HP1 recruits activity-dependent neuroprotective protein to H3K9me3 marked pericentromeric heterochromatin for silencing of major satellite repeats

H3 lysine 9 trimethylation (H3K9me3) is a histone posttranslational modification (PTM) that has emerged as hallmark of pericentromeric heterochromatin. This constitutive chromatin domain is composed of repetitive DNA elements, whose transcription is differentially regulated. Mammalian cells contain three HP1 proteins, HP1α, HP1β and HP1γ These have been shown to bind to H3K9me3 and are thought to mediate the effects of this histone PTM. However, the mechanisms of HP1 chromatin regulation and the exact functional role at pericentromeric heterochromatin are still unclear. Here, we identify activity-dependent neuroprotective protein (ADNP) as an H3K9me3 associated factor. We show that ADNP does not bind H3K9me3 directly, but that interaction is mediated by all three HP1 isoforms in vitro. However, in cells ADNP localization to areas of pericentromeric heterochromatin is only dependent on HP1α and HP1β. Besides a PGVLL sequence patch we uncovered an ARKS motif within the ADNP homeodomain involved in HP1 dependent H3K9me3 association and localization to pericentromeric heterochromatin. While knockdown of ADNP had no effect on HP1 distribution and heterochromatic histone and DNA modifications, we found ADNP silencing major satellite repeats. Our results identify a novel factor in the translation of H3K9me3 at pericentromeric heterochromatin that regulates transcription.

Epigenotype switching at the CD14 and CD209 genes during differentiation of human monocytes to dendritic cells

Using an in vitro model for the differentiation of human blood-derived monocytes into dendritic cells (DCs), we have undertaken an investigation of epigenetic changes that take place at CD14 and CD209 (DC-SIGN) genes that encode cell surface antigens that are crucial for the function of monocytes and DCs, respectively. Upon differentiation the cell surface expression of CD14 is lost, whilst CD209 expression is increased. These reciprocal changes are associated with the loss of epigenetic markers of "activation" at the CD14 locus, but the acquisition of the same at the CD209 locus. There is little change in "repressive" histone marks and CpG methylation at the CD14 locus. By contrast there are changes in both the "repressive" histone marks and CpG methylation at the CD209 locus. In particular, two CpG dinucleotides, designated CpG2 and CpG3, show a marked demethylation at the CD209 promoter upon differentiation. These data provide insight into the epigenetic demands that are necessary to effect the reciprocal changes in expression of the CD14 and CD209 genes upon terminal differentiation of monocytes into DCs. For repression of the active CD14 gene the loss of "activation" histone modifications is likely necessary and sufficient for silencing. By contrast the activation of the silent CD209 gene appears to require an acquisition of "active" histone modifications and concomitant loss of both "repressive" histone marks and CpG methylation.

HP1 proteins--what is the essential interaction?

There are three mammalian HP1 genes, Cbx5 (encoding HP1alpha), Cbx1 (encoding HP1beta) and Cbx3 (encoding HP1gamma). Despite their high degree of sequence homology mutational analysis has revealed different phenotypes indicating that they possess different functions. Notably, the Cbx1 mutation is lethal in its homozygous condition. The Cbx1 null phenotype is therefore more severe than the Suv(3)9h1/h2 double-mutant mouse, indicating that the essential function of the Cbx1 gene product, HP1beta, is likely to lie outside its interaction with the heterochromatic H3K9me3 determinant of the "histone code" imposed by the Suv(3)9h1/h2 HMTases. Comparisons of HPI mutants in flies and fungi with corresponding mutations in Suv(3)9 genes show that HP1 mutations are invariably more severe than mutation in Suv(3)9 genes. The implications of these data for HP1 function are discussed.

Variation in umami taste perception in the German and Norwegian population

In this study, we investigated inter-individual differences in sensitivity to mono-sodium glutamate (MSG) and elucidated the familiarity to umami taste in two European populations. The study consisted of two parts: (1) a survey based on questionnaire and (2) psychophysical screening for inter-individual variation of MSG sensitivity. The psychophysical tests revealed that 3.2% of the German participants and 4.6% of the Norwegian participants were potential non-tasters of MSG. In conclusion, our study confirms inter-individual differences in sensitivity to MSG in humans.

The essential function of HP1 beta: a case of the tail wagging the dog?

A large body of work in various organisms has shown that the presence of HP1 structural proteins and methylated lysine 9 of histone H3 (H3K9me) represent the characteristic hallmarks of heterochromatin. We propose that a more critical assessment of the physiological importance of the H3K9me-HP1 interaction is warranted in light of recent studies on the mammalian HP1 beta protein. Based on this new research, we conclude that the essential function of HP1 beta (and perhaps that of its orthologues in other species) lies outside the canonical heterochromatic H3K9me-HP1 interaction. We suggest instead that binding of a small fraction of HP1 beta to the H3 histone fold performs a critical role in heterochromatin function and organismal survival.

Achieving reimbursement for regenerative medicine products in the USA

Achieving reimbursement for regenerative medicine products is potentially a greater challenge than gaining US FDA approval, making it a decisive factor in the success or failure of small businesses. However, the mechanisms by which reimbursement is achieved are still seen as something of a ‘black box’, especially to those outside of the USA. This report aims to provide insights into the mechanisms of reimbursement and variety of payers in the USA, and to act as a starting point for a successful US reimbursement strategy. Fundamental concepts such as coverage, payment and coding are explained and linked with the factors that potentially determine the successful reimbursement of regenerative medicine products, including cost of goods and clinical study design. Finally, important considerations for the design of clinical studies that satisfy both the payers and the FDA are discussed and the key elements of a successful company strategy identified.

HP1gamma function is required for male germ cell survival and spermatogenesis

BACKGROUND

HP1 proteins are conserved components of eukaryotic constitutive heterochromatin. In mammals, there are three genes that encode HP1-like proteins, termed HP1alpha, HP1beta and HP1gamma, which have a high degree of homology This paper describes for the first time, to our knowledge, the physiological function of HP1gamma using a gene-targeted mouse.

RESULTS

While targeting the Cbx3 gene (encoding the HP1gamma protein) with a conditional targeting vector, we generated a hypomorphic allele (Cbx3hypo), which resulted in much reduced (barely detectable) levels of HP1gamma protein. Homozygotes for the hypomorphic allele (Cbx3hypo/hypo) are rare, with only 1% of Cbx3hypo/hypo animals reaching adulthood. Adult males exhibit a severe hypogonadism that is associated with a loss of germ cells, with some seminiferous tubules retaining only the supporting Sertoli cells (Sertoli cell-only phenotype). The percentage of seminiferous tubules that are positive for L1 ORF1 protein (ORF1p) in Cbx3hypo/hypo testes is greater than that for wild-type testes, indicating that L1 retrotransposon silencing is reversed, leading to ectopic expression of ORF1p in Cbx3hypo/hypo germ cells.

CONCLUSIONS

The Cbx3 gene product (the HP1gamma protein) has a non-redundant function during spermatogenesis that cannot be compensated for by the other two HP1 isotypes. The Cbx3hypo/hypo spermatogenesis defect is similar to that found in Miwi2 and Dnmt3L mutants. The Cbx3 gene-targeted mice generated in this study provide an appropriate model for the study of HP1gamma in transposon silencing and parental imprinting.

Transcriptional regulation of mouse mast cell protease-2 by interleukin-15

Mast cells (MCs) play a critical role in innate and adaptive immunity through the release of cytokines, chemokines, lipid mediators, biogenic amines, and proteases. We recently showed that the activities of MC proteases are transcriptionally regulated by intracellularly retained interleukin-15 (IL-15), and we provided evidence that this cytokine acts as a specific regulator of mouse mast cell protease-2 (mMCP-2). Here, we show that in wild-type bone marrow-derived mast cells (BMMCs) IL-15 inhibits mMCP-2 transcription indirectly by inducing differential expression and mMCP-2 promoter binding of the bifunctional transcription factors C/EBPbeta and YY1. In wild-type BMMCs, C/EBPbeta expression predominates over YY1 expression, and thus C/EBPbeta preferentially binds to the mMCP-2 promoter. In IL-15-deficient BMMCs, the opposite is found: YY1 expression predominates and binds to the mMCP-2 promoter at the expense of C/EBPbeta. Hypertranscription of the mMCP-2 gene in IL-15-deficient BMMCs is associated with histone acetylation and, intriguingly, with methylation of non-CpG dinucleotides within the MCP-2 promoter. This suggests a novel model of cytokine-controlled protease transcription: non-CpG methylation maintains a chromosomal domain in an "open" configuration that is permissive for gene expression.

HP1-beta is required for development of the cerebral neocortex and neuromuscular junctions

HP1 proteins are thought to be modulators of chromatin organization in all mammals, yet their exact physiological function remains unknown. In a first attempt to elucidate the function of these proteins in vivo, we disrupted the murine Cbx1 gene, which encodes the HP1-β isotype, and show that the Cbx1^−/−-null mutation leads to perinatal lethality. The newborn mice succumbed to acute respiratory failure, whose likely cause is the defective development of neuromuscular junctions within the endplate of the diaphragm. We also observe aberrant cerebral cortex development in Cbx1^−/− mutant brains, which have reduced proliferation of neuronal precursors, widespread cell death, and edema. In vitro cultures of neurospheres from Cbx1^−/− mutant brains reveal a dramatic genomic instability. Our results demonstrate that HP1 proteins are not functionally redundant and that they are likely to regulate lineage-specific changes in heterochromatin organization.

Experience with plaque excision and dermal grafting in the surgical treatment of Peyronie's disease

INTRODUCTION

Peyronie's disease is a common cause of sexual dysfunction. We assess the technique of plaque excision and dermal grafting for the treatment of Peyronie's disease.

METHODS

A total of 11 patients, aged 38-55 years, were operated for Peyronie's disease. All patients had stable plaque on the dorsum or dorsolateral aspect of the penile shaft. All patients had penile curvature, nine (81.8 percent) had painful erections, six (54.5 percent) had penile pain and three (27.3 percent) had erectile dysfunction. All suffered difficulty in intercourse. We performed plaque excision and dermal grafting. Main outcome measures were relief of penile pain, relief of painful erection, performance of satisfactory coitus and straight penis while erection.

RESULTS

All patients had relief of penile pain and painful erection. Nine (81.8 percent) patients had straight penis and had satisfactory coitus. Two (18.2 percent) patients suffered postoperative erectile dysfunction which was mild and responded to Sildenafil tabs.

CONCLUSION

Although experience with this technique is limited, the initial results are encouraging. We found this technique feasible with satisfactory results.

Use of tissue ink to maintain identification of individual cores on needle biopsies of the prostate

BACKGROUND

There is an increasing necessity to extract the maximum amount of information, beyond even a cancer diagnosis, from prostate biopsies. Thus, maintaining site-specific information regarding individual biopsy cores might be critical.

AIM

To evaluate the applicability of employing tissue ink to maintain the identity of individual prostatic biopsy cores.

METHOD

In this ongoing study, 12 core prostate biopsy specimens are sent to the laboratory in individual pots labelled according to anatomical site. The specimens are placed in two separate multi-compartment cassettes. They are inked with different colours to identify the site of origin from each lobe. The cassettes are then processed with a single paraffin block for each side; the six cores from each side can be mounted on a single slide.

RESULTS

The different colours used adhere well to the biopsy cores, thus maintaining the identity of each core. Six cores from each side are embedded in a single paraffin block and examined on a single slide, making it cost-effective, while maintaining high quality, accurate histopathological information.

CONCLUSION

Differential inking of prostate biopsy cores is an easily applicable method that is cost-effective and provides tumour location information. Prostate biopsy data archived to maintain individual core information might be used to determine applicability of such information to predict extra-capsular extension by correlating with imaging and radical prostatectomy findings, and for treatment planning.

Bilateral single system ectopic ureters: case report with literature review

Bilateral single system ureteral ectopia (BSSEU) is one of the rarest entities in urology, with less than 80 cases reported so far. Incontinence resulting from the underlying anomaly can be devastating to the child. It is generally agreed that suitable urinary continence and long dry intervals are seldom obtainable because of poorly developed trigone and bladder neck area. We herein report a case of BSSEU managed by bilateral ureteric reimplantation, achieving satisfactory continence and bladder capacity without the need for urinary diversion or bladder neck reconstruction.

Primary cavernous hemangioma of the glans penis: rare case report with a review of the literature

Hemangiomas of the urinary tract are rare lesions, and those of the glans penis are even rarer. A 23-year-old man with a hemangioma of the glans penis treated successfully with intralesional sclerotherapy is presented. Other options for the management of this disorder are discussed.

gammaH2AX foci form preferentially in euchromatin after ionising-radiation

Background

The histone variant histone H2A.X comprises up to 25% of the H2A complement in mammalian cells. It is rapidly phosphorylated following exposure of cells to double-strand break (DSB) inducing agents such as ionising radiation. Within minutes of DSB generation, H2AX molecules are phosphorylated in large chromatin domains flanking DNA double-strand breaks (DSBs); these domains can be observed by immunofluorescence microscopy and are termed γH2AX foci. H2AX phosphorylation is believed to have a role mounting an efficient cellular response to DNA damage. Theoretical considerations suggest an essentially random chromosomal distribution of X-ray induced DSBs, and experimental evidence does not consistently indicate otherwise. However, we observed an apparently uneven distribution of γH2AX foci following X-irradiation with regions of the nucleus devoid of foci.

Methodology/Principle Findings

Using immunofluorescence microscopy, we show that focal phosphorylation of histone H2AX occurs preferentially in euchromatic regions of the genome following X-irradiation. H2AX phosphorylation has also been demonstrated previously to occur at stalled replication forks induced by UV radiation or exposure to agents such as hydroxyurea. In this study, treatment of S-phase cells with hydroxyurea lead to efficient H2AX phosphorylation in both euchromatin and heterochromatin at times when these chromatin compartments were undergoing replication. This suggests a block to H2AX phosphorylation in heterochromatin that is at least partially relieved by ongoing DNA replication.

Conclusions/Significance

We discus a number of possible mechanisms that could account for the observed pattern of H2AX phosphorylation. Since γH2AX is regarded as forming a platform for the recruitment or retention of other DNA repair and signaling molecules, these findings imply that the processing of DSBs in heterochromatin differs from that in euchromatic regions. The differential responses of heterochromatic and euchromatic compartments of the genome to DSBs will have implications for understanding the processes of DNA repair in relation to nuclear and chromatin organization.

Effects of estradiol-17beta and 17alpha, 20beta-dihydroxy-4-pregnen-3-one on different phospholipids metabolism and histological changes in ovary during reproductive growth in the catfish, Heteropneustes fossilis (Bloch)

Effect of cumulative doses of estradiol -17beta (E2-7, 14 and 28 mg/kg body weight) and 17alpha, 20beta-dihydroxy-4-pregnen-3-one (17alpha,20betaP-7, 14 and 28 mg/kg body weight) on total phospholipids (TP) and various phospholipids- phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylethanolamine (PE) on liver plasma and ovary were investigated during the reproductively active preparatory and prespawning phases of the annual reproductive cycle in the freshwater female catfish, H. fossilis. The effect of E2 on TP was generally stimulatory and has pronounced effect than 17alpha,20betaP during both the phases. The levels of PC was promoted high during prespawning phase by E2 comparatively very less than by 17alpha, 20betaP in studied tissues during both the phases. The levels of PS after E2 treatments was maximum in all tissues during prespawning phase whereas 17alpha,20betaP was effective only in liver during this phase. The PI was elevated in liver during preparatory phase but its elevation was in all studied tissues during prespawning phase after E2 treatments. The levels of PI was most effective in ovary during preparatory phase in response to 17alpha,20betaP. The levels of PE was declined in liver but elevated in ovary after E2 treatments during both the phases. Treatments of E2 during preparatory phase showed greater number of vitellogenic oocytes as compared to 17alpha,20betaP treatments. The present finding has demonstrated that estradiol-17beta has more pronounced effects than the 17alpha,20beta P in regulation of different phospholipids and ovarian recrudescence during reproductively active phases and among the phospholipids the PC is the main phospholipids of vitellogenin/ovarian lipids in H. fossilis.

Plasticity of HP1 proteins in mammalian cells

We have compared the distribution of endogenous heterochromatin protein 1 (HP1) proteins (α, β and γ) in different epithelial lines, pluripotent stem cells and embryonic fibroblasts. In parallel, we have interrogated assembly and dynamics of newly expressed HP1-GFP proteins in cells lacking both HP1α and HP1β alleles, blocked at the G1-S boundary, or cultured in the presence of HDAC and HAT inhibitors. The results reveal a range of cell type and differentiation state-specific patterns that do not correlate with `fast' or `slow' subunit exchange in heterochromatin. Furthermore, our observations show that targeting of HP1γ to heterochromatic sites depends on HP1α and H1β and that, on an architectural level, HP1α is the most polymorphic variant of the HP1 family. These data provide evidence for HP1 plasticity under shifting microenvironmental conditions and offer a new conceptual framework for understanding chromatin dynamics at the molecular level.

Interleukin-21: a new modulator of immunity, infection, and cancer

Interleukin-21 is the most recently discovered member of the type-I cytokine family. Structurally, IL-21 shows homology to IL-2, IL-4, and IL-15 proteins. IL-21 shares the common gamma-chain with the other three cytokines but, in addition, binds to a unique IL-21Ralpha chain, and activates the JAK/STAT pathway. IL-21 is mainly produced by activated T-cells but targets a broad range of lymphoid and myeloid cells of the immune system and therefore is able to regulate innate and acquired immune responses. This review intends to give the reader an overview of the recent findings concerning the biology of IL-21 and its physiological role in immunity, infection, and cancer.

Mammalian Polycomb Scmh1 mediates exclusion of Polycomb complexes from the XY body in the pachytene spermatocytes

The product of the Scmh1 gene, a mammalian homolog of Drosophila Sex comb on midleg, is a constituent of the mammalian Polycomb repressive complexes 1 (Prc1). We have identified Scmh1 as an indispensable component of the Prc1. During progression through pachytene, Scmh1 was shown to be excluded from the XY body at late pachytene, together with other Prc1 components such as Phc1, Phc2, Rnf110 (Pcgf2), Bmi1 and Cbx2. We have identified the role of Scmh1 in mediating the survival of late pachytene spermatocytes. Apoptotic elimination of Scmh1(-/-) spermatocytes is accompanied by the preceding failure of several specific chromatin modifications at the XY body, whereas synapsis of homologous autosomes is not affected. It is therefore suggested that Scmh1 is involved in regulating the sequential changes in chromatin modifications at the XY chromatin domain of the pachytene spermatocytes. Restoration of defects in Scmh1(-/-) spermatocytes by Phc2 mutation indicates that Scmh1 exerts its molecular functions via its interaction with Prc1. Therefore, for the first time, we are able to indicate a functional involvement of Prc1 during the meiotic prophase of male germ cells and a regulatory role of Scmh1 for Prc1, which involves sex chromosomes.

Dorsal onlay buccal mucosal graft urethroplasty in long anterior urethral stricture

OBJECTIVE

To assess the success of buccal mucosal graft (BMG) urethroplasty by the dorsal onlay technique in long anterior urethral stricture (> 2 cm long) through the midline perineal incision.

MATERIALS AND METHODS

From January 1998 to December 2003, 43 patients with long anterior urethral strictures were managed by dorsal onlay BMG urethroplasty. After voiding trial, they were followed up at 3 months with uroflowmetry, retrograde urethrogram (RGU) and American Urological Association symptoms score (AUA symptoms scores). Successful outcome was defined as normal voiding with a maximum one attempt of visual internal urethrotomy (VIU) after catheter removal. Patients were further followed-up with uroflowmetry at 3 months interval and RGU every 6 months interval.

RESULTS

Mean stricture length was 4.8 cm (range 3 to 9 cm) and mean follow up was 48 months (range 12 to 84 months). Only five patients were found to develop stricture at anastomotic site, during follow-up. Two of them voided normally after single attempt of VIU. Other three patients (6.9%) required further open surgery or repeat VIU during follow up and were considered as failure.

CONCLUSION

Dorsal onlay BMG urethroplasty is a simple technique with good surgical outcome.

Epigenetic regulation of facultative heterochromatinisation in Planococcus citri via the Me(3)K9H3-HP1-Me(3)K20H4 pathway

Using RNA interference (RNAi) we have conducted a functional analysis of the HP1-like chromobox gene pchet2 during embryogenesis of the mealybug Planococcus citri. Knocking down pchet2 expression results in decondensation of the male-specific chromocenter that normally arises from the developmentally-regulated facultative heterochromatinisation of the paternal chromosome complement. Together with the disappearance of the chromocenter the staining levels of two associated histone modifications, tri-methylated lysine 9 of histone H3 [Me(3)K9H3] and tri-methylated lysine 20 of histone H4 [Me(3)K20H4], are reduced to undetectable levels. Embryos treated with double-stranded RNA (dsRNA) targeting pchet2 also exhibit chromosome abnormalities, such as aberrant chromosome condensation, and also the presence of metaphases that contain 'lagging' chromosomes. We conclude that PCHET2 regulates chromosome behavior during metaphase and is a crucial component of a Me(3)K9H3-HP1-Me(3)K20H4 pathway involved in the facultative heterochromatinisation of the (imprinted) paternal chromosome set.

A decade's experience with vesicovaginal fistula in India

A retrospective analysis of 252 cases of vesicovaginal fistulae was done to analyse its etio-pathology and management in an Indian population. After a thorough evaluation, different techniques of fistula closure were used for repair and the results were listed. The main outcome measures were the etiology of the fistula, need for tissue interposition and cure rate per repair as well as the overall cure rate. We compared our results with literature and concluded that simple and small fistulae should be repaired with layered closure. All complicated fistulae should be repaired with tissue interposition or tissue graft. This is the first study from India compiling 10 years of experience on vesicovaginal fistula.

Uncoupling global and fine-tuning replication timing determinants for mouse pericentric heterochromatin

Mouse chromocenters are clusters of late-replicating pericentric heterochromatin containing HP1 bound to trimethylated lysine 9 of histone H3 (Me₃K9H3). Using a cell-free system to initiate replication within G1-phase nuclei, we demonstrate that chromocenters acquire the property of late replication coincident with their reorganization after mitosis and the establishment of a global replication timing program. HP1 dissociated during mitosis but rebound before the establishment of late replication, and removing HP1 from chromocenters by competition with Me₃K9H3 peptides did not result in early replication, demonstrating that this interaction is neither necessary nor sufficient for late replication. However, in cells lacking the Suv39h1,2 methyltransferases responsible for K9H3 trimethylation and HP1 binding at chromocenters, replication of chromocenter DNA was advanced by 10–15% of the length of S phase. Reintroduction of Suv39h1 activity restored the later replication time. We conclude that Suv39 activity is required for the fine-tuning of pericentric heterochromatin replication relative to other late-replicating domains, whereas separate factors establish a global replication timing program during early G1 phase.