Generation of a tropoelastin mRNA variant by alternative polyadenylation site selection in sun-damaged human skin and ultraviolet B-irradiated fibroblasts

Skin Protection by Carotenoid Pigments

Sunlight, despite its benefits, can pose a threat to the skin, which is a natural protective barrier. Phototoxicity caused by overexposure, especially to ultraviolet radiation (UVR), results in burns, accelerates photoaging, and causes skin cancer formation. Natural substances of plant origin, i.e., polyphenols, flavonoids, and photosynthetic pigments, can protect the skin against the effects of radiation, acting not only as photoprotectors like natural filters but as antioxidant and anti-inflammatory remedies, alleviating the effects of photodamage to the skin. Plant-based formulations are gaining popularity as an attractive alternative to synthetic filters. Over the past 20 years, a large number of studies have been published to assess the photoprotective effects of natural plant products, primarily through their antioxidant, antimutagenic, and anti-immunosuppressive activities. This review selects the most important data on skin photodamage and photoprotective efficacy of selected plant carotenoid representatives from in vivo studies on animal models and humans, as well as in vitro experiments performed on fibroblast and keratinocyte cell lines. Recent research on carotenoids associated with lipid nanoparticles, nanoemulsions, liposomes, and micelles is reviewed. The focus was on collecting those nanomaterials that serve to improve the bioavailability and stability of carotenoids as natural antioxidants with photoprotective activity.

The Bidirectional Link Between RNA Cleavage and Polyadenylation and Genome Stability: Recent Insights From a Systematic Screen

The integrity of the genome is governed by multiple processes to ensure optimal survival and to prevent the inheritance of deleterious traits. While significant progress has been made to characterize components involved in the DNA Damage Response (DDR), little is known about the interplay between RNA processing and the maintenance of genome stability. Here, we describe the emerging picture of an intricate bidirectional coupling between RNA processing and genome integrity in an integrative manner. By employing insights from a recent large-scale RNAi screening involving the depletion of more than 170 components that direct (alternative) polyadenylation, we provide evidence of bidirectional crosstalk between co-transcriptional RNA 3′end processing and the DDR in a manner that optimizes genomic integrity. We provide instructive examples illustrating the wiring between the two processes and show how perturbations at one end are either compensated by buffering mechanisms at the other end, or even propel the initial insult and thereby become disease-eliciting as evidenced by various disorders.

3' end mRNA processing: molecular mechanisms and implications for health and disease

Recent advances in the understanding of the molecular mechanism of mRNA 3' end processing have uncovered a previously unanticipated integrated network of transcriptional and RNA-processing mechanisms. A variety of human diseases impressively reflect the importance of the precision of the complex 3' end-processing machinery and gene specific deregulation of 3' end processing can result from mutations of RNA sequence elements that bind key specific processing factors. Interestingly, more general deregulation of 3' end processing can be caused either by mutations of these processing factors or by the disturbance of the well-coordinated equilibrium between these factors. From a medical perspective, both loss of function and gain of function can be functionally relevant, and an increasing number of different disease entities exemplifies that inappropriate 3' end formation of human mRNAs can have a tremendous impact on health and disease. Here, we review the mechanistic hallmarks of mRNA 3' end processing, highlight the medical relevance of deregulation of this important step of mRNA maturation and illustrate the implications for diagnostic and therapeutic strategies.

Regulation of the extracellular matrix remodeling by lutein in dermal fibroblasts, melanoma cells, and ultraviolet radiation exposed fibroblasts

With aging and cancer there is increased expression or activity of matrix metalloproteinases (MMPs) that degrade and remodel the structural extracellular matrix (ECM). In addition, exposure of skin to ultraviolet (UV) radiation (photoaging) leads to loss of cell viability, membrane damage, and deposition of excessive elastotic material. Lutein has antioxidant, anti-inflammatory, photoprotective, and anti-carcinogenic properties. The goal of this research was to investigate lutein's anti-aging and anti-carcinogenic effects via the regulation of the extracellular matrix remodeling. To this purpose, the effects of lutein on the expression of MMPs and their inhibitors (TIMPs, tissue inhibitors of metalloproteinases) in dermal fibroblasts (intrinsic aging) and melanoma cells were examined. Further, for lutein's photoprotective effects, the regulation of cell viability, membrane integrity, and elastin expression in the non-irradiated, and UVA or UVB radiation exposed fibroblasts were analyzed. Lutein significantly inhibited MMP-1 expression, transcriptionally, and MMP-2 protein levels in dermal fibroblasts, without altering TIMPs expression. It significantly inhibited MMP-1 expression in melanoma cells while stimulating TIMP-2. Lutein did not alter fibroblast or melanoma cell viability or membrane integrity. In ultraviolet radiation exposed fibroblasts, lutein improved cell viability, membrane integrity and inhibited elastin expression, though more significantly in the UVB exposed fibroblasts. In summary, the mechanism to lutein's anti-aging and anti-carcinogenic effects include the inhibition of MMP to TIMP ratio in dermal fibroblasts and melanoma cells, and the inhibition of cell loss, membrane damage and elastin expression in ultraviolet radiation exposed fibroblasts.

Spectroscopic studies into the influence of UV radiation on elastin hydrolysates in water solution

An investigation into the influence of UV irradiation on elastin hydrolysates dissolved in water was carried out using UV-Vis spectroscopy and spectrofluorometry. It was found that the absorption of elastin hydrolysates in solution increased during irradiation of the sample. For fluorescence of elastin hydrolysates we observed both, a decrease and increase of this value during irradiation of the sample. After UV irradiation of the elastin solution we observed a minor increase of overall absorption, most notably between 250 nm and 280 nm. Moreover, after UV irradiation a wide peak emerged between 290 nm and 310 nm with maximum at about 305 nm. The new peak suggests that new photoproducts are formed during UV irradiation of elastin hydrolysates. The fluorescence of elastin hydrolysates was observed at 305 nm and at 380 nm after excitation at 270 nm. UV irradiation caused fluorescence fading at 305 nm and 380 nm. After 30 min of irradiation a new broad weak band of fluorescence, attributable to new photoproducts, emerged in the UV wavelength region with emission maximum between 400 nm and 500 nm.

Predominant effects of Polypodium leucotomos on membrane integrity, lipid peroxidation, and expression of elastin and matrixmetalloproteinase-1 in ultraviolet radiation exposed fibroblasts, and keratinocytes

BACKGROUND

Polypodium leucotomos has been reported to have antioxidant, anti-inflammatory and photoprotective properties. Exposure of skin to ultraviolet (UV) radiation can lead to deposition of excessive elastotic material, reduction in collagen, and increased expression of matrix metalloproteinases (MMPs).

OBJECTIVE

The goal of this research was to determine the effects of P. leucotomos in the absence or presence of UVA or UVB radiation on membrane damage, lipid peroxidation, and expression of elastin and MMP-1 in fibroblasts and keratinocytes, respectively.

METHODS

Fibroblasts and keratinocytes, respectively, were irradiated by a single exposure to UVA (0.6, 1.8 or 3.6 J) or UVB radiation (0.75, 2.5 or 7.5 mJ), and then incubated with, or without, P. leucotomos (0.01, 0.1 and 1%) and examined for membrane damage, lipid peroxidation, expression of elastin (protein levels) and MMP-1 (protein levels or MMP-1 promoter activity).

RESULTS

UV radiation did not significantly alter membrane integrity, lipid peroxidation or MMP-1 expression, but increased elastin expression. P. leucotomos significantly improved membrane integrity, inhibited lipid peroxidation, increased elastin expression, and inhibited MMP-1 expression in both fibroblasts, and keratinocytes. The effects of P. leucotomos predominated in the presence of UVA or UVB in both fibroblasts and keratinocytes, respectively, with the exception of inhibition of MMP-1 protein levels in fibroblasts only in combination with UV radiation.

CONCLUSION

Lower concentration of P. leucotomos (lower than 0.1%), may be beneficial in preventing photoaging by improving membrane integrity and inhibiting MMP-1, without increasing elastin expression. Higher concentration (greater than 0.1%) of P. leucotomos may reverse the loss of normal elastic fibers associated with intrinsic aging.

Differential calmodulin gene expression in the rodent brain

Apparently redundant members of the calmodulin (CaM) gene family encode for the same amino acid sequence. CaM, a ubiquitous cytoplasmic calcium ion receptor, regulates the function of a variety of target molecules even in a single cell. Maintenance of the fidelity of the active CaM-target interactions in different compartments of the cell requires a rather complex control of the total cellular CaM pool comprising multiple levels of regulatory circuits. Among these mechanisms, it has long been proposed that a multigene family maximizes the regulatory potentials at the level of the gene expression. CaM genes are expressed at a particularly profound level in the mammalian central nervous system (CNS), especially in the highly polarized neurons. Thus, in the search for clear evidence of the suggested differential expression of the CaM genes, much of the research has been focused on the elements of the CNS. This review aims to give a comprehensive survey on the current understanding of this field at the level of the regulation of CaM mRNA transcription and distribution in the rodent brain. The results indicate that the CaM genes are indeed expressed in a gene-specific manner in the developing and adult brain under physiological conditions. To establish local CaM pools in distant intracellular compartments (dendrites and glial processes), local protein synthesis from differentially targeted mRNAs is also employed. Moreover, the CaM genes are controlled in a unique, gene-specific fashion when responding to certain external stimuli. Additionally, putative regulatory elements have been identified on the CaM genes and mRNAs.

The BARD1-CstF-50 interaction links mRNA 3' end formation to DNA damage and tumor suppression

The mRNA polyadenylation factor CstF interacts with the BRCA1-associated protein BARD1, and this interaction represses the nuclear mRNA polyadenylation machinery in vitro. Given the suspected role of BRCA1/BARD1 in DNA repair, we tested whether inhibition of mRNA processing is linked to DNA damage. Strikingly, we found that 3' cleavage in extracts from cells treated with hydroxyurea or ultraviolet light was strongly, but transiently, inhibited. Although no changes were detected in CstF, BARD1, and BRCA1 protein levels, increased amounts of a CstF/BARD1/BRCA1 complex were detected. Supporting the physiological significance of these results, a previously identified tumor-associated germline mutation in BARD1 (Gln564His) reduced binding to CstF and abrogated inhibition of polyadenylation. Together these results indicate a link between mRNA 3' processing and DNA repair and tumor suppression.

Fibrillin-rich microfibrils are reduced in photoaged skin. Distribution at the dermal-epidermal junction

Chronic sun exposure results in photoaged skin with deep coarse wrinkles and loss of elasticity. We have examined the distribution and abundance of fibrillin-rich microfibrils, key structural components of the elastic fiber network, in photoaged and photoprotected skin. Punch biopsies taken from photoaged forearm and from photoprotected hip and upper inner arm of 16 subjects with a clinical range of photoaging were examined for fibrillin-1 and fibrillin-2 expression and microfibril distribution. In situ hybridization revealed decreased fibrillin-1 mRNA but unchanged fibrillin-2 mRNA levels in severely photoaged forearm biopsies relative to photoprotected dermal sites. An immunohistochemical approach demonstrated that microfibrils at the dermal-epidermal junction were significantly reduced in moderate to severely photoaged forearm skin. Confocal microscopy revealed that the papillary dermal microfibrillar network was truncated and depleted in photoaged skin. These studies highlight that the fibrillin-rich microfibrillar network associated with the upper dermis undergoes extensive remodeling following solar irradiation. These changes may contribute to the clinical features of photoaging, such as wrinkle formation and loss of elasticity.