Expression profiling of stemness markers in testicular germline stem cells from neonatal and adult Swiss albino mice during their transdifferentiation in vitro.

BACKGROUND: Spermatogonial stem cells (SSCs) were considered to be stem cells with limited potencies due to their existence in adult organisms. However, the production of spermatogonial stem cell colonies with broader differentiation capabilities in primary germ cell cultures from mice of select genetic backgrounds (C57BL6/Tg14, ddY, FVB and 129/Ola) indicated that SSCs from these strains were pluripotent. METHODS: We established primary cultures of SSCs from neonatal and adult Swiss 3T3 Albino mice. Stemness of SSC colonies were evaluated by performing real-time PCR and immunofluorescence analysis for a panel of chosen stemness markers. Differentiation potentials of SSCs were examined by attempting the generation of embryoid bodies and evaluating the expression of ectodermal, mesodermal and endodermal markers using immunofluorescence and real-time PCR analysis. RESULTS: Spermatogonial stem cells from neonatal and mature mice testes colonised in vitro and formed compact spermatogonial stem cell colonies in culture. The presence of stem cell markers ALPL, ITGA6 and CD9 indicated stemness in these colonies. The differentiation potential of these SSC colonies was demonstrated by their transformation into embryoid bodies upon withdrawal of growth factors from the culture medium. SSC colonies and embryoid bodies formed were evaluated using immunofluorescence and real-time PCR analysis. Embryoid body like structures derived from both neonatal and adult mouse testis were quite similar in terms of the expression of germ layer markers. CONCLUSION: These results strongly suggest that SSC-derived EB-like structures could be used for further differentiation into cells of interest in cell-based therapeutics.

A Case-Control Study of the Association of Leptin Gene Polymorphisms with Plasma Leptin Levels and Obesity in the Kerala Population.

Background: Over the last few years, the importance of leptin in energy metabolism has been extensively studied in both animal models and in humans. Very few results are available on the association between human leptin gene (LEP) variants and obesity traits in India. We designed this study to analyse the polymorphisms in human leptin gene and the association of sequence variants with obesity among the population in Kerala, South India. Methods: In this case-control design of 148 study participants, data were collected on socioeconomic aspects and anthropometric measurements. Plasma glucose, insulin, leptin, and lipid profile were measured. Genotyping was done by automated DNA sequencing. Results: The common Single Nucleotide Polymorphism (SNP) of 5'-UTR of LEP - 2548G/A was found to be present in the study population with "A" variant as dominant allele. A novel synonymous mutation Thr5Thr of exon 2 of LEP was identified in heterozygous form in one subject with morbid obesity with hyperleptinemia. A novel missense mutation Phe17Leu was observed in two subjects with obesity in heterozygous condition. A novel missense mutation Lys36Arg in exon 2 of LEP was observed in one subject with abdominal obesity and decreased serum leptin level. Conclusion: LEP - 2548G/A at 5'-untranslated region was found to be common with the mutant "A" variant in the study population. SNPs of exons in LEP were found to be rare but associated with morbid obesity and altered levels of serum leptin in the study population in Kerala, India.

Spermatogonial stem cells: A story of self-renewal and differentiation.

Mammalian spermatogenesis is a complex but well-coordinated process in which spermatogonial stem cells (SSC) of the testis develop to form spermatozoa. During testicular homeostasis, the spermatogonial stem cells self-renew to maintain the stem cell pool or differentiate to form a progeny of germ cells which sequentially transform to spermatozoa. Accumulating evidence from clinical data and diverse model organisms suggest that the fate of spermatogonial stem cells towards self-renewal or differentiation is governed by intrinsic signals within the cells and by extracellular signals from the SSC niche. Here, we review the past and the most recent developments in understanding the nature of spermatogonial stem cells and the regulation of their homeostasis in mice. We also review the potential clinical applications of spermatogonial stem cells in male infertility as well as in germline modification, by virtue of gene correction and conversion of somatic cells to biologically competent male germline cells.

Autoimmune Regulator Enhanced the Expression of Caspase-3 and Did Not Induce Massive Germ Cell Apoptosis in GC1-Spg Cells.

BACKGROUND/AIMS: AIRE is known for its involvement in autoreactive T-cell deletion in thymic epithelium. Though extrathymic expression of AIRE is well documented, the functional relevance of AIRE in non-thymus tissues is emerging. AIRE is expressed in neonatal and adult testis, and has been implicated in sporadic germ cell apoptosis in developing testis. In this study we examined whether AIRE has any role in inducing apoptosis in cultured spermatogonial cells. METHODS: We over-expressed AIRE or CARD domain of AIRE in GC1-spg cells and evaluated its impact on cell cycle using fluorescence activated cell sorting following Hoechst 33342 staining. Apoptosis was assayed using Annexin-V staining. Caspase-3 cleavage was assessed on western blots and caspase-3 expression was quantitated using realtime PCR. RESULTS: We report that C18-4 cells which are derived from Type A spermatogonia expressed AIRE, while GC1-spg which is closer to Type B spermatogonia was negative for AIRE expression. Overexpression of AIRE or CARD domain of AIRE induced Caspase-3 expression in GC1-spg cells. Silencing of AIRE in C18-4 cells inhibited Caspase-3 expression. When overexpressed, AIRE and CARD brought about a very negligible increase in germ cell death and resulted in altered cell cycle pattern with a reduction in G1 phase. This was not associated with any increase in activation of Caspase-3. CONCLUSION: We conclude that the CARD domain of AIRE enhances caspase-3 expression through possible direct DNA binding and triggers non-apoptotic downstream signaling in cultured spermatogonial cells.

Impact of semen-derived amyloid (SEVI) on sperm viability and motility: its implication in male reproductive fitness.

Human semen contains a large number of macromolecules, including proteins/enzymes and carbohydrates, regulating and protecting sperm cells. Proteomic analysis of human seminal fluid led to the discovery of semen amyloids derived from short peptide fragments of the proteins prostatic acid phosphatase (PAP) and semenogelin (SG) which are known to play a crucial role in enhancing HIV infection. However, the relevance of their existence in human semen and role in maintaining sperm behavior remains unclear. Distinct physiological, biochemical, and biophysical attributes might cause these amyloids to influence sperm behavior positively or negatively, affecting fertilization or other reproductive processes. We assessed the direct effect of amyloids derived from a PAP248-286 fragment, on sperm motility and viability, which are crucial parameters for assessment of sperm quality in semen. Co-incubation of human sperm with PAP248-286 amyloids at normal physiological concentrations formed in buffer led to significant reduction in sperm viability, though approximately a 10× higher concentration was needed to show a similar effect with amyloid formed in seminal fluid. Both forms of PAP248-286 amyloid also had a significant impact on sperm motility at physiological levels, in agreement with a previous report. Our study suggests that PAP248-286 amyloids can directly influence sperm motility and viability in a concentration-dependent manner. We hypothesise that the direct toxic effect of PAP248-286 amyloid is normally mitigated by other seminal fluid ingredients, but that in pathological conditions, where PAP248-286 concentrations are elevated and it plays a role in determining sperm health and viability, with relevance for male fertility as well as sterility.

Retinoic acid signaling in regulation of meiosis during embryonic development in mice.

In the embryonic gonads of mice, the genetic and epigenetic regulatory programs for germ cell sex specification and meiosis induction or suppression are intertwined. The quest for garnering comprehensive understanding of these programs has led to the emergence of retinoic acid (RA) as an important extrinsic factor, which regulates initiation of meiosis in female fetal germ cells that have attained a permissive epigenetic ground state. In contrast, germ cells in fetal testis are protected from the exposure to RA due to the activity of CYP26B1, an RA metabolizing enzyme, which is highly expressed in fetal testis. In this review, we provide an overview of the molecular mechanisms operating in fetal gonads of mice, which enable regulation of meiosis via RA signaling.

Silencing of dedicator of cytokinesis (DOCK180) obliterates pregnancy by interfering with decidualization due to blockage of nuclear entry of autoimmune regulator (AIRE).

PROBLEM: Dedicator of cytokinesis (DOCK 180) involved in cytoskeletal reorganization is primarily a cytosolic molecule. It is recently shown to be nuclear in HeLa cells but its nuclear function is not known. METHOD OF STUDY: The spatiotemporal distribution of DOCK180 in uterus was studied in uterine cytoplasmic and nuclear compartments during the "window of implantation." The functional significance of nuclear DOCK180 was explored by homology modeling, co-immunoprecipitation assays, and mass spectrometric analysis. Dock180's role in early pregnancy was ascertained by Dock 180 silencing and subsequent quantitative real-time PCR and Western blotting analysis. RESULTS: Our study shows a nuclear DOCK180 in the uterus during "window of implantation." Estrogen and progesterone mediate expression and nuclear translocation of DOCK180. The nuclear function of DOCK180 is attributed to its ability to import autoimmune regulator (AIRE) into the nucleus. Silencing of Dock180 inhibited AIRE nuclear shuttling which influenced its downstream targets, thereby affecting decidualization with AIRE and HOXA-10 as the major players as well as lack of implantation site formation due to impact on angiogenesis-associated genes. CONCLUSION: DOCK180 has an indispensable role in pregnancy establishment as knocking down Dock180 abrogates pregnancy by a consolidated impact on decidualization and angiogenesis by regulating AIRE nuclear entry.

Expression of protocadherin 11Yb (PCDH11Yb) in seminal germ cells is correlated with fertility status in men.

Protocadherin 11 Y-linked (PCDH11Y), a member of the cadherin superfamily, is predominantly expressed in the central nervous system, is encoded by the Yp11.2 locus and exists in three isoforms: 11Ya, 11Yb and 11Yc. PCDH11Y is upregulated by retinoic acid signalling and is essential for spermatogonial differentiation and initiation of meiosis. PCDH11Y mediates Wnt signalling, which plays a crucial role in the differentiation of various cell types. PCDH11Y has been implicated in neuronal cell differentiation and proliferation, but its association with spermatogenesis has not yet been addressed. Hence, in order to address the possible role of PCDH11Y in relation to spermatogenesis, the expression analysis of PCDH11Y in the seminal germ cells of fertile and infertile males were carried out employing RT-PCR, western blotting and immunofluorescence analysis. In the present study, PCDH11Yb, but not PCDH11Ya or PCDH11Yc, was expressed in germ cells isolated from the semen of all 13 men with proven fertility. However, in several subjects from various infertility classes, there was complete absence or a significant reduction in the expression of PCDH11Yb. PCDH11Y exhibited prominent localisation on the head and midpiece region of spermatozoa from fertile men, whereas spermatozoa from infertile subjects had either weak or abnormal localisation patterns for PCDH11Y. In addition, downregulation of canonical Wnt signalling was correlated with defective expression of PCDH11Y in spermatozoa of infertile men, as evidenced by downregulation of the Wnt targets C-Myc and C-Jun. In conclusion, expression levels of PCDH11Yb in germ cells in the semen were correlated with the fertility status of men.

Expression of Cnnm1 and Its Association with Stemness, Cell Cycle, and Differentiation in Spermatogenic Cells in Mouse Testis.

Cyclin M1 (CNNM1) functions as a copper storage protein in neuronal cells. We report that Cnnm1 is expressed in mouse testis and brain and has a coding sequence of 1761 bp that encodes a 586 amino acid protein with a molecular weight of 66 kDa. Cnnm1 is expressed in the testes of mice from neonatal to adult stages with relatively higher levels in neonates. CNNM1 expression appeared to be restricted to c-KIT- and OCT3/4-positive cells in the testis, indicating that they are early spermatogonial cells. Spermatogonial stem cells in primary culture expressed Cnnm1, and their differentiation into embryoid body-like clusters in vitro resulted in the loss of Cnnm1 expression. Silencing of Cnnm1 in GC1-spg cells resulted in a significant reduction in the number of cells in G1 phase with concomitant increase in the numbers of cells in both S and G2/M phases. Further, retinoic acid downregulated the expression of Cnnm1 in GC1-spg cells. We conclude that CNNM1 is associated with stemness and self-renewal, and its downregulation triggers differentiation in spermatogonial cells in mouse.

Autoimmune Regulator (AIRE) Is Expressed in Spermatogenic Cells, and It Altered the Expression of Several Nucleic-Acid-Binding and Cytoskeletal Proteins in Germ Cell 1 Spermatogonial (GC1-spg) Cells.

Autoimmune regulator (AIRE) is a gene associated with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). AIRE is expressed heavily in the thymic epithelial cells and is involved in maintaining self-tolerance through regulating the expression of tissue-specific antigens. The testes are the most predominant extrathymic location where a heavy expression of AIRE is reported. Homozygous Aire-deficient male mice were infertile, possibly due to impaired spermatogenesis, deregulated germ cell apoptosis, or autoimmunity. We report that AIRE is expressed in the testes of neonatal, adolescent, and adult mice. AIRE expression was detected in glial cell derived neurotrophic factor receptor alpha (GFRα)(+) (spermatogonia), GFRα(-)/synaptonemal complex protein (SCP3)(+) (meiotic), and GFRα(-)/Phosphoglycerate kinase 2 (PGK2)(+) (postmeiotic) germ cells in mouse testes. GC1-spg, a germ-cell-derived cell line, did not express AIRE. Retinoic acid induced AIRE expression in GC1-spg cells. Ectopic expression of AIRE in GC1-spg cells using label-free LC-MS/MS identified a total of 371 proteins that were differentially expressed. 100 proteins were up-regulated, and 271 proteins were down-regulated. Data are available via ProteomeXchange with identifier PXD002511. Functional analysis of the differentially expressed proteins showed increased levels of various nucleic-acid-binding proteins and transcription factors and a decreased level of various cytoskeletal and structural proteins in the AIRE overexpressing cells as compared with the empty vector-transfected controls. The transcripts of a select set of the up-regulated proteins were also elevated. However, there was no corresponding decrease in the mRNA levels of the down-regulated set of proteins. Molecular function network analysis indicated that AIRE influenced gene expression in GC1-spg cells by acting at multiple levels, including transcription, translation, RNA processing, protein transport, protein localization, and protein degradation, thus setting the foundation in understanding the functional role of AIRE in germ cell biology.

Aberrant expression of TAR DNA binding protein-43 is associated with spermatogenic disorders in men.

Loss of function of TAR DNA-binding protein (TDP-43) has been implicated in neurodegenerative disorders in both humans and animal models. TDP-43 has also been shown to be cis-acting transcriptional repressor of the acrosome vesicle (Acrv) gene in mice. In the present study, we investigated the expression of the TDP-43 transcript (TARDBP) and protein in germ cells from 11 fertile and 98 subfertile men to verify its potential association with poor seminograms. The expression profile of TDP-43 was characterised in immature germ cells and spermatozoa from semen from fertile and subfertile men using reverse transcription-polymerase chain reaction, western blotting and immunofluorescence. Although germ cells from subfertile men tested negative for TARDBP, the full-length message of the same was detected in fertile men. TDP-43 was detected in spermatozoa from fertile men using western blot analysis and immunofluorescence. The expression of this protein was negligible in spermatozoa from men with primary spermatogenic dysfunction. We conclude that a deficiency in the TDP-43 expression is associated with defective spermatogenesis and male infertility. We propose that TDP-43 could be used as a marker of male factor infertility.

Aberrant Expression of Dynein light chain 1 (DYNLT1) is Associated with Human Male Factor Infertility.

DYNLT1 is a member of a gene family identified within the t-complex of the mouse, which has been linked with male germ cell development and function in the mouse and the fly. Though defects in the expression of this gene are associated with male sterility in both these models, there has been no study examining its association with spermatogenic defects in human males. In this study, we evaluated the levels of DYNLT1 and its expression product in the germ cells of fertile human males and males suffering from spermatogenic defects. We screened fertile (n = 14), asthenozoospermic (n = 15), oligozoospermic (n = 20) and teratozoospermic (n = 23) males using PCR and Western blot analysis. Semiquantitative PCR indicated either undetectable or significantly lower levels of expression of DYNLT1 in the germ cells from several patients from across the three infertility syndrome groups, when compared with that of fertile controls. DYNLT1 was localized on head, mid-piece, and tail segments of spermatozoa from fertile males. Spermatozoa from infertile males presented either a total absence of DYNLT1 or its absence in the tail region. Majority of the infertile individuals showed negligible levels of localization of DYNLT1 on the spermatozoa. Overexpression of DYNLT1 in GC1-spg cell line resulted in the up-regulation of several cytoskeletal proteins and molecular chaperones involved in cell cycle regulation. Defective expression of DYNLT1 was associated with male factor infertility syndromes in our study population. Proteome level changes in GC1-spg cells overexpressing DYNLT1 were suggestive of its possible function in germ cell development. We have discussed the implications of these observations in the light of the known functions of DYNLT1, which included protein trafficking, membrane vesiculation, cell cycle regulation, and stem cell differentiation.

Dramatic changes in 67 miRNAs during initiation of first wave of spermatogenesis in Mus musculus testis: global regulatory insights generated by miRNA-mRNA network analysis.

We mapped global changes in miRNA and mRNA profiles spanning the first wave of spermatogenesis using prepubertal (Postnatal Day 8 [P8]), pubertal (P16), and adolescent (P24) Mus musculus testes and identified the differential expression of 67 miRNAs and 8226 mRNAs. These two data sets were integrated into miRNA-dependent regulatory networks based on miRWalk predictions. In a network representing the P8 to P16 transition, downregulation of four miRNAs and upregulation of 19 miRNAs were linked with 81 upregulated target mRNAs and 228 downregulated target mRNAs, respectively. Furthermore, during the P16 to P24 transition, two miRNAs were downregulated, and eight miRNAs were upregulated, which linked with 64 upregulated mRNAs and 389 downregulated mRNAs, respectively. Only three of the miRNAs present in the network (miR-34b-5p, miR-34c, and miR-449a) showed a progressive increase from P8 through P16 to P24, while the remaining miRNAs in the network showed statistically significant changes in their levels either during the P8 to P16 transition or during the P16 to P24 transition. Analysis of the chromosomal location of these differentially expressed miRNAs showed that 14 out of 25 miRNAs upregulated from P8 to P16, and 18 out of 40 miRNAs upregulated from P8 to P24 were X-linked. This is suggestive of their escape from meiotic sex chromosome inactivation and postmeiotic sex chromatin. This integrated network of miRNA-level and mRNA-level changes in mouse testis during the first wave of spermatogenesis is expected to build a base for evaluating the role of miRNA-mediated gene expression regulation in maturing mammalian testis.

AIRE1A might be involved in cyclin B2 degradation in testicular lysates.

The autoimmune regulator gene Aire shows predominant expression in thymus and other immunologically relevant tissues, and is assigned the major function of programming autoreactive T-cell deletion. However, the expression of this gene in tissues outside the immune system raises a question about its possible function beyond the T-cell deletion dogma. We detected Aire in mouse testis, and the expression of AIRE protein was remarkably high in postmeiotic germ cells. Sequencing results indicate that testis expressed Aire variant 1a. AIRE could be detected in spermatozoa, with heavy localization on the principal acrosomal domains. Mouse oocytes stained negatively for AIRE before fertilization, but stained positively for AIRE 30 min after fertilization. In the zygote, the levels of AIRE correlated negatively with cyclin B2 levels. Goat testicular lysates spiked with recombinant human AIRE exhibited augmented cyclin B2 degradation in the presence of protease inhibitors, which was inhibited by MG-132, indicating the operation of proteasomal pathways. Thus, this study identifies a correlation between the presence of AIRE and proteasomal breakdown of cyclin B2, which leads us to speculate that cyclin B2 could be a target of AIRE's E3-ubiquitin ligase activity.

The role of trp ion channels in testicular function.

Transient receptor potential (TRP) proteins are homologues of Drosophila transient receptor potential ion channels first identified in the photo receptors and reported to be involved in calcium entry following calcium store depletion during photo transduction. TRP is a large super family divided in several families including the TRPC (Canonical) family, the TRPV (Vanilloid) family, the TRPM (Melastatin) family, the TRPP (Polycystin) family, the TRPML (Mucolipin) family, the TRPA (Ankyrin) family, and the TRPN (NOMPC) family. TRP proteins are six transmembrane ion channels and act as components of multimeric complexes which allow cation entry either after internal calcium depletion or in response to receptor stimulation. TRP ion channels have been reported to act as molecular sensors of environment. Trp genes are expressed in a wide range of tissues including testis. In addition to this TRP proteins have also been detected in mature sperm from a number of species including humans. TRP may be involved in regulating calcium dependent functions of sperm including motility, capacitation, and acrosome reaction. Here we review the available information about TRP proteins reported in the sperm, as well as in other cells/tissue systems.

Wounds due to a modified shot gun (home-made): a case report.

In a case of firearm fatality, the autopsy surgeon is required to opine as to the range of fire in addition to the cause of death which will help in reconstruction of the events. Problems may arise in estimating the range of fire based on wound ballistics when there is an alteration or modification in the internal ballistics. We encountered such a case in the department of Forensic Medicine, Kasturba Medical College, Manipal, which is discussed.

Molecular characterization and expression analysis of BmNOX in two strains of Bombyx mori with contrasting viral resistance phenotype.

We recently documented the identification of a 26.5 kDa protein named BmNox in the gut fluid of Nistari strain of Bombyx mori, which possessed antiviral activity against BmNPV in vitro. In this report, we report the characterization of the full-length gene encoding BmNOX and the levels of expression of this gene in select tissues of silkworm larvae from a BmNPV-susceptible and a BmNPV-resistant strain to the defense capability in Bombyx mori larvae challenged with BmNPV. We also evaluated the BmNox expression in various stages of larval life of a resistant and a susceptible strain of Bombyx mori selected from among a panel of strains of silkworm. Nistari, a multivoltine strain of silkworm, expressed BmNOX during all five larval stages, and were highly resistant to BmNPV infection. In sharp contrast, CSR(2), a bivoltine strain, showed weaker expression of BmNOX in the anterior midgut in larval life and was highly susceptible to BmNPV infection. BmNOX is a secretory protein with dual expression in gut fluid and mid gut tissue. BmNOX is expressed heavily in the posterior mid gut, with weaker expression in the fore- and mid-gut regions.

Thalidomide attenuates nitric oxide-driven angiogenesis by interacting with soluble guanylyl cyclase.

BACKGROUND AND PURPOSE: Nitric oxide (NO) promotes angiogenesis by activating endothelial cells. Thalidomide arrests angiogenesis by interacting with the NO pathway, but its putative targets are not known. Here, we have attempted to identify these targets. EXPERIMENTAL APPROACH: Cell-based angiogenesis assays (wound healing of monolayers and tube formation in ECV304, EAhy926 and bovine arterial endothelial cells), along with ex vivo and in vivo angiogenesis assays, were used to explore interactions between thalidomide and NO. We also carried out in silico homology modelling and docking studies to elucidate possible molecular interactions of thalidomide and soluble guanylyl cyclase (sGC). KEY RESULTS: Thalidomide inhibited pro-angiogenic functions in endothelial cell cultures, whereas 8-bromo-cGMP, sildenafil (a phosphodiesterase inhibitor) or a NO donor [sodium nitroprusside (SNP)] increased these functions. The inhibitory effects of thalidomide were reversed by adding 8-bromo-cGMP or sildenafil, but not by SNP. Immunoassays showed a concentration-dependent decrease of cGMP in endothelial cells with thalidomide, without affecting the expression level of sGC protein. These results suggested that thalidomide inhibited the activity of sGC. Molecular modelling and docking experiments revealed that thalidomide could interact with the catalytic domain of sGC, which would explain the inhibitory effects of thalidomide on NO-dependent angiogenesis. CONCLUSION AND IMPLICATIONS: Our results showed that thalidomide interacted with sGC, suppressing cGMP levels in endothelial cells, thus exerting its anti-angiogenic effects. These results could lead to the formulation of thalidomide-based drugs to curb angiogenesis by targeting sGC.

Identification of a soluble NADPH oxidoreductase (BmNOX) with antiviral activities in the gut juice of Bombyx mori.

Silkworms show high variability in silk quality and disease resistance. Attempts are on to combine the disease tolerance of multivoltine races and the silk quality of bivoltine races to generate new races with desirable phenotypic traits. We report the identification of a 26.5-kDa protein that is overexpressed in the gut juice of disease-resistant multivoltine races and that has anti-BmNPV activity. We have characterized this protein as a soluble NADH-oxidoreductase-like protein (BmNOX). Treatment of live BmNPV particles with BmNOX inhibited the capability of the viral particles to infect BmN cells in vitro.

Profiling of E-cadherin, beta-catenin and Ca(2+) in embryo-uterine interactions at implantation.

Establishment of early pregnancy is promoted by a complex network of signalling molecules that mediate cell-to-cell and cell-to-extracellular matrix communications between the receptive endometrium and the invasive trophectoderm. In this study, we have attempted to evaluate the expression profiles of cadherin and catenin during embryo implantation in the mouse. Western blotting studies along with immunocytochemical analysis revealed that E-cadherin is expressed rather ubiquitously in the uterine epithelial cells, distinct enrichment is observed on the apical membrane in the endometrium of peri-implantation uterus specifically at the implantation sites and not at the inter-implanation sites. beta-Catenin also is upregulated and is specifically restricted to apical membrane of epithelial cells of implantation sites. Progesterone induced expression of E-cadherin and 17beta-estradiol regulated the expression of catenin in implantation-delayed uteri. Interestingly, estradiol imparted negative modulation on cadherin expression when co-administered with progesterone. On the contrary, trophoblast exhibits a striking down regulation of cadherin, catenin and Ca(2+) at peri implanting stage. These observations suggest that the trophoblasts exhibited an invasive phenotype while the endometrial epithelium displayed an adhesive phenotype during the window of implantation. Thus, embryo implantation presents an instance where two interacting surfaces showed mutually complementing interaction phenotypes.