Immunohistochemical study of vascular endothelial growth factor (VEGF), tumor suppressor protein (p53) and intercellular adhesion molecule (ICAM-1) in the conjunctiva of diabetic patients

Summary The expression pattern of VEGF, p53 and ICAM-1 was studied in conjunctiva of diabetic patients with and without retinopathy. All patients underwent a complete ophthalmic examination, including retinal fluorescein angiography. Indirect immunoperoxidase method was performed on 20 eyes of 20 patients with type II diabetes without DR and on 5 eyes of 5 patients with PDR. A control study was performed on 6 normal conjunctiva undertaken during cataract surgery. Immunoreactivity of VEGF, p53 and ICAM-1 was found in epithelial, fibroblast and vascular endothelial cells. For the same duration of diabetes, a strong to moderate or weak immunoreactivity was observed in the conjunctiva of patients without retinopathy. In patients with PDR, the expression was strong for all these proteins. The immunoreactivity was correlated between VEGF, p53 and ICAM-1. In the normal conjunctiva, a weak to negative immunostaining was observed. The presence of these proteins in the conjunctiva of diabetic patients without retinopathy may add new data in the pathogenesis of diabetic retinopathy. Further studies are needed to confirm this hypothesis.     

Regulation of ultraviolet B radiation-mediated activation of AP1 signaling by retinoids in primary keratinocytes

The main cause of skin cancer and photo-aging is chronic exposure to ultraviolet B (UVB) radiation. Such damage can be ameliorated by retinoid treatment. UVB-radiation-induced skin carcinogenesis is associated with the induction of activator protein 1 (AP1) signaling and factors, namely FOS and JUN family members. We investigated the effects of several retinoids, all-trans-retinoic acid (tRA), 9-cis-retinoic acid (cRA), and N-(4-hydroxyphenyl)-retinamide (HPR), on UVB-induced damage in primary mouse keratinocytes. In addition, the interplay between UVB radiation, retinoid receptors, and AP1 signaling was assessed using Western blot analysis and ribonuclease protection and gene reporter assays. Exposure of keratinocytes to UVB radiation caused a down-regulation of the retinoid receptor protein levels in a proteasome-mediated manner. In contrast, FOS and JUN proteins were transiently induced shortly after exposure to UVB radiation. Retinoid treatment caused a dose-dependent reduction in the levels of retinoid receptor proteins. When irradiated cells were treated with retinoids, no significant effects on AP1 protein expression were noted. Interestingly, pretreatments with tRA and cRA, but not HPR, suppressed UVB-radiation-induced AP1 activity by more than 50%, whereas post-treatment failed to produce similar effects. Our findings indicate that the inhibition of AP1 activity by retinoids explains, at least in part, the chemopreventive potential of retinoids in UV-radiation-associated epidermal damage.     

Identification,Evolutionary Patterns and Intragenic Recombination of the Gametophytic Self Incompatibility Pollen Gene (SFB) in Tunisian Prunus Species (Rosaceae)

Plant Molecular Biology Reporter - Plum (Prunus L.) is a species which exhibits a gametophytic self-incompatibility system “GSI” as the majority of species belonging to the Rosaceae...     

Possible use of miRNAs-146a and -499 expression and their polymorphisms as diagnostic markers for rheumatoid arthritis

A novel polycyclic bridged-ring xanthene 2 was synthesized by nucleophilic substitution followed by Michael addition reaction between parent dibenzoxanthene 1 and acetylacetone. The structure of compound 2 was also confirmed by single-crystal X-ray diffraction. We studied the binding activity of this compound with bovine serum albumin (BSA) by fluorescent and UV–visible spectra. The results showed that compound had strong binding ability with BSA. Cell viability in five tumor cell lines was studied by MTT assay. The cytotoxic effect of bridged-ring xanthene 2 against BEL-7402 cells was examined by morphological analyses and biochemical assays. Significant nuclear damages of BEL-7402 cells were observed after cells were treated with compound in a comet assay. The compound also caused DNA damage and S phase arrest in BEL-7402 cells. The efficient induction of apoptosis by the compound was confirmed by flow cytometry. Additionally, the characteristic nuclear and morphological changes during apoptotic cell death were investigated by fluorescent microscopy. The compound 2 enhanced the reactive oxygen species (ROS) and decreased the mitochondrial membrane potential. Western blot assay indicated that the compound can active caspase-3, caspase-7, down-regulate the level of Bcl-2, Bcl-x, and up-regulate the level of pro-apoptosis protein Bax. The compound 2 induces apoptosis of BEL-7402 cells through a ROS-mediated mitochondrial dysfunction pathway.     

The enhancer domain of the human cytomegalovirus major immediate-early promoter determines cell type-specific expression in transgenic mice.

The human cytomegalovirus (HCMV) major immediate-early promoter (MIEP) is one of the first promoters to activate upon infection. To examine HCMV MIEP tissue-specific expression, transgenic mice were established containing the lacZ gene regulated by the MIEP (nucleotides -670 to +54). In the transgenic mice, lacZ expression was demonstrated in 19 of 29 tissues tested by histochemical and immunochemical analyses. These tissues included brain, eye, spinal cord, esophagus, stomach, pancreas, kidney, bladder, testis, ovary, spleen, salivary gland, thymus, bone marrow, skin, cartilage, and cardiac, striated and smooth muscles. Although expression was observed in multiple organs, promoter activity was restricted to specific cell types. The cell types which demonstrated HCMV MIEP expression included retinal cells of the eye, ductile cells of the salivary gland, exocrine cells of the pancreas, mucosal cells of the stomach and intestine, neuronal cells of the brain, muscle fibers, thecal cells of the corpus luteum, and Leydig and sperm cells of the testis. These observations indicate that the HCMV MIEP is not a pan-specific promoter and that the majority of expressing tissues correlate with tissues naturally infected by the virus in the human host.     

RNase III-dependent regulation of yeast telomerase

In bakers' yeast, in vivo telomerase activity requires a ribonucleoprotein (RNP) complex with at least four associated proteins (Est2p, Est1p, Est3p, and Cdc13p) and one RNA species (Tlc1). The function of telomerase in maintaining chromosome ends, called telomeres, is tightly regulated and linked to the cell cycle. However, the mechanisms that regulate the expression of individual components of telomerase are poorly understood. Here we report that yeast RNase III (Rnt1p), a double-stranded RNA-specific endoribonuclease, regulates the expression of telomerase subunits and is required for maintaining normal telomere length. Deletion or inactivation of RNT1 induced the expression of Est1, Est2, Est3, and Tlc1 RNAs and increased telomerase activity, leading to elongation of telomeric repeat tracts. In silico analysis of the different RNAs coding for the telomerase subunits revealed a canonical Rnt1p cleavage site near the 3' end of Est1 mRNA. This predicted structure was cleaved by Rnt1p and its disruption abolished cleavage in vitro. Mutation of the Rnt1p cleavage signal in vivo impaired the cell cycle-dependent degradation of Est1 mRNA without affecting its steady-state level. These results reveal a new mechanism that influences telomeres length by controlling the expression of the telomerase subunits.