Osman V. Patel

Implantation and placental development in somatic cell clone recipient cows.

Successful somatic cloned animal production has been reported in various domesticated species, including cattle; however, it is associated with a high rate of pregnancy failure. The low cloning yield could possibly arise from either an abnormal and/or poorly developed placenta. In comparison to control cows, fewer placentomes were found in somatic cell nuclear recipient (NT) cows at day 60 of gestation, suggesting a retardation of fetal/placental growth in these animals. NT cows not only had fewer numbers of chorionic villi but also had poorly developed caruncles. Macroscopic examination revealed atypical development of the placentome in terms of shape and size. Histological disruption of chorionic villi and caruncular septum was found in NT cows. Of particular interest was that the expression of genes, as well as proteins in the placentome, was disparate between NT and artificially inseminated cows, especially placental lactogen (PL) and pregnancy-associated glycoprotein (PAG). In contrast, prolactin-related protein-1 (PRP-1) signals were comparable across cows, including NT cows carrying immotile fetuses. The expression of extracellular matrix degrading molecule, heparanase (HPA), in NT cows was divergent from that of control cows. Microarray data suggest that gene expression was disorientated in early stages of implantation in NT cows, but this was eliminated with progression of gestation. These findings strongly support a delay in trophoblast development during early stages of placentation in NT cows, and suggest that placental specific proteins, including PLs, PAGs, and HPA, are key indicators for the aberration of gestation and placental function in cows.

Identification of Novel Bovine Cumulus Cell Molecular Markers Predictive of Oocyte Competence: Functional and Diagnostic Implications

Abstract The present study was undertaken to discover molecular markers in bovine cumulus cells predictive of oocyte competence and to elucidate their functional significance. Differences in RNA transcript abundance in cumulus cells harvested from oocytes of adult versus prepubertal animals (a model of poor oocyte quality) were identified by microarray analysis. Four genes of interest encoding for the lysosomal cysteine proteinases cathepsins B, S, K, and Z and displaying greater transcript abundance in cumulus cells surrounding oocytes harvested from prepubertal animals were chosen for further investigation. Greater mRNA abundance for such genes in cumulus cells of prepubertal oocytes was confirmed by real-time RT-PCR. Elevated transcript abundance for cathepsins B, S, and Z also was observed in cumulus cells surrounding adult metaphase II oocytes that developed to the blastocyst stage at a low percentage following parthenogenetic activation versus those that developed at a high percentage. Functional significance of cumulus cell cathepsin expression to oocyte competence was confirmed by treatment of cumulus-oocyte complexes during in vitro oocyte maturation with a cell-permeable cysteine proteinase (cathepsin) inhibitor. Inhibitor treatment decreased apoptotic nuclei in the cumulus layer and enhanced development of parthenogenetically activated and in vitro-fertilized adult oocytes to the blastocyst stage. Stimulatory effects of inhibitor treatment during meiotic maturation on subsequent embryonic development were not observed when oocytes were matured in the absence of cumulus cells. The present results support a functional role for cumulus cell cathepsins in compromised oocyte competence and suggest that cumulus cell cathepsin mRNA abundance may be predictive of oocyte quality.

Gene expression and maintenance of pregnancy in bovine: roles of trophoblastic binucleate cell-specific molecules

Cell to cell interaction plays a pivotal role in the regulation of placentogenesis and exchange of stage-specific developmental signals between the fetal and maternal units. Specifically, these interactions are paramount for programmed fetal growth, maternal adaptation to pregnancy and coordination of parturition. However, little is known about the precise regulation of placentation and maintenance of gestation in cattle. Therefore, the aim of the present study was to decipher the complex networks ofcell communication to gain an insight into the multifaceted developmental process and understand the profound consequences of flawed communication. In the ruminant, the binucleate cell plays a central role in forming the structures and secretions at the fetomaternal interface that are crucial in establishing and maintaining pregnancy. Herein, we summarise differences in the abundance of specific RNA transcripts in the bovine cotyledon and caruncle using global gene expression profiling and further investigate the relationship of mRNA abundance for selected pregnancy-specific genes of interest (identified from microarray studies) that are localised exclusively to the binucleate cell, such as placental lactogen, prolactin-related proteins and pregnancy-associated glycoproteins. The results suggest that a well-orchestrated transcriptional command from binucleate cells is pivotal to the establishment and progression of pregnancy in cattle.

JY-1, an oocyte-specific gene, regulates granulosa cell function and early embryonic development in cattle

Oocyte-specific gene products play a key role in regulation of fertility in mammals. Here, we describe the discovery, molecular characterization, and function of JY-1, a bovine oocyte-expressed gene shown to regulate both function of ovarian granulosa cells and early embryogenesis in cattle and characteristics of JY-1 loci in other species. The JY-1 gene encodes for a secreted protein with multiple mRNA transcripts containing an identical ORF but differing lengths of 3′ UTR. JY-1 mRNA and protein are oocyte-specific and detectable throughout folliculogenesis. Recombinant JY-1 protein regulates function of follicle-stimulating hormone-treated ovarian granulosa cells, resulting in enhanced progesterone synthesis accompanied by reduced cell numbers and estradiol production. JY-1 mRNA of maternal origin is also present in early bovine embryos, temporally regulated during the window from meiotic maturation through embryonic genome activation, and is required for blastocyst development. The JY-1 gene has three exons and is located on bovine chromosome 29. JY-1-like sequences are present on syntenic chromosomes of other vertebrate species, but lack exons 1 and 2, including the protein-coding region, suggestive of species specificity in evolution and function of this oocyte-specific gene.

Expression of Trophoblast Cell-Specific Pregnancy-Related Genes in Somatic-Cell-Cloned Bovine Pregnancies

Abstract We compared the expression of bovine prolactin-related protein-1 (bPRP-1), placental lactogen (bPL), and pregnancy-associated glycoproteins-1 (bPAG-1) and -9 (bPAG-9) genes in artificially inseminated (AI) and nuclear transferred (NT) cows during the first trimester of gestation using real-time reverse transcription-polymerase chain reaction and in situ hybridization. Placentomal (cotyledonary, caruncular) and interplacentomal (intercotyledonary, intercaruncular) tissues of AI and NT cows carrying either motile (M) or immotile (IM) fetuses were examined. Transcripts for bPL and bPAG-9 were lower (P < 0.01) in the fetal membranes of NT (n = 4) cows at Day 30 of gestation, compared with AI (n = 4) cows. There was no difference in the mean (± SEM) levels of expressions of bPRP-1, bPL, and PAG-1 in the placentomal and interplacentomal tissues of AI (n = 5) and NT (M, n = 4) cows at Day 60 of gestation. The mRNAs for bPRP-1, bPL, bPAG-1, and bPAG-9 genes were higher (P < 0.01) in the caruncular tissue of AI cows, compared with NT (IM, n = 4) cows at Day 60 of gestation. Expression of bPRP-1, bPL, bPAG-1, and bPAG-9 in the placentomal and interplacentomal tissues of the NT (n = 3) group varied considerably more, compared with the AI (n = 4) group at Day 100 of gestation. These findings suggest defective binucleate cell-specific gene transcriptional commands in NT cows.

Molecular signatures reveal circadian clocks may orchestrate the homeorhetic response to lactation.

Genes associated with lactation evolved more slowly than other genes in the mammalian genome. Higher conservation of milk and mammary genes suggest that species variation in milk composition is due in part to the environment and that we must look deeper into the genome for regulation of lactation. At the onset of lactation, metabolic changes are coordinated among multiple tissues through the endocrine system to accommodate the increased demand for nutrients and energy while allowing the animal to remain in homeostasis. This process is known as homeorhesis. Homeorhetic adaptation to lactation has been extensively described; however how these adaptations are orchestrated among multiple tissues remains elusive. To develop a clearer picture of how gene expression is coordinated across multiple tissues during the pregnancy to lactation transition, total RNA was isolated from mammary, liver and adipose tissues collected from rat dams (n = 5) on day 20 of pregnancy and day 1 of lactation, and gene expression was measured using Affymetrix GeneChips. Two types of gene expression analysis were performed. Genes that were differentially expressed between days within a tissue were identified with linear regression, and univariate regression was used to identify genes commonly up-regulated and down-regulated across all tissues. Gene set enrichment analysis showed genes commonly up regulated among the three tissues enriched gene ontologies primary metabolic processes, macromolecular complex assembly and negative regulation of apoptosis ontologies. Genes enriched in transcription regulator activity showed the common up regulation of 2 core molecular clock genes, ARNTL and CLOCK. Commonly down regulated genes enriched Rhythmic process and included: NR1D1, DBP, BHLHB2, OPN4, and HTR7, which regulate intracellular circadian rhythms. Changes in mammary, liver and adipose transcriptomes at the onset of lactation illustrate the complexity of homeorhetic adaptations and suggest that these changes are coordinated through molecular clocks.

Transcriptomes reveal alterations in gravity impact circadian clocks and activate mechanotransduction pathways with adaptation through epigenetic change

Few studies have investigated the impact of alterations in gravity on mammalian transcriptomes. Here, we describe the impact of spaceflight on mammary transcriptome of late pregnant rats and the effect of hypergravity exposure on mammary, liver, and adipose transcriptomes in late pregnancy and at the onset of lactation. RNA was isolated from mammary collected on pregnancy day 20 from rats exposed to spaceflight from days 11 to 20 of gestation. To measure the impact of hypergravity on mammary, liver, and adipose transcriptomes we isolated RNA from tissues collected on P20 and lactation day 1 from rats exposed to hypergravity beginning on pregnancy day 9. Gene expression was measured with Affymetrix GeneChips. Microarray analysis of variance revealed alterations in gravity affected the expression of genes that regulate circadian clocks and activate mechanotransduction pathways. Changes in these systems may explain global gene expression changes in immune response, metabolism, and cell proliferation. Expression of genes that modify chromatin structure and methylation was affected, suggesting adaptation to gravity alterations may proceed through epigenetic change. Altered gravity experiments offer insights into the role of forces omnipresent on Earth that shape genomes in heritable ways. Our study is the first to analyze the impact of alterations in gravity on transcriptomes of pregnant and lactating mammals. Findings provide insight into systems that sense gravity and the way in which they affect phenotype, as well as the possibility of sustaining life beyond Earths orbit.

Lipogenesis impaired in periparturient rats exposed to altered gravity is independent of prolactin and glucocorticoid secretion

Perturbed prolactin (PRL) secretion and concomitant downregulation of PRL receptor (PRLR) in periparturient dams exposed to altered gravity are linked to aberrant lipogenesis and reduced neonatal survival. PRL and glucocorticoids (GC) are known to modulate PRLR expression. We hypothesized that improving levels of PRLR would mitigate the increased gravity [hypergravity (HG)]-induced effects of impaired mammary lipogenesis and increase neonatal survival. The objective of this study was to determine if prepartum PRL or GC supplementation would override the HG-induced repression of PRLR along with lipogenic genes and increase tissue fatty acid synthesis. Pregnant rats were exposed to either 2g (HG) or kept at 1g (control) from day 11 of gestation (G11) through Postnatal day 1 (P1). HG exposed rats were supplemented with either PRL or corticosterone or a placebo from G13 to P1. On P1, mammary, liver and adipose tissues were collected to measure glucose incorporation into lipids and mRNA abundance of PRL long and short form receptors (Prlr-l, Prlr-s), glucocorticoid receptor (Nr3c1), Acetyl CoA carboxylase-α (Acaca), fatty acid synthase (Fasn), lipoprotein lipase (Lpl), Sterol Regulatory Element Binding Protein-1 (Srebp1) and protein kinase B (Akt1) genes by quantitative polymerase chain reaction (qPCR). PRL and GC supplementation had a limited effect on lipogenesis in the three tissues of HG group likely due to their inability to increase abundance of key down-regulated genes, including Prlr-l and Nr3c1. There was no difference in the abundance of genes coding for milk proteins or those associated with milk fat globule formation and secretion. These data suggest that reduced lipogenesis in HG exposed dams is independent of PRL and GC secretion but may be associated with dysregulation of multiple metabolic regulators at the level of mRNA expression.

261 IDENTIFICATION OF OOCYTE- AND CUMULUS-DERIVED CO-REGULATED AND DIFFERENTIALLY REGULATED TRANSCRIPTS ASSOCIATED WITH BOVINE MEIOTIC MATURATION

Understanding the process of oocyte maturation is critical for efficient application of biotechnologies such as in vitro embryo production and nuclear transfer/cloning. Intercellular communication between the oocyte and the encompassing somatic (cumulus) cells is pivotal for successful growth of ovarian follicles and oocyte maturation. Therefore, we utilized global gene expression profiling to determine changes in the transcriptome of oocytes and their adjacent cumulus cells during meiotic maturation in vitro to identify both co-regulated and differentially regulated transcripts within the two cell compartments of the cumulus oocyte complex (COC). Germinal vesicle (GV) and in vitro matured metaphase II (MII) COC (n = 5 pools of 5 COC per group) were denuded and separated into oocytes and cumulus cells. RNA was extracted from the oocytes and cumulus cells and subjected separately to microarray analysis using a bovine cDNA array containing expressed sequence tags (ESTs) representing 15 500 unique genes. A combined total of 1045 genes displaying greater mRNA abundance in GV oocytes and associated cumulus cells compared to MII samples were detected (P < 0.05; false discovery rate (FDR) = 5%). A combined total of 711 genes displaying greater mRNA abundance in MII oocytes and enclosing cumulus cells compared to GV samples were detected (P < 0.05; FDR = 5%). Fourteen transcripts were identified that were co-regulated and of greater abundance in GV or MII oocytes and in their matching cumulus cells (P < 0.05; FDR = 5%). The co-regulated transcripts identified are implicated in metabolism (e.g. heme oxygenase-2, leukotriene B4 12-hydroxydehydrogenase), signal transduction (e.g. caveolin 1, ring finger protein 31), and cell growth (e.g. BTG family member 2, myosin regulatory light chain 2). In contrast, thirteen transcripts differentially regulated in the GV oocyte versus MII cumulus cells were identified (P < 0.05; FDR = 5%). Similarly, nine transcripts differentially regulated in the MII oocyte versus GV cumulus cells were identified (P < 0.05; FDR = 5%). Some of the identified differentially regulated transcripts encode for genes associated with the cytoskeleton (e.g. tropomyosin 1), apoptotic activity (e.g. death effector domain containing protein 2) and DNA replication (e.g. epsilon polymerase). The results provide novel insights into the identity of transcripts whose abundance is co-regulated or differentially regulated between the oocyte and cumulus cells during the transition of a COC from the GV to the MII stage. Characterization of the signaling pathways driving changes in transcript abundance for co-regulated and differentially regulated genes in oocytes versus associated cumulus cells may lead to a better understanding of regulation of meiotic maturation and potential cross-talk between germ cells and somatic cells during the oocyte maturation cascade. This work was supported by the Rackham Foundation and the MI Agriculture Experiment Station.