LIM-homeodomain transcription factor, Lhx2, is involved in transcriptional control of brain-specific promoter/exon 1f of the mouse aromatase gene

Neurosteroidal oestrogen has been proposed to play important roles in a variety of reproductive behaviours. Aromatase, a key enzyme in oestrogen synthesis, is localised in neural nuclei of specific brain regions and is developmentally regulated, with a transient expression peak at the perinatal period. The brain-specific promoter of the aromatase gene was analysed aiming to determine the transcriptional control mechanisms that could help explain the spatiotemporal expression. We previously reported that a 202-bp sequence, which is upstream from the transcriptional initiation site, is essential for the basal transcriptional activity. The 202-bp upstream region of brain-specific exon 1 comprises at least three types of cis-acting elements: aro-AI (Arom-Aα), aro-AII (Arom-Aβ) and aro-B (Arom-B). To identify the binding proteins for the cis-acting elements, a yeast one-hybrid screen was performed with these cis-element sequences using a mouse foetal cDNA library. Lhx2, a LIM-homeodomain protein, was identified as one of the aro-B binding proteins. The identification was further confirmed using the gel shift assay, which demonstrated binding competition of nuclear proteins to the aro-B element with a typical Lhx2-binding element. In addition, a chromatin immunoprecipitation assay with an anti-Lhx2 antibody demonstrated that Lhx2 bound to the aro-B site in vivo. A reporter assay of the brain-specific promoter demonstrated increased Lhx2-dependent promoter activity. Furthermore, the time-dependent increase in aromatase mRNA in primary cultured foetal neurones was suppressed by an small-interfering RNA-mediated knockdown of Lhx2 expression. These results show that Lhx2 is involved in the transcriptional regulation of aromatase in the rodent brain.

PD-1/PD-L1 expression in human T-cell leukemia virus type 1 carriers and adult T-cell leukemia/lymphoma patients

Adult T-cell leukemia/lymphoma (ATLL) develops after infection with human T-cell leukemia virus-1 (HTLV-1) after a long latency period. The negative regulatory programmed death-1/programmed death-1 ligand 1 (PD-1/PD-L1) pathway has been implicated in the induction of cytotoxic T-lymphocyte (CTL) exhaustion during chronic viral infection along with tumor escape from host immunity. To determine whether the PD-1/PD-L1 pathway could be involved in the establishment of persistent HTLV-1 infections and immune evasion of ATLL cells in patients, we examined PD-1/PD-L1 expression on cells from 27 asymptomatic HTLV-1 carriers (ACs) and 27 ATLL patients in comparison with cells from 18 healthy donors. PD-1 expression on HTLV-1-specific CTLs from ACs and ATLL patients was dramatically elevated. In addition, PD-1 expression was significantly higher on CD8+ T cells along with cytomegalovirus (CMV)- and Epstein-Barr virus (EBV)-specific CTLs in ATLL patients compared with ACs and control individuals. Primary ATLL cells in 21.7% of ATLL patients expressed PD-L1, whereas elevated expression was not observed in cells from ACs. Finally, in functional studies, we observed that an anti-PD-L1 antagonistic antibody upregulated HTLV-1-specific CD8+T-cell response. These observations suggest that the PD-1/PD-L1 pathway plays a role in fostering persistent HTLV-1 infections, which may further ATLL development and facilitate immune evasion by ATLL cells.

Oversulfated fucoidan inhibits the basic fibroblast growth factor-induced tube formation by human umbilical vein endothelial cells: its possible mechanism of action

We have previously demonstrated that chemically oversulfated fucoidan (OSF) but not native fucoidan (NF) effectively suppresses the tube structure formation by human umbilical vein endothelial cells (HUVEC) on the basement membrane preparation, Matrigel. In this study, using more defined systems where basic fibroblast growth factor (bFGF) induces the tube formation by HUVEC on collagen gel, we investigated the mechanism responsible for the inhibition of angiogenesis by OSF in vitro. Unlike NF and desulfated fucoidan (desF), OSF potently inhibited the bFGF-induced HUVEC migration and tube formation. ELISA for tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) in the culture media indicated that OSF increased the bFGF-induced release of PAI-1 antigen, but not of t-PA antigen. Analyses of the binding of bFGF to HUVEC surfaces and the following protein tyrosine phosphorylation revealed that OSF could promote the cell binding and autophosphorylation of 140 and 160 kDa receptors. In heparitinase-treated HUVEC, contrarily, the bFGF binding and PAI-1 release were decreased by OSF. These results suggest that OSF is a highly sulfated unique polysaccharide that can promote the binding of bFGF to the heparan sulfate molecules required for binding to the high affinity receptors with tyrosine kinase activity. The resultant increase in PAI-1 release may play a key role for the prevention of cell migration accompanied by matrix proteolysis.