Expression of CSF-1/c-fms and SF/c-kit mRNA during preimplantation mouse development

Optimization of human recombinant granulocyte-colony stimulating factor supplementation during in vitro production of porcine embryos to improve the efficiency of resource utilization of poor-quality cumulus-oocyte complexes

Granulocyte colony-stimulating factor (G-CSF), a pleiotropic cytokine, is secreted by the reproductive tract. Furthermore, our previous study indicated that human recombinant G-CSF (hrG-CSF) supplementation during porcine oocyte in vitro maturation (IVM) or during embryo in vitro culture (IVC) improved their quality and development potential when using cumulus-oocyte complexes (COCs) with more than three cumulus cell layers (CCL >3). Thus, in this study, we investigate the optimal conditions of hrG-CSF supplementation throughout the in vitro production (IVP: IVM + IVC) system to improve the embryo production efficiency of "poor-quality (CCL ≤3)" oocytes. COCs were classified into two groups according to the number of CCL (>3 and ≤3) and embryonic viability was analyzed after treatment with hrG-CSF during IVC. The mRNA transcription levels of G-CSF in COCs were compared based on their type and the period of IVM. Finally, developmental capacity and quality were evaluated after treatment with hrG-CSF for different periods of IVP. No marked effects on the developmental potential of embryos when using CCL ≤3 type COCs were observed after supplementing hrG-CSF only during IVC. Moreover, the mRNA transcription level of G-CSF increased gradually with IVM culture time and was higher in CCL ≤3 COCs than in >3. Supplementing hrG-CSF only during the IVM period resulted in the best embryo developmental potential, while supplementing hrG-CSF during the IVP period resulted in the best quality embryos, reflected in the increased total cell number and decreased apoptotic nuclei index of blastocysts. These findings indicate that "poor-quality" COCs may have a greater demand for G-CSF than "good-quality", meanwhile hrG-CSF supplementation throughout IVP improves resource utilization efficiency in poor-quality COCs.

Stem cell factor's role in enhancing the quality of fertilized and cloned porcine embryos for improved embryonic stem cell derivation

Stem cell factor (SCF), a cytokine growth factor, is expressed in various tissues of the male and female reproductive organs, including the testis, ovary, and endometrium. Its primary function involves cell survival, differentiation, and proliferation, achieved through its binding to the c-kit receptor. This study aimed to scrutinize the effects of SCF treatment during in vitro culture (IVC) on both the developmental potential and the efficiency of establishing embryonic stem cells (ESCs) from fertilized and cloned porcine embryos. The rates of cleavage and blastocyst formation exhibited no significant differences between fertilized and cloned embryos, even with the addition of SCF. However, it's worth noting that embryos cloned with Cloud eGFP as donor cells demonstrated notably increased rates of hatched blastocysts when treated with SCF, and this increase was statistically significant (p < 0.05). Furthermore, following the complete dissection of the blastocysts, although there was no significant difference in the SCF-treated group, the area of expansion was significantly reduced (p < 0.01) in the group treated with the antagonistic blocker (ACK2) compared to both the control and SCF-treated groups. These outcomes suggest that the SCF/c-kit signaling pathway might play a pivotal role in embryo implantation. As anticipated, the efficiency of deriving ESCs was significantly higher (p < 0.01) in the group subjected to SCF treatment (12.82 ± 1.02%) compared to the control group (5.41 ± 2.25%). In conclusion, this study highlights the crucial role of SCF in enhancing the quality of porcine embryos, a vital step in obtaining high-quality ESCs.

Variants Affecting the C-Terminal of CSF1R Cause Congenital Vertebral Malformation Through a Gain-of-Function Mechanism

CSF1R encodes the colony-stimulating factor 1 receptor which regulates the proliferation, differentiation, and biological activity of monocyte/macrophage lineages. Pathogenic variants in CSF1R could lead to autosomal dominant adult-onset leukoencephalopathy with axonal spheroids and pigmented glia or autosomal recessive skeletal dysplasia. In this study, we identified three heterozygous deleterious rare variants in CSF1R from a congenital vertebral malformation (CVM) cohort. All of the three variants are located within the carboxy-terminal region of CSF1R protein and could lead to an increased stability of the protein. Therefore, we established a zebrafish model overexpressing CSF1R. The zebrafish model exhibits CVM phenotypes such as hemivertebral and vertebral fusion. Furthermore, overexpression of the mutated CSF1R mRNA depleted of the carboxy-terminus led to a higher proportion of zebrafish with vertebral malformations than wild-type CSF1R mRNA did (p = 0.03452), implicating a gain-of-function effect of the C-terminal variant. In conclusion, variants affecting the C-terminal of CSF1R could cause CVM though a potential gain-of-function mechanism.

Cytokines in embryonic secretome as potential markers for embryo selection

Despite performing certain morphological assessments for selecting the best embryo for transfer, the results have not been satisfactory. Given the global tendency for performing quick and noninvasive tests for embryo selection, great efforts have been made to discover the predictive biomarkers of embryo implantation potential. In recent years, many factors have been detected in embryo culture media as a major source of embryo secretions. Previous studies have evaluated cytokines, miRNAs, extracellular vesicles, and other factors such as leukemia inhibitory factor, colony-stimulating factor, reactive oxygen species, soluble human leukocyte antigen G, amino acids, and apolipoproteins in these media. Given the key role of cytokines in embryo implantation, these factors can be considered promising molecules for predicting the implantation success of assisted reproductive technology (ART). The present study was conducted to review embryo-secreted molecules as potential biomarkers for embryo selection in ART.

The M-CSF receptor in osteoclasts and beyond

Colony-stimulating factor 1 receptor (CSF1R, also known as c-FMS) is a receptor tyrosine kinase. Macrophage colony-stimulating factor (M-CSF) and IL-34 are ligands of CSF1R. CSF1R-mediated signaling is crucial for the survival, function, proliferation, and differentiation of myeloid lineage cells, including osteoclasts, monocytes/macrophages, microglia, Langerhans cells in the skin, and Paneth cells in the intestine. CSF1R also plays an important role in oocytes and trophoblastic cells in the female reproductive tract and in the maintenance and maturation of neural progenitor cells. Given that CSF1R is expressed in a wide range of myeloid cells, altered CSF1R signaling is implicated in inflammatory, neoplastic, and neurodegenerative diseases. Inhibiting CSF1R signaling through an inhibitory anti-CSF1R antibody or small molecule inhibitors that target the kinase activity of CSF1R has thus been a promising therapeutic strategy for those diseases. In this review, we cover the recent progress in our understanding of the various roles of CSF1R in osteoclasts and other myeloid cells, highlighting the therapeutic applications of CSF1R inhibitors in disease conditions.

Drugs directed at a key signaling receptor involved in breaking down bone tissue could help treat diseases marked by pathological bone loss and destruction. In a review article, Kyung-Hyun Park-Min and colleagues from the Hospital for Special Surgery in New York, USA, discuss the essential roles played by the colony-stimulating factor 1 receptor (CSF1R) protein in the survival, function, proliferation and differentiation of myeloid lineage stem cells in the bone marrow, including bone-resorbing osteoclasts. They explore the links between the CSF1R-mediated signaling pathway and diseases such as cancer and neurodegeneration. The authors largely focus on bone conditions, highlighting mouse studies in which CSF1R-blocking drugs were shown to ameliorate bone loss and inflammatory symptoms in models of arthritis, osteoporosis and metastatic cancer. Clinical trials are ongoing to test therapeutic applications.

Effects of stem cell factor on in vitro growth of buffalo oocytes

Stem cell factor (SCF) plays important roles in primordial follicle activation, oocyte growth and survival, granulosa cell proliferation, theca cell recruitment, and ovarian steroidogenesis. The aim of this study was to investigate the effect of SCF on in vitro growth of buffalo oocytes. Oocyte-granulosa cell complexes (OGCs) were dissected from early antral follicles of slaughtered buffalo ovaries and cultured for 6 days in media supplemented with 0, 50 or 100 ng/mL SCF. In vitro grown oocytes were further cultured for in vitro maturation for 24 h. The results showed that SCF significantly (P < 0.05) increased oocyte diameter in vitro. The percentages of surviving oocytes were 60, 81 and 92 in 0, 50 and 100 ng/mL SCF supplemented group, respectively. SCF promoted formation of antrum-like structures in culture. The results also showed that SCF enhanced the maturation of in vitro grown buffalo oocytes. Here, 14% in vitro grown oocytes reached metaphase II (MII) stage in 50 ng/mL SCF supplemented group, whereas the percentage was increased to 26% in 100 ng/mL SCF treated group. These results show that SCF supports the growth, viability and nuclear maturation of buffalo oocytes in vitro.

Bi-allelic CSF1R Mutations Cause Skeletal Dysplasia of Dysosteosclerosis-Pyle Disease Spectrum and Degenerative Encephalopathy with Brain Malformation

Colony stimulating factor 1 receptor (CSF1R) plays key roles in regulating development and function of the monocyte/macrophage lineage, including microglia and osteoclasts. Mono-allelic mutations of CSF1R are known to cause hereditary diffuse leukoencephalopathy with spheroids (HDLS), an adult-onset progressive neurodegenerative disorder. Here, we report seven affected individuals from three unrelated families who had bi-allelic CSF1R mutations. In addition to early-onset HDLS-like neurological disorders, they had brain malformations and skeletal dysplasia compatible to dysosteosclerosis (DOS) or Pyle disease. We identified five CSF1R mutations that were homozygous or compound heterozygous in these affected individuals. Two of them were deep intronic mutations resulting in abnormal inclusion of intron sequences in the mRNA. Compared with Csf1r-null mice, the skeletal and neural phenotypes of the affected individuals appeared milder and variable, suggesting that at least one of the mutations in each affected individual is hypomorphic. Our results characterized a unique human skeletal phenotype caused by CSF1R deficiency and implied that bi-allelic CSF1R mutations cause a spectrum of neurological and skeletal disorders, probably depending on the residual CSF1R function.

Stem cell factor-induced AKT cell signaling pathway: Effects on porcine trophectoderm and uterine luminal epithelial cells

Stem cell factor (SCF) is a multipotent growth factor that elicits diverse biological actions in various aspects of embryogenesis and animal development. The aim of the present study was to assess SCF-induced intracellular signaling and cellular activities in porcine trophectoderm (pTr) and uterine luminal epithelial (pLE) cells which are well known as useful to elucidate developmental events. SCF induced abundances of p-AKT, p-P70RSK and RPS6 proteins in pTr cells reached to their maximum, and then returned to basal levels by 120min. In pLE cells, SCF induced protracted effect to increase AKT phosphorylation which was well correlated with the time course for P70RSK and RPS6 phosphorylation. LY294002 (an inhibitor of AKT) decreased SCF-induced p-AKT, p-P70RSK and p-RPS6 proteins. Also, immunofluorescence analyses revealed that p-RPS6 was abundant within the cytoplasm of SCF-treated cells, but p-RPS6 was present only at basal levels in cells treated with LY294002. In the presence of LY294002, both SCF-stimulated transient and sustained AKT phosphorylation were inhibited in pLE cells. Furthermore, SCF increased migration of pTr and pLE cells, but LY294002 significantly reduced this effect of SCF. In conclusion, results of the present study suggest that SCF secreted by the endometrium induces autocrine/paracrine signaling responses that stimulate migration of pTr and pLE cells through activation of the AKT cell signaling pathway. Those results support the hypothesis that SCF is a critical regulatory factor for conceptus development and implantation during pregnancy in pigs.

Transcriptional mechanisms that control expression of the macrophage colony-stimulating factor receptor locus

The proliferation, differentiation, and survival of cells of the macrophage lineage depends upon signals from the macrophage colony-stimulating factor (CSF) receptor (CSF1R). CSF1R is expressed by embryonic macrophages and induced early in adult hematopoiesis, upon commitment of multipotent progenitors to the myeloid lineage. Transcriptional activation of CSF1R requires interaction between members of the E26 transformation-specific family of transcription factors (Ets) (notably PU.1), C/EBP, RUNX, AP-1/ATF, interferon regulatory factor (IRF), STAT, KLF, REL, FUS/TLS (fused in sarcoma/ranslocated in liposarcoma) families, and conserved regulatory elements within the mouse and human CSF1R locus. One element, the Fms-intronic regulatory element (FIRE), within intron 2, is conserved functionally across all the amniotes. Lineage commitment in multipotent progenitors also requires down-regulation of specific transcription factors such as MYB, FLI1, basic leucine zipper transcriptional factor ATF-like (BATF3), GATA-1, and PAX5 that contribute to differentiation of alternative lineages and repress CSF1R transcription. Many of these transcription factors regulate each other, interact at the protein level, and are themselves downstream targets of CSF1R signaling. Control of CSF1R transcription involves feed–forward and feedback signaling in which CSF1R is both a target and a participant; and dysregulation of CSF1R expression and/or function is associated with numerous pathological conditions. In this review, we describe the regulatory network behind CSF1R expression during differentiation and development of cells of the mononuclear phagocyte system.

Regulation of Embryonic and Postnatal Development by the CSF-1 Receptor

Macrophages are found in all tissues and regulate tissue morphogenesis during development through trophic and scavenger functions. The colony stimulating factor-1 (CSF-1) receptor (CSF-1R) is the major regulator of tissue macrophage development and maintenance. In combination with receptor activator of nuclear factor κB (RANK), the CSF-1R also regulates the differentiation of the bone-resorbing osteoclast and controls bone remodeling during embryonic and early postnatal development. CSF-1R-regulated macrophages play trophic and remodeling roles in development. Outside the mononuclear phagocytic system, the CSF-1R directly regulates neuronal survival and differentiation, the development of intestinal Paneth cells and of preimplantation embryos, as well as trophoblast innate immune function. Consistent with the pleiotropic roles of the receptor during development, CSF-1R deficiency in most mouse strains causes embryonic or perinatal death and the surviving mice exhibit multiple developmental and functional deficits. The CSF-1R is activated by two dimeric glycoprotein ligands, CSF-1, and interleukin-34 (IL-34). Homozygous Csf1-null mutations phenocopy most of the deficits of Csf1r-null mice. In contrast, Il34-null mice have no gross phenotype, except for decreased numbers of Langerhans cells and microglia, indicating that CSF-1 plays the major developmental role. Homozygous inactivating mutations of the Csf1r or its ligands have not been reported in man. However, heterozygous inactivating mutations in the Csf1r lead to a dominantly inherited adult-onset progressive dementia, highlighting the importance of CSF-1R signaling in the brain.

Role of macrophage colony-stimulating factor (M-CSF) in human granulosa cells

Macrophage colony-stimulating factor (M-CSF) has been proved to have a positive role in the follicular development. We investigated its effect on human granulosa cells and found that M-CSF could stimulate the production of E₂. The production of FSH receptors was enhanced by M-CSF in vitro in a dose-dependent manner with or without the addition of tamoxifen (p <0.05). Correspondingly, FSH was also able to coordinate the expression of M-CSF and its receptor (p <0.05). That maybe important to maintain the level of Nppc and the meiotic arrest of the oocyte. The protein p-JAK2 and p-STAT3 in JAK/STAT-signaling pathway elevated after the influence of M-CSF (p < 0.05). These results suggest that M-CSF has a role in regulating the response of granulosa cells to gonadotropins. Its function is associated with JAK/STAT-signaling pathway.

The Role of CSF-1 in Normal Physiology of Mammary Gland and Breast Cancer: An Update

Colony stimulating factor (CSF-1) and its receptor (CSF-1R, product of c-fms proto-oncogene) were initially implicated as essential for normal monocyte development as well as for trophoblastic implantation. However, studies have demonstrated that CSF-1 and CSF-1R have additional roles in mammary gland development during pregnancy and lactation. This apparent role for CSF-1/CSF-1R in normal mammary gland development is very intriguing because this receptor/ligand pair has also been found to be important in the biology of breast cancer in which abnormal expression of CSF-1 and its receptor correlates with tumor cell invasiveness and adverse clinical prognosis. Recent findings also implicate tumor-produced CSF-1 in promotion of bone metastasis in breast cancer, and a certain membrane-associated form of CSF-1 appears to induce immunity against tumors. This review aims to summarize recent findings on the role of CSF-1 and its receptor in normal and neoplastic mammary development that may elucidate potential relationships of growth factor–induced biological changes in the breast during pregnancy and tumor progression.

Female tract cytokines and developmental programming in embryos

In the physiological situation, cytokines are pivotal mediators of communication between the maternal tract and the embryo. Compelling evidence shows that cytokines emanating from the oviduct and uterus confer a sophisticated mechanism for 'fine-tuning' of embryo development, influencing a range of cellular events from cell survival and metabolism, through division and differentiation, and potentially exerting long-term impact through epigenetic remodelling. The balance between survival agents, including GM-CSF, CSF1, LIF, HB-EGF and IGFII, against apoptosis-inducing factors such as TNFα, TRAIL and IFNg, influence the course of preimplantation development, causing embryos to develop normally, adapt to varying maternal environments, or in some cases to arrest and undergo demise. Maternal cytokine-mediated pathways help mediate the biological effects of embryo programming, embryo plasticity and adaptation, and maternal tract quality control. Thus maternal cytokines exert influence not only on fertility and pregnancy progression but on the developmental trajectory and health of offspring. Defining a clear understanding of the biology of cytokine networks influencing the embryo is essential to support optimal outcomes in natural and assisted conception.

Recurrent triploidy due to a failure to complete maternal meiosis II: whole-exome sequencing reveals candidate variants

Triploidy is a relatively common cause of miscarriage; however, recurrent triploidy has rarely been reported. A healthy 34-year-old woman was ascertained because of 18 consecutive miscarriages with triploidy found in all 5 karyotyped losses. Molecular results in a sixth loss were also consistent with triploidy. Genotyping of markers near the centromere on multiple chromosomes suggested that all six triploid conceptuses occurred as a result of failure to complete meiosis II (MII). The proband's mother had also experienced recurrent miscarriage, with a total of 18 miscarriages. Based on the hypothesis that an inherited autosomal-dominant maternal predisposition would explain the phenotype, whole-exome sequencing of the proband and her parents was undertaken to identify potential candidate variants. After filtering for quality and rarity, potentially damaging variants shared between the proband and her mother were identified in 47 genes. Variants in genes coding for proteins implicated in oocyte maturation, oocyte activation or polar body extrusion were then prioritized. Eight of the most promising candidate variants were confirmed by Sanger sequencing. These included a novel change in the PLCD4 gene, and a rare variant in the OSBPL5 gene, which have been implicated in oocyte activation upon fertilization and completion of MII. Several variants in genes coding proteins playing a role in oocyte maturation and early embryonic development were also identified. The genes identified may be candidates for the study in other women experiencing recurrent triploidy or recurrent IVF failure.

Control of CSF-1 induced inflammation in teleost fish by a soluble form of the CSF-1 receptor

The colony-stimulating factor-1 (CSF-1) is the principal regulator of the survival, proliferation, differentiation, and function of macrophages and their precursors, and has been shown to play a role in the etiology of inflammation. We recently identified a novel mechanism for the control of CSF-1 activity in teleost fish, through the production of an inhibitory soluble form of the CSF-1 receptor (sCSF-1R). Primary goldfish kidney macrophages selectively expressed sCSF-1R during the senescence phase, which corresponds to a defined stage of in vitro culture development where inhibition of macrophage proliferation and apoptotic cell death are prominent. In contrast, primary macrophage cultures undergoing active proliferation displayed low levels of sCSF-1R expression. Addition of purified recombinant sCSF-1R to developing primary macrophage cultures leads to a dose-dependent decrease in macrophage proliferation and inhibits macrophage antimicrobial functions including chemotaxis, phagocytosis, and production of reactive oxygen intermediates. Using a goldfish in vivo model of self-resolving peritonitis, we found that sCSF-1R plays a role in the inhibition of inflammation, following an initial acute phase of antimicrobial responses within an inflammatory site. Soluble CSF-1R inhibits pro-inflammatory cytokine production, inhibits leukocyte recruitment to the inflammatory site and decreases ROS production in a dose-dependent manner. This sCSF-1R-dependent regulation of inflammation appears to be an elegant mechanism for the control of macrophage numbers at inflammatory sites of lower vertebrates. Overall, our results provide new insights into the evolutionary origins of the CSF-1 immune regulatory axis.

Identification of an isoform of colony-stimulating factor 1 receptor mRNA in the rat testis

Because alternative RNA splicing regulation in the testis is prevalent, we explored testes of Sprague-Dawley rats for existence of alternatively spliced colony-stimulating factor 1 receptor (CSF-1R) mRNA. Using RT-PCR and sequencing, we identified a variant of CSF-1R mRNA that was 284 bp shorter than the full-length CSF-1R transcript. This variant was present in the testis (late fetal stage to adult) and in other organs of rats (7 and 60 days old). The deletion of 284 bp disrupted the open reading frame, resulting in a noncoding mRNA product. When testicular macrophages were stimulated with CSF-1R ligand and lipopolysaccharide, proportionally increased expression of both short isoform and full-length CSF-1R mRNA was observed. Thus, the identified isoform of CSF-1R mRNA may interfere with the expression of full-length CSF-1R mRNA, thereby affecting the biological activity of the ligand/receptor signaling axis in Sprague-Dawley rats.

Enlarging the nosological spectrum of hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS)

Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is an autosomal dominant disease clinically characterized by cognitive decline, personality changes, motor impairment, parkinsonism and seizures. Recently, mutations in the colony-stimulating factor-1 receptor (CSF1R) gene have been shown to be associated with HDLS. We report clinical, neuropathological and molecular genetic findings of patients from a new family with a mutation in the CSF1R gene. Disease onset was earlier and disease progression was more rapid compared with previously reported patients. Psychiatric symptoms including personality changes, alcohol abuse and severe depression were the first symptoms in male patients. In the index, female patient, the initial symptom was cognitive decline. Magnetic resonance imaging (MRI) showed bilateral, confluent white matter lesions in the cerebrum. Stereotactic biopsy revealed loss of myelin and microglial activation as well as macrophage infiltration of the parenchyma. Numerous axonal swellings and spheroids were present. Ultrastructural analysis revealed pigment-containing macrophages. Axonal swellings were detected by electron microscopy not only in the central nervous system (CNS) but also in skin nerves. We identified a heterozygous mutation (c.2330G>A, p.R777Q) in the CSF1R gene. Through this report, we aim to enlarge the nosological spectrum of HDLS, providing new clinical descriptions as well as novel neuropathological findings from the peripheral nervous system.

Stem cell factor/c-Kit signaling in in vitro cultures supports early mouse embryonic development by accelerating proliferation via a mechanism involving Akt-downstream genes

PURPOSE

stem cell factor (SCF)/c-Kit regulates the proliferation and survival of germ cells or stem cells; however, little is known about the role of SCF/c-Kit in pre-implantation embryo development.

METHODS

using exogenous SCF supplementation and c-Kit siRNA injection, we investigated the role and mechanism of SCF/c-Kit in pre-implantation mouse embryos.

RESULTS

addition of soluble SCF to the culture medium improved blastocyst formation. c-Kit gene silencing reduced the rate of blastocyst formation and delayed embryonic development. The number of proliferating cells in c-Kit gene-silenced blastocysts decreased, whereas the number of apoptotic cells in blastocysts obtained from both experimental and the control groups was not affected. RT-PCR, immunostaining and western blotting revealed that proliferation-related Akt downstream targets were substantially affected by c-Kit gene silencing.

CONCLUSION

SCF/c-Kit signaling through Akt downstream targets is likely involved in mediating the cleavage and proliferation of blastomeres during mouse pre-implantation embryogenesis.

Cytokines and embryo/endometrial interactions

Experimental animal models have shown that the in vitro embryo culture involved in many treatments for infertility results in a dramatic reduction in embryo viability. Recent advances in methodology such as RT-PCR for localization and quantitation of cytokines and their receptors, are revealing the role that this group of growth factors plays in the basic physiology of embryo development and the process of implantation itself. These studies offer the likelihood of dramatically improving in vitro embryo culture in humans and other species by supplementation of culture medium with growth factors or antagonists to improve embryo viability and hence implantation rates.

Development of macrophages of cyprinid fish

The innate immune responses of early vertebrates, such as bony fishes, play a central role in host defence against infectious diseases and one of the most important effector cells of innate immunity are macrophages. In order for macrophages to be effective in host defence they must be present at all times in the tissues of their host and importantly, the host must be capable of rapidly increasing macrophage numbers during times of need. Hematopoiesis is a process of formation and development of mature blood cells, including macrophages. Hematopoiesis is controlled by soluble factors known as cytokines, that influence changes in transcription factors within the target cells, resulting in cell fate changes and the final development of specific effector cells. The processes involved in macrophage development have been largely derived from mammalian model organisms. However, recent advancements have been made in the understanding of macrophage development in bony fish, a group of organisms that rely heavily on their innate immune defences. Our understanding of the growth factors involved in teleost macrophage development, as well as the receptors and regulatory mechanisms in place to control them has increased substantially. Furthermore, model organisms such as the zebrafish have emerged as important instruments in furthering our understanding of the transcriptional control of cell development in fish as well as in mammals. This review highlights the recent advancements in our understanding of teleost macrophage development. We focused on the growth factors identified to be important in the regulation of macrophage development from a progenitor cell into a functional macrophage and discuss the important transcription factors that have been identified to function in teleost hematopoiesis. We also describe the findings of in vivo studies that have reinforced observations made in vitro and have greatly improved the relevance and importance of using teleost fish as model organisms for studying developmental processes.

Colony stimulating factor-1 (CSF-1) in pregnancy

Uterine growth factors appear to play a role in the regulation of pregnancy. One of these, colony stimulating factor-1 (CSF-1), synthesized by the uterine epithelium under the control of female sex steroids, has been shown to have important functions both before implantation and during the formation of the placenta. In the female reproductive tract the CSF-1 receptor, the product of the c-fms proto-oncogene, is expressed in decidual cells, trophoblasts and macrophages, indicating that these cells are the primary targets for CSF-1. This article reviews the biology of CSF-1 during gestation as well as the possible involvement of CSF-1 and its receptor in the aetiology of gynaecological tumours.

The molecular signature of spermatogonial stem/progenitor cells in the 6-day-old mouse testis

To characterize the molecular phenotype of spermatogonial stem cells (SSCs), we examined genes that are differentially expressed in the stem/progenitor spermatogonia compared to nonstem spermatogonia. We isolated type A spermatogonia (stem and nonstem type A) from 6-day-old mice using sedimentation velocity at unit gravity and further selected the stem/progenitor cell subpopulation by magnetic activated cell sorting with an antibody to GDNF-receptor-alpha-1 (GFRA1). It has been previously shown that GFRA1 is expressed in SSCs and is required for their stemness. The purity of the isolated cells was approximately 95% to 99% as indicated by immunocytochemistry using anti-GFRA1. Comparison of GFRA1-positive and GFRA1-negative spermatogonia by microarray analysis revealed 99 known genes and 12 uncharacterized transcripts that are overexpressed in the former cell population with a >2-fold change. Interestingly, the highest level of overexpression was observed for Csf1r, encoding the receptor for macrophage colony-stimulating factor (M-CSF, official symbol CSF1), which has a well-established role in the regulation of myeloid progenitor cells. Analysis of our microarray data with a bioinformatics software program (Ingenuity Systems) revealed the potential role of various signaling pathways in stem/progenitor spermatogonia and suggested a common pathway for GFRA1 and CSF1R that may lead to their proliferation. Further investigation to test this hypothesis has shown that CSF1 promotes cell proliferation in primary cultures of the isolated type A spermatogonia and in the spermatogonial-derived stem cell line C18-4. Semiquantitative RT-PCR and immunohistochemistry confirmed the previously mentioned microarray data. Collectively, this study provides novel molecular signatures for stem/progenitor spermatogonia and demonstrates a role for CSF1/CSF1R signaling in regulating their proliferation.

Protective potential of SCF for mice preimplantation embryos cultured in vitro in suboptimal conditions

PURPOSE

To examine the effect of stem cell factor (SCF) to embryos exposed to detrimental factors.

METHODS

Mice embryos cultured in control medium or Exp.1. with FasL or FasL+SCF Exp.2. with hydrogen peroxide (HP) or HP+SCF; Exp.3. frozen-thawed and cultured with or without SCF. Immunohistochemistry for Fas and c-kit receptors was performed in blastocysts. Blastocyst rates, total numbers of blastocyst cells (TB) and inner cell mass cell counts (ICM) were determined.

RESULTS

Immunohistochemical studies revealed expression of both Fas and c-kit in blastocyst cells. Exp.1. Significantly more blastocysts were found in control when compared to FasL group and to FasL+SCF group. TB and ICM counts in control and FasL+SCF group were significantly higher comparing to FasL group. Exp.2. We found significant differences between three groups in all three evaluated parameters. The highest blastocyst rates, TB and ICM counts were found in control, lower in HP+SCF group and the worst in HP group. Exp.3. No significant differences in TB and ICM counts were found. More embryos formed blastocyst in control than in two cryopreserved groups. Blastocyst rates did not differ between two cryopreserved groups.

CONCLUSION

SCF may improve culture of embryos exposed to unfavorable milieu.

Kit ligand 2 promotes murine oocyte growth in vitro

Oocyte-granulosa cell communication, mediated by paracrine factors, is essential for oocyte development. Kit ligand (KITL) is expressed in granulosa cells as soluble (KITL1) or membrane-associated (KITL2) proteins. However, the relative biopotency of each isoform during oocyte development is unknown. Our initial results showed that Kitl2 was down-regulated in cultured granulosa cells. To determine the effect of the two isoforms of KITL on oocyte growth, Kitl-deficient fibroblasts were transfected with constructs expressing either KITL1 or KITL2, and growing oocytes were isolated from 12-day-old mice and cultured on the transfected fibroblasts for 2 days. At the end of culture, oocyte diameters were measured, the incidence of spontaneous germinal vesicle breakdown (GVBD) was noted, and oocytes were analyzed for KIT receptor expression. Oocyte growth occurred only in the presence of the KITL2-producing fibroblasts, and suppression of KITL2 expression impaired oocyte growth. Up-regulation of KIT expression occurred in the presence of KITL2 but not KITL1. The presence of KITL2 inhibited spontaneous GVBD. Meiosis inhibitors did not attenuate the GVBD that occurred in the absence of KITL2, suggesting that this process reflects oocyte degeneration rather than meiotic progression. These results indicate that KITL2 is the principal KITL isoform required for oocyte growth and survival in vitro.

Effect of bacterial endotoxins on superovulated mouse embryos in vivo: is CSF-1 involved in endotoxin-induced pregnancy loss?

Mammalian embryonic development is regulated by several cytokines and growth factors from embryonic or maternal origins. Since CSF-1 plays important role in embryonic development and implantation, we investigated its role in gram-negative bacterial LPS-induced implantation failure. The effect of LPS on normal (nonsuperovulated) and superovulated in vivo-produced embryos was assessed by signs of morphological degeneration. A significantly similar number of morphologically degenerated embryos recovered from both nonsuperovulated and superovulated LPS treated animals on day 2.5 of pregnancy onwards were morphologically and developmentally abnormal as compared to their respective controls (P < .001. Normal CSF-1 expression level and pattern were also altered through the preimplantation period in the mouse embryos and uterine horns after LPS treatment. This deviation from the normal pattern and level of CSF-1 expression in the preimplantation embryos and uterine tissues suggest a role for CSF-1 in LPS-induced implantation failure.

Role of c-kit/SCF in cause and treatment of gastrointestinal stromal tumors (GIST)

c-Kit encodes for the receptor tyrosine kinase (RTK) and belongs to type III receptor family. This includes platelet derived growth factor (PDGF) alpha and beta and macrophage colony stimulating factor (mCSF) apart from others. Their characteristic features are the presence of five immunologlobulin like domains in the extracellular region and 70-100 residues long kinase insert domain in the cytoplasmic region. The RTKs activate several signaling pathways within the cells leading to cell proliferation, differentiation, migration or metabolic changes. The Kit ligand-stem cell factor (SCF) induces a rapid and complete receptor dimerization resulting in activation by autophosphorylation of the catalytic tyrosine kinase and generation of signal transduction leading to regulation of cell growth. Various mutations in c-kit such as insertions and deletions (without affecting reading frame) and point mutations in the inhibitory juxtamembrane (JM) domain encoded by exon 11 have been reported in gastrointestinal stromal tumors (GISTs). Thus, c-kit signaling is believed to play a role in tumorigenesis. Efforts are being made to control and treat these tumors by blocking kit signaling using Imatinib with varying degrees of success. This review deals with the features of c-kit, its ligand and roles in gastrointestinal stromal tumors.

Conditional deletion of the colony stimulating factor-1 receptor (c-fms proto-oncogene) in mice

Colony stimulating factor-1 (CSF-1) is the primary regulator of the mononuclear phagocytic lineage acting through its transmembrane tyrosine kinase receptor, CSF-1R, that is the product of the c-fms proto-oncogene. Null mutations in either the ligand or the receptor genes result in a severe osteopetrosis as well as a number of other phenotypes, including reproductive defects and perturbations in organ development. The CSF-1R is also expressed in oocytes, myoblast progenitors, decidual, and trophoblastic cells. To distinguish cell type specific phenotypes, we have created a conditional allele of the Csf1r by placing LoxP sites around Exon 5 of the Csf1r gene in mice. Excision of this floxed sequence results in a null allele that in the homozygous state gives a phenotype indistinguishable of the complete Csf1r null mutant mouse. This conditional allele will prove extremely valuable to study the spatial and temporal roles of CSF-1R.

The Cell-Surface Isoform of Colony Stimulating Factor 1 (CSF1) Restores but Does Not Completely Normalize Fecundity in CSF1-Deficient Mice1

The complete genetic absence of colony stimulating factor 1 (CSF1) in CSF1-deficient Csf1(op)/Csf1(op) mice leads to reproductive defects in males and females. Although the cell-surface or membrane-bound isoform of CSF1 (mCSF1) is biologically active in bone, little is known about its role in reproduction. Transgenic mice expressing mCSF1 under the control of the 2.4-kb rat collagen type I alpha promoter were developed [Tg(Col1a1-mCSF1)1Gqy] and bred onto a Csf1(op)/Csf1(op) background [Csf1(op)/Csf1(op); Tg(Col1a1-mCSF1)1Gqy] to examine the effects of the mCSF1 isoform in bone in vivo. Surprisingly, when interbred, these mice were fertile. The Csf1(op)/Csf1(op); Tg(Col1a1-mCSF1)1Gqy transgenic male mice have normal libido, sperm number and percent of motile sperm. In Csf1(op)/Csf1(op); Tg(Col1a1-mCSF1)1Gqy females, puberty and estrus cycles are at expected age and duration. Further, females are able to carry pregnancies to term and nurse their offspring. Crosses of Csf1(op)/Csf1(op); Tg(Col1a1-mCSF1)1Gqy males or females with their control littermates showed no significant differences in either number or viability of offspring. However, crossing Csf1(op)/Csf1(op); Tg(Col1a1-mCSF1)1Gqy males with Csf1(op); Tg(Col1a1-mCSF1)1Gqy females resulted in a decline in both the number and viability of offspring, suggesting that a subtle reproductive defect might persist in the transgenic animals that was only manifest when the animals were interbred. Although the gravid murine uterus expresses extremely high levels of CSF1 that are thought to be important for reproduction, uterine tissue levels of CSF1 remained low and unchanged during pregnancy in Csf1(op)/Csf1(op); Tg(Col1a1-mCSF1)1Gqy mice. Low levels of CSF1 protein were detected in serum and in lung and uterine tissue in Csf1(op)/Csf1(op); Tg(Col1a1-mCSF1)1Gqy mouse, which likely result from the known proteolytic shedding of mCSF1 from the cell surface. These data are consistent with the conclusion that mCSF1, when shed from the cell surface, can support reproduction and that high uterine tissue levels of CSF1 may not be required for mouse reproduction.

Modulation of CSF-1-regulated post-natal development with anti-CSF-1 antibody

Colony-stimulating factor-1 (CSF-1) regulates the survival, proliferation and differentiation of macrophages. CSF-1-deficient mice are osteopetrotic due to a lack of osteoclasts, while their tissue macrophage deficiencies and an absence of CSF-1 regulation of CSF-1 receptor-expressing cells in the female reproductive tract contribute to their pleiotropic phenotype. To further understand CSF-1 regulation of macrophages in vivo, we developed a neutralizing anti-mouse CSF-1 antibody which was expressed as a recombinant Fab' fragment and coupled to 40 kDa polyethylene glycol. As developmental regulation by CSF-1 is highest during the early post-natal period, the ability of this anti-CSF-1 reagent to inhibit development was tested by regular subcutaneous injection of mice from post-natal days 0.5-57.5. Antibody treatment decreased growth rate, decreased osteoclast number, induced osteopetrosis, decreased macrophage density in bone marrow, liver, dermis, synovium and kidney and decreased adipocyte size in adipose tissue, thereby inducing phenotypes shared by CSF-1- and CSF-1 receptor-deficient mice. While the antibody blocked macrophage development in some tissues, macrophage densities in other tissues were initially high and were reduced by treatment, proving that the antibody also blocked macrophage maintenance. Since cell surface CSF-1 is sufficient for the maintenance of normal synovial macrophage densities, these studies suggest that anti-CSF-1 Fab'-PEG efficiently neutralizes all three CSF-1 isoforms in vivo, namely the secreted proteoglycan, secreted glycoprotein and cell surface glycoprotein. Since CSF-1 has been shown to enhance chronic disease development in a number of mouse model systems, these studies demonstrate the feasibility of neutralizing CSF-1 effects in these models with an anti-CSF-1 antibody.

Evaluation of the quality of porcine somatic cell nuclear transfer embryo by gene transcription profiles

This study aimed to evaluate the quality of porcine somatic cell nuclear transfer (SCNT) embryos by examining its gene transcription patterns. Embryos were produced by SCNT, intracytoplasmic sperm injection (ICSI) or under different conditions, and transcripts of genes for fibroblast growth factor receptor (FGFr) 2IIIc, FGFr72IIIb, X inactive-specific transcript (Xist), interleukin 6 (IL6), IL6 receptor (IL6r) alpha and c-kit ligand, were detected by real-time RT-PCR. The percentages of embryos in which these transcripts were detected were similar in SCNT and ICSI embryos. On the other hand, the transcriptional levels of the FGFr72IIIb and IL6ralpha genes were 0.5 times less and 2 times more, respectively, in SCNT blastocysts than those of ICSI blastocysts (p<0.05). When nuclear transfer was performed before or after activation of oocytes, embryos in the latter case showed significantly lower frequencies of having FGFr72IIIb (74% vs. 90%) and Xist (3% vs. 33%) transcripts compared to the former case embryos (p<0.05). When two lines of nuclear donor cells with different developmental potencies were used, the transcriptional profiles in the reconstructed embryos did not show any significant differences. Our study suggests that expression profiles of FGFr72IIIb, IL6ralpha, and Xist can be used as markers for the diagnosis of the developmental potency of porcine nuclear transfer embryos.

Expression of mRNA and protein of macrophage colony-stimulating factor and its receptor in human follicular luteinized granulosa cells

OBJECTIVE

To evaluate the concentration of macrophage colony-stimulating factor (M-CSF) in serum and follicular fluid (FF) at the time of oocyte retrieval and to detect expression of M-CSF and its receptor by luteinized granulosa cells (GCs).

DESIGN

Collection of serum and FF at the time of oocyte retrieval.

SETTING

A university IVF- intracytoplasmic sperm injection (ICSI) program.

PATIENT(S)

Serum and FF were obtained from 85 women undergoing oocyte retrieval.

INTERVENTION(S)

Serum and FF were obtained from 85 women. The GCs were pooled from 15 (3 x 5) patients (3-14 oocytes each).

MAIN OUTCOME MEASURE(S)

The M-CSF concentration was determined by ELISA, the expression of M-CSF and its receptor by the immunocytochemical technique and reverse transcription polymerase chain reaction analysis. In addition, M-CSF expression was investigated by cell culture time course studies.

RESULTS

The median M-CSF concentration in FF (2,409.2 pg/mL) was significantly higher than that in serum (242.5 pg/mL). The M-CSF and its receptor were expressed by GCs.

CONCLUSION(S)

The significantly higher level of M-CSF in FF than in serum and the expression of M-CSF and its receptor in FF by GCs suggest an important role for this growth factor in ovarian function.

Animal models of implantation

Implantation is an intricately timed event necessary in the process of viviparous birth that allows mammals to nourish and protect their young during early development. Human implantation begins when the blastocyst both assumes a fixed position in the uterus and establishes a more intimate relationship with the endometrium. Due to the impracticalities of studying implantation in humans, animal models are necessary to decipher the molecular and mechanical events of this process. This review will discuss the differences in implantation between different animal models and describe how these differences can be utilized to investigate discrete implantation stages. In addition, factors that have been shown to be involved in implantation in the human and other various animal models including growth factors, cytokines, modulators of cell adhesion, and developmental factors will be discussed, and examples from each will be given.

Colony-stimulating factor-1 promotes clonogenic growth of normal murine colonic crypt epithelial cells in vitro

The intestinal epithelium is a continuously renewing tissue. In the colon, stem cells are maintained at the base of highly organized crypts, where they undergo asymmetric division and give rise to daughter cells that proliferate and migrate up the crypt as they differentiate, then become senescent and are finally shed into the intestinal lumen. The growth factor requirements of fetal and prenatal colon cells for colony formation and that influence the establishment of cell lines from Immorto-mouse (Charles River, Wilmington, MA) transgenic embryos were explored. Single cell suspensions were isolated and cultured in a large range of growth factor combinations and conditions to determine their growth properties in soft agar. We report an important advance in the culture of mouse colonocytes by using macrophage colony-stimulating factor (CSF-1) and granulocyte-macrophage colony-stimulating factor (GM-CSF). A substantial proportion of colonies grown under low oxygen tension in the presence of CSF-1 and GM-CSF express intestinal epithelial A33 antigen, have the expected gene expression profile, including c-fms and transcription factor c-myb, and show an appropriate epithelial cell morphology and undetectable CD45. Confocal microscopy on isolated crypts displays basolateral expression of c-Fms and E-cadherin on most epithelial cells. Fetal colon cultures from the Immorto-mouse with CSF-1 produced rapid outgrowth and readily established cell lines, in contrast to cultures without CSF-1. These observations have implications for the understanding of colon epithelial development and recovery following cytotoxic damage as well as providing a basis for the observation that some colon (and other epithelial) tumor cells respond to CSF-1 and GM-CSF.

Molecular cloning and expression analysis of a macrophage-colony stimulating factor receptor-like gene from rainbow trout, Oncorhynchus mykiss

The M-CSF and its receptor (M-CSFR, CSF-1R or c-fms proto-oncogene) system were initially implicated as essential in mammals for normal monocyte development as well as for pregnancy. To allow a comparison with the M-CSF and M-CSFR system of an oviparous animal, we cloned a M-CSFR-like gene from rainbow trout (Oncorhynchus mykiss). The gene was cloned from a cDNA library of head kidney. It contained an open reading frame encoding 967 amino acids with a predicted size of 109 kDa. The putative amino acid sequence of rainbow trout M-CSFR showed 54% amino acid identity to fugu (Takifugu rubripes) M-CSFR, 52% to zebrafish (Danio rerio) M-CSFR and 40% to mouse (Mus musculus) and human (Homo sapiens) M-CSFR. The M-CSFR-like gene was constitutively expressed in head kidney, kidney, intestine, spleen and blood. The gene was detected especially in the ovary of immature female rainbow trout. These results suggest that a M-CSFR-like receptor may be involved in female reproductive tracts even in an oviparous animal like fish.

Coculture with a human granulosa cell line enhanced the development of murine preimplantation embryos via SCF/c-kit system

PURPOSE

To evaluate the effect on the coculture of murine embryos with a human ovarian granulosa tumor derived cell line (KGN cells).

METHODS

We observed microscopically the growth of murine preimplantation embryos in the coculture system with KGN cells or in the presence with exogenous stem cell factor (SCF). The reverse transcriptase-polymerase chain reaction (RT-PCR) method was used to analyze the gene expression of SCF in KGN cells cocultured with murine embryos.

RESULTS

The coculture system with KGN cells significantly increased the rate of embryo development to late blastocyst and to hatching stage. We also found that coculture with murine embryos enhanced the gene expression of SCF in KGN cells. Adding human recombinant SCF to the medium significantly enhanced embryo development to late blastocyst and hatching stage.

CONCLUSIONS

KGN cells may facilitate preimplantion embryo development through SCF/c-kit paracrine system.

Identification of the M-CSF Receptor in Endometriosis by Immunohistochemistry and RT-PCR

PROBLEM

The aim of this paper is to provide further evidence that the dystopic proliferation of endometriotic epithelia is caused by the stimulation of peritoneal macrophages. It is essential to show that endometriotic epithelial cells express the macrophage colony-stimulating factor receptor (M-CSFR) which binds the M-CSF produced by the peritoneal macrophages.

METHOD OF STUDY

For the detection of M-CSFR, samples of ectopic endometrium (n = 79) and eutopic endometrium (n = 18) were compared. The specimens were gained at operative laparoscopy in the proliferative phase of the cycle. Cryostat sections were used for immunohistochemical detection. For in vitro reverse transcriptase polymerase chain reaction (RT-PCR) tests, the tissue was immediately shock frozen on paraffin sections. For the in situ RT-PCR technique the specimens were placed in a para-formaldehyde solution, embedded in paraffin and later processed. The Gene Amp 1000 in situ PCR system (Perkin Elmer) was used as the thermal cycler.

RESULTS

M-CSF and the M-CSF receptor are present in eutopic and ectopic endometrium. Qualitatively, with both PCR techniques we found the M-CSF receptor to be present in all samples examined. Using the histochemical detection technique, the M-CSF receptor was found in nearly 70% of endometriosis patients compared with a statistically significant lower percentage in normal endometrium.

CONCLUSIONS

The in situ RT-PCR technique and immunohistochemistry elaborated the need to trace the cellular sources of the M-CSF receptor. The identification of the M-CSF receptor in endometriotic tissue and in endometrium is apt to open a new experimental field in endometriosis research.

Pre-Implantation Conceptus and Maternal Uterine Communications: Molecular Events Leading to Successful Implantation

Implantation, a critical step for mammals in establishing pregnancy, requires successful completion of sequential events such as maternal uterine development, conceptus development and attachment, and placental formation. To reach the stage of placental formation, synchronized development of the conceptus and uterus throughout the implantation period is absolutely required. A number of factors expressed at the uterine endometrium and/or conceptus, which are associated with peri-implantation development, have been identified. In addition to a temporal and spatial expression of these factors, their roles in intra- and inter-cellular interactions make it difficult to fully understand physiological roles played during the critical period. This paper focuses on early conceptus development, maternal preparation for implantation and uterine-conceptus communication during the pre-implantation period, rather than the subsequent events such as conceptus attachment to the maternal endometrium. New aspects of pre-implantation processes are evaluated through simultaneous expressions of transcription factors as they possibly regulate the complex processes of implantation events in murine species and ruminant ungulates.

Dynamic regulation of expression of colony-stimulating factor 1 in the reproductive tract of cattle during the estrous cycle and in pregnancy

Colony-stimulating factor 1 (CSF-1) is a hematopoetic cytokine that also plays an important role in placental physiology. We report here the molecular cloning of two alternative splice variants of the bovine gene coding for a putative secreted and a membrane-bound form of the cytokine and the dynamic regulation of expression in the reproductive tract of cattle during the estrous cycle and pregnancy. Bovine CSF-1 was expressed mainly as the 3- and 4-kilobase (kb) transcripts, but 1.4- and 0.8-kb mRNAs were also detected in Day 50-70 pregnant uterine tissue. During the estrous cycle, both the 4- and 3-kb mRNAs were present, but the 3-kb putative membrane-bound form was more abundant than the 4-kb secreted form during diestrus. This pattern of expression was reversed in pregnancy, so that the exponential increase in CSF-1 expression seen during pregnancy was due predominantly to increased abundance of the 4-kb transcript. The change in the 4-kb:3-kb ratio was detected between Day 14 and Day 17, approximately the time of maternal recognition of pregnancy. Thus, CSF-1 was identified as one gene whose expression in the uterus might be altered early in response to the presence of the conceptus. CSF-1 was also expressed in the extraembryonic membranes of the conceptus and in the trophoblastic cells of the fetal cotyledons after the formation of the placentomes. The high level of CSF-1 expression during bovine pregnancy in uteroplacental tissues is consistent with its proposed role in placental physiology.

Characterization of the fertility of Kit haplodeficient male mice

The role of the proto-oncogene Kit expression during gonadal development, then in differentiated spermatogonia has been thoroughly established. The present study was designed to investigate the consequences of a partial defect in Kit gene expression on sperm fertilizing ability, using Kit haplodeficient mice (kitW-lacZ/+). Same inbred mice (kit+/+) were used as controls. Epididymal sperm characteristics and in vivo fertility were assessed, then in vitro-fertilization experiments were carried out for mice of both genotypes. Epididymal sperm count was drastically reduced, and sperm motility was also decreased in kitW-lacZ/+ compared with kit+/+ males. Both in vivo or in vitro fertility were greatly reduced in kitW-lacZ/+ compared with kit+/+ males. By contrast, the fertility of kitW-lacZ/+ females was apparently unaffected. Additionally, a higher number of spermatozoa with undetected acrosomal contents was revealed by fluorescein isothiocyanate-labelled Pisum sativum agglutinin acrosomal staining after epididymal sperm retrieval in kitW-lacZ/+ mice, whereas no difference was observed after induction of acrosomal reaction in mice of either genotype. Ultra-structural data confirmed the higher frequency of abnormal acrosome in spermatozoa of kitW-lacZ/+ mice. Thus, sperm production is impaired in Kit haplodeficient mice both on a quantitative and a qualitative basis. Finally, we show that one single copy of Kit gene is not sufficient to maintain genuine fertility in male mice.

Targeted disruption of the mouse colony-stimulating factor 1 receptor gene results in osteopetrosis, mononuclear phagocyte deficiency, increased primitive progenitor cell frequencies, and reproductive defects

The effects of colony-stimulating factor 1 (CSF-1), the primary regulator of mononuclear phagocyte production, are thought to be mediated by the CSF-1 receptor (CSF-1R), encoded by the c-fms proto-oncogene. To investigate the in vivo specificity of CSF-1 for the CSF-1R, the mouse Csf1r gene was inactivated. The phenotype of Csf1(-)/Csf1r(-) mice closely resembled the phenotype of CSF-1-nullizygous (Csf1(op)/Csf1(op)) mice, including the osteopetrotic, hematopoietic, tissue macrophage, and reproductive phenotypes. Compared with their wild-type littermates, splenic erythroid burst-forming unit and high-proliferative potential colony-forming cell levels in both Csf1(op)/Csf1(op) and Csf1(-)/Csf1r(-) mice were significantly elevated, consistent with a negative regulatory role of CSF-1 in erythropoiesis and the maintenance of primitive hematopoietic progenitor cells. The circulating CSF-1 concentration in Csf1r(-)/Csf1r(-) mice was elevated 20-fold, in agreement with the previously reported clearance of circulating CSF-1 by CSF-1R-mediated endocytosis and intracellular destruction. Despite their overall similarity, several phenotypic characteristics of the Csf1r(-)/Csf1r(-) mice were more severe than those of the Csf1(op)/Csf1(op) mice. The results indicate that all of the effects of CSF-1 are mediated via the CSF-1R, but that subtle effects of the CSF-1R could result from its CSF-1-independent activation.

The influence of growth factors on the development of preimplantation mammalian embryos

The development of the preimplantation mammalian embryo from a fertilized egg to a blastocyst capable of implanting in the uterus is a complex process. Cell division must be carefully programmed. The embryonic genome must be activated at the appropriate stage of development, and the pattern of gene expression must be carefully coordinated for the initiation of the correct program of differentiation. Cell fates must be chosen to establish specific cell types such as the inner cell mass and the trophectoderm, which give rise to the embryo proper and the placenta, respectively. This review summarizes recent findings concerning the influence of growth factors on the development of preimplantation mammalian embryos. Maternal factors secreted into the lumen of the female reproductive tract as well as substances synthesized by the developing embryo itself help to regulate this process. Studies of embryos in culture and investigations using homologous recombination to create embryos and animals null for specific genes have enabled the identification of several growth factors that appear essential for preimplantation mammalian embryo development. Some of the factors are required maternal factors; others are embryo-derived autocrine and paracrine factors. Studies using molecular biology are beginning to identify differences in the patterns of genes expressed by naturally derived embryos and those developing in culture. The knowledge gained from studies on growth factors, media, embryonic development, and gene expression should help improve culture conditions for embryos and will provide for safer outcomes from assisted reproductive procedures in human and animal clinics.

Preimplantation development of the mammalian embryo and its regulation by growth factors

Preimplantation development in mammals involves both the development of the embryo and the preparation of the uterus in anticipation of blastocysts implantation. Preparation of the uterus for implantation is primarily under the control of the ovarian sex steroids, estrogen and progesterone. Increasing evidence is revealing that their effects on cell proliferation and differentiation in the uterus are medicated by locally produced growth factors and cytokines. In contrast, preimplantation development of the embryo to the blastocyst stage appears to be independent of exogenous growth factors. Implantation, the point at which the blastocyst forms a more intimate association with the maternal tissues, is regulated by the uterine expression of leukemia inhibitory factor (LIF). LIF is required both to promote embryo attachment and for decidualization of the uterus. In the absence of LIF, neither of these events occur. Uterine expression of LIF at the time of implantation has been described in many species, suggesting that LIF may be of general significance in regulating embryo implantation in mammals.

Function of 90-kDa heat shock protein in cellular differentiation of human embryonal carcinoma cells

Heat shock proteins (HSPs) have been recognized as molecules that maintain cellular homeostasis during changes in the environment. Here we report that HSP90 functions not only in stress responses but also in certain aspects of cellular differentiation. We found that HSP90 showed remarkably high expression in undifferentiated human embryonal carcinoma (EC) cells, which were subsequently dramatically down-regulated during in vitro cellular differentiation, following retinoic acid (RA) treatment, at the protein level. Surprisingly, heat shock treatment also triggered the down-regulation of HSP90 within 48 h at the protein level. Furthermore, the heat treatment induced cellular differentiation into neural cells. This down-regulation of HSP90 by heat treatment was shifted to an up-regulation pattern after cellular differentiation in response to RA treatment. In order to clarify the functions of HSP90 in cellular differentiation, we conducted various experiments, including overexpression of HSP90 via gene transfer. We showed that the RA-induced differentiation of EC cells into a neural cell lineage was inhibited by overexpression of the HSP90alpha or -beta isoform via the gene transfer method. On the other hand, the overexpression of HSP90beta alone impaired cellular differentiation into trophoectoderm. These results show that down-regulation of HSP90 is a physiologically critical event in the differentiation of human EC cells and that specific HSP90 isoforms may be involved in differentiation into specific cell lineages.

Colony-stimulating factor-1 (CSF-1) expression in the uteroplacental unit of mice with spontaneous and induced pregnancy loss

CSF-1 plays an important role in female reproduction and normal embryo development. To understand further CSF-1 function in normal and, especially, in compromised pregnancy, we studied the pattern of its mRNA expression as well as expression of its receptor (c-fms) in the uteroplacental units of mice with induced (cyclophosphamide (CY)-treated) and spontaneous (CBA/J x DBA/2J mating combination) pregnancy loss. RNase protection analysis demonstrated the presence of two forms of CSF-1 mRNA in the uteroplacental unit corresponding to 1400- and 263-bp protective fragments. Densitometric analysis demonstrated that the level of 1400-bp mRNA form was decreased by 40% in the uteroplacental units of mice with CY-induced pregnancy loss compared with the control mice. About 20% decrease in 263-bp protective fragment was registered in resorbing versus non-resorbed placenta of CBA/J females mated to DBA/2J males. As judged by in situ hybridization assay, CSF-1 mRNA transcripts were localized in the uterine epithelium and stroma, while c-fms mRNA was found mainly in the trophoblast. The number of metrial gland cells as well as the number of uterine leucocytes expressing CSF-1 and c-fms mRNAs was substantially lower in the uteroplacental unit of mice with pregnancy loss than in control animals. Maternal immunostimulation, while significantly decreasing the resorption rate in mice with CY-induced pregnancy loss, also strengthened CSF-1 mRNA expression at the fetomaternal interface and resulted in reconstitution in the number of CSF-1+ uterine leucocytes and metrial gland cells. These data suggest a role for uterine CSF-1 in the physiology of normal and compromised pregnancy and demonstrate a possible involvement of CSF-1-associated signalling in mechanisms of placenta and endometrium repair following immunopotentiation.

The potential role of stem cell factor and its receptor c-kit in the mouse blastocyst implantation

Embryo implantation is a complex process that requires the interaction of embryo and endometrium. Several growth factors and cytokines appear to be involved in this process. Stem cell factor (SCF) and its receptor c-kit regulate the proliferation and survival of germ cells and play an important role in follicular development. However, little information is available on the role of SCF and c-kit in the process of blastocyst implantation. In the present study, we examined the expression of SCF and c-kit mRNA in mouse embryos and in the stromal and epithelial cells of the uterine endometrium by reverse transcription-polymerase chain reaction (RT-PCR). SCF mRNA was expressed in the spreading blastocysts and endometrial cells, with especially strong expression occurring in the stromal cells. Expression of c-kit mRNA was detected in the blastocysts and spreading blastocysts, as well as in the endometrial cells. By immunocytochemical studies, staining for c-kit protein was observed in the in-vitro spreading trophoblasts. We found that 50-100 ng/ml SCF significantly promoted the expansion of the surface area of the spreading blastocysts (P < 0.01). These results are consistent with the hypothesis that SCF derived from endometrial cells and the implanting embryo exerts paracrine and/or autocrine action on the process of implantation by stimulating trophoblast outgrowth through its receptor c-kit.

Hormonal control of H-type alpha(1-2)fucosyltransferase messenger ribonucleic acid in the mouse uterus

The H epitope, an alpha(1-2)fucosylated carbohydrate structure, has been implicated in initial attachment of the murine blastocyst to luminal uterine epithelial cells in vitro. In this study, the expression of the H-type alpha(1-2)fucosyltransferase (FUT1) gene was examined in endometrium of mice. Northern blotting of luminal epithelial RNA identified a single 6.2-kilobase transcript. In situ hybridization studies showed a signal for FUT1 mRNA on Days 1-3 of pregnancy in glands and luminal epithelium. The signal diminished by Day 4 and could not be detected on Day 5 of pregnancy. The in situ signal in endometrial epithelia was highest at estrus and metestrus and was absent at diestrus. Estrogen treatment after ovariectomy gave strong FUT1 mRNA expression in epithelia, but with progesterone, progesterone + estrogen, or vehicle, no message could be detected. A semiquantitative reverse transcription-polymerase chain reaction (PCR) analysis of FUT1 mRNA from luminal epithelium generated large amounts of PCR product on Day 1 of pregnancy; this diminished on Days 2, 3, and 4, and the product was barely detectable on Day 5. A kinetic analysis of FUT1 activity on Day 1 of pregnancy suggested a single enzyme with a Michaelis-Menten constant (Km) of 0.29 mM towards phenyl-beta-D-galactoside and of 1.75 mM towards Galbeta(1-3)GalNAc. These results suggest that expression of the H epitope is regulated at the level of FUT1 transcription and that transcription is stimulated by estrogen in the endometrial epithelium.

Changes in macrophage colony-stimulating factor concentration in serum and follicular fluid in in-vitro fertilization and embryo transfer cycles

OBJECTIVE

To evaluate the changes of macrophage colony-stimulating factor concentration in serum and compare macrophage colony-stimulating factor concentration in follicular fluid (FF) through IVF-ET cycles.

DESIGN

Sera and the matched FFs were collected serially through the IVF-ET cycles and analyzed retrospectively with respect to macrophage colony-stimulating factor concentration.

SETTING

Department of Obstetrics and Gynecology of Kumamoto University Hospital.

PATIENT(S)

Ninety-four women underwent 129 cycles of ovulation induction by using GnRH agonist (GnRHa)-hMG-hCG for IVF-ET program.

INTERVENTION(S)

Serum and FF macrophage colony-stimulating factor concentrations were measured by ELISA.

MAIN OUTCOME MEASURE(S)

Concentrations of macrophage colony-stimulating factor in serum and FF.

RESULT(S)

Serum macrophage colony-stimulating factor concentration was gradually increased throughout ovarian stimulation, and reached a peak from the day of oocyte retrieval to 2 days after oocyte retrieval, whereas no significant change in macrophage colony-stimulating factor was observed in cases of poor ovarian response to hMG. The macrophage colony-stimulating factor concentration in follicles was significantly higher than that in sera on the day of oocyte retrieval, and the concentrations in follicles from which oocyte could be retrieved were significantly higher than those from which oocyte could not be retrieved.

CONCLUSION(S)

These results suggest that gonadotropins lead to an increase in ovarian macrophage colony-stimulating factor production, and that this macrophage colony-stimulating factor production in response to hMG administration is lost in poor ovarian responders. Thus, macrophage colony-stimulating factor may play an important role in the process of follicular maturation and ovulation as an intraovarian regulator.

Colony-stimulating factor-1 plays a major role in the development of reproductive function in male mice

Colony-stimulating factor-1 (CSF-1) is the principal regulator of cells of the mononuclear phagocytic lineage that includes monocytes, tissue macrophages, microglia, and osteoclasts. Macrophages are found throughout the reproductive tract of both males and females and have been proposed to act as regulators of fertility at several levels. Mice homozygous for the osteopetrosis mutation (csfm[op]) lack CSF-1 and, consequently, have depleted macrophage numbers. Further analysis has revealed that male csfm(op)/csfm(op) mice have reduced mating ability, low sperm numbers, and 90% lower serum testosterone levels. The present studies show that this low serum testosterone is due to reduced testicular Leydig cell steroidogenesis associated with severe ultrastructural abnormalities characterized by disrupted intracellular membrane structures. In addition, the Leydig cells from csfm(op)/ csfm(op) males have diminished amounts of the steroidogenic enzyme proteins P450 side chain cleavage, 3beta-hydroxysteroid dehydrogenase, and P450 17alpha-hydroxylase-lyase, with associated reductions in the activity of all these steroidogenic enzymes, as well as in 17beta-hydroxysteroid dehydrogenase. The CSF-1-deficient males also have reduced serum LH and disruption of the normal testosterone negative feedback response of the hypothalamus, as demonstrated by the failure to increase LH secretion in castrated males and their lack of response to exogenous testosterone. However, these males are responsive to GnRH and LH treatment. These studies have identified a novel role for CSF-1 in the development and/or regulation of the male hypothalamic-pituitary-gonadal axis.

Colony stimulating factor-1 in human follicular fluid

OBJECTIVE

To evaluate colony stimulating factor-1 (CSF-1) concentrations in serum and follicular fluid (FF) at the time of oocyte retrieval and to test for presence of messenger RNA (mRNA) for CSF-1 and its receptor, c-fms, in FF cells.

DESIGN

Collection of serum and FF at the time of oocyte retrieval.

SETTING

A university IVF program.

PATIENT(S)

Forty-five women undergoing oocyte retrieval for IVF.

INTERVENTION(S)

Serum and FF were obtained from 24 women, and FF only was obtained from 21 women.

MAIN OUTCOME MEASURE(S)

Colony-stimulating factor-1 concentrations were determined by RIA, and the presence of mRNA for CSF-1 and c-fms was determined by reverse transcriptase-polymerase chain reaction.

RESULT(S)

Mean FF concentrations of CSF-1 were significantly higher than mean serum levels (10.0 +/- 1.3 and 3.6 +/- 0.3 (+/-SE) ng/mL, respectively). Colony-stimulating factor-1 and c-fms message were detected in FF cells, and alternatively spliced forms of CSF-1 message were present.

CONCLUSION(S)

The presence of CSF-1, a primary regulator of tissue macrophages, in FF, and the presence of mRNA for CSF-1 and its receptor c-fms in FF-derived cells, suggest a role for this growth factor in ovarian function.

Role of colony-stimulating factor-1 in reproduction and development

The CSF-1 null mouse, osteopetrotic, has provided a powerful model in which to study the biological functions of CSF-1. In this review, I will describe our studies that have used this mouse model to determine the impact of a lack of CSF-1 on developmental processes and in reproduction. A role for CSF-1 in reproduction was originally suggested by the sex steroid hormone-regulated uterine epithelial synthesis of CSF-1 and the expression of its receptor in trophoblast and decidual cells. Studies on the fertility of CSF-1 deficient osteopetrotic mice (csfmop/csfmop) mice confirmed this suggestion and in addition revealed an unexpected function for CSF-1 in male fertility. In both sexes, CSF-1 appears to regulate gonadal steroidogenesis, probably through its action on macrophages that are abundant throughout the ovary and testis. In the female, CSF-1 affects ovulation in vivo and in vitro, and impacts the preimplantation embryo, increasing both its rate of development and the number of trophectodermal cells in the blastocyst. CSF-1 also has a role in mammary gland development during pregnancy, since at mid-gestation in csfmop/csfmop mice, ductal branching is impaired, and after partiturition, there is a failure to switch to lactation. The relative failure of csfmop/csfmop mice to respond to external stimuli also suggested a role for CSF-1 in the brain. CSF-1 mRNA is expressed in a regional specific manner in the brain through development whilst the CSF-1 receptor is expressed throughout the brain in microglia. CSF-1 is neurotrophic in embryonic neuronal cultures and its absence in csfmop/csfmop mice results in severe electro-physiological abnormalities in the cortex. This suggests that CSF-1 is a neurotrophic factor acting through the microglia. The pleiotropic roles for CSF-1 in reproduction and in the brain suggest that CSF-1 exerts many of its action through the trophic activities of cells of the mononuclear phagocytic lineage.