AHCYL1 is mediated by estrogen-induced ERK1/2 MAPK cell signaling and microRNA regulation to effect functional aspects of the avian oviduct

Detection of polymorphisms in six genes and their association analysis with litter size in sheep

Litter size in sheep is a complex trait controlled by micro-effective polygenes. APAF1, CLSTN2, CTH, PLCB1, PLCB4, and CHST11 are all involved in mammalian reproduction. However, the effects of these genes on litter size in sheep are still unclear. Therefore, in this study, we used Sequenom MassARRAY® SNP assay technology to type the single nucleotide polymorphisms (SNPs) loci of six genes in five sheep breeds. The results showed that most sheep breeds contain three genotypes at each locus. Then, we conducted population genetic analysis on the SNPs of six genes and found that the polymorphic information content in all sheep breeds ranged from 0 to 0.37, and most sheep breeds were in Hardy-Weinberg equilibrium (p > 0.05). In addition, association analysis in Small Tail Han sheep indicated that the rs399534524 locus in CLSTN2 was highly associated with first parity litter size, and litter size in ewes with CT genotype was higher than that in ewes with CC genotype or TT genotype. Furthermore, the rs407142552 locus in CTH was highly associated with second parity litter size in Small Tail Han sheep, and litter size in ewes with CT genotype was higher than that in ewes with TT genotype. Finally, we predicted the CTH and CLSTN2 protein interaction network and found that HTR1E, NOM1, CCDC174 and ALPK3 interact with CLSTN2 and have been reported as candidate genes related to litter size in sheep. These results suggest that they may be useful genetic markers for increasing litter size in sheep.

DNA methylome and transcriptome identified Key genes and pathways involved in Speckled Eggshell formation in aged laying hens

BACKGROUND

The quality of poultry eggshells is closely related to the profitability of egg production. Eggshell speckles reflect an important quality trait that influences egg appearance and customer preference. However, the mechanism of speckle formation remains poorly understood. In this study, we systematically compared serum immune and antioxidant indices of hens laying speckled and normal eggs. Transcriptome and methylome analyses were used to elucidate the mechanism of eggshell speckle formation.

RESULTS

The results showed that seven differentially expressed genes (DEGs) were identified between the normal and speckle groups. Gene set enrichment analysis (GSEA) revealed that the expressed genes were mainly enriched in the calcium signaling pathway, focal adhesion, and MAPK signaling pathway. Additionally, 282 differentially methylated genes (DMGs) were detected, of which 15 genes were associated with aging, including ARNTL, CAV1, and GCLC. Pathway analysis showed that the DMGs were associated with T cell-mediated immunity, response to oxidative stress, and cellular response to DNA damage stimulus. Integrative analysis of transcriptome and DNA methylation data identified BFSP2 as the only overlapping gene, which was expressed at low levels and hypomethylated in the speckle group.

CONCLUSIONS

Overall, these results indicate that aging- and immune-related genes and pathways play a crucial role in the formation of speckled eggshells, providing useful information for improving eggshell quality.

Sequential verification of exogenous protein production in OVA gene-targeted chicken bioreactors

The chicken has potential as an efficient bioreactor system because of its outstanding protein production capacity and low cost. The CRISPR/Cas9-mediated gene-editing system enables production of highly marketable exogenous proteins in transgenic chicken bioreactors. However, because it takes approximately 18 mo to evaluate the recombinant protein productivity of the bioreactor due to the generation interval from G0 founders to G1 egg-laying hens, to verification of the exogenous protein at the early stage is difficult. Here we propose a system for sequential validation of exogenous protein production in chicken bioreactors as in hatching female chicks as well as in egg-laying hens. We generated chicken OVALBUMIN (OVA) EGFP knock-in (KI) chicken (OVA EGFP KI) by CRISPR/Cas9-mediated nonhomologous end joining at the chicken OVA gene locus. Subsequently, the estrogen analog, diethylstilbestrol (DES), was subcutaneously implanted in the abdominal region of 1-wk-old OVA EGFP KI female chicks to artificially increase OVALBUMIN expression. The oviducts of DES-treated OVA EGFP KI female chicks expressed OVA and EGFP at the 3-wk-old stage (10 d after DES treatment). We evaluated the expression of EGFP protein in the oviduct, along with the physical properties of eggs and egg white from OVA EGFP KI hens. The rapid identification and isolation of exogenous protein can be confirmed at a very early stage and high-yield production is possible by targeting the chicken oviduct.

RNA-Sequencing based analysis of bovine endometrium during the maternal recognition of pregnancy

BACKGROUND

Maternal recognition is the crucial step for establishing pregnancy in cattle. This study aims to identify endometrial genes and biological pathways involved in the maternal recognition of pregnancy. Caruncular endometrial tissues were collected from Day 15-17 of gestation (pregnant), non-pregnant (absence of conceptus), and cyclic (non-bred) heifers.

RESULTS

Total RNAs were isolated from the caruncular endometrial tissues of pregnant, non-pregnant, and cyclic heifers, and were subjected to high-throughput RNA-sequencing. The genes with at least two-fold change and Benjamini and Hochberg p-value ≤ 0.05 were considered differentially expressed genes and further confirmed with quantitative real-time PCR. A total of 107 genes (pregnant vs cyclic) and 98 genes (pregnant vs non-pregnant) were differentially expressed in the pregnant endometrium. The most highly up-regulated genes in the pregnant endometrium were MRS2, CST6, FOS, VLDLR, ISG15, IFI6, MX2, C15H11ORF34, EIF3M, PRSS22, MS4A8, and TINAGL1. Interferon signaling, immune response, nutrient transporter, synthesis, and secretion of proteins are crucial pathways during the maternal recognition of pregnancy.

CONCLUSIONS

The study demonstrated that the presence of conceptus at Day 15-17 of gestation affects the endometrial gene expression related to endometrial remodeling, immune response, nutrients and ion transporters, and relevant signaling pathways in the caruncular region of bovine endometrium during the maternal recognition of pregnancy.

Comparative transcriptome analysis of Indian domestic duck reveals candidate genes associated with egg production

Egg production is an important economic trait and a key indicator of reproductive performance in ducks. Egg production is regulated by several factors including genes. However the genes involved in egg production in duck remain unclear. In this study, we compared the ovarian transcriptome of high egg laying (HEL) and low egg laying (LEL) ducks using RNA-Seq to identify the genes involved in egg production. The HEL ducks laid on average 433 eggs while the LEL ducks laid 221 eggs over 93 weeks. A total of 489 genes were found to be significantly differentially expressed out of which 310 and 179 genes were up and downregulated, respectively, in the HEL group. Thirty-eight differentially expressed genes (DEGs), including LHX9, GRIA1, DBH, SYCP2L, HSD17B2, PAR6, CAPRIN2, STC2, and RAB27B were found to be potentially related to egg production and folliculogenesis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis suggested that DEGs were enriched for functions related to glutamate receptor activity, serine-type endopeptidase activity, immune function, progesterone mediated oocyte maturation and MAPK signaling. Protein-protein interaction network analysis (PPI) showed strong interaction between 32 DEGs in two distinct clusters. Together, these findings suggest a mix of genetic and immunological factors affect egg production, and highlights candidate genes and pathways, that provides an understanding of the molecular mechanisms regulating egg production in ducks and in birds more broadly.

Genetic variants in SCNN1B and AHCYL1 are associated with eggshell quality in Chinese domestic laying ducks (Anas platyrhynchos)

1. The objective of this study was to investigate the evolution of SCNN1B and AHCYL1 proteins among 10 domestic and mammalian animals, to uncover the expression patterns of SCNN1B and AHCYL1 genes in ducks, identify the genetic variants of the SCNN1B and AHCYL1 genes and analyse their effects on eggshell quality.2. Expression profiles of the SCNN1B and AHCYL1 genes in Sansui female ducks were determined using real-time fluorescence quantitative PCR to identify SNPs. The duck SCNN1B and AHCYL1 genes were amplified to identify SNPs. A total of 502 Sansui female ducks were genotyped by sequencing, and the associations between the mRNA expression/SNP genotypes and six eggshell quality indices were analysed using PASW Statistics 18.0.3. The results showed that the SCNN1B and AHCYL1 proteins are highly conserved in different mammalian or domestic animals, especially the AHCYL1 protein. The SCNN1B and AHCYL1 genes were widely expressed in different tissues of male and female ducks, and expression level in the uterus was greater than in other tissues. The expression of SCNN1B and AHCYL1 during oviposition cycle indicated that expression levels were related to the eggshell mineralisation stage.4. The mRNA expression levels of uterine SCNN1B and AHCYL1 genes were positively correlated with eggshell strength (ESS), percentage (ESP) and weight (ESW) (P<0.05), respectively. Ten novel SNPs in SCNN1B and AHCYL1 genes from Chinese domestic laying ducks were identified through PCR amplicon sequencing.5. Genetic association analysis indicated g.797509 C > T, g.797573 C > T and g.797834 C > T in SCNN1B gene and g.169244 T > A, g.169265 T > C and g.175311T > C in AHCYL1 gene had a significant effect on eggshell quality. Correlation analysis between the SNP genotype and SCNN1B and AHCYL1 genes expression in the uterus showed that the genotypes of g.797509 C>T, g.797573 C>T, g.797834 C>T, g.169244 T>A and g.175311T>C sites affected the expression of SCNN1B and AHCYL1 genes in utero (P<0.05).6. The study indicated SCNN1B and AHCYL1 as candidate genes to improve eggshell traits in ducks.

Adenosylhomocysteinase like 1 interacts with nonstructural 5A and regulates hepatitis C virus propagation

Hepatitis C virus (HCV) life cycle is highly dependent on cellular proteins for viral propagation. In order to identify the cellular factors involved in HCV propagation, we previously performed a protein microarray assay using the HCV nonstructural 5A (NS5A) protein as a probe. Of ∼9,000 human cellular proteins immobilized in a microarray, adenosylhomocysteinase like 1 (AHCYL1) was among 90 proteins identified as NS5A interactors. Of these candidates, AHCYL1 was selected for further study. In the present study, we verified the physical interaction between NS5A and AHCYL1 by both in vitro pulldown and coimmunoprecipitation assays. Furthermore, HCV NS5A interacted with endogenous AHCYL1 in Jc1-infected cells. Both NS5A and AHCYL1 were colocalized in the cytoplasmic region in HCV-replicating cells. siRNAmediated knockdown of AHCYL1 abrogated HCV propagation. Exogenous expression of the siRNA-resistant AHCYL1 mutant, but not of the wild-type AHCYL1, restored HCV protein expression levels, indicating that AHCYL1 was required specifically for HCV propagation. Importantly, AHCYL1 was involved in the HCV internal ribosome entry site-mediated translation step of the HCV life cycle. Finally, we demonstrated that the proteasomal degradation pathway of AHCYL1 was modulated by persistent HCV infection. Collectively, these data suggest that HCV may modulate the AHCYL1 protein to promote viral propagation.

IRBIT activates NBCe1-B by releasing the auto-inhibition module from the transmembrane domain

Key points

The electrogenic Na⁺/HCO₃⁻cotransporter NBCe1‐B is widely expressed in many tissues, including pancreas, submandibular gland, brain, heart, etc. NBCe1‐B has very low activity under basal condition due to auto‐inhibition, but can be fully activated by protein interaction with the IP3R‐binding protein released with inositol 1,4,5‐trisphosphate (IRBIT).

The structural components of the auto‐inhibition domain and the IRBIT‐binding domain of NBCe1‐B are finely characterized based on systematic mutations in the present study and data from previous studies.

Reducing negative charges on the cytosol side of the transmembrane domain greatly decreases the magnitude of the auto‐inhibition of NBCe1‐B.

We propose that the auto‐inhibition domain functions as a brake module that inactivates NBCe1‐B by binding to, via electrostatic attraction, the transmembrane domain; IRBIT activates NBCe1‐B by releasing the brake from the transmembrane domain via competitive binding to the auto‐inhibition domain.

Abstract

The electrogenic Na⁺/HCO₃⁻ cotransporter NBCe1‐B is widely expressed in many tissues in the body. NBCe1‐B exhibits only basal activity due to the action of the auto‐inhibition domain (AID) in its unique amino‐terminus. However, NBCe1‐B can be activated by interaction with the IP3R‐binding protein released with inositol 1,4,5‐trisphosphate (IRBIT). Here, we investigate the molecular mechanism underlying the auto‐inhibition of NBCe1‐B and its activation by IRBIT. The IRBIT‐binding domain (IBD) of NBCe1‐B spans residues 1−52, essentially consisting of two arms, one negatively charged (residues 1−24) and the other positively charged (residues 40−52). The AID mainly spans residues 40−85, overlapping with the IBD in the positively charged arm. The magnitude of auto‐inhibition of NBCe1‐B is greatly decreased by manipulating the positively charged residues in the AID or by replacing a set of negatively charged residues with neutral ones in the transmembrane domain. The interaction between IRBIT and NBCe1‐B is abolished by mutating a set of negatively charged Asp/Glu residues (to Asn/Gln) plus a set of Ser/Thr residues (to Ala) in the PEST domain of IRBIT. However, this interaction is not affected by replacing the same set of Ser/Thr residues in the PEST domain with Asp. We propose that: (1) the AID, acting as a brake, binds to the transmembrane domain via electrostatic interaction to slow down NBCe1‐B; (2) IRBIT activates NBCe1‐B by releasing the brake from the transmembrane domain.

The electrogenic Na⁺/HCO₃⁻cotransporter NBCe1‐B is widely expressed in many tissues, including pancreas, submandibular gland, brain, heart, etc. NBCe1‐B has very low activity under basal condition due to auto‐inhibition, but can be fully activated by protein interaction with the IP3R‐binding protein released with inositol 1,4,5‐trisphosphate (IRBIT).

The structural components of the auto‐inhibition domain and the IRBIT‐binding domain of NBCe1‐B are finely characterized based on systematic mutations in the present study and data from previous studies.

Reducing negative charges on the cytosol side of the transmembrane domain greatly decreases the magnitude of the auto‐inhibition of NBCe1‐B.

We propose that the auto‐inhibition domain functions as a brake module that inactivates NBCe1‐B by binding to, via electrostatic attraction, the transmembrane domain; IRBIT activates NBCe1‐B by releasing the brake from the transmembrane domain via competitive binding to the auto‐inhibition domain.

Putative Epigenetic Biomarkers of Stress in Red Blood Cells of Chickens Reared Across Different Biomes

Production animals are constantly subjected to early adverse environmental conditions that influence the adult phenotype and produce epigenetic effects. CpG dinucleotide methylation in red blood cells (RBC) could be a useful epigenetic biomarker to identify animals subjected to chronic stress in the production environment. Here we compared a reduced fraction of the RBC methylome of chickens exposed to social isolation to non-exposed. These experiments were performed in two different locations: Brazil and Sweden. The aim was to identify stress-associated DNA methylation profiles in RBC across these populations, in spite of the variable conditions to which birds are exposed in each facility and their different lineages. Birds were increasingly exposed to a social isolation treatment, combined with food and water deprivation, at random periods of the day from weeks 1-4 after hatching. We then collected the RBC DNA from individuals and compared a reduced fraction of their methylome between the experimental groups using two bioinformatic approaches to identify differentially methylated regions (DMRs): one using fixed-size windows and another that preselected differential peaks with MACS2. Three levels of significance were used (P ≤ 0.05, P ≤ 0.005, and P ≤ 0.0005) to identify DMRs between experimental groups, which were then used for different analyses. With both of the approaches more DMRs reached the defined significance thresholds in BR individuals compared to SW. However, more DMRs had higher fold change values in SW compared to BR individuals. Interestingly, ChrZ was enriched above expectancy for the presence of DMRs. Additionally, when analyzing the locations of these DMRs in relation to the transcription starting site (TSS), we found three peaks with high DMR presence: 10 kb upstream, the TSS itself, and 20-40 kb downstream. Interestingly, these peaks had DMRs with a high presence (>50%) of specific transcription factor binding sites. Three overlapping DMRs were found between the BR and SW population using the most relaxed p-value (P ≤ 0.05). With the most stringent p-value (P ≤ 0.0005), we found 7 and 4 DMRs between treatments in the BR and SW populations, respectively. This study is the first approximation to identify epigenetic biomarkers of long-term exposure to stress in different lineages of production animals.

Activation of mouse NBCe1-B by Xenopus laevis and mouse IRBITs: Role of the variable Nt appendage of IRBITs

The IP3 receptor binding protein released with inositol 1,4,5-trisphosphate (IRBIT) plays important roles in the regulation of intracellular Ca²⁺ signaling and intracellular pH. The mammals express two IRBIT paralogs, i.e., IRBIT1 (encoded by AHCYL1) and IRBIT2 (encoded by AHCYL2). The clawed frog Xenopus laevis oocyte is widely used for biophysical studies on ion channels and transporters. It remains unknown whether endogenous IRBIT is expressed in Xenopus oocytes. Here, we cloned from frog oocyte irbit2.L and irbit2.S, orthologs of mammalian IRBIT2. When over-expressed, the frog IRBITs powerfully stimulate the electrogenic Na⁺/HCO₃^- cotransporter NBCe1-B as mouse IRBIT2-V2 does. Expression of an isolated Nt fragment of NBCe1-B containing the IRBIT-binding domain greatly decreases NBCe1-B activity in oocytes, suggesting that the basal activity of NBCe1-B contains a large component derived from the stimulation by endogenous frog IRBIT. The frog IRBITs are highly homologous to the mammalian ones in the carboxyl-terminal region, but varies greatly in the amino-terminal (Nt) appendage. Interestingly, truncation study showed that the Nt appendage of IRBIT1 and the long Nt appendage of IRBIT2-V2 modestly enhance, whereas the short Nt appendage of IRBIT2-V4 greatly inhibits the functional interaction between IRBIT and NBCe1-B. Finally, Ala-substitution of Ser68, a key phosphorylation site in the PEST domain of IRBIT, causes distinct functional consequences depending on the structural context of the Nt appendage in different IRBIT isoforms. We conclude that the Nt appendage of IRBITs is not necessary for, but plays an important regulatory role in the functional interaction between IRBIT and NBCe1-B.

Identification of key genes and pathways associated with neuropathic pain in uninjured dorsal root ganglion by using bioinformatic analysis

Purpose

Neuropathic pain is a complex chronic condition occurring post-nervous system damage. The transcriptional reprogramming of injured dorsal root ganglia (DRGs) drives neuropathic pain. However, few comparative analyses using high-throughput platforms have investigated uninjured DRG in neuropathic pain, and potential interactions among differentially expressed genes (DEGs) and pathways were not taken into consideration. The aim of this study was to identify changes in genes and pathways associated with neuropathic pain in uninjured L4 DRG after L5 spinal nerve ligation (SNL) by using bioinformatic analysis.

Materials and methods

The microarray profile GSE24982 was downloaded from the Gene Expression Omnibus database to identify DEGs between DRGs in SNL and sham rats. The prioritization for these DEGs was performed using the Toppgene database followed by gene ontology and pathway enrichment analyses. The relationships among DEGs from the protein interactive perspective were analyzed using protein–protein interaction (PPI) network and module analysis. Real-time polymerase chain reaction (PCR) and Western blotting were used to confirm the expression of DEGs in the rodent neuropathic pain model.

Results

A total of 206 DEGs that might play a role in neuropathic pain were identified in L4 DRG, of which 75 were upregulated and 131 were downregulated. The upregulated DEGs were enriched in biological processes related to transcription regulation and molecular functions such as DNA binding, cell cycle, and the FoxO signaling pathway. Ctnnb1 protein had the highest connectivity degrees in the PPI network. The in vivo studies also validated that mRNA and protein levels of Ctnnb1 were upregulated in both L4 and L5 DRGs.

Conclusion

This study provides insight into the functional gene sets and pathways associated with neuropathic pain in L4 uninjured DRG after L5 SNL, which might promote our understanding of the molecular mechanisms underlying the development of neuropathic pain.

Expression and localization of matrix metalloproteinases (MMP-2, -7, -9) and their tissue inhibitors (TIMP-2, -3) in the chicken oviduct during maturation

Although participation of matrix metalloproteinases (MMPs) in reproductive tract remodeling has been strongly suggested in mammalian species, the role of MMPs in the avian oviduct has received little attention. To gain a better understanding of the potential role of the MMP system in avian oviduct development, mRNA and protein expression, localization of selected MMPs and their tissue inhibitors (TIMPs), and gelatinolytic activity in the oviduct of growing chickens were examined. The oviducts were collected from Hy-Line Brown hens before (10, 12, 14 and 16 weeks of age) and after (week 17) the onset of egg laying. The MMP-2, -7, -9 and TIMP-2 and -3 genes were found to be differentially expressed in all examined oviductal sections: the infundibulum, magnum, isthmus and shell gland on both mRNA (by real time polymerase chain reaction) and protein (by western blotting and immunohistochemistry) levels. In the course of oviduct development, the relative expression of all genes decreased in most sections. Protein level of MMP-9 was diminished, while MMP-7 and TIMP-3 were elevated in the oviduct of growing birds. MMP-2 and TIMP-2 protein levels remained constant, with a slight increase in MMP-2 concentration just before reaching maturity. The relative activity of MMP-2 and -9 (assessed by gelatin zymography) was higher (P < 0.05, P < 0.01) in immature birds compared with adults. Immunohistochemistry demonstrated cell- and tissue-specific localization of MMPs and TIMPs in the wall of the chicken oviduct. We concluded that changes in the expression of examined MMPs and their inhibitors, as well as alterations in MMP activity occurring simultaneously with changes in the morphology of the chicken oviduct, suggest the involvement of the MMP system in the proper development and functioning of this organ. Mechanisms regulating the expression and activity of MMPs require further clarification.

Differential expression of vitelline membrane outer layer protein 1: hormonal regulation of expression in the oviduct and in ovarian carcinomas from laying hens

Vitelline membrane outer layer protein 1 (VMO1), a basic protein present in the outer layer of the vitelline membrane of eggs, plays essential roles in separating the yolk from the egg white and preventing infection from bacteria by forming a barrier of fibrous layers in avian eggs. Although VMO1 is expressed in the oviduct of hens, little is known about endocrine regulation of transcription of VMO1 in the oviduct and its expression in cancerous ovaries of laying hens. Results of present study indicated that expression of VMO1 mRNA increased in the chick oviduct in response to diethylstilbestrol (DES, a synthetic non-steroidal estrogen). VMO1 mRNA and protein were particularly abundant in the glandular epithelium (GE) and luminal epithelium (LE) of the magnum of the oviducts of chicks treated with DES. Also, during the regression and recrudescence phases of the oviduct during induced molting with zinc feeding, VMO1 expression decreased as the oviduct regressed and increased with remodeling and recrudescence of the oviduct in laying hens. In addition, changes in relative expression of specific microRNAs (miR-1623, miR-1552-3p, miR-1573, miR-22-3p, miR-124a and miR-1764) regulating VMO1 gene were detected in the oviducts during the molting period. Moreover, abundant expression of VMO1 was found in GE of cancerous, but not normal ovaries of laying hens. Results of the present study suggest that VMO1 is regulated by estrogen and target microRNAs in the chicken oviduct and that it is a potential diagnostic marker of ovarian cancer in laying hens.

Characterization and miRNA-mediated posttranscriptional regulation of vitelline membrane outer layer protein I in the adult chicken oviduct

The laying hen is the best model for oviduct growth and development. The chicken oviduct produces the egg components, including the egg white and eggshell. However, the mechanism of egg component production during oviduct development requires further investigation. Vitelline membrane outer layer protein 1 (VMO-1) is found in the outer layer of the vitelline membrane of avian eggs. Comparison of the chicken VMO-1 protein-coding sequence and the human, mouse, rat, and bovine VMO-1 proteins via multiple sequence alignment analysis revealed high degrees of homology of 55%, 53%, 48%, and 54%, respectively. Although the avian homologue of VMO-1 is highly expressed in the magnum of the oviduct, little is known about the transcriptional and posttranscriptional regulation of VMO-1 during oviduct development. The results of this study revealed that estrogen induces VMO-1 messenger RNA (mRNA) expression in oviduct cells in vitro. The expression of genes interacting with VMO-1 by RNA interference (RNAi) functional analysis revealed that ovomucin expression was decreased by VMO-1 silencing. In addition, gga-miR-1623, 1552-3p, and 1651-3p influenced VMO-1 expression via its 3'-UTR, suggesting the posttranscriptional regulation of VMO-1 expression in chickens. Collectively, these results suggest that VMO-1 is an estrogen-induced gene that is posttranscriptionally regulated by microRNAs (miRNAs). The present study may contribute to an understanding of egg component production during chicken oviduct development.

A proteomic approach to monitor the dynamic response of the female oviductal epithelial cell surface to male gametes

Sophisticated strategies to analyze cell surface proteins are indispensable to study fundamental biological processes, such as the response of cells to environmental changes or cell-cell communication. Herein, we describe a refined mass spectrometry-based approach for the specific characterization and quantitation of cell surface proteins expressed in the female reproductive tract. The strategy is based on in situ biotinylation of rabbit oviducts, affinity enrichment of surface exposed biotin tagged proteins and dimethyl labeling of the obtained tryptic peptides followed by LC-MS/MS analysis. This approach proved to be sensitive enough to analyze small sample amounts (<1μg) and allowed further to trace the dynamic composition of the surface proteome of the oviductal epithelium in response to male gametes. The relative protein expression ratios of 175 proteins were quantified. Thirty-one of them were found to be altered over time, namely immediately, 1h and 2h after insemination compared to the time-matched control groups. Functional analysis demonstrated that structural reorganization of the oviductal epithelial cell surface was involved in the early response of the female organ to semen. In summary, this study outlines a workflow that is capable to monitor alterations in the female oviduct that are related to key reproductive processes in vivo.

BIOLOGICAL SIGNIFICANCE

The proper interaction between the female reproductive tract, in particular, the oviduct and the male gametes, is fundamental to fertilization and embryonic development under physiological conditions. Thereby the oviductal epithelial cell surface proteins play an important role. Besides their direct interaction with male gametes, these molecules participate in signal transduction and, thus, are involved in the mandatory cellular response of the oviductal epithelium. In this study we present a refined LC-MS/MS based workflow that is capable to quantitatively analyze the expression of oviductal epithelial cell surface proteins in response to insemination in vivo. A special focus was on the very early interaction between the female organ and the male gametes. At first, this study clearly revealed an immediate response of the surface proteome to semen, which was modulated over time. The described methodology can be applied for studies of further distinct biological events in the oviduct and therefore contribute to a deeper insight into the formation of new life.

Expression and regulation of avian cathepsin L in the oviduct during molting

Cathepsins (CTSs) are peptidases that have biological roles in degrading extracellular matrix, catabolism of intracellular proteins, and processing of pro-hormones. Of these, cathepsin L (CTSL) is closely associated with morphological changes in reproductive organs required for proper function in mammals, including humans and mice, but little is known about CTSL in avian species. In the present study, the expression of CTSL was investigated in the oviduct of hens during regression and recrudescence in response to molting. Our results revealed that expression of CTSL mRNA increased (P<0.001) when the oviduct underwent regression during the molting period in hens. In situ hybridization and immunohistochemial analyses detected CTSL mRNA and protein predominantly in the luminal (LE) and glandular epithelia (GE) during regression of the oviduct, but not during regeneration of the oviduct. Expression of CTSL decreased in the oviduct of chicks treated with diethylstilbestrol (DES, a synthetic estrogen agonist). Furthermore, we discovered four miRNAs including miR-23b, miR-551, miR-1464 and miR-1803 that regulate expression of the CTSL gene at the post-transcriptional level, which suggests that CTSL mRNA can be regulated by specific miRNAs via 3'-UTR in chickens. Results of the present research suggest that estrogen regulates expression of CTSL during regression of the oviduct during molting and that down-regulation of CTSL is likely a prerequisite for the normal regeneration of oviductal tissues following molting in laying hens.

Avian SERPINB12 expression in the avian oviduct is regulated by estrogen and up-regulated in epithelial cell-derived ovarian carcinomas of laying hens

Serine protease inhibitors (SERPINs) are involved in a variety of biological processes such as blood clotting, angiogenesis, immune system, and embryogenesis. Although, of these, SERPINB12 is identified as the latest member of clade B in humans, little is known of it in chickens. Thus, in this study, we investigated SERPINB12 expression profiles in various tissues of chickens and focused on effects of steroid hormone regulation of its expression. In the chicken oviduct, SERPINB12 mRNA and protein are abundant in the luminal (LE) and glandular (GE) epithelia of the magnum in response to endogenous or exogenous estrogen. Furthermore, SERPINB12 mRNA and protein increase significantly in GE of cancerous ovaries of laying hens with epithelia-derived ovarian cancer. Collectively, these results indicate that SERPINB12 is a novel estrogen-stimulated gene that is up-regulated by estrogen in epithelial cells of the chicken oviduct and that it is a potential biomarker for early detection of ovarian carcinomas in laying hens and women.

Inhibition of cellular methyltransferases promotes endothelial cell activation by suppressing glutathione peroxidase 1 protein expression

S-adenosylhomocysteine (SAH) is a negative regulator of most methyltransferases and the precursor for the cardiovascular risk factor homocysteine. We have previously identified a link between the homocysteine-induced suppression of the selenoprotein glutathione peroxidase 1 (GPx-1) and endothelial dysfunction. Here we demonstrate a specific mechanism by which hypomethylation, promoted by the accumulation of the homocysteine precursor SAH, suppresses GPx-1 expression and leads to inflammatory activation of endothelial cells. The expression of GPx-1 and a subset of other selenoproteins is dependent on the methylation of the tRNA(Sec) to the Um34 form. The formation of methylated tRNA(Sec) facilitates translational incorporation of selenocysteine at a UGA codon. Our findings demonstrate that SAH accumulation in endothelial cells suppresses the expression of GPx-1 to promote oxidative stress. Hypomethylation stress, caused by SAH accumulation, inhibits the formation of the methylated isoform of the tRNA(Sec) and reduces GPx-1 expression. In contrast, under these conditions, the expression and activity of thioredoxin reductase 1, another selenoprotein, is increased. Furthermore, SAH-induced oxidative stress creates a proinflammatory activation of endothelial cells characterized by up-regulation of adhesion molecules and an augmented capacity to bind leukocytes. Taken together, these data suggest that SAH accumulation in endothelial cells can induce tRNA(Sec) hypomethylation, which alters the expression of selenoproteins such as GPx-1 to contribute to a proatherogenic endothelial phenotype.

Identification of novel regulatory genes in development of the avian reproductive tracts

The chicken reproductive system is unique in maintaining its functions including production of eggs or sperm, fertilization of the egg by sperm maintained in sperm nests, production of hormones regulating its growth, development and function, and reproduction. Development of the reproductive organs is a highly regulated process that results in differentiation and proliferation of germ cells in response to predominant regulatory factors such as hormones and transcription factors. However, only a few genes are known to determine morphogenesis of the chicken reproductive tract and their mechanisms are unknown. Therefore, in the present study, we investigated the expression patterns of four genes including SNCA, TOM1L1, TTR and ZEB1 in the gonads at embryonic days 14 and 18, and in immature (12-week-old) and mature (50-week-old) chickens, as well as the reproductive tract including ovary, oviduct and testes of the respective sexes by qRT-PCR, in situ hybridization and immunofluorescence analyses. The expression of SNCA, TOM1L1 and ZEB1 genes was higher in immature and mature female reproductive tracts than expression of TTR. In addition, different temporal and spatial patterns of expression of the four genes were observed during maturation of testis in chickens. Specifically, SNCA, TOM1L1 and TTR were highly expressed in testes of 12-week-old chickens. Moreover, several chicken specific microRNAs (miRs) were demonstrated to affect expression of target gene mRNAs by directly binding to the 3′-UTR of their target genes through actions at the post-transcriptional level as follows: miR-153 and miR-1643 for SNCA; miR-1680* for TTR; and miR-200b and miR-1786 for ZEB1. These results suggest that four-selected genes play an important role in development of the male and female reproductive tract in chickens and expression of most candidate genes is regulated at the post-transcriptional level through specific microRNAs.

IRBIT: a regulator of ion channels and ion transporters

IRBIT (also called AHCYL1) was originally identified as a binding protein of the intracellular Ca(2+) channel inositol 1,4,5-trisphosphate (IP3) receptor and functions as an inhibitory regulator of this receptor. Unexpectedly, many functions have subsequently been identified for IRBIT including the activation of multiple ion channels and ion transporters, such as the Na(+)/HCO3(-) co-transporter NBCe1-B, the Na(+)/H(+) exchanger NHE3, the Cl(-) channel cystic fibrosis transmembrane conductance regulator (CFTR), and the Cl(-)/HCO3(-) exchanger Slc26a6. The characteristic serine-rich region in IRBIT plays a critical role in the functions of this protein. In this review, we describe the evolution, domain structure, expression pattern, and physiological roles of IRBIT and discuss the potential molecular mechanisms underlying the coordinated regulation of these diverse ion channels/transporters through IRBIT. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.

Endogenous retrovirus EAV-HP linked to blue egg phenotype in Mapuche fowl

Oocyan or blue/green eggshell colour is an autosomal dominant trait found in native chickens (Mapuche fowl) of Chile and in some of their descendants in European and North American modern breeds. We report here the identification of an endogenous avian retroviral (EAV-HP) insertion in oocyan Mapuche fowl and European breeds. Sequencing data reveals 100% retroviral identity between the Mapuche and European insertions. Quantitative real-time PCR analysis of European oocyan chicken indicates over-expression of the SLCO1B3 gene (P<0.05) in the shell gland and oviduct. Predicted transcription factor binding sites in the long terminal repeats (LTR) indicate AhR/Ar, a modulator of oestrogen, as a possible promoter/enhancer leading to reproductive tissue-specific over-expression of the SLCO1B3 gene. Analysis of all jungle fowl species Gallus sp. supports the retroviral insertion to be a post-domestication event, while identical LTR sequences within domestic chickens are in agreement with a recent de novo mutation.

MicroRNAs in domestic livestock

microRNAs (miRNAs) are a class of small noncoding RNA that bind to complementary sequences in the untranslated regions of multiple target mRNAs resulting in posttranscriptional regulation of gene expression. The recent discovery and expression-profiling studies of miRNAs in domestic livestock have revealed both their tissue-specific and temporal expression pattern. In addition, breed-dependent expression patterns as well as single nucleotide polymorphisms in either the miRNA or in the target mRNA binding site have revealed associations with traits of economic importance and highlight the potential use of miRNAs in future genomic selection programs.