Molecular Human Reproduction - Advance Access

microRNA 21 (miR-21): Response to Hormonal Therapies and Regulatory Function in Leiomyoma, Transformed Leiomyoma and Leiomyosarcoma cells

Pan, Q., Luo, X., Chegini, N. — Wed, 11 Nov 2009 07:06:47 PST

Aberrant expression of microRNAs (miRNAs), including miR-21, and alteration of their target genes stability, have been associated with cellular transformation and tumorigenesis. We investigated the expression, regulation, and function of miR-21 in leiomyomas which develop from myometrial cellular transformation. The results indicated that miR-21 is overexpressed in leiomyomas with specific elevation during the secretory phase of the menstrual cycle, and in women who received Depo-Provera and oral contraceptives (OCPs), but reduced due to GnRHa therapy (P<0.05). Bioinformatic analysis of microarray gene expression profiles previously obtained from the above cohorts, and myometrial and leiomyoma smooth muscle cells (MSMC and LSMC) treated with GnRHa, TGF-β and TGF-β receptor type II (TGF-βRII) antisense oligomer, indicated that a number of miR-21 predicted target genes were co-expressed and differentially regulated in these cohorts. Gain- and loss-of function of miR-21 in MSMC, LSMC, transformed LSMC (t-LSMC) and leiomyosarcoma cell line (SKLM-S1) resulted in differential expression of many genes, including some of the miR-21 predicted/validated target genes, PTEN, PDCD4 and E2F1, and TGF-βRII, in cell-specific manner. Gain-of miR-21 function in MSMC and LSMC reduced TGF-β-induced expression of fibromodulin and TGIF (P<0.05), and moderately altered the rate of cell growth and caspase 3/7 activity in these cells. We concluded that miR-21 is aberrantly expressed and hormonally regulated in leiomyomas where, through functional interaction with ovarian steroids and the TGF-β signaling pathway, either directly or indirectly regulates a number of genes whose products are critical in leiomyoma growth and regression as well as their potential cellular transformation.

The Human Sperm Epigenome and its Potential Role in Embryonic Development

Carrell, D. T., Hammoud, S. S. — Wed, 11 Nov 2009 07:06:46 PST

Along with many of the genome-wide transitions in chromatin composition throughout spermatogenesis, epigenetic modifications on histone tails and DNA are continuously modified to ensure stage specific gene expression in the maturing spermatid. Recent findings have suggested that the repertoire of epigenetic modifications in the mature sperm may have a potential role in the developing embryo and alterations in the epigenetic profile has been associated with infertility. These changes include DNA demethylation and the retention of modified histones at important developmental, signaling, and micro-RNA genes, which resemble the epigenetic state of an embryonic stem cell. This review assesses the significance of epigenetic changes during spermatogenesis, and provides insight on recent associations made between altered epigenetic profiles in the mature sperm and its relationship to infertility.

Progestin regulates chemokine (C-X-C motif) ligand 14 transcript level in human endometrium

Tue, 10 Nov 2009 04:08:13 PST

Leukocyte populations change profoundly in the human endometrium during the menstrual cycle. However the predominant cell, the uterine NK cell does not contain steroid receptors. From gene array analysis we identified a transcript encoding CXCL14 which is markedly up-regulated in the secretory phase of the cycle. We confirm this data by northern blotting and quantitative PCR. Using in situ hybridisation we localised CXCL14 mRNA to the glandular epithelial cells where it was detected only in the secretory phase of the cycle. Candidate progesterone response elements were identified at positions -2028/-2007 and -722/-697 (PRE1 and PRE2 respectively) relative to the translation start site. These were functionally tested using lucifersase reporter deletion constructs, electrophoretic mobility shift assays and site-directed mutagenesis. The deletion/mutation of these sites reduced progesterone induction by 40% and 20% respectively. Finally, we demonstrated that recombinant CXCL14 stimulated uNK cell chemotaxis in vitro. We therefore conclude that CXCL14 is likely to be regulated by progesterone in human endometrium and that it may exert a chemoattractive effect on uNK cells and in part be responsible for their clustering around the epithelial glands.

Memoirs of an insult: sperm as a possible source of transgenerational epimutations and genetic instability

de Boer, P., Ramos, L., de Vries, M., Gochhait, S. — Fri, 06 Nov 2009 05:26:58 PST

Male transgenerational epigenetic effects have been discovered in the discipline of mouse radiation genetics, using genetic and non-genetic readouts. The mechanism to explain the origin of the transmission of epigenetic and genetic instability is still unknown. In a search for a hypothesis that could satisfy the data, we propose that regulation of chromosome structure in the germline, by the occupancy of matrix/scaffold associated regions, contains molecular memory function. The male germline is strikingly dynamic as to chromatin organization. This could explain why experience of irradiation stress leaves a persistent mark in the male germline only. To be installed, such memory requires both S-phase and chromatin reorganization during spermatogenesis and in the zygote, that likely also involves reorganization of loop domains. By this reorganization, another layer of information is added, needed to accommodate early embryonic development. Observations point at the involvement of DNA repair as inducer of transgenerational epigenetic modulation.

Nuclear structure, chromatin composition and loop domain organization are aspects of human sperm variability, that in many cases of assisted reproduction is increased due to inclusion of more incompletely differentiated/maturated sperm nuclei. Adjustment of loop domains in early embryo development can be anticipated and zygotic and cleavage stage S-phase repair activity will have to deal with potential paternal DNA lesions. Therefore, by changing male nucleus structure due to reproduction from impaired spermatogenesis, the transgenerational information content could be changed as well. We discuss aspects of male reproductive performance in the context of this hypothesis.

Genetic Association of Phase I and Phase II Detoxification Genes with Recurrent Miscarriages among North Indian Women

Parveen, F., Faridi, R.M., Das, V., Tripathi, G., Agrawal, S. — Thu, 05 Nov 2009 05:27:15 PST

Allelic variants of the detoxification genes that have impaired biotransformation functions may increase susceptibility to reproductive toxicity leading to endometriosis, recurrent miscarriage (RM) or poor pregnancy outcome. In the present study, we have investigated CYP1A1, CYP2D6, GSTT1, GSTP1 and GSTM1, which are involved in the phase I and phase II detoxification systems, in relation to their role in the etiology of unexplained recurrent miscarriages (RM). In a case control study, we have investigated 200 females with RM and 300 age and ethnically matched healthy controls with successful reproductive history from North India. The frequencies of phase I wild-type genotypes of CYP1A1 and CYP2D6 in RM cases were 0.56 and 0.60, whereas in controls these were 0.68 and 0.65 respectively (both p<0.05). The GSTM1 null-genotype frequencies were 0.66 and 0.84 among RM cases and controls respectively, the GSTT1 null- genotype frequencies were 0.52 and 0.45 (p<0.005) and the GSTP1 variant allele frequencies were 0.23 and 0.20 respectively. In conclusion, we observed significant protective effects of phase I wild-type genotypes and association of the GSTT1 null genotype with RM. Through combined analyses we have highlighted the importance of the balance of phase I/phase II detoxification systems, in the etiology of recurrent miscarriage.

CAG repeat number is not inversely associated with androgen receptor activity in vitro

Sun, 01 Nov 2009 23:52:16 PST

A negative linear association between androgen receptor (AR) function and the CAG repeat numbers is generally assumed. However, in vivo data concerning the association between CAG number and androgenic effects have been conflicting.

Since former in vitro studies mostly have been based on extreme CAG lengths and reporter-systems containing viral promoters, the objective of this study was to investigate ARs with CAG lengths within normal range (16, 22 and 28) in a reporter-assay with the human prostate specific antigen promoter as target. We also wished to elucidate whether the interpretation of the results was depending on the methods used for adjustment of transfection efficiency and protein content.

With ß-galactosidase as transfection control, 22CAG had the highest activity (set to 100%) compared to 16CAG (mean 78% [range 41- 132], p=0.005) and 28CAG (68% [26-162], p=0.006), whereas renilla-luciferase resulted in 16CAG behaving similar to 22CAG (104% [56- 165], p=0.7) and 28CAG having lower activity (59% [33-101], p=0.004). In these experiments, also the empty vector displayed considerable background activity.

When adjusting for AR protein, the 22CAG genotype had the highest activity; 16CAG and 28CAG displaying 20% (10-47, p<0.0001) and 12% (5-21, p<0.0001) thereof. Similar results were obtained with adjustment for total protein

Thus, by normalising for AR-content, contrary to various control vectors, the highest AR activity was confined to the 22CAG and not 16 CAG, which may at least partly explain the discrepancy in data aiming to link physiological conditions to CAG repeat length.

Novel Pathways for Implantation and Establishment and Maintenance of Pregnancy in Mammals

Fri, 30 Oct 2009 07:26:29 PDT

Uterine receptivity to implantation varies among species, and involves changes in expression of genes that are coordinate with attachment of trophectoderm to uterine lumenal and superficial glandular epithelia, modification of phenotype of uterine stromal cells, silencing of receptors for progesterone and estrogen, suppression of genes for immune recognition, alterations in membrane permeability to enhance conceptus-maternal exchange of factors, angiogenesis and vasculogenesis, increased vascularity of the endometrium, activation of genes for transport of nutrients into the uterine lumen, and enhanced signaling for pregnancy recognition. Differential expression of genes by uterine epithelial and stromal cells in response to progesterone, glucocorticoids, prostaglandins and interferons may influence uterine receptivity to implantation in mammals. Uterine receptivity to implantation is progesterone-dependent; however, implantation is preceded by loss of expression of receptors for progesterone (PGR) so that progesterone most likely acts via PGR-positive stromal cells throughout pregnancy. Endogenous retroviruses expressed by the uterus and/or blastocyst also affect implantation and placentation in various species. Understanding the roles of the variety of hormones, growth factors and endogenous retroviral proteins in uterine receptivity for implantation is essential to enhancing reproductive health and fertility in humans and domestic animals.

Demethylation of LHR in dehydroepiandrosterone-induced mouse model of polycystic ovary syndrome

Zhu, J.-Q., Zhu, L., Liang, X.-W., Xing, F.-Q., Schatten, H., Sun, Q.-Y. — Wed, 14 Oct 2009 07:27:16 PDT

The cause of polycystic ovary syndrome (PCOS), a complex endocrine disorder, is unknown, but its familial aggregation implies underlying genetic influences. Hyperandrogenemia is regarded as a major endocrine character of the PCOS. In this study, we employed bisulfite sequencing and bisulfite restriction analysis to investigate the DNA methylation status of LHR, AR, FSHR and H19 in dehydroepiandrosterone (DHEA)-induced mouse PCOS model. The results showed that methylation of LHR was lost in ovary from induced PCOS mouse. However, AR, FSHR and H19 had similar methylation pattern in DHEA-treated group and control groups. These data provide evidence for close linkage between DNA demethylation of LHR and PCOS.

Nucleolar transplantation in oocytes and zygotes: challenges for further research

Fulka, H., Fulka, J. — Fri, 09 Oct 2009 00:32:27 PDT

In germinal vesicles (GVs) of immature mammalian oocytes, including humans, as well as in pronuclei in one-cell stage embryos, prominent nuclear organelles – nucleoli, can be easily detected even under a relatively low magnification. In humans, it has been clearly documented that their number, position and distribution in pronuclei can be used as an indicator of embryonic developmental potential. In the light of some recent experiments showing the feasibility of nucleolar manipulation we discuss here if these new approaches can be used to rescue those embryos with abnormal pronuclear nucleolar patterns.

Toxicants and human sperm chromatin integrity

Delbes, G., Hales, B. F., Robaire, B. — Wed, 07 Oct 2009 00:36:56 PDT

The integrity of the paternal genome is essential as the spermatozoon can bring genetic damage into the oocyte at fertilization and contribute to the development of abnormal pregnancy outcome. During the past two decades, many assays have been developed to measure sperm DNA strand breaks, chromatin structure and compaction, and assess the proteins associated with the DNA, as well as epigenetic modifications. Using these assays, it has been shown that exposure to physical agents or to chemicals, including therapeutic drugs and environmental toxicants, can affect the integrity of sperm chromatin, inducing structural, genetic and/or epigenetic abnormalities. The mechanisms by which such damage is triggered are still largely unresolved and the susceptibility of each individual will depend on their genetic background, lifestyle and exposure to various insults. Depending on the nature of the chemicals, they may directly target the DNA, induce an oxidative stress, or modify epigenetic elements. The significance of measuring sperm chromatin integrity comes from the fact that this endpoint correlates well with low IVF and ICSI outcomes, and idiopathic infertility. Nevertheless, it is hard to establish a direct link between paternal sperm chromatin integrity and the health of the future generations. Thus, it seems essential to undertake studies that will resolve the impact of chemical and environmental factors on chromatin structure and epigenetic components of human spermatozoa and to elucidate what sperm nuclear endpoints are predictors of the quality of progeny outcome.

Prokineticin (PROK1) modulates interleukin (IL)-11 expression via prokineticin receptor (PROKR1) and the calcineurin/NFAT signalling pathway

Sat, 03 Oct 2009 03:09:30 PDT

Prokineticin-1 (PROK1) is a multifunctional secreted protein which signals via the G-protein coupled receptor (GPCR), PROKR1. Previous data from our laboratory using a human genome survey microarray showed that PROK1-PROKR1 signalling regulates numerous genes important for establishment of early pregnancy, including the cytokine IL-11. Here we have shown that PROK1-PROKR1 induces the expression of IL-11 in PROKR1 Ishikawa cells and first trimester decidua via the calcium-calcineurin signalling pathway in a guanine nucleotide-binding protein (G_q/11), extracellular signal-regulated kinases (ERK), Ca²⁺ and calcineurin-nuclear factor of activated T cells (NFAT) dependent manner. Conversely, treatment of human decidua with a lentiviral miRNA to abolish endogenous PROK1 expression results in a significant reduction in IL-11 expression and secretion. Importantly, we have also shown a regulatory role for the regulator of calcineurin 1 isoform 4 (RCAN1-4). Overexpression of RCAN1-4 in PROKR1 Ishikawa cells using an adenovirus leads to a reduction in PROK1 induced IL-11 indicating that RCAN1-4 is a negative regulator in the calcineurin-mediated signalling to IL-11. Finally, we have shown the potential for both autocrine and paracrine signalling in the human endometrium by co-localizing IL-11, IL-11R and PROKR1 within the stromal and glandular epithelial cells of non pregnant endometrium and first trimester decidua. Overall we have identified and characterised the signalling components of a novel PROK1-PROKR1 signalling pathway regulating IL-11.

Genomic assessment of follicular marker genes as pregnancy predictors for human IVF

Hamel, M., Dufort, I., Robert, C., Leveille, M.-C., Leader, A., Sirard, M.-A. — Thu, 24 Sep 2009 04:10:24 PDT

Embryo selection efficiency in human IVF procedure is still suboptimal as shown by low pregnancy rates with single embryo transfer (SET). Bidirectional communication between the oocyte and follicular cells (FC) is essential to achieve developmental competence of the oocyte. Differences in the gene expression profile of FCs from follicles leading to pregnancy could provide useful markers of oocyte developmental competence. FCs were recovered by individual follicle puncture. FC expression levels of potential markers were assessed by Q-PCR with an intra-patient and an inter-patient analysis approach. Using gene expression, a predictive model of ongoing pregnancy was investigated. Using intra-patient analysis, 4 candidate genes, phosphoglycerate kinase 1 (PGK1), regulator of G-protein signalling 2 (RGS2), regulator of G-protein signalling 3 (RGS3) and cell division cycle 42 (CDC42) showed a difference between FCs from follicles leading to a pregnancy or developmental failure. The best predictors for ongoing pregnancy were PGK1 and RGS2. Additionally, inter-patient analysis revealed differences in FC expression for PGK1 and CDC42 between follicles leading to a transferred embryo with positive pregnancy results and those with negative results. Both inter-patient and intra-patient approaches must be taken into consideration to delineate gene expression variations in the context of follicular competence. A predictor model using biomarkers could improve the efficiency of predicting developmental competence of oocytes. These new approaches provide useful tools in the context of embryo selection and in the improvement of pregnancy rates with SET.

Genomic changes detected by array CGH in human embryos with developmental defects

Wed, 23 Sep 2009 23:29:21 PDT

Developmental abnormalities of human embryos can be visualized in utero using embryoscopy. Our previous embryoscopic and genetic evaluations detected developmental abnormalities in the majority of both euploid (74%) and aneuploid or polyploid (90%) miscarriages. Since we found the pattern of morphological changes to be similar in euploid and noneuploid embryos, we proposed that lethal submicroscopic changes, not detected by standard chromosome testing, may be responsible for miscarriage of euploid embryos. Whole genome oligo and bacterial artificial chromosome (BAC) array comparative genome hybridization ( CGH) was used to screen for submicroscopic chromosomal changes (DNA copy number variants or CNVs) in 17 euploid embryonic miscarriages, with a range of developmental abnormalities documented by embryoscopy. The CNV breakpoints were refined using a custom array (Agilent) with a high resolution coverage of the CNVs. Six unique CNVs, previously not reported, were identified in 5 of the 17 embryos (29% of all cases or 50% of cases studied with higher resolution arrays). All 6 unique CNVs were less than 250kb in size. Based on parental array CGH analysis, a de novo origin of a CNV was determined for one embryo (at 13q32.1) and suspected for another (at 10p15.3). Three CNVs, at Xq28, 1q25.3 and 7p14.3, were inherited and a CNV at 17p13.1 was of unknown origin. The genes contained within these unique CNVs will be discussed, with specific reference to rearrangements of syntaxin and tryptophan-aspartic acid (WD) repeat genes. Our report describes for the first time, de novo and inherited unique CNVs in euploid human embryos with specific developmental defects.

Immature rat seminiferous tubules reconstructed in vitro express markers of Sertoli cell maturation after xenografting into nude mouse hosts

Gassei, K., Ehmcke, J., Wood, M. A., Walker, W. H., Schlatt, S. — Mon, 21 Sep 2009 06:01:35 PDT

Sertoli cells undergo a maturation process during postnatal testicular development that leads to the adult - type Sertoli cell, which is required for spermatogenesis. Understanding Sertoli cell maturation is therefore necessary to gain insight into the underlying causes of impaired spermatogenesis and male infertility. The present study characterized the cellular and molecular differentiation of Sertoli cells in a xenograft model of mammalian testicular development. Immature rat Sertoli cells were cultured in a three - dimensional culture system to allow the formation of cord - like structures. The in vitro Sertoli cell cultures were then grafted into nude mice. Sertoli cell proliferation, morphological differentiation and mRNA expression of Sertoli cell maturation markers were evaluated in xenografts. Sertoli cell proliferation significantly decreased between one week and four weeks (6.7 %±0.9 vs. 1.2 %±0.1, p<0.001), and was maintained at low levels thereafter. Sertoli cell cord - like structures significantly decreased between one week and four weeks (59.6 % vs. 21 %, p<0.05), whereas Sertoli cell tubules were more frequently observed after four weeks (13.3 % vs. 73.1 %, p<0.05). Furthermore, expression of androgen binding protein, transferrin, and follicle stimulating hormone receptor, markers for mature Sertoli cells, was detected after one week of grafting and increased significantly thereafter. We conclude from these results that rat Sertoli cells continue maturation after xenografting to the physiological environment of a host. This model of in vitro tubule formation will be helpful in future investigations addressing testicular maturation in the mammalian testis.

Function of Sperm Chromatin Structural Elements in Fertilization and Development

Ward, W. S. — Fri, 11 Sep 2009 00:34:13 PDT

Understanding how DNA is packaged in the mammalian sperm cell has important implications for human infertility as well as for the cell biology. Recent advances in the study of mammalian sperm chromatin structure and function have altered our perception of this highly condensed, inert chromatin. Sperm DNA is packaged very tightly to protect the DNA during the transit that occurs before fertilization. However, this condensation cannot sacrifice chromosomal elements that are essential for the embryo to access the correct sequences of the paternal genome for proper initiation of the embryonic developmental program. The primary levels of sperm chromatin structure can be divided into three main categories; the large majority of DNA is packaged by protamines, a smaller amount (2-15%) retains histone bound chromatin, and the DNA is attached to the nuclear matrix at roughly 50 kb intervals. Current data suggest that the latter two structural elements are transferred to the paternal pronucleus after fertilization where they have important functional roles. The nuclear matrix organization is essential for DNA replication, and the histone bound chromatin identifies genes that are important for embryonic development. These data support the emerging view of the sperm genome as providing, in addition to the paternal DNA sequence, a structural framework that includes molecular regulatory factors that are required for proper embryonic development.

Elevated levels of oxidised low-density lipoprotein and of catalase activity in follicular fluid of obese women

Thu, 03 Sep 2009 04:18:17 PDT

The intrafollicular levels of oxidised low-density lipoprotein (oxLDL) and of enzyme antioxidants might contribute to reproductive disorders in obese and infertile women. Relevant data are missing. Eighty-four patients were grouped according to obese versus non-obese status and whether they had polycystic ovary syndrome (PCOS). The concentrations of oxLDL and the activities of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione reductase (GR) in serum and follicular fluid (FF) were measured. Obese women with and without PCOS had significantly greater amounts of oxLDL in FF as compared to non-obese women. The level of oxLDL in FF was 1000-times lower than in serum. Obese women with and without PCOS had significantly higher catalase activity in FF as compared to non-obese women. No differences were found for SOD activity in FF. The GPx and GR acitivities were up-regulated in obese patients without and with PCOS, yet not in respect to each serum and FF sample. We conclude that elevated levels of oxLDL in the FF of obese women are associated with higher catalase activity; both parameters are independent of PCOS. The levels of oxLDL and catalase activity appear to indicate different degrees of oxidative stress.

Aromatase over expression transgenic murine models for aromatase inhibitor studies

Li, X. — Wed, 02 Sep 2009 03:57:47 PDT

In recent years the emerging importance of estrogen signaling in males in addition to its major role in the female reproductive system became highlighted. Aromatase is the key enzyme for synthesis of estrogens from androgens and is responsible for controlling the androgen/estrogen ratio. Inhibition of aromatase gene expression can be achieved in different ways, and is important for the treatment of several estrogen-dependent diseases, such as breast cancer in females or gynecomastia/breast cancer in males, or for non-tumorigenic conditions like precocious puberty and the induction of ovulation. The inhibition of aromatase could also serve as a tool for studying the role of estrogens during development or adulthood. Using transgenic models, we are able to analyze in more detail the involvement of aromatase in the molecular mechanisms underlying the essential balance of the androgen/estrogen ratio. In this review we focus on male phenotype characterization in the aromatase overexpressing transgenic murine models and how these models can further serve as a tool for aromatase inhibitor research.

Effects of highly purified urinary FSH and human menopausal FSH on Uterine Myoelectrical Dynamics

Hascalik, S., Celik, O., Tagluk, M.E., Yildirim, A., Aydin, N.E. — Mon, 31 Aug 2009 00:58:53 PDT

The aim of the study was to investigate the effects of urinary FSH compounds on the electrical activity of myometrium using signal-processing techniques. Thirty animals were involved in the experiment. After two successive normal estrous cycles, 15 of these animals were put into three equal subgroups. Group 1 was the control; animals were given solvent. Groups 2 and 3 were treated with Urofollitropin and Menotropin, respectively. The other 15 animals were ovariectomized and subjected to the same protocol. Their uterine myoelectrical signals were recorded over a period of at least three minutes at a sampling frequency of 500 Hz, and analyzed through software assisted signal processing. The results show the power and some characteristic spectral components of myoelectrical signal were differentially reduced with the administration of highly purified urinary FSH and human menopausal FSH but significant differences were not detected between their histology. In conclusion, uterine myoelectrical signals change with administration of urinary FSH preparations. Human menopausal FSH and more precisely highly purified FSH suppress the spectral components and modify the power of the myoelectrical signals which provides uterine quiescence.

Sperm surface proteomics: from protein lists to biological function

Brewis, I. A., Gadella, B. M. — Fri, 28 Aug 2009 00:50:35 PDT

Proteomics technologies have matured significantly in recent years and proteomics driven research papers in reproductive biology and medicine are increasingly common. The key challenge is to move from lists of identified proteins to informed understanding of biological function. This review introduces the range of proteomics workflows most commonly used for protein identification before focusing on the mammalian sperm cell at fertilization as an exemplar for proteomic studies. We review the work of others on entire cells but then argue that proper subcellular fractionation and proper solubilisation strategies offers critical advantages to achieving increased biological understanding. In relation to understanding initial gamete recognition events at fertilization (capacitation, zona binding and acrosomal exocytosis) it is imperative to study the sperm surface proteome by using purified plasma membrane fractions. Whilst this task is challenging there are now strategies at our disposal to achieve comprehensive coverage of the proteins at the sperm surface. Within this context it is also important to understand the milieu of the sperm cell during transit from the testis to the oviduct as proteins (or other entities) from the genital tract epithelia and fluids may also affect the composition and organisation of proteins on the sperm surface. Finally the arguments presented for studying the cell plasma membrane proteome to understand the role of the cell surface equally apply to all cell types with important roles in reproductive function.

On the possible origins of DNA damage in human spermatozoa

Aitken, R.J., De Iuliis, G.N. — Fri, 31 Jul 2009 00:37:58 PDT

DNA damage in the male germ line has been linked with a variety of adverse clinical outcomes including impaired fertility, an increased incidence of miscarriage and an enhanced risk of disease in the offspring. The origins of this DNA damage could, in principle, involve: (1) abortive apoptosis initiated post meiotically when the ability to drive this process to completion is in decline (2) unresolved strand breaks created during spermiogenesis to relieve the torsional stresses associated with chromatin remodelling and (3) oxidative stress. In this article we present a 2-step hypothesis for the origins of DNA damage in human spermatozoa that highlights the significance of oxidative stress acting on vulnerable, poorly protaminated cells generated as a result of defective spermiogenesis. We further propose that these defective cells are characterized by several hallmarks of ‘dysmaturity’ including the retention of excess residual cytoplasm, persistent nuclear histones, poor zona binding and disrupted chaperone content. The oxidative stress experienced by these cells may originate from infiltrating leukocytes or, possibly, the entry of spermatozoa into an apoptosis-like cascade characterized by the mitochondrial generation of reactive oxygen species. This oxidative stress may be exacerbated by a decline in local antioxidant protection, particularly during epididymal maturation. Finally, if oxidative stress is a major cause of sperm DNA damage then antioxidants should have an important therapeutic role to play in the clinical management of male infertility. Carefully controlled studies are now needed to critically examine this possibility.