👤 Melanie Ehrlich

Genome-wide studies of differential DNA methylation often focus on its role in turning transcription on or off. Here we report some atypical epigenetic/transcription relationships for 92 genes that are highly and preferentially expressed in primary human myoblasts relative to heterologous cell cultures. We compared methylomes and myoblast-specific differentially methylated regions (DMRs) with methylomes, chromatin profiles, and transcriptomes for many different cell populations. We found that myoblast-associated promoter hypomethylation was unusually prevalent among the 92 myoblast-preferential genes. Sometimes this promoter hypomethylation was seen as a myoblast-associated extension of their constitutively unmethylated region at a CpG island. All 92 genes showed some myoblast-specific hypomethylation, including 32 genes at tissue-specific super-enhancers or broad H3K4-trimethylated promoters. Myoblast hypermethylated DMRs were also associated with almost half of the myoblast-preferential genes. These hypermethylated DMRs were often in intragenic locations embedded in H3K36-trimethylated chromatin in myoblasts. Our analysis suggests that some of the hypermethylated DMRs repress cryptic, alternative, or adjacent promoters. Myoblast hypermethylated DMRs may also downmodulate expression in myoblasts to avoid yet higher RNA levels found in adult or fetal skeletal muscle tissue. The epigenetic insights that were obtained can help elucidate the transcription regulation of some of these genes (e.g., Show less

Continuous glucose monitoring (CGM) offers a unique opportunity to assess Q6 glucose patterns across the 24-hour day, including nighttime. In individuals with pregnancy hyperglycemia, evidence suggests that optimizing nocturnal glucose levels reduces the risk of large-for-gestational-age births and future metabolic dysfunction. However, the behavioral correlates of nocturnal glucose levels remain poorly understood. Continuous movement devices assess physical activity (PA) and sedentary behavior (SED) across 24-hour days, and to the best of our knowledge, have not been paired with CGM data in individuals with pregnancy hyperglycemia. This secondary analysis of a feasibility trial explored the association of day-time PA and SED with nighttime (i.e., 12-6 AM) interstitial glucose levels in individuals with gestational diabetes mellitus (GDM) or gestational glucose intolerance (GGI). Participants (N = 13; ~31 weeks gestation) wore a Dexcom G6 CGM and ActiGraph Insight Watch for 7 days. Mixed effects models examined associations between daytime moderate-tovigorous physical activity (MVPA), light physical activity (LPA), and sedentary behavior (SED) with nocturnal glucose metrics, including mean glucose, time in range (TIR; 60-99 mg/dL), and area under the curve (AUC). Adjusted models revealed that each 10-minute increase in MVPA was associated with 0.86 mg/dL [95% confidence interval (CI) 0.002, 1.73] higher mean glucose and 313 mg/ dL*min (CI 0.98, 624.55) higher AUC. No associations were observed for total activity, LPA, or SED. These findings illustrate the feasibility and potential of combining CGM with activity monitor data, and the need to further integrate dietary intake data. Improvements in glucose and activity monitoring technology hold great promise for improving scientific and clinical understanding and supporting the development of personalized, data-driven glucose management tools during pregnancy. Show less

Anorexia nervosa (AN) is a mental disorder marked by a significantly low body weight. Differentially methylated CpG sites have been reported to be involved in body weight regulation. Methylation pattern may change during considerable weight gain by in-patient treatment. Consequently, we aimed to (1) replicate the hypomethylation at the NR1H3 gene locus (identified in our previous epigenome-wide association study) in independent study groups of 189 female patients with AN and 67 healthy-lean female controls, and (2) identify regions associated with large weight gain associated DNA methylation changes in three patients with AN through whole-genome bisulfite sequencing in CD14 Show less

Mutations leading to a reduced or loss of function in genes of the leptin-melanocortin system confer a risk for monogenic forms of obesity. Yet, gain of function variants in the melanocortin-4-receptor (MC4R) gene predispose to a lower BMI. In individuals with reduced body weight, we thus expected mutations leading to an enhanced function in the respective genes, like leptin (LEP) and MC4R. Therefore, we have Sanger sequenced the coding regions of LEP and MC4R in 462 female patients with anorexia nervosa (AN), and 445 healthy-lean controls. In total, we have observed four and eight variants in LEP and MC4R, respectively. Previous studies showed different functional in vitro effects for the detected frameshift and non-synonymous variants: (1) LEP: reduced/loss of function (p.Val94Met), (2) MC4R: gain of function (p.Val103Ile, p.Ile251Leu), reduced or loss of function (p.Thr112Met, p.Ser127Leu, p.Leu211fsX) and without functional in vitro data (p.Val50Leut). In LEP, the variant p.Val94Met was detected in one patient with AN. For MC4R variants, one patient with AN carried the frameshift variant p.Leu211fsX. One patient with AN was heterozygous for two variants at the MC4R (p.Val103Ile and p.Ser127Leu). All other functionally relevant variants were detected in similar frequencies in patients with AN and lean individuals. Show less

Dual specificity protein phosphatase 6 (DUSP6) was recently identified as a key hub gene in a causal To investigate the role of DUSP6 in AD, we stereotactically injected AAV5-DUSP6 or AAV5-GFP (control) into the dorsal hippocampus (dHc) of both female and male 5xFAD or wild type mice, to induce overexpression of DUSP6 or GFP. Barnes maze testing indicated that DUSP6 overexpression in the dHc of 5xFAD mice improved memory deficits and was associated with reduced amyloid plaque load, Aß In summary, DUSP6 overexpression in dHc reduced amyloid deposition and memory deficits in male but not female 5xFAD mice, whereas reduced neuroinflammation and microglial activation were observed in both males and females, suggesting that DUSP6-induced reduction of microglial activation did not contribute to sex-dependent improvement in memory deficits. The sex-dependent regulation of synaptic pathways by DUSP6 overexpression, however, correlated with the improvement of spatial memory deficits in male but not female 5xFAD. Show less

We recently reported that the dopamine (DA) analogue CA140 modulates neuroinflammatory responses in lipopolysaccharide-injected wild-type (WT) mice and in 3-month-old 5xFAD mice, a model of Alzheimer's disease (AD). However, the effects of CA140 on Aβ/tau pathology and synaptic/cognitive function and its molecular mechanisms of action are unknown. To investigate the effects of CA140 on cognitive and synaptic function and AD pathology, 3-month-old WT mice or 8-month-old (aged) 5xFAD mice were injected with vehicle (10% DMSO) or CA140 (30 mg/kg, i.p.) daily for 10, 14, or 17 days. Behavioral tests, ELISA, electrophysiology, RNA sequencing, real-time PCR, Golgi staining, immunofluorescence staining, and western blotting were conducted. In aged 5xFAD mice, a model of AD pathology, CA140 treatment significantly reduced Aβ/tau fibrillation, Aβ plaque number, tau hyperphosphorylation, and neuroinflammation by inhibiting NLRP3 activation. In addition, CA140 treatment downregulated the expression of cxcl10, a marker of AD-associated reactive astrocytes (RAs), and c1qa, a marker of the interaction of RAs with disease-associated microglia (DAMs) in 5xFAD mice. CA140 treatment also suppressed the mRNA levels of s100β and cxcl10, markers of AD-associated RAs, in primary astrocytes from 5xFAD mice. In primary microglial cells from 5xFAD mice, CA140 treatment increased the mRNA levels of markers of homeostatic microglia (cx3cr1 and p2ry12) and decreased the mRNA levels of a marker of proliferative region-associated microglia (gpnmb) and a marker of lipid-droplet-accumulating microglia (cln3). Importantly, CA140 treatment rescued scopolamine (SCO)-mediated deficits in long-term memory, dendritic spine number, and LTP impairment. In aged 5xFAD mice, these effects of CA140 treatment on cognitive/synaptic function and AD pathology were regulated by dopamine D1 receptor (DRD1)/Elk1 signaling. In primary hippocampal neurons and WT mice, CA140 treatment promoted long-term memory and dendritic spine formation via effects on DRD1/CaMKIIα and/or ERK signaling. Our results indicate that CA140 improves neuronal/synaptic/cognitive function and ameliorates Aβ/tau pathology and neuroinflammation by modulating DRD1 signaling in primary hippocampal neurons, primary astrocytes/microglia, WT mice, and aged 5xFAD mice. Show less

The bone-derived adipokine lipocalin-2 is relevant for body weight regulation by stimulating the leptin-melanocortin pathway. We aimed to (i) detect variants in the lipocalin-2 gene ( Sanger sequencing of the coding region of Fourteen Lipocalin-2 levels are positively associated with body mass index (BMI). Single Show less

Dual specificity protein phosphatase 6 (DUSP6) was recently identified as a key hub gene in a causal network that regulates late-onset Alzheimer's disease. Importantly, decreased DUSP6 levels are correlated with an increased clinical dementia rating in human subjects, and DUSP6 levels are additionally decreased in the 5xFAD amyloidopathy mouse model. AAV5-DUSP6 or AAV5-GFP (control) were stereotactically injected into the dorsal hippocampus (dHc) of female and male 5xFAD or wild type mice to overexpress DUSP6 or GFP. Spatial learning memory of these mice was assessed in the Barnes maze, after which hippocampal tissues were isolated for downstream analysis. Barnes maze testing indicated that DUSP6 overexpression in the dHc of 5xFAD mice improved memory deficits and was associated with reduced amyloid plaque load, Aß In summary, our data indicate that DUSP6 overexpression in dHc reduced amyloid deposition and memory deficits in male but not female 5xFAD mice, whereas reduced neuroinflammation and microglial activation were observed in both males and females. The sex-dependent regulation of synaptic pathways by DUSP6 overexpression, however, correlated with the improvement of spatial memory deficits in male but not female 5xFAD. Show less

A better understanding of the biological and environmental variables that contribute to exceptional longevity has the potential to inform the treatment of geriatric diseases and help achieve healthy aging. Here, we compared the gut microbiome and blood metabolome of extremely long-lived individuals (94-105 years old) to that of their children (50-79 years old) in 116 Han Chinese families. We found extensive metagenomic and metabolomic remodeling in advanced age and observed a generational divergence in the correlations with socioeconomic factors. An analysis of quantitative trait loci revealed that genetic associations with metagenomic and metabolomic features were largely generation-specific, but we also found 131 plasma metabolic quantitative trait loci associations that were cross-generational with the genetic variants concentrated in six loci. These included associations between FADS1/2 and arachidonate, PTPA and succinylcarnitine and FLVCR1 and choline. Our characterization of the extensive metagenomic and metabolomic remodeling that occurs in people reaching extreme ages may offer new targets for aging-related interventions. Show less

To understand tissue-specific regulation of angiopoietin/angiopoietin-like (ANGPT/ANGPTL) genes (especially the five genes embedded in introns of host genes) and their association with atherosclerosis. Transcription and epigenomic databases from various normal tissues were examined in the vicinity of ANGPT1, ANGPT2, ANGPTL1, ANGPTL2, ANGPTL3, ANGPTL4 and ANGPTL8. We identified tissue-specific enhancer chromatin regions that are likely to regulate transcription of ANGPT/ANGPTL genes and were intragenic, intergenic or host gene-linked. In addition, we found atherosclerosis-linked differentially methylated regions associated with ANGPT2 and with sequences encoding miR-145, a microRNA that targets ANGPT2 mRNA in cancers. Our findings implicate enhancers as major contributors to tissue-specific expression of ANGPT/ANGPTL genes, which play critical roles in angiogenesis, atherosclerosis, cancer, and inflammatory and metabolic diseases. Show less

Dexamethasone, a common therapy for reducing hypertrophic scar, sometimes fails. However, in cell culture, all dexamethasone-treated fibroblasts die. In co-cultures, gap junction intercellular communications between mast cells and fibroblasts promote profibrotic activities. Does the co-culture of mast cells with fibroblasts prevent dexamethasone-induced fibroblast death? Survival of fibroblasts co-cultured with RMC-1 cells, a rat mast cell line, receiving dexamethasone was studied. RMC-1 cells pretreated with a secretagogue that degranulated mast cells and/or with a long-acting gap junction intercellular communications inhibitor were compared to untreated RMC-1 cells co-cultured with fibroblasts and dexamethasone. Fibroblasts alone treated with dexamethasone all died in 3 hours. Fibroblasts co-cultured with intact RMC-1 cells or with degranulated RMC-1 cells in dexamethasone all survived. No fibroblasts survived, co-cultured with RMC-1 cells unable to form gap junction intercellular communications with fibroblasts. Dexamethasone-treated fibroblasts, forming gap junction intercellular communications with mast cells, may explain why dexamethasone therapy sometimes fails. Gap junction intercellular communications between scar mast cells and fibroblasts or myofibroblasts apparently blocks the death of these cell populations. Preventing gap junction intercellular communications between mast cells and fibroblasts by including anti-gap junction intercellular communication agents may enhance the effectiveness of steroid therapy in treating excessive scarring. Show less

The prominent inflammatory cell identified in excessive scarring is the mast cell. Hypertrophic scar exhibits myofibroblasts derived from the transformation of fibroblasts, increased collagen synthesis, and stationary nonmigratory resident cells. The co-culture of fibroblasts with an established rat mast cell line (RMC-1) was used to explore the hypothesis of whether mast cells through gap junctional intercellular communications guide fibroblasts in promoting excessive scarring. Human dermal fibroblasts were cultured alone or co-cultured with RMC-1 cells as is or with either blocked gap junctional intercellular communications or devoid of cytoplasmic granules. Collagen synthesis was analyzed by dot blot analysis; immunohistology identified myofibroblasts, and a cell migration assay measured fibroblast locomotion. Fibroblasts co-cultured with RMC-1 cells transformed into myofibroblasts, had increased collagen synthesis, and showed retarded cell migration. In contrast, RMC-1 cells unable to form gap junctional intercellular communications were similar to fibroblasts alone, failing to promote these activities. Degranulated RMC-1 cells were as effective as intact RMC-1 cells. Mast cells induce fibroblast activities associated with hypertrophic scarring through gap junctional intercellular communications. Eliminating the mast cell or its gap junctional intercellular communications with fibroblasts may be a possible approach in preventing hypertrophic scarring or reducing fibrotic conditions. Show less

Mast cells' association with fibrosis is known, but the mechanics of that association are unclear. The hypothesis is that mast cells promote fibroblast profibrotic activities through heterocellular gap junctional intercellular communications. Casting populated collagen lattices with both human mastocytoma cell line (HMC-1), an established mast cell line, and fibroblasts enhances lattice contraction via gap junctional intercellular communications. Unfortunately, in monolayer culture, HMC-1 cells and fibroblasts do not form heterocellular gap junctional intercellular communications. Freshly isolated rat peritoneal mast cells, however, establish these communications with fibroblasts in monolayer culture. Isolated rat peritoneal mast cells, however, survive only 7 days. Establishing a rat mast cell line that grows in the same medium as fibroblasts advances the study of mast cell-fibroblast interactions. HMC-1 cells thrive without supplements, suggesting that they release the factor(s) necessary for their viability. Spent HMC-1 medium may contain the factor(s) that generate a viable rat mast cell line. Rat peritoneal-isolated mast cells grew in culture medium containing spent HMC-1 medium for 4 weeks. At 4 weeks, rat mast cells (RMC-1) were successfully maintained in Dulbecco's Modified Eagle Medium with 10% serum. RMC-1 cells formed heterocellular gap junctional intercellular communications with fibroblasts, enhancing both fibroblast proliferation and co-cultured RMC-1/fibroblast/populated collagen lattice contraction. Enhanced fibroblast proliferation and lattice contraction failed to occur by including RMC-1 cells unable to establish gap junctional intercellular communications with fibroblasts, but cell proliferation was not affected by including degranulated RMC-1 cells. Heterocellular gap junctional intercellular communications with mast cells increase in fibroblast proliferation and fibroblast PCL contraction, two hypertrophic scar fibroblast activities. Show less

The influence of mast cells upon aberrant wound repair and excessive fibrosis has supportive evidence, but the mechanism for these mast cell activities is unclear. It is proposed that heterocellular gap junction intercellular communication (GJIC) between fibroblasts and mast cells directs some fibroblast activities. An in vitro model was used employing a rodent derived peritoneal mast cell line (RMC-1) and human dermal derived fibroblasts. The influence of the expression of the gap junction channel structural protein, connexin 43 (Cx-43) on heterocellular GJIC, the expression of microtubule β-tubulin and microfilament α smooth muscle actin (SMA) were investigated. The knockdown of Cx-43 by siRNA in RMC-1 cells completely blocked GJIC between RMC-1 cells. SiRNA knockdown of Cx-43 within fibroblasts only dampened GJIC between fibroblasts. It appears Cx-43 is the only expressed connexin (Cx) in RMC-1 cells. Fibroblasts express other Cxs that participate in GJIC between fibroblasts in the absence of Cx-43 expression. Heterocellular GJIC between RMC-1 cells and fibroblasts transformed fibroblasts into myofibroblasts, expressing α SMA within cytoplasmic stress fibers. The knockdown of Cx-43 in RMC-1 cells increased β-tubulin expression, but its knockdown in fibroblasts reduced β-tubulin expression. Knocking down the expression of Cx-43 in fibroblasts limited αSMA expression. Cx-43 participation is critical for heterocellular GJIC between mast cells and fibroblasts, which may herald a novel direction for controlling fibrosis. Show less