Transcriptional regulation of two RTE-like genes of carnation during flower senescence and upon ethylene exposure, wounding treatment and sucrose supply

RTE1 (REVERSION-TO-ETHYLENE SENSITIVITY1) was identified as a positive regulator of ETR1 (ethylene resistant1) function in Arabidopsis; RTEs are a small gene family. Ethylene plays a crucial role in the senescence of carnation (Dianthus caryophyllus L.) flowers. Two cDNA clones encoding putative RTE-like protein (DCRTE1 and DCRTH1) were obtained from total RNA isolated from senescing carnation petals using RT-PCR and RACE techniques. The predicted proteins of DCRTE1 and DCRTH1 consist of 228 and 233 amino acids, respectively. Interestingly, the deduced DCRTE1 protein, like most other RTEs, includes two putative transmembrane domains, while the deduced DCRTH1 protein includes five putative transmembrane domains, according to the TMHMM database. Northern blots showed that the level of DCRTE1 mRNA in petals first decreased then increased remarkably after ethylene production started, and DCRTE1 expression showed an increasing trend in ovaries during natural flower senescence. The amount of DCRTH1 transcripts increased gradually in both petals and ovaries during natural senescence. Exogenous ethylene increased transcript abundance of DCRTE1 and DCRTH1 to various degrees in both petals and ovaries. STS treatment decreased the level of DCRTH1 mRNA in petals and ovaries compared with the control. DCRTE1 and DCRTH1 showed a rapid increase and then a decrease in mRNA accumulation in leaves after wounding. These results suggest that both DCRTE1 and DCRTH1 could play important roles in flower senescence-related signalling. Sucrose treatment did not remarkably affect the amount of DCRTE1 and DCRTH1 mRNAs.

Generation of dopaminergic neurons by fusion of neural stem cells and midbrain neurons

Neural stem cells (NSCs) are multipotent and self-renewing that can potentially generate various neurons for clinical purposes. However, the mechanism of regulating differentiation from NSCs to neurons is not well understood. In this report, we established a new method to obtain specific neurons from NSCs by cell fusion. NSCs were fused with midbrain neurons, resulting in hybrid cells that express an antigen pattern characteristic of dopaminergic neurons. Analysis of the marker enzyme tyrosine hydroxylase (TH) showed that hybrid cells were reprogrammed to somatic cells. This report represents a new significant contribution toward revealing the directional differentiation of NSCs and eventually providing the application in clinical transplantation therapy.

Collagen triple helix repeat containing-1 inhibits transforming growth factor-b1-induced collagen type I expression in keloid

BACKGROUND

Keloids are benign skin tumours occurring during wound healing in genetically predisposed patients. There is evidence that transforming growth factor (TGF)-b is involved in keloid formation. Collagen triple helix repeat containing- 1 (Cthrc1) was identified as a novel gene expressed in the adventitia and neointima on arterial injury. It is indicated to be a cell type-specific inhibitor of TGF-b, which functionally increases cell migration while reducing collagen type I and III deposition. However, to our knowledge expression and regulatory mechanisms of Cthrc1 and TGF-b1 in keloid and normal skin have not been studied before.

OBJECTIVES

Cthrc1 gene regulation and potential role in keloid formation were determined, and its correlation with TGF-b1 involved in keloid pathogenesis was examined in human fibroblasts of keloids and normal skin.

METHODS

The expression of Cthrc1 and TGF-b1 was investigated in fibroblasts of keloid and normal skin. Collagen type I expression and collagen synthesis in keloid fibroblasts induced by TGF-b1 were examined. Then, recombinant Cthrc1 was applied to assess its correlation with TGF-b1.

RESULTS

Increased TGF-b1 and Cthrc1 expression was examined in keloid compared with normal skin. Cthrc1 expression increased in a concentration-dependent manner induced by TGF-b1 in keloid fibroblasts. TGF-b1 stimulated collagen type I expression and collagen synthesis in keloid fibroblasts, which can be reversed by recombinant Cthrc1.

CONCLUSIONS

TGF-b1 was upregulated in keloid fibroblasts and recombinant Cthrc1 inhibited TGF-b1-stimulated collagen type I synthesis, which suggests that Cthrc1 may be a potential therapeutic option for keloids.

The tumor-suppressor gene ARHI (DIRAS3) suppresses ovarian cancer cell migration through inhibition of the Stat3 and FAK/Rho signaling pathways

Ovarian cancers migrate and metastasize over the surface of the peritoneal cavity. Consequently, dysregulation of mechanisms that limit cell migration may be particularly important in the pathogenesis of the disease. ARHI is an imprinted tumor-suppressor gene that is downregulated in >60% of ovarian cancers, and its loss is associated with decreased progression-free survival. ARHI encodes a 26-kDa GTPase with homology to Ras. In contrast to Ras, ARHI inhibits cell growth, but whether it also regulates cell motility has not been studied previously. Here we report that re-expression of ARHI decreases the motility of IL-6- and epidermal growth factor (EGF)-stimulated SKOv3 and Hey ovarian cancer cells, inhibiting both chemotaxis and haptotaxis. ARHI binds to and sequesters Stat3 in the cytoplasm, preventing its translocation to the nucleus and localization in focal adhesion complexes. Stat3 siRNA or the JAK2 inhibitor AG490 produced similar inhibition of motility. However, the combination of ARHI expression with Stat3 knockdown or inhibition produced greatest inhibition in ovarian cancer cell migration, consistent with Stat3-dependent and Stat3-independent mechanisms. Consistent with two distinct signaling pathways, knockdown of Stat3 selectively inhibited IL-6-stimulated migration, whereas knockdown of focal adhesion kinase (FAK) preferentially inhibited EGF-stimulated migration. In EGF-stimulated ovarian cancer cells, re-expression of ARHI inhibited FAK(Y397) and Src(Y416) phosphorylation, disrupted focal adhesions, and blocked FAK-mediated RhoA signaling, resulting in decreased levels of GTP-RhoA. Re-expression of ARHI also disrupted the formation of actin stress fibers in a FAK- and RhoA-dependent manner. Thus, ARHI has a critical and previously uncharacterized role in the regulation of ovarian cancer cell migration, exerting inhibitory effects on two distinct signaling pathways.

Association of β-2 adrenergic agonist and corticosteroid injection in the treatment of lipomas

AIM

The aim of this study was to evaluate the efficacy of isoproterenol and prednisolone in the treatment of subcutaneous lipomas.

METHODS

The first experiment evaluated in vitro lipolysis induced by isoproterenol 10(-6) M alone and across a range of prednisolone concentrations to determine the optimal dose to maximize lipolysis. The second experiment evaluated lipolysis in a lipoma and subcutaneous fat by in vivo microdialysis in five subjects to isoproterenol 10(-6) M with and without prednisolone 10(-6) M. These five subjects and five additional subjects had a lipoma treated five times a week for 4 weeks in a 4-cm grid with 0.2 ml injections of 10(-6) M isoproterenol and 10(-6) M prednisolone. Lipoma size was followed monthly for 1 year or until surgical removal.

RESULTS

Prednisolone increased in vitro lipolysis to isoproterenol and 10(-6) M was the optimal concentration of both drugs. Lipomas responded with less lipolysis to isoproterenol than subcutaneous fat during microdialysis, and prednisolone treatment increased lipolysis in both lipomas and subcutaneous fat. Injection treatment of the lipomas decreased their volume 50%. All but one lipoma grew after treatment. Eight of the 10 subjects elected for surgical treatment, and the histology of the lipomas was normal fat tissue.

CONCLUSIONS

Prednisolone and isoproterenol in combination increased lipolysis, and injections of the combination into lipomas decreased their volume 50% over 4 weeks. Eight of the 10 subjects elected for surgical removal.