👤 Luo Jianhua

It is well known that social defeat stress can induce depressive behaviours and cognitive impairment. However, the molecular mechanism by which only a minority of stress-exposed individuals are affected is not clear. In this study, thirty 3-week-old male c57BL/6 mice were exposed to 30 days of social defeat stress, following which susceptible (socially avoidant) and unsusceptible (socially interactive) mice were identified using social investigation. Twenty-four hours after the last episode of defeat, separate groups of mice were tested in the sucrose preference, open field, elevated plus-maze and Morris water maze behavioural assays. Also, the levels of memory-associated proteins in the hippocampus were examined, including postsynaptic density 95 (PSD95), postsynaptic density 93 (PSD93), and Protein kinase A (PKA). The levels of PSD95, PSD93, and PKA were significantly lower in susceptible mice. We also found that the upstream regulatory factor of these proteins, phosphorylated Camp-Responsive Element-Binding Protein (CREB), was reduced after social defeat in the susceptible group only, while the level of histone deacetylase 6 (HDAC6) was significantly elevated. These data suggest that memory-associated proteins and phosphorylated CREB may play important roles in memory impairment and behavioural responses to chronic stress. Show less

Signaling by fibroblast growth factor (FGF) receptor (FGFR) 2IIIb regulates branching morphogenesis in the mammalian lung. FGFR2IIIb is primarily expressed in epithelial cells, whereas its ligands, FGF-10 and keratinocyte growth factor (KGF; FGF-7), are expressed in mesenchymal cells. FGF-10 null mice lack lungs, whereas KGF null animals have normal lung development, indicating that FGF-10 regulates lung branching morphogenesis. In this study, we determined the effects of FGF-10 on lung branching morphogenesis and accompanying gene expression in cultures of embryonic rat lungs. Embryonic day 14 rat lungs were cultured with FGF-10 (0-250 ng/ml) in the absence or presence of heparin (30 ng/ml) for 4 days. Gene expression profiles were analyzed by Affymetrix microchip array including pathway analysis. Some of these genes, functionally important in FGF-10 signaling, were further analyzed by Northern blot, real-time PCR, in situ hybridization and immunohistochemistry. Exogenous FGF-10 inhibited branching and induced cystic lung growth only in cultures containing heparin. In total, 252 upregulated genes and 164 downregulated genes were identified, and these included Spry1 (Sprouty-1), Spry2 (Sprouty-2), Spred-1, Bmp4 (bone morphogenetic protein-4, BMP-4), Shh (sonic hedgehog, SHH), Pthlh (parathyroid hormone-related protein, PTHrP), Dusp6 (MAP kinase phosphatase-3, MKP-3) and Clic4 (chloride intracellular channel-4, CLIC-4) among the upregulated genes and Igf1 (insulin-like growth factor-1, IGF-1), Tcf21 (POD), Gyg1 (glycogenin 1), Sparc (secreted protein acidic and rich in cysteine, SPARC), Pcolce (procollagen C-endopeptidase enhancer protein, Pro CEP) and Lox (lysyl oxidase) among the downregulated genes. Gsk3β and Wnt2, which are involved in canonical Wnt signaling, were up- and downregulated, respectively. Unlike FGF-7, FGF-10 effects on lung branching morphogenesis are heparin-dependent. Sprouty-2, BMP-4, SHH, IGF-1, SPARC and POD are known to regulate branching morphogenesis; however, potential roles of CLIC-4 and MKP-3 in lung branching morphogenesis remain to be investigated. FGF-10 may also function in regulating branching morphogenesis or inducing cystic lung growth by inhibiting Wnt2/β-catenin signaling. Show less