Similar to the mammalian intestine the adult midgut has resident stem

Similar to the mammalian intestine the adult midgut has resident stem cells that support growth and regeneration. homolog). Together this work reveals that this Misshapen-Warts-Yorkie pathway acts in enteroblasts Pazopanib HCl to control niche signaling to intestinal stem cells. These findings also provide a model in which to study requirements for MAP4K4-related kinases in MST1/2-impartial regulation of LATS and YAP. adult midgut ISCs are evenly distributed along the basal side of the epithelium (Micchelli and Perrimon 2006 Ohlstein and Spradling 2006 ISCs are the only mitotic cells in the adult midgut and therefore are critical for intestinal homeostasis. After an ISC division Delta-Notch signaling establishes the asymmetry between the renewed ISC and the neighboring enteroblast (EB) (Ohlstein and Spradling 2007 Perdigoto et al. 2011 Although the mechanism that establishes the asymmetric Delta is largely unknown it is clear that the strength of Notch pathway stimulation is usually a key to determinant of whether the EB differentiates to become an enterocyte (EC) for nutrient absorption or an enteroendocrine cell (EE) for hormone secretion (Fig. 1K) (de Navascues et al. 2012 Goulas et al. 2012 Kapuria et al. 2012 Ohlstein and Spradling 2007 Perdigoto et al. 2011 Physique 1 Loss of Msn causes midgut hyperplasia Many conserved signaling pathways regulate ISC division. EGF and JAK-STAT pathways regulate ISC division and subsequent differentiation and therefore are essential for midgut homeostasis (Beebe et al. 2010 Biteau and Jasper 2011 Buchon et al. 2010 Jiang et al. 2010 Liu et al. Pazopanib HCl 2010 Ragab et al. 2011 Xu et al. 2011 Zhou et al. 2013 The Insulin receptor TSC-TOR and Myc pathways are important for the coordination of midgut growth (Amcheslavsky et al. Pazopanib HCl (GW786034) 2011 Amcheslavsky et al. 2009 Choi et al. 2011 Kapuria et Pazopanib HCl al. 2012 Ren et al. 2013 The Hippo-Warts-Yorkie (Hpo-Wts-Yki) pathway has functions in both ECs and ISCs to regulate ISC division and regeneration (Huang et al. 2014 Karpowicz et al. 2010 Ren et al. 2010 Shaw et al. 2010 Staley and Irvine 2010 Recent evidence suggests that ISC division and asymmetry are flexible and can adapt to environmental factors such as nutrient availability (O��Brien et al. 2011 Other evolutionarily conserved pathways such as Wingless JNK BMP and PVFs are also involved in the maintenance and stress response of ISCs (Bond and Foley 2012 Choi et al. 2008 Guo et al. 2013 Hochmuth et al. 2011 Li et al. 2013 Li et al. 2013 Lin et al. 2008 Tian and Jiang 2014 How these many conserved regulatory pathways are coordinated to achieve intestinal homeostasis remains to be clarified. Here we show a niche mechanism that depends on Misshapen (Msn) a member of the germinal center protein kinase (GCK) family acting within EBs to repress the expression of the JAK-STAT pathway ligand Upd3. Mechanistically Msn function is usually impartial of JNK or Hpo but instead interacts with Wts to suppress Yki activity and Upd3 expression. We also show that this mammalian Msn homolog MAP4K4 interacts with LATS to suppress YAP activity in Rabbit polyclonal to AGPAT2. mammalian cells suggesting that this is an evolutionarily conserved mechanism possibly employed in various biological contexts. RESULTS Loss of Msn function in the adult midgut causes hyperplasia To identify regulators essential for midgut homeostasis we used the promoter-Gal4; tubulin-Gal80ts; UAS-mCD8GFP (esgts>GFP) as driver and marker to perform Pazopanib HCl RNA interference (RNAi) assays of various genes. This driver is usually expressed in both ISCs and EBs (Fig. 1K) and the Gal80ts heat sensitive repressor provides temporal control of the Gal4 activity (Amcheslavsky et al. 2011 Micchelli and Perrimon 2006 Two impartial transgenic UAS-dsRNA lines (and caused a large increase of the number of GFP+ cells. Optical cross-sections indicated an intestinal hyperplasia phenotype (Fig. 1A-D). Knockdown of increased substantially the number of p-H3+ cells (Fig. 1E) a marker for mitotic ISCs (Micchelli and Perrimon 2006 Ohlstein and Spradling 2006 In all these experiments was induced by heat shift in adult flies so the hyperplasia phenotype is not a developmental defect. To confirm that this dsRNA-induced phenotype was due to loss of Msn function we performed a rescue experiment. Two impartial transgenic lines carrying a full-length cDNA together with the RNAi construct showed an almost complete suppression of the.