AIM: To determine the effects of a low dose latrunculin (LAT)-A on dexamethasone (Dex)-induced upregulation of extracellular matrix proteins fibronectin (FN) in cultured human trabecular meshwork (HTM) cells. METHODS: HTM cells were cultured to confluent and incubated with 0.4 mu mol/L Dex and/or 0.05 mu mol/L LAT-A. FN expression in HTM cells was evaluated by Western blot and immunofluorescence microscopy. RESULTS: Dex up-regulated FN production in HTM cells, failed to do so when co-incubated with LAT-A. LAT-A decreased production of FN in cultured HTM cells. CONCLUSION: This study indicated that LAT-A may modulate the expression of fibronectin in trabecular meshwork to achieve treatment for steroids and other types of glaucoma. It has an important prospect as an intraocular pressure-lowering drug.
Formins have been paid much attention for their potent nucleating activity. However, the connection between the in vivo functions of AtFHs （Arabidopsis thaliana formin homologs） and their effects on actin organization is poorly understood, in this study, we characterized the bundling activity of AtFH8 in vitro and in vivo. Biochemical analysis showed that AtFH8（FH1FH2） could form dimers and bundle preformed actin filaments or induce stellar structures during actin polymerization. Expression of truncated forms of AtFH8 and immunolocalization analysis showed that AtFH8 localized primarily to nuclear envelope in interphase and to the new cell wall after cytokinesis, depending primarily on its N-terminal transmembrane domain. GUS histochemical staining showed AtFH8 was predominantly expressed in Arabidopsis root meristem, vasculature, and outgrowth points of lateral roots. The primary root growth and lateral root initiation of atfh8 could be decreased by latrunculin B （LatB）. Analysis of the number of dividing cells in Arabidopsis root tips showed that much fewer dividing cells in Lat B-treated atfh8 plants than wild-type plants, which indicates that AtFH8 was involved in cell division. Actin cytoskeleton in root meristem of atfh8-1 was more sensitive to LatB treatment than that of wild-type. Altogether, our results indicate that AtFH8 is an actin filament nucleator and bundler that functions in cell division and root development.
