Epigenetics of osteoarticular diseases: recent developments.

A variety of osteoarticular conditions possess an underlying genetic aetiology. Large-scale genome-wide association studies have identified several genetic loci associated with osteoarticular conditions, but were unable to fully account for their estimated heritability. Epigenetic modifications including DNA methylation, histone modification, nucleosome positioning, and microRNA expression may help account for this incomplete heritability. This articles reviews insights from epigenetic studies in osteoarticular diseases, focusing on osteoarthritis, but also examines recent advances in rheumatoid arthritis, osteoporosis, systemic lupus erythematosus (SLE), ankylosing spondylitis, and sarcoma. Genome-wide methylation studies are permitting identification of novel candidate genes and molecular pathways, and the pathogenic mechanisms with altered methylation status are beginning to be elucidated. These findings are gradually translating into improved understanding of disease pathogenesis and clinical applications. Functional studies in osteoarthritis, rheumatoid arthritis, and SLE are now identifying downstream molecular alterations that may confer disease susceptibility. Epigenetic markers are being validated as prognostic and therapeutic disease biomarkers in sarcoma, and clinical trials of hypomethylating agents as treatments for sarcoma are being conducted. In concert with advances in throughput and cost-efficiency of available technologies, future epigenetic research will enable greater characterisation and treatment for both common and rare osteoarticular diseases.

Quantitative PCR analysis used to characterize physiological changes in brain tissue of senescent sockeye salmon.

Senescence varies considerably among fishes, and understanding the evolutionary basis for this diversity has become an important area of study. For rapidly senescing species such as Pacific salmon, senescence is a complex process as these fish are initiating anorexia while migrating to natal spawning grounds, and die within days of reproduction. To better understand senescence in Pacific salmon we examined expression patterns for a suite of genes in brain tissue of pre-senescent and senescent sockeye salmon. Interestingly, a significant increase in expression of genes involved in telomere repair and immune activity was observed in senescent salmon. These data provide insight into physiological changes in salmon undergoing senescence and the factors contributing to variation in observed senescence rates among individuals and populations.

Altered cleavage and secretion of a recombinant beta-APP bearing the Swedish familial Alzheimer's disease mutation.

Mutations within the beta-amyloid precursor protein gene cosegregate with the early-onset form of familial Alzheimer's Disease (FAD). It is not known how these mutations result in disease; however, one early-onset AD mutation in a Swedish kindred increases potentially amyloidogenic fragments and beta-protein production in cells expressing the mutant beta-APP. Using a novel recombinant reporter system we found a qualitative change in the secreted product, from cleavage within the beta-protein sequence to cleavage near the N-terminal region of the beta-protein, even though the total amount of secreted mutant product is similar to wild-type. The results suggest that the increased formation of potentially amyloidogenic fragments in cells expressing the Swedish FAD occurs by enzymatic cleavage in the secretory pathway. Alterations in the secretory process may predispose an individual to AD.

Standardizing Electronic Health Record Data on AD/ADRD to Accelerate Health Equity in Prevention, Detection, and Treatment.

Improving the prevention, detection, and treatment of Alzheimer's disease and Alzheimer's disease related dementias (AD/ADRD) across racial, ethnic, and other diverse populations is a national priority. To this end, this paper proposes the development of the Standard Health Record for Dementia (SHRD, pronounced "shared") for collecting and sharing AD/ADRD real-world data (RWD). SHRD would replace the current unstandardized, fragmented, or missing state of key RWD with an open source, consensus-based, and interoperable common data standard. This paper describes how SHRD could leverage the best practices of the Minimal Common Oncology Data Elements (mCODETM) initiative to advance prevention, detection, and treatment; gain adoption by clinicians and electronic health record (EHR) vendors; and establish sustainable business and governance models. It describes a range of potential use cases to advance equity, including strengthening public health surveillance by facilitating AD/ADRD registry reporting; improving case detection and staging; and diversifying participation in clinical trials.

Differential phosphorylation of the transcription factor Oct1 during the cell cycle.

Orderly progression through the somatic cell division cycle is accompanied by phase-specific transcription of a variety of different genes. During S phase, transcription of mammalian histone H2B genes requires a specific promoter element and its cognate transcription factor Oct1 (OTF1). A possible mechanism for regulating histone H2B transcription during the cell cycle is direct modulation of Oct1 activity by phase-specific posttranslational modifications. Analysis of Oct1 during progression through the cell cycle revealed a complex temporal program of phosphorylation. A p34cdc2-related protein kinase that is active during mitosis may be responsible for one mitotic phosphorylation of Oct1. However, the temporally controlled appearance of Oct1 phosphopeptides suggests the involvement of multiple kinases and phosphatases. These results support the idea that cell cycle-regulated transcription factors may be direct substrates for phase-specific regulatory enzymes.

Mitotic phosphorylation of the Oct-1 homeodomain and regulation of Oct-1 DNA binding activity.

Oct-1 is a transcription factor involved in the cell cycle regulation of histone H2B gene transcription and in the transcription of other cellular housekeeping genes. Oct-1 is hyperphosphorylated as cells enter mitosis, and mitosis-specific phosphorylation is reversed as cells exit mitosis. A mitosis-specific phosphorylation site in the homeodomain of Oct-1 was phosphorylated in vitro by protein kinase A. Phosphorylation of this site correlated with inhibition of Oct-1 DNA binding activity in vivo and in vitro. The inhibition of Oct-1 DNA binding during mitosis suggests a mechanism by which the general inhibition of transcription during mitosis might occur.

RNA polymerase II transcription factors H4TF-1 and H4TF-2 require metal to bind specific DNA sequences.

Specific DNA-binding and in vitro transcription activities of H4TF-1 and H4TF-2 are inactivated by chelating agents. Binding activity is restored by addition of Zn2+, and H4TF-2 is also reactivated by Fe2+. In contrast, preformed factor-DNA complexes are resistant to chelators. Therefore, metal ions are a required component of the H4TF-1 and H4TF-2 DNA-binding domains.

Thoracolumbar kyphosis in patients with mucopolysaccharidoses: clinical outcomes and predictive radiographic factors for progression of deformity.

AIMS: Clinical and radiological data were reviewed for all patients with mucopolysaccharidoses (MPS) with thoracolumbar kyphosis managed non-operatively or operatively in our institution. METHODS: In all 16 patients were included (eight female: eight male; 50% male), of whom nine had Hurler, five Morquio and two Hunter syndrome. Six patients were treated non-operatively (mean age at presentation of 6.3 years; 0.4 to 12.9); mean kyphotic progression +1.5(o)/year; mean follow-up of 3.1 years (1 to 5.1) and ten patients operatively (mean age at presentation of 4.7 years; 0.9 to 14.4); mean kyphotic progression 10.8(o)/year; mean follow-up of 8.2 years; 4.8 to 11.8) by circumferential arthrodesis with posterior instrumentation in patients with flexible deformities (n = 6). RESULTS: In the surgical group (mean age at surgery of 6.6 years; 2.4 to 16.8); mean post-operative follow-up of 6.3 years (3.5 to 10.3), mean pre-operative thoracolumbar kyphosis of 74.3(o) (42(o) to 110(o)) was corrected to mean of 28.6(o) (0(o) to 65(o)) post-operatively, relating to a mean deformity correction of 66.9% (31% to 100%). Surgical complications included a deep wound infection treated by early debridement, apical non-union treated by posterior re-grafting, and stable adjacent segment spondylolisthesis managed non-operatively. Thoracolumbar kyphosis > +38(o) at initial presentation was identified as predicting progressively severe deformity with 90% sensitivity and 83% specificity. DISCUSSION: This study demonstrates that severe thoracolumbar kyphosis in patients with MPS can be effectively treated by circumferential arthrodesis. Severity of kyphosis at initial presentation may predict progression of thoracolumbar deformity. Patients with MPS may be particularly susceptible to post-operative complications due to the underlying connective tissue disorder and inherent immunological compromise. TAKE HOME MESSAGE: Clinical and radiological data were reviewed for all patients with mucopolysaccharidoses with thoracolumbar kyphosis managed non-operatively or operatively in our institution.

Nucleotide sequences of Caenorhabditis elegans core histone genes. Genes for different histone classes share common flanking sequence elements.

We have determined the nucleotide sequence of core histone genes and flanking regions from two of approximately 11 different genomic histone clusters of the nematode Caenorhabditis elegans. Four histone genes from one cluster (H3, H4, H2B, H2A) and two histone genes from another (H4 and H2A) were analyzed. The predicted amino acid sequences of the two H4 and H2A proteins from the two clusters are identical, whereas the nucleotide sequences of the genes have diverged 9% (H2A) and 12% (H4). Flanking sequences, which are mostly not similar, were compared to identify putative regulatory elements. A conserved sequence of 34 base-pairs is present 19 to 42 nucleotides 3' of the termination codon of all the genes. Within the conserved sequence is a 16-base dyad sequence homologous to the one typically found at the 3' end of histone genes from higher eukaryotes. The C. elegans core histone genes are organized as divergently transcribed pairs of H3-H4 and H2A-H2B and contain 5' conserved sequence elements in the shared spacer regions. One of the sequence elements, 5' CTCCNCCTNCCCACCNCANA 3', is located immediately upstream from the canonical TATA homology of each gene. Another sequence element, 5' CTGCGGGGACACATNT 3', is present in the spacer of each heterotypic pair. These two 5' conserved sequences are not present in the promoter region of histone genes from other organisms, where 5' conserved sequences are usually different for each histone class. They are also not found in non-histone genes of C. elegans. These putative regulatory sequences of C. elegans core histone genes are similar to the regulatory elements of both higher and lower eukaryotes. The coding regions of the genes and the 3' regulatory sequences are similar to those of higher eukaryotes, whereas the presence of common 5' sequence elements upstream from genes of different histone classes is similar to histone promoter elements in yeast.

Sequence comparisons of non-allelic late histone genes and their early stage counterparts. Evidence for gene conversion within the sea urchin late stage gene family.

We have determined the nucleotide sequence of sea urchin (Lytechinus pictus) late stage H3 and H4 histone genes contained on the clone pLpH3H4 -21 and of the early stage H3 gene contained on the plasmid pLpA . Comparison of these differentially regulated histone genes with each other and with other L. pictus late and early stage histone H3 and H4 genes previously sequenced confirms that members of each histone gene family (early and late) are more homologous to each other than they are to members of other histone gene families. The spacer regions between two late H3-H4 gene pairs on the clones pLpH3H4 -19 and pLpH3H4 -21 have diverged to the point where they are no longer homologous. However, comparative analysis of the 5' flanking DNA has identified a sequence 5'C-T-C-A-T-G-T-A-T-T3' upstream of both late H4 genes and another, 5'A-G-A-T-T-C-A3', upstream of both H3 genes. Except for a short conserved sequence near the initiation codon, the transcribed 5' leaders of the late mRNAs differ in length and sequence in the two non-allelic late histone gene pairs. This divergence contrasts with the 95 to 96% conservation found between late histone gene coding sequences. The results suggest that there is intergenic exchange in the germline among members of the late histone gene family and that the unit of exchange is the individual gene rather than the heterotypic dimer which includes the common spacer DNA.

Molecular characterization of the histone gene family of Caenorhabditis elegans.

The core histone genes (H2A, H2B, H3 and H4) of Caenorhabditis elegans are arranged in approximately 11 dispersed clusters and are not tandemly arrayed in the genome. Three well-characterized genomic clones, which contain histone genes, have one copy of each core histone gene per cluster. One of the clones (lambda Ceh-1) carries one histone cluster surrounded by several thousand base-pairs of non-histone DNA, and another clone (lambda Ceh-3) contains a histone cluster duplication surrounded by non-histone DNA. A third clone (lambda Ceh-2) carries a cluster of core histone genes flanked on one side (12,000 base-pairs away) by a single H2B gene and on the other by non-histone DNA. A fourth cluster (clone BE9) has one copy each of H3 and H4 and two copies each of H2A and H2B. This cluster is also flanked by non-histone DNA. Analysis of cosmid clones which overlap three of the clusters shows that no other histone clusters are closer than 8000 to 60,000 base-pairs, although unidentified non-histone transcription units are present on the flanking regions. Gene order within the histone clusters varies, and histone mRNAs are transcribed from both DNA strands. No H1 sequences are found on these core histone clones. Restriction fragment length polymorphisms between two related nematode strains (Bristol and Bergerac) were used as phenotypic markers in genetic crosses to map one histone cluster to linkage group V and another to linkage group IV. Hybridization of gene-specific probes from sea urchin to C. elegans RNA identifies C. elegans core histone messenger RNAs of sizes similar to sea urchin early stage histone mRNAs (H2A, H2B, H3 and H4). The organization of histone genes in C. elegans resembles the clustering found in most vertebrate organisms and does not resemble the tandem patterns of the early stage histone gene family of sea urchins or the major histone locus of Drosophila.

The natural history of primary anterior dislocation of the glenohumeral joint in adolescence.

The natural history of primary anterior dislocation of the glenohumeral joint in adolescent patients remains unclear and there is no consensus for management of these patients. The objectives of this study were to report the natural history of primary anterior dislocation of the glenohumeral joint in adolescent patients and to identify the risk factors for recurrent dislocation. We reviewed prospectively-collected clinical and radiological data on 133 adolescent patients diagnosed with a primary anterior dislocation of the glenohumeral joint who had been managed non-operatively at our hospital between 1996 and 2008. There were 115 male (86.5%) and 18 female patients (13.5%) with a mean age of 16.3 years (13 to 18) and a mean follow-up of 95.2 months (1 to 215). During follow-up, 102 (absolute incidence of 76.7%) patients had a recurrent dislocation. The median interval between primary and recurrent dislocation was ten months (95% CI 7.4 to 12.6). Applying survival analysis the likelihood of having a stable shoulder one year after the initial injury was 59% (95% CI 51.2 to 66.8), 38% (95% CI 30.2 to 45.8%) after two years, 21% (95% CI 13.2 to 28.8) after five years, and 7% (95% CI 1.1 to 12.9) after ten years. Neither age nor gender significantly predicted recurrent dislocation during follow-up. We conclude that adolescent patients with a primary anterior dislocation of the glenohumeral joint have a high rate of recurrent dislocation, which usually occurs within two years of their initial injury: these patients should be considered for early operative stabilisation.

Differential skeletal muscle expression of myostatin across teleost species, and the isolation of multiple myostatin isoforms.

Two myostatin (MSTN) isoforms were isolated from brook trout with 92% identity in corresponding regions at the nucleotide level. One isoform was isolated from muscle and brain and the second from ovarian tissue. To our knowledge this is the first time two MSTN isoforms have been isolated from a given vertebrate species. Within the brain, MSTN transcripts were localized to the optic lobes, hindbrain, and hypothalamus. In the trout ovary, MSTN transcripts were upregulated at ovulation in several females. MSTN cDNA fragments were also isolated from several other fish species and differential expression of MSTN among muscle fiber types was observed.

Energy costs of fat and protein deposition in the human infant.

The energy costs of depositing fat and protein in the low-birth-weight infant were determined by multiple-regression analysis from published information on metabolizable-energy intake and fat and protein deposition in groups of subjects fed different dietary regimes. The total energy requirement for deposition was 1.17 kJ/kJ deposited for fat (ie, 1 kJ deposited and 0.17 kJ expended for deposition, and 2.38 kJ/kJ for protein. These values are similar to published determinations for animal species with simple stomachs. The metabolizable-energy requirement for weight gain during infancy was calculated (range, 12.2-25.1 kJ/g, or 2.9-6.0 kcal/g; means, 18.7 kJ/g, or 4.5 kcal/g) from the energy costs of fat and protein deposition and published information on changes in body composition during the first year of life.

Effects of age on energy balance.

The effects of aging on energy requirements and energy balance have been studied by several research groups using the doubly labeled water method. The weight of evidence from these investigations suggests that current recommended dietary allowances underestimate the usual energy needs of adults of all ages, including older adults. In addition, doubly labeled water studies have found a significant negative association between body fatness and energy expenditure for physical activity, and a significant positive association between energy expenditure for physical activity and fat-free mass. Further studies are needed to refine estimates of energy requirements for different population groups and to address the role of physical activity in the prevention and treatment of obesity.

Effect of high-fat and low-fat diets on voluntary energy intake and substrate oxidation: studies in identical twins consuming diets matched for energy density, fiber, and palatability.

There remains controversy over the effects of dietary fat content on voluntary energy intake. Additionally, the question of whether there is a genetic susceptibility to overeating high-fat diets has not been resolved. To address these issues, we designed two diets: a low-fat diet providing approximately 20% of energy as fat and a high-fat diet with approximately 40% of energy as fat. The diets were matched for energy density, fiber, and palatability. In a two-phase, 18-d intervention study, voluntary energy intakes and macronutrient oxidation rates during the fasting and fed states were determined in seven pairs of identical male twins. In contrast with results of previous intervention studies, in which low-fat and high-fat diets were not matched for energy density and other associated variables, we observed no significant difference in voluntary energy intake between the low-fat and high-fat phases, and mean daily intakes were similar (10.3 and 10.7 MJ/d, respectively). Postprandial rates of fat oxidation tended to reflect fat intakes in the two dietary phases, thus helping to explain the lack of a difference in mean energy intakes. There was also a significant twin-pair similarity in differences in energy intakes between dietary phases (P = 0.013). These results suggest that dietary fat content does not have a major influence on voluntary energy intake when dietary variables usually associated with fat are controlled for and that there may be a familial influence on the effects of dietary fat content on energy intake.

Fat oxidation in response to four graded energy challenges in younger and older women.

We examined whether older individuals have an impairment in their ability to oxidize dietary fat, a factor that could help to explain age-associated weight gain. The subjects were 16 healthy younger and older women. Fat oxidation was determined by indirect calorimetry before and after consumption of four different test meals consumed > or = 5 d apart. The intervention meals contained 0, 1046, 2092, or 4184 kJ (simulating extended fasting, and consumption of a snack, a small meal, and a moderately large meal, respectively), with 35% of energy from fat. The duration of each measurement was the amount of time required for postprandial energy expenditure to return to the premeal fasting value. A total of 96 measurements were obtained, including duplicates for all meal sizes in the younger women (in the follicular and luteal phases of the menstrual cycle). Total postprandial fat oxidation increased in proportion to meal size in the younger subjects, but did not increase above that for the 2092-kJ meal in the older women. In addition, older subjects had significantly lower total fat oxidation after consumption of the 4184-kJ meal (781 compared with 1029 kJ/measurement, P < 0.02) and also significantly greater fat deposition (745 compared with 464 kJ/measurement, P < 0.02). These findings suggest that, relative to younger women, older women have a reduced ability to oxidize dietary fat when they consume large meals.

Influence of age on energy requirements.

The effects of aging on energy requirements and energy expenditure were investigated in 35 healthy young men (mean +/- SE age, 22.7 +/- 0.6 y) and elderly men (68.0 +/- 1.5 y). Over a 10-d metabolic balance study, measurements were made of metabolizable energy intake for weight maintenance, total energy expenditure, resting energy expenditure, and thermic effect of feeding. Values for both metabolizable energy intake and total energy expenditure were significantly higher than the current recommended dietary allowance for energy in both age groups (P < 0.01). Total energy expenditures were 14.48 +/- 0.65 and 11.26 +/- 5.40 MJ/d in young and elderly men, respectively. The difference in total energy expenditure between the groups was accounted for by a significant decrease in all the major components of expenditure. These results suggest that the current recommended dietary allowances for energy may underestimate the usual energy needs of healthy adult men.

Lactational performance in relation to energy intake in the baboon.

The relationship between energy intake and lactational performance in the baboon was investigated by determining energy intake, milk output and energy balance in animals fed ad libitum during a nonreproductive phase and during lactation, or fed 80% or 60% of ad libitum intake during lactation. No evidence was found for an increased efficiency of energy utilization during lactation when feeding was ad libitum, as judged by calculated energy used on activity and maintenance. Restricted feeding did however produce an increase in efficiency, estimated at 17-25%. This change enabled milk output and body nutrient stores to be protected when the restriction was to 80% of the ad libitum intake but at 60% of ad libitum intake, milk output was reduced and body nutrient mobilization was increased. It is proposed that low maternal food intake is associated with impairment of lactational performance when it is also severe enough to increase body nutrient mobilization.

Why are nutritionally stunted children at increased risk of obesity? Studies of metabolic rate and fat oxidation in shantytown children from São Paulo, Brazil.

BACKGROUND: Previous research suggested that nutritionally stunted children may have increased risk of obesity, but little is known about potential underlying mechanisms. OBJECTIVE: We sought to test the hypothesis that stunted children have a low metabolic rate and impaired fat oxidation relative to nonstunted children. DESIGN: The subjects were 58 prepubertal boys and girls aged 8-11 y from the shantytowns of São Paulo, Brazil. Twenty-eight were stunted (height-for-age z score <-1.5) and 30 had similar weight-for-height but normal height (height-for-age z score >-1.5). Parents of children in the 2 groups had equivalent height and body mass index values. Fasting and postprandial energy expenditure, respiratory quotient (RQ), and substrate oxidation were measured with indirect calorimetry in a 3-d resident study in which all food was provided and body composition was measured with dual-energy X-ray absorptiometry. RESULTS: Stunted children had normal resting energy expenditure relative to body composition compared with control children (4559 +/- 90 and 4755 +/- 86 kJ/d, respectively; P: = 0.14) and had normal postprandial thermogenesis (2.4 +/- 0.3% and 2.0 +/- 0.3% of meal load, respectively; P: = 0.42). However, fasting RQ was significantly higher in the stunted group (0.92 +/- 0.009 compared with 0.89 +/- 0.007; P: = 0.04) and consequently, fasting fat oxidation was significantly lower (25 +/- 2% compared with 34 +/- 2% of energy expenditure; P: < 0.01). CONCLUSIONS: Childhood nutritional stunting is associated with impaired fat oxidation, a factor that predicted obesity in other at-risk populations. This finding may help explain recent increases in body fatness and the prevalence of obesity among stunted adults and adolescents in developing countries.