancer. This underlines the cooperation between SPRY2 deficiency and PTEN or PP2A inactivation in promoting tumorigenesis. Overall, we propose SPRY2, PTEN, and PP2A status as an important determinant of prostate cancer progression. Characterization of this trio may facilitate patient stratification for targeted therapies and chemopreventive interventions.