H2B Type 1-K Accumulates in Senescent Fibroblasts with Persistent DNA Damage along with Methylated and Phosphorylated Forms of HMGA1

The ABCs of the H2Bs: The histone H2B sequences, variants, and modifications

Histone proteins are the building blocks of chromatin, and function by wrapping DNA into complex structures that control gene expression. Histone proteins are regulated by post-translational modifications (PTMs) and by histone variant exchange. In this review, we will provide an overview of one of these histones: H2B. We will first define the sequences of human and mouse H2B proteins and discuss potential designations for canonical H2B. We will also describe the differential functions of H2B variants compared with canonical H2B. Finally, we will summarize known H2B modifications and their functions in regulating transcription. Through review of H2B genes, proteins, variants, and modifications, we aim to highlight the importance of H2B for epigenetic and transcriptional regulation of the cell.

TriHex 2.0-Advancing Skin Health Science and the TriHex Technology

BACKGROUND

The original TriHex combination-Tripeptide-1 and Hexapeptide-12 (TriHex) encompasses a peptide combination selected for its ability to modulate the extracellular matrix (ECM) by progressively eliminating clumped collagen and elastin fragments and then stimulating replacement with new collagen and elastin. Incorporation of a proprietary, patent-pending Octapeptide-45 (Octa) to the TriHex original provides potential for added benefit based on the peptide's capacity to stimulate hyaluronic acid (HA) and its anticipated added benefit in wound healing. This is named TriHex 2.0 in the paper.

MATERIALS AND METHODS

A full-scale validation process was structured to assess Octa synergy with TriHex using an ex vivo model, assessing ECM changes histologically in relation to elastin, HA and basement membrane components. In addition, gene expression studies were undertaken, including bulk and single cell sequencing analysis to assess the particular changes that occurred by adding Octa to the TriHex. Following the gene expression analysis, a further round of ex vivo studies was conducted to assess protein expression of the defined differentially expressed genes using histological staining.

RESULTS

Octa synergized with TriHex as demonstrated by significantly upregulated genes (p < 0.05) affecting the ECM and basement membrane. A histological assessment using the ex vivo model demonstrated tropoelastin intensity significantly increasing with TriHex (43%) and 2.0 (42%) (p < 0.05 for both) compared to untreated explants. HA levels (CD44 intensity) significantly increased with TriHex (69%; p < 0.01), while TriHex 2.0 demonstrated HA levels 160% greater (p < 0.001) than the untreated tissue. Single cell sequencing identified a gene expression profile upregulation relating to ECM modulation and wound healing in both TriHex and 2.0, but TriHex 2.0 showed additional activities in basement membrane physiology, stem cell recruitment, and protection of fibroblasts against cellular senescence.

CONCLUSION

The addition of Octapeptide-45 to TriHex technology in the form of TriHex 2.0 is a significant advance to TriHex technology science. Both forms demonstrate ECM remodeling and positive wound healing, but supplementary benefits are evident including increased elastin and hyaluronic acid stimulation, added effects on the basement membrane, additional wound healing capacity in basal keratinocytes and anti-senescent effects in fibroblasts. This is helpful for pre-conditioning of the skin prior to procedures and post procedure related to additional ECM remodeling, wound healing advantages, senescent cell targeting and DEJ strengthening. Clinical studies to follow.

Multidimensional Epigenetic Clocks Demonstrate Accelerated Aging Across Physiological Systems in Schizophrenia: A Meta-Analysis

IMPORTANCE

Schizophrenia is associated with increased age-related morbidity, mortality, and frailty, which are not entirely explained by behavioral factors. Prior studies using epigenetic clocks have suggested that schizophrenia is associated with accelerated aging, however these studies have primarily used unidimensional clocks that summarize aging as a single "biological age" score.

OBJECTIVE

This meta-analysis uses multidimensional epigenetic clocks that split aging into multiple scores to analyze biological aging in schizophrenia. These novel clocks may provide more granular insights into the mechanistic relationships between schizophrenia, epigenetic aging, and premature morbidity and mortality.

STUDY SELECTION

Selected studies included patients with schizophrenia-spectrum disorders and non- psychiatric controls with available DNA methylation data. Seven cross-sectional datasets were available for this study, with a total sample size of 1,891 patients with schizophrenia and 1,881 controls.

DATA EXTRACTION AND SYNTHESIS

Studies were selected by consensus Meta-analyses were performed using fixed-effect models.

MAIN OUTCOMES AND MEASURES

We analyzed multidimensional epigenetic clocks, including causality- enriched CausAge clocks, physiological system-specific SystemsAge clocks, RetroelementAge, DNAmEMRAge, and multi omics-informed OMICmAge. Meta-analyses examined clock associations with schizophrenia disease status and clozapine use, after accounting for age and sex.

RESULTS

Overall SystemsAge, CausAge, DNAmEMRAge, and OMICmAge scores demonstrated increased epigenetic aging in patients with schizophrenia after strict multiple-comparison testing. Ten of the eleven SystemsAge sub-clocks corresponding to different physiological systems demonstrated increased aging, with strongest effects for Heart and Lung followed by Metabolic and Brain systems. The causality- enriched clocks indicated increases in both damaging and adaptive aging, though these effects were weaker compared to SystemsAge scores. OMICmAge indicated changes in multiple clinical biomarkers, including hematologic and hepatic markers that support system-specific aging, as well as novel proteins and metabolites not previously linked to schizophrenia. Most clocks demonstrated age acceleration at the first psychotic episode. Notably, clozapine use was associated with increased Heart and Inflammation aging, which may partially be driven by smoking. Most results survived strict Bonferroni multiple testing correction.

CONCLUSIONS AND RELEVANCE

These are the first analyses of novel multidimensional clocks in patients with schizophrenia and provide a nuanced view of aging that identifies multiple organ systems at high risk for disease in schizophrenia-related disorders.

Histone deficiency and hypoacetylation in the aging retinal pigment epithelium

Histones serve as a major carrier of epigenetic information in the form of post-translational modifications which are vital for controlling gene expression, maintaining cell identity, and ensuring proper cellular function. Loss of histones in the aging genome can drastically impact the epigenetic landscape of the cell leading to altered chromatin structure and changes in gene expression profiles. In this study, we investigated the impact of age-related changes on histone levels and histone acetylation in the retinal pigment epithelium (RPE) and retina of mice. We observed a global reduction of histones H1, H2A, H2B, H3, and H4 in aged RPE/choroid but not in the neural retina. Transcriptomic analyses revealed significant downregulation of histones in aged RPE/choroid including crucial elements of the histone locus body (HLB) complex involved in histone pre-mRNA processing. Knockdown of HINFP, a key HLB component, in human RPE cells induced histone loss, senescence, and the upregulation of senescence-associated secretory phenotype (SASP) markers. Replicative senescence and chronological aging in human RPE cells similarly resulted in progressive histone loss and acquisition of the SASP. Immunostaining of human retina sections revealed histone loss in RPE with age. Acetyl-histone profiling in aged mouse RPE/choroid revealed a specific molecular signature with loss of global acetyl-histone levels, including H3K14ac, H3K56ac, and H4K16ac marks. These findings strongly demonstrate histone loss as a unique feature of RPE aging and provide critical insights into the potential mechanisms linking histone dynamics, cellular senescence, and aging.

Unraveling Histone Loss in Aging and Senescence

As the global population experiences a notable surge in aging demographics, the need to understand the intricate molecular pathways exacerbated by age-related stresses, including epigenetic dysregulation, becomes a priority. Epigenetic mechanisms play a critical role in driving age-related diseases through altered gene expression, genomic instability, and irregular chromatin remodeling. In this review, we focus on histones, a central component of the epigenome, and consolidate the key findings of histone loss and genome-wide redistribution as fundamental processes contributing to aging and senescence. The review provides insights into novel histone expression profiles, nucleosome occupancy, disruptions in higher-order chromatin architecture, and the emergence of noncanonical histone variants in the aging cellular landscape. Furthermore, we explore the current state of our understanding of the molecular mechanisms of histone deficiency in aging cells. Specific emphasis is placed on highlighting histone degradation pathways in the cell and studies that have explored potential strategies to mitigate histone loss or restore histone levels in aging cells. Finally, in addressing future perspectives, the insights gained from this review hold profound implications for advancing strategies that actively intervene in modulating histone expression profiles in the context of cellular aging and identifying potential therapeutic targets for alleviating a multitude of age-related diseases.

Progression of irradiated mesenchymal stromal cells from early to late senescence: Changes in SASP composition and anti-tumour properties

Genotoxic injuries converge on senescence-executive program that promotes production of a senescence-specific secretome (SASP). The study of SASP is particularly intriguing, since through it a senescence process, triggered in a few cells, can spread to many other cells and produce either beneficial or negative consequences for health. We analysed the SASP of quiescent mesenchymal stromal cells (MSCs) following stress induced premature senescence (SIPS) by ionizing radiation exposure. We performed a proteome analysis of SASP content obtained from early and late senescent cells. The bioinformatics studies evidenced that early and late SASPs, besides some common ontologies and signalling pathways, contain specific factors. In spite of these differences, we evidenced that SASPs can block in vitro proliferation of cancer cells and promote senescence/apoptosis. It is possible to imagine that SASP always contains core components that have an anti-tumour activity, the progression from early to late senescence enriches the SASP of factors that may promote SASP tumorigenic activity only by interacting and instructing cells of the immune system. Our results on Caco-2 cancer cells incubated with late SASP in presence of peripheral white blood cells strongly support this hypothesis. We evidenced that quiescent MSCs following SIPS produced SASP that, while progressively changed its composition, preserved the capacity to block cancer growth by inducing senescence and/or apoptosis only in an autonomous manner.

Progression of irradiated mesenchymal stromal cells from early to late senescence: Changes in SASP composition and anti-tumour properties

Genotoxic injuries converge on senescence-executive program that promotes production of a senescence-specific secretome (SASP). The study of SASP is particularly intriguing, since through it a senescence process, triggered in a few cells, can spread to many other cells and produce either beneficial or negative consequences for health. We analysed the SASP of quiescent mesenchymal stromal cells (MSCs) following stress induced premature senescence (SIPS) by ionizing radiation exposure. We performed a proteome analysis of SASP content obtained from early and late senescent cells. The bioinformatics studies evidenced that early and late SASPs, besides some common ontologies and signalling pathways, contain specific factors. In spite of these differences, we evidenced that SASPs can block in vitro proliferation of cancer cells and promote senescence/apoptosis. It is possible to imagine that SASP always contains core components that have an anti-tumour activity, the progression from early to late senescence enriches the SASP of factors that may promote SASP tumorigenic activity only by interacting and instructing cells of the immune system. Our results on Caco-2 cancer cells incubated with late SASP in presence of peripheral white blood cells strongly support this hypothesis. We evidenced that quiescent MSCs following SIPS produced SASP that, while progressively changed its composition, preserved the capacity to block cancer growth by inducing senescence and/or apoptosis only in an autonomous manner.