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We isolated a transposon-induced nonmotile mutant of the cyanobacterium Synechocystis sp. PCC 6803. The mutant was revealed to have a Tn5 insertion in the slr1443 gene that showed sequence similarity to a eukaryotic-type protein kinase. Thick pili were not observed on the mutant cell surface under the electron microscope. The slr1443 gene was not involved in transcription or translation of the pilA1 gene encoding pilin, the major component of thick pili. In the mutant, lower molecular mass pilin peptides were detected than in the wild-type. The pilin variant was not truncated at the N- or C-terminus of mature PilA1. The reduced molecular mass may have resulted from insufficient post-translational modification. The amounts of pilin variants were remarkably reduced in the periplasmic and surface fractions. The pilin variants were released into liquid media without being assembled into pili. Our finding suggests that Slr1443 plays an important role in pilus biogenesis at the level of the post-translational modification of pilin. [Copyright &y& Elsevier]

Parvin-β is an adaptor protein that binds to integrin-linked kinase (ILK) and is significantly downregulated in breast tumors and breast cancer cell lines. We treated the breast cancer cell line MCF7 with 24-methylenecycloartanyl ferulate (24-MCF), a γ-oryzanol compound. We observed upregulation of parvin-β (GenBank Accession No. AF237769 ) and peroxisome proliferator-activated receptor (PPAR)-γ2 (GenBank Accession No. NM_015869 ). Among γ-oryzanol compounds, only treatment with 24-MCF led to the formation of reverse transcription-PCR products of parvin-β (650 and 500 bp) and PPAR-γ2 (580 bp) in MCF7 cells, but not in T47D, SK-BR-3, or MDA-MB-231 cells. 24-MCF treatment increased the mRNA and protein levels of parvin-β in MCF7 cells in a dose-dependent manner. We hypothesized that there is a correlation between parvin-β expression and induction of PPAR-γ2. This hypothesis was investigated by using a promoter-reporter assay, chromatin immunoprecipitation, and an electrophoretic mobility shift assay. 24-MCF treatment induced binding of PPAR-γ2 to a peroxisome proliferator response element-like cis -element (ACTAGGACAAAGGACA) in the parvin-β promoter in MCF7 cells in a dose-dependent manner. 24-MCF treatment significantly decreased anchorage-independent growth and inhibited cell movement in comparison to control treatment with dimethyl sulfoxide. 24-MCF treatment reduced the levels of GTP-bound Rac1 and Cdc42. Evaluation of Akt1 inhibition by 24-MCF revealed that the half maximal effective concentration was 33.3 μM. Docking evaluations revealed that 24-MCF binds to the ATP-binding site of Akt1(PDB ID: 3OCB ) and the compound binding energy is -8.870 kcal/mol. Taken together, our results indicate that 24-MCF treatment increases parvin-β expression, which may inhibit ILK downstream signaling. [ABSTRACT FROM AUTHOR]

Abstract: Insulin-like growth factors (IGF), polypeptides that regulate growth, differentiation, and survival in cells and tissues, were found to enhance gene expression from both heterologous and homologous promoters in the presence of constitutively active STAT5. This highly conserved 700-bp DNA region contains two closely located consensus STAT5-binding sites. Hypoxia regulates the IGF-1 gene expression through the STAT5b. We confirmed STAT5b is up-regulated under hypoxic conditions, and the increased STAT5b binds strongly to the STAT5-binding sites 1 and 2 contained within the distal 5′-flanking region of IGF-1 gene in HepG2 cells. EMSA studies showed that STAT5-binding activities to the IGF-1 promoter distinctly increased under hypoxia in STAT5b-transfected COS-7 cells. The IGF-1 gene expression was also increased by hypoxia in HepG2 cells. STAT5b expression was inhibited by siRNA experiments leading to decreased IGF-1. These results provide a basis of molecular targets for cancer treatment via the STAT5b-IGF-1 pathway in solid tumor cells. [Copyright &y& Elsevier]