Heat shock protein 25 plays multiple roles during mouse skin development

Heat Shock Proteins in Tooth Development and Injury Repair

Heat shock proteins (HSPs) are a class of molecular chaperones with expression increased in response to heat or other stresses. HSPs regulate cell homeostasis by modulating the folding and maturation of intracellular proteins. Tooth development is a complex process that involves many cell activities. During tooth preparation or trauma, teeth can be damaged. The damaged teeth start their repair process by remineralizing and regenerating tissue. During tooth development and injury repair, different HSPs have different expression patterns and play a special role in odontoblast differentiation and ameloblast secretion by mediating signaling pathways or participating in protein transport. This review explores the expression patterns and potential mechanisms of HSPs, particularly HSP25, HSP60 and HSP70, in tooth development and injury repair.

Single-cell RNA-Seq reveals the transcriptional landscape and heterogeneity of skin macrophages in Vsir-/- murine psoriasis

Rationale: V-domain immunoglobulin suppressor of T cell activation (VISTA) is a novel inhibitory immune checkpoint molecule. Vsir-/- mice have exacerbated psoriasis-like skin inflammation. The immune cell subsets involved in inflammation in Vsir-/- psoriatic mice are largely unknown. We have used scRNA-seq as an unbiased profiling strategy to study the heterogeneity of immune cells at a single cell level in the skin of Vsir-/- psoriatic mice. Methods: In the present study, the right ear and shaved back skin of wild type and Vsir-/- mice were treated with IMQ for 5 consecutive days to induce psoriasis-like dermatitis. Then, the single-cell RNA sequencing analysis of mouse back skin lesions was performed using 10 × Genomics technique. Results: We identified 12 major cell subtypes among 23,258 cells. The major populations of the skin cells included macrophages, dendritic cells and fibroblasts. Macrophages constituted the main immune cell population in the WT (61.29%) and Vsir-/- groups (77.7%). It should be noted that DCs and fibroblasts were expanded in the Vsir-/- psoriatic mice. Furthermore, the gene expression signatures were assessed. We observed that Hspb1 and Cebpb were significantly upregulated in the Vsir-/- psoriatic mice. Differential gene expression and gene ontology enrichment analyses revealed specific gene expression patterns distinguishing these subsets and uncovered putative functions of each cell type. Date analysis resulted in the discovery of a number of novel psoriasis-associated genes in Vsir-/- mice. Conclusion: We present a comprehensive single-cell landscape of the skin immune cells in Vsir-/- psoriatic mice. These unprecedented data uncovered the transcriptional landscape and phenotypic heterogeneity of skin macrophages in psoriasis and identified their gene expression signature suggesting specialized functions in Vsir-/- mice. Our findings will open novel opportunities to investigate the role of VISTA in driving psoriasis.

The Impact of Proteomic Investigations on the Development and Improvement of Skin Laser Therapy: A Review Article

Introduction: Different molecular approaches have contributed to finding various responses of skin to external and internal tensions such as laser irradiation and many important mediators of skin disease have been identified through these approaches. However, different essential signals of skin biomarker pathways and proteins are partially detected or completely unknown. In the present study, the impact of proteomics on the evaluation of laser therapy for the treatment of skin diseases is investigated. Methods: The keywords of "Proteomics", "Laser therapy", "Skin", and "Skin disease" were searched in Google Scholar, Scopus and PubMed search engines. After screening, 53 documents were included in the study. Results: The global assessments revealed that different proteins in different signaling pathways of skin metabolism in terms of health or illness after laser therapy are expressed differentially. The results indicated that the application of proteomics is a useful method for promoting the results of laser interventions. Conclusion: This kind of research dealt with the practical proteomics of skin diseases and skin laser therapy.

Heat shock proteins in the physiology and pathophysiology of epidermal keratinocytes

Heat shock proteins (HSPs), a large group of highly evolutionary conserved proteins, are considered to be main elements of the cellular proteoprotection system. HSPs are encoded by genes activated during the exposure of cells to proteotoxic factors, as well as by genes that are expressed constitutively under physiological conditions. HSPs, having properties of molecular chaperones, are involved in controlling/modulation of multiple cellular and physiological processes. In the presented review, we summarize the current knowledge on HSPs in the biology of epidermis, the outer skin layer composed of stratified squamous epithelium. This tissue has a vital barrier function preventing from dehydratation due to passive diffusion of water out of the skin, and protecting from infection and other environmental insults. We focused on HSPB1 (HSP27), HSPA1 (HSP70), HSPA2, and HSPC (HSP90), because only these HSPs have been studied in the context of physiology and pathophysiology of the epidermis. The analysis of literature data shows that HSPB1 plays a role in the regulation of final steps of keratinization; HSPA1 is involved in the cytoprotection, HSPA2 contributes to the early steps of keratinocyte differentiation, while HSPC is essential in the re-epithelialization process. Since HSPs have diverse functions in various types of somatic tissues, in spite of multiple investigations, open questions still remain about detailed roles of a particular HSP isoform in the biology of epidermal keratinocytes.

Screening of differentially expressed genes in the growth plate of broiler chickens with tibial dyschondroplasia by microarray analysis

Background

Tibial dyschondroplasia (TD) is a common skeletal disorder in broiler chickens. It is characterized by the presence of a non-vascularized and unmineralized cartilage in the growth plate. Previous studies have investigated differential expression of genes related to cartilage development during latter stages of TD. The aim of our study was to identify differentially expressed genes (DEGs) in the growth plate of broiler chickens, which were associated with early stage TD. We induced TD using tetramethylthiuram disulfide (thiram) for 1, 2, and 6 days and determined DEGs with chicken Affymetrix GeneChip assays. The identified DEGs were verified by quantitative polymerase chain reaction (qPCR) assays.

Results

We identified 1630 DEGs, with 82, 1385, and 429 exhibiting at least 2.0-fold changes (P < 0.05) at days 1, 2, and 6, respectively. These DEGs participate in a variety of biological processes, including cytokine production, oxidation reduction, and cell surface receptor linked signal transduction on day 1; lipid biosynthesis, regulation of growth, cell cycle, positive and negative gene regulation, transcription and transcription regulation, and anti-apoptosis on day 2; and regulation of cell proliferation, transcription, dephosphorylation, catabolism, proteolysis, and immune responses on day 6. The identified DEGs were associated with the following pathways: neuroactive ligand-receptor interaction on day 1; synthesis and degradation of ketone bodies, terpenoid backbone biosynthesis, ether lipid metabolism, JAK-STAT, GnRH signaling pathway, ubiquitin mediated proteolysis, TGF-β signaling, focal adhesion, and Wnt signaling on day 2; and arachidonic acid metabolism, mitogen-activated protein kinase (MAPK) signaling, JAK-STAT, insulin signaling, and glycolysis on day 6. We validated seven DEGs by qPCR.

Conclusions

Our findings demonstrate previously unrecognized changes in gene transcription associated with early stage TD. The DEGs we identified by microarray analysis will be used in future studies to clarify the molecular pathogenic mechanisms of TD. From these findings, potential pathways involved in early stage TD warrant further investigation.

Transcriptional regulation of small HSP-HSF1 and beyond

The members of the small heat shock protein (sHSP) family are molecular chaperones that play major roles in development, stress responses, and diseases, and have been envisioned as targets for therapy, particularly in cancer. The molecular mechanisms that regulate their transcription, in normal, stress, or pathological conditions, are characterized by extreme complexity and subtlety. Although historically linked to the heat shock transcription factors (HSFs), the stress-induced or developmental expression of the diverse members, including HSPB1/Hsp27/Hsp25, αA-crystallin/HSPB4, and αB-crystallin/HSPB5, relies on the combinatory effects of many transcription factors. Coupled with remarkably different cis-element architectures in the sHsp regulatory regions, they confer to each member its developmental expression or stress-inducibility. For example, multiple regulatory pathways coordinate the spatio-temporal expression of mouse αA-, αB-crystallin, and Hsp25 genes during lens development, through the action of master genes, like the large Maf family proteins and Pax6, but also HSF4. The inducibility of Hsp27 and αB-crystallin transcription by various stresses is exerted by HSF-dependent mechanisms, by which concomitant induction of Hsp27 and αB-crystallin expression is observed. In contrast, HSF-independent pathways can lead to αB-crystallin expression, but not to Hsp27 induction. Not surprisingly, deregulation of the expression of sHSP is associated with various pathologies, including cancer, neurodegenerative, or cardiac diseases. However, many questions remain to be addressed, and further elucidation of the developmental mechanisms of sHsp gene transcription might help to unravel the tissue- and stage-specific functions of this fascinating class of proteins, which might prove to be crucial for future therapeutic strategies. This article is part of a Directed Issue entitled: Small HSPs in physiology and pathology.

Small heat shock protein expression and functions during development

The expression of small heat shock proteins is tightly regulated during development in multiple organisms. As housekeeping proteins, small heat shock proteins help protect cells from apoptosis, stabilize the cytoskeleton and contribute to proteostasis. Consistently, depletion of one small heat shock protein is usually not detrimental due to a certain level of redundancy between the functions of each small heat shock protein. However, while their stress-induced expression is regulated by heat shock factors, their constitutive expression is under the control of other specific transcription factors, suggesting the existence of very specialized functions. This review focuses on the expression patterns and functions of small heat shock proteins in various organisms during development. This article is part of a Directed Issue entitled: Small HSPs in physiology and pathology.

Importance of transient receptor potential vanilloid 4 (TRPV4) in epidermal barrier function in human skin keratinocytes

The state of the skin changes drastically depending on the ambient temperature. Skin epidermal keratinocytes express thermosensitive transient receptor potential vanilloid (TRPV) cation channels, TRPV3 and TRPV4. These multimodal receptors are activated by various kinds of chemical and physical stimuli, including warm temperatures (>30°C). It has been suggested that TRPV4 is involved in cell-cell junction maturation; however, the effect of temperature fluctuations on TRPV4-dependent barrier homeostasis is unclear. In the present study, we demonstrated that activation of TRPV4 was crucial for barrier formation and recovery, both of which were critical for the prevention of excess dehydration of human skin keratinocytes. TRPV4 activation by physiological skin temperature (33°C), GSK1016790A or 4α-PDD allowed influx of Ca(2+) from extracellular spaces which promoted cell-cell junction development. These changes resulted in augmentation of intercellular barrier integrity in vitro and ex vivo. TRPV4 disruption reduced the increase in trans-epidermal resistance and increased intercellular permeation after a Ca(2+) switch. Furthermore, barrier recovery after the disruption of the stratum corneum was accelerated by the activation of TRPV4 either by warm temperature or a chemical activator. Our results suggest that physiological skin temperatures play important roles in cell-cell junction and skin barrier homeostasis through TRPV4 activation.

Systematic evaluations of skin damage irradiated by an erbium:YAG laser: histopathologic analysis, proteomic profiles, and cellular response

BACKGROUND

The erbium:yttrium-aluminum-garnet (Er:YAG) laser is used for surgical resurfacing. It has ablative properties with water as its main chromophore.

OBJECTIVE

This study attempted to establish the cutaneous effect and cellular response to Er:YAG laser irradiation using different fluences (7.5 and 15 J/cm(2)).

METHODS

Female nude mouse was used as the animal model in the study. Physiological parameters were examined and histology was evaluated at 4, 24 and 96 h after laser exposure. A proteomic analysis and immunoblotting were also used to determine the mechanisms of the laser's effect on the skin.

RESULTS

Both fluences were associated with a significant increase in transepidermal water loss (TEWL), erythema (a*), and the skin pH at 4 and 24h. In contrast, at 96 h, the levels of these parameters had generally decreased to the baseline. The histology examined by light microscopy and transmission electron microscopy (TEM) showed vacuolization, hydropic degeneration and epidermal necrosis of laser-irradiated skin. The higher fluence (15 J/cm(2)) exhibited more-severe disruption of the skin. Bulous and scarring were observed in skin treated with the higher fluence during the recovery period. p53 and p21 proteins were significantly activated in skin following exposure to the laser. However, proliferating cell nuclear antigen and cytokeratin expressions were downregulated by the low fluence (7.5 J/cm(2)).

CONCLUSION

Both proliferation and apoptosis occurred when the laser-irradiated the skin.

Hormetic modulation of differentiation of normal human epidermal keratinocytes undergoing replicative senescence in vitro

Normal human epidermal keratinocytes (NHEK) show both the Hayflick phenomenon of replicative senescence and differentiation in vitro, depending upon the culture conditions. Using this experimental model system, we have studied age-related changes in the ability of serially passaged NHEK to enter into differentiation in the presence of calcium, as measured by the levels of differentiation markers involucrin, p38 and Hsp27. The results obtained in these studies show that calcium-induced differentiation of NHEK becomes progressively delayed during cellular aging in vitro, which can be modulated by treatments such as mild heat stress, kinetin and curcumin. Whereas all these treatments on their own were able to increase the levels of various differentiation markers to varying extents, their effects were synergistic and rapid in the presence of calcium. Furthermore, all three modulators tested in the present study bring about their effects by inducing stress response pathways in terms of an increase in the levels of stress proteins Hsp90, Hsp70 and heme-oxygenase-1 (HO-1), which is indicative of stress-induced hormesis bringing about the biologically beneficial effects.

Insights into function and regulation of small heat shock protein 25 (HSPB1) in a mouse model with targeted gene disruption

The mammalian small heat shock protein (sHSPs) family is comprised of 10 members and includes HSPB1, which is proposed to play an essential role in cellular physiology, acting as a molecular chaperone to regulate diverse cellular processes. Whilst differential roles for sHSPs are suggested for specific tissues, the relative contribution of individual sHSP family members in cellular and organ physiology remains unclear. To address the function of HSPB1 in vivo and determine its tissue-specific expression during development and in the adult, we generated knock-in mice where the coding sequence of hspb1 is replaced by a lacZ reporter gene. Hspb1 expression marks myogenic differentiation with specific expression first confined to developing cardiac muscles and the vascular system, and later in skeletal muscles with specific expression at advanced stages of myoblast differentiation. In the adult, hspb1 expression was observed in other tissues, such as stratified squamous epithelium of skin, oronasal cavity, tongue, esophagus, and uterine cervix but its expression was most prominent in the musculature. Interestingly, in cardiac muscle hsbp1 expression was down-regulated during the neonatal period and maintained to a relatively low steady-level throughout adulthood. Despite this widespread expression, hspb1-/- mice were viable and fertile with no apparent morphological abnormalities in tissues under physiological conditions. However, at the cellular level and under stress conditions (heat challenge), HSPB1 act synergistically with the stress-induced HSPA1 (HSP70) in thermotolerance development, protecting cells from apoptosis. Our data thus indicate a nonessential role for HSPB1 in embryonic development and for maintenance of tissues under physiological conditions, but also shows that it plays an important role by acting synergistically with other HSPs during stress conditions to exert cytoprotection and anti-apoptotic effects.