Increased mitochondrial mutation heteroplasmy induces aging phenotypes in pluripotent stem cells and their differentiated progeny.

The mitochondrial genome (mtDNA) is an important source of inherited extranuclear variation. Clonal increases in mtDNA mutation heteroplasmy have been implicated in aging and disease, although the impact of this shift on cell function is challenging to assess. Reprogramming to pluripotency affects mtDNA mutation heteroplasmy.

Chimeric mitochondrial RNA transcripts predict mitochondrial genome deletion mutations in mitochondrial genetic diseases and aging.

While it is well understood that mitochondrial DNA (mtDNA) deletion mutations cause incurable diseases and contribute to aging, little is known about the transcriptional products that arise from these DNA structural variants. We hypothesized that mitochondrial genomes containing deletion mutations express chimeric mitochondrial RNAs. To test this, we analyzed human and rat RNA sequencing data to identify, quantitate, and characterize chimeric mitochondrial RNAs.

Clinical consequences of age-related skin barrier dysfunction. Part I. Structural, molecular and physiologic changes with cutaneous aging.

Aging is associated with significant changes to skin structure and function. As the United States population ages, dermatologists are increasingly presented with the clinical consequences of these changes. Understanding the biology of aging skin allows dermatologists to best guide patients towards proactive treatment of age-related skin disease.

Clinical consequences of age-related skin barrier dysfunction. Part II. Approach to barrier dysfunction in the geriatric population.

Aging is associated with significant changes to skin structure and function which lead to distinct clinical needs in geriatric dermatology patients. By understanding the relationship between altered skin function with aging and the clinical implications for geriatric dermatology patients, dermatologists can guide patients in developing a preventive regimen and managing age-related skin pathology. The second article of this 2-part continuing medical education series reviews the most common conditions affecting geriatric dermatology patients and specific treatment considerations with a focus on the impact of age-related skin barrier dysfunction.

Nanopore sequencing identifies a higher frequency and expanded spectrum of mitochondrial DNA deletion mutations in human aging.

Mitochondrial DNA (mtDNA) deletion mutations cause many human diseases and are linked to age-induced mitochondrial dysfunction. Mapping the mutation spectrum and quantifying mtDNA deletion mutation frequency is challenging with next-generation sequencing methods. We hypothesized that long-read sequencing of human mtDNA across the lifespan would detect a broader spectrum of mtDNA rearrangements and provide a more accurate measurement of their frequency.

A Genetically Heterogeneous Rat Model with Divergent Mitochondrial Genomes.

We generated a genetically heterogenous rat model by a 4-way cross strategy using 4 inbred strains (Brown Norway [BN], Fischer 344 [F344], Lewis [LEW], and Wistar Kyoto [KY]) to provide investigators with a highly genetically diverse rat model from commercially available inbred rats. We made reciprocal crosses between males and females from the 2 F1 hybrids to generate genetically heterogeneous rats with mitochondrial genomes from either the BN (OKC-HETB, a.k.

Long read mitochondrial genome sequencing using Cas9-guided adaptor ligation.

The mitochondrial genome (mtDNA) is an important source of disease-causing genetic variability, but existing sequencing methods limit understanding, precluding phased measurement of mutations and clear detection of large sporadic deletions. We adapted a method for amplification-free sequence enrichment using Cas9 cleavage to obtain full length nanopore reads of mtDNA. We then utilized the long reads to phase mutations in a patient with an mtDNA-linked syndrome and demonstrated that this method can map age-induced mtDNA deletions.

Alopecia areata in a patient with WNT10A heterozygous ectodermal dysplasia.

We report a case of a patient with ectodermal dysplasia attributed to a heterozygous 321C>A mutation in WNT10A who developed overlying autoimmune mediated hair loss. To the best of our knowledge this is the first reported case of alopecia areata in a patient with WNT10A heterozygous ectodermal dysplasia. This case highlights the importance of considering multiple pathways of hair loss in patients with underlying genetic defects and raises the possibility of a shared genetic predisposition.

Detection of viral gene expression in risk-stratified biopsies reveals no active HPV in cutaneous squamous cell carcinoma.

Background: Human papillomavirus (HPV) infection is known to promote the development of mucosal squamous cell carcinoma (mSCC), including pathologically high-grade lesions, but its role in cutaneous squamous cell carcinoma (cuSCC) remains unclear, particularly in lesions that are considered high risk.

Objective: We aimed to determine whether enhanced HPV transcriptional activity can be detected in high-risk cuSCC samples compared with low-grade SCC samples or normal skin.

Methods: We performed RNA sequencing of cuSCC across 23 risk-stratified skin lesions.

Mitochondrial DNA deletion mutations increase exponentially with age in human skeletal muscle.

Background: Mitochondrial DNA (mtDNA) deletion mutations lead to electron transport chain-deficient cells and age-induced cell loss in multiple tissues and mammalian species. Accurate quantitation of somatic mtDNA deletion mutations could serve as an index of age-induced cell loss. Quantitation of mtDNA deletion molecules is confounded by their low abundance in tissue homogenates, the diversity of deletion breakpoints, stochastic accumulation in single cells, and mosaic distribution between cells.

Blood Leukocyte DNA Methylation Predicts Risk of Future Myocardial Infarction and Coronary Heart Disease.

Background: DNA methylation is implicated in coronary heart disease (CHD), but current evidence is based on small, cross-sectional studies. We examined blood DNA methylation in relation to incident CHD across multiple prospective cohorts.

Methods: Nine population-based cohorts from the United States and Europe profiled epigenome-wide blood leukocyte DNA methylation using the Illumina Infinium 450k microarray, and prospectively ascertained CHD events including coronary insufficiency/unstable angina, recognized myocardial infarction, coronary revascularization, and coronary death.

DNA methylation-based measures of biological age: meta-analysis predicting time to death.

Estimates of biological age based on DNA methylation patterns, often referred to as "epigenetic age", "DNAm age", have been shown to be robust biomarkers of age in humans. We previously demonstrated that independent of chronological age, epigenetic age assessed in blood predicted all-cause mortality in four human cohorts. Here, we expanded our original observation to 13 different cohorts for a total sample size of 13,089 individuals, including three racial/ethnic groups.

DNA methylation is stable during replication and cell cycle arrest.

DNA methylation is an epigenetic modification with important functions in development. Large-scale loss of DNA methylation is a hallmark of cancer. Recent work has identified large genomic blocks of hypomethylation associated with cancer, EBV transformation and replicative senescence, all of which change the proportion of actively proliferating cells within the population measured.

Age and sun exposure-related widespread genomic blocks of hypomethylation in nonmalignant skin.

Background: Aging and sun exposure are the leading causes of skin cancer. It has been shown that epigenetic changes, such as DNA methylation, are well established mechanisms for cancer, and also have emerging roles in aging and common disease. Here, we directly ask whether DNA methylation is altered following skin aging and/or chronic sun exposure in humans.