Nuclear factor (NF)-κB transcription factors are involved in the control of a large number of normal cellular and organismal processes, such as immune and inflammatory responses, developmental processes, cellular growth, and apoptosis. Transcription of the human immunodeficiency virus type 1 (HIV-1) genome depends on the intracellular environment where the integrate viral DNA is regulated by a complex interplay among viral regulatory proteins, such as Tat, and host cellular transcription factors, such as NF-κB, interacting with the viral long terminal repeat region. CBP (CREB-binding protein) and p300, containing an intrinsic histone acetyltransferase (HAT) activity, have emerged as coactivators for various DNA-binding transcription factors. Here, we show that the p50 subunit as well as the p50/p65 of NF-κB, and not other factors such as SP1, TFIIB, polymerase II, TFIIA, or p65, can be acetylated by CBP/p300 HAT domain. Acetylation of p50 was completely dependent on the presence of both HAT domain and Tat proteins, implying that Tat influences the transcription machinery by aiding CBP/p300 to acquire new partners and increase its functional repertoire. Three lysines, Lys-431, Lys-440, and Lys-441 in p50 were all acetylated in vitro, and a sequence similarity among p50, p53, Tat, and activin receptor type I on these particular lysines was observed. All proteins have been shown to be acetylated by the CBP/p300 HAT domain. Acetylated p50 increases its DNA binding properties, as evident by streptavidin/biotin pull-down assays when using labeled NF-κB oligonucleotides. Increased DNA binding on HIV-1 long terminal repeat coincided with increases in the rate of transcription. Therefore, we propose that acetylation of the DNA binding domain of NF-κB aids in nuclear translocation and enhanced transcription and also suggest that the substrate specificity of CBP/p300 can be altered by small peptide molecules, such as HIV-encoded Tat.

Purpose. To investigate the effect of pirfenidone, a novel antifibrotic agent, on proliferation, migration, and collagen contraction of human Tenon’s fibroblasts (HTFs). methods. After treatment of HTFs with pirfenidone, cell proliferation was measured by MTT assay. Cell migration was investigated by scratch assay. Contractility was evaluated in fibroblast-populated collagen gels. Cell viability was determined by trypan blue exclusion assay. The expression of TGF-β1, -β2, and -β3 was estimated with RT-PCR, Western blot, and immunofluorescence analyses. results. Pirfenidone induced significant dose-dependent inhibition of HTF proliferation and migration and collagen contraction. After treatment with different concentrations of pirfenidone (0.15, 0.3, and 1 mg/mL) for 24 and 72 hours, cell viability was not different in the treatment and control groups. After 24 hours of treatment with pirfenidone, HTFs showed dose-dependent decreases in mRNA and protein levels of TGF-β1, -β2, and -β3. conclusions. These findings indicate that pirfenidone inhibits proliferation, migration, and collagen contraction of HTFs at nontoxic concentrations. A decrease in autocrine TGF-β signaling may have a role in the effects of pirfenidone.

Infection with human T-cell leukemia virus type 1 (HTLV-1) results in adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Tax, a 40-kDa protein, regulates viral and cellular transcription, host signal transduction, the cell cycle, and apoptosis. Tax has been shown to modulate cellular CREB and NFkappaB pathways; however, to date, its role in binding to various host cellular proteins involved in tumorigenesis has not been fully described. In this study, we describe the Tax-associated proteins and their functions in cells using several approaches. Tax eluted from a sizing column mostly at an apparent molecular mass of 1800 kDa. Following Tax immunoprecipitation, washes with high salt buffer, two-dimensional gel separation, and mass spectrometric analysis, a total of 32 proteins was identified. Many of these proteins belong to the signal transduction and cytoskeleton pathways and transcription/chromatin remodeling. A few of these proteins, including TXBP151, have been shown previously to bind to Tax. The interaction of Tax with small GTPase-cytoskeleton proteins, such as ras GAP1m, Rac1, Cdc42, RhoA, and gelsolin, indicates how Tax may regulate migration, invasion, and adhesion in T-cell cancers. Finally, the physical and functional association of Tax with the chromatin remodeling SWI/SNF complex was assessed using in vitro chromatin remodeling assays, chromatin remodeling factor BRG1 mutant cells, and RNA interference experiments. Collectively, Tax is able to bind and regulate many cellular proteins that regulate transcription and cytoskeletal related pathways, which might explain the pleiotropic effects of Tax leading to T-cell transformation and leukemia in HTLV-1-infected patients.

Exposure to ambient fine particulate matter (fine PM) pollution has been previously associated with ocular surface diseases. But, to the best of our knowledge, the in vivo long-term effects of fine PM on the ocular surface have not been investigated. We aimed to evaluate the effects of fine PM on cultured human corneal epithelial (HCE) cells and on the ocular surfaces of mice, with standard reference material of fine PM(SRM 2786). We applied fine PM suspension to the eyes of C57BL/6 mice for up to 6 months. In vivo examinations, including tear secretion, tear film break-up time (TBUT) and corneal fluorescein staining, were performed in the 3^rd and 6^th month. At the end of the in vivo study, the corneal histological changes and conjunctival goblet cells were examined by staining, and cytokines in tissue were also detected. In addition, HCE cells were treated with fine PM for 12 h and 24 h. Then, cell apoptosis and reactive oxygen species (ROS) formation was detected. We found that fine PM damages the mouse eye in a dose- and time-dependent manner. In mice, the tear secretion and tear film break-up time were significantly reduced, along with the development of corneal epithelial damage, apoptosis of conjunctival epithelial cells and hypoplasia of conjunctival goblet cells. In addition, IL-18, IL-22, IL-23 and MCP-1 were increased in both conjunctiva and cornea of the fine PM-treated animals. Furthermore, increased apoptosis and ROS production were observed in time- and dose-dependent manner in HCE cells after fine PM exposure for 12 h and 24 h. Our results indicate that fine PM is cytotoxic to both HCE cells and the ocular surface. Long-term topical application of fine PM suspension in mice results in ocular surface changes that are similar to those observed with dry eye.