Development of a novel protocol for isolation and purification of human granulosa cells.

PURPOSE: To develop an optimal method of isolation and purification of human granulosa cells from ovarian follicular fluid. METHODS: Follicular fluid was collected from patients undergoing oocyte retrieval. A series of isolation and purification techniques was performed, involving density gradient centrifugation and use of different antibody-bead complexes. RESULTS: The highest percent yield of live purified granulosa cells came from density gradient centrifugation using sucrose polymer followed by positive selection of granulosa cells using primary antibody to MISRII and secondary antibody coupled to iron oxide beads. CONCLUSIONS: A novel protocol for granulosa cell purification has been developed yielding samples that are largely free of nondesirable cells. This protocol provides a purification solution, especially for patient samples that have significant RBC contamination.

Oct-4A isoform is expressed in human cord blood-derived CD133 stem cells and differentiated progeny.

OBJECTIVES: This study aims to establish whether the pluripotent embryonic stem cell marker and nuclear transcription factor Oct-4A isoform is expressed in human umbilical cord blood CD133 stem cells (CD133 cells) and their differentiated progeny. MATERIALS AND METHODS: CD133 cells were examined for expression of the embryonic stem cell marker Oct-4A by reverse transcription-polymerase chain reaction using primers specific for the coding region of the Oct-4A isoform. Immunocytochemistry and flow cytometry were performed using an antibody raised to a peptide from the unique amino-terminal domain of the Oct-4A isoform, that does not exist in the Oct-4B isoform. Furthermore, specificity was confirmed by pre-adsorption of the antibody with the peptide immunogen. Differentiation was determined before and after expansion in culture, by flow cytometry for haematopoietic stem cell and differentiation markers. For many studies, after 7 days of culture CD133-positive and CD133-negative cells were separated by flow cytometry for additional analyses. Multilineage haematopoietic proliferative potential was determined using colony-forming assays. RESULTS: Freshly isolated CD133 cells expressed Oct-4A mRNA and protein. The cells proliferated rapidly in culture producing only a small proportion of CD133-positive cells and a much larger proportion of non-self-renewing CD133-negative cells. Proliferation was also associated with loss of other adult stem cell markers, gain of differentiated haematopoietic markers, and maintenance of potential to generate haematopoietic lineages. Oct-4A mRNA and protein were expressed throughout these changes. CONCLUSIONS: Oct-4A, which is associated with self-renewal in embryonic stem cells, neither defines nor confers self-renewal to CD133 stem cells.

Directed engineering of umbilical cord blood stem cells to produce C-peptide and insulin.

OBJECTIVES: In this study, we investigated the potential of umbilical cord blood stem cell lineages to produce C-peptide and insulin. MATERIALS AND METHODS: Lineage negative, CD133+ and CD34+ cells were analyzed by flow cytometry to assess expression of cell division antigens. These lineages were expanded in culture and subjected to an established protocol to differentiate mouse embryonic stem cells (ESCs) toward the pancreatic phenotype. Phase contrast and fluorescence immunocytochemistry were used to characterize differentiation markers with particular emphasis on insulin and C-peptide. RESULTS: All 3 lineages expressed SSEA-4, a marker previously reported to be restricted to the ESC compartment. Phase contrast microscopy showed all three lineages recapitulated the treatment-dependent morphological changes of ESCs as well as the temporally restricted expression of nestin and vimentin during differentiation. After engineering, each isolate contained both C-peptide and insulin, a result also obtained following a much shorter protocol for ESCs. CONCLUSIONS: Since C-peptide can only be derived from de novo synthesis and processing of pre-proinsulin mRNA and protein, we conclude that these results are the first demonstration that human umbilical cord blood-derived stem cells can be engineered to engage in de novo synthesis of insulin.

Polypyrimidine tract-binding protein-associated splicing factor is a negative regulator of transcriptional activity of the porcine p450scc insulin-like growth factor response element.

The porcine P-450 cholesterol side-chain cleavage enzyme gene (P450scc) contains a 30-bp region [insulin-like growth factor response element (IGFRE)] that mediates insulin-like growth factor I (IGF-I)-stimulated gene expression and binds Sp1. In this study, we showed that polypyrimidine tract-binding protein (PTB)-associated splicing factor (PSF), an RNA-binding component of spliceosomes, binds to the IGFRE. Southwestern analysis with an IGFRE oligonucleotide showed that a protein (from Sp1-immunodepleted HeLa extract) fractionated on SDS-PAGE at 100 kDa. Microsequence analysis of 100-kDa band HeLa proteins detected PSF. DNA affinity chromatography, using an IGFRE mutant oligonucleotide that does not bind Sp1, isolated a protein that immunoreacted with PSF antibody. Deoxyribonuclease I (DNase I) footprint analysis showed recombinant PSF binds 5' of the Sp1-binding GC box of the IGFRE, and mutant oligonucleotides further delineated this region to a palindrome, CTGAGTC. Functional analysis of these mutants by transfection experiments in a cell line overexpressing the IGF-I receptor (NWTb3) found that an inability to bind PSF significantly increased the IGFRE transcriptional activity, while retaining responsiveness to IGF-I. Moreover, transfection of expression vectors for Sp1 and PSF in porcine granulosa cells found that Sp1 expression stimulated IGFRE transcriptional activity while PSF inhibited activity even with coexpression of Sp1. In conclusion, we identified PSF as an independent, inhibitory regulator of the transcriptional activity of the porcine P450scc IGFRE.

Troglitazone inhibits progesterone production in porcine granulosa cells.

Troglitazone (a thiazolidinedione that improves insulin resistance) lowers elevated androgen concentrations in women with polycystic ovarian syndrome. In this study, we assessed the direct effects of troglitazone on steroidogenesis in porcine granulosa cells. Troglitazone inhibited progesterone production in a dose- and time-dependent manner (earliest effects at 4 h, maximum at 24 h) without affecting cell viability. Progesterone production was also inhibited by troglitazone in the presence of 25-hydroxycholesterol, indicating that the drug does not affect intracellular cholesterol transport. Troglitazone also inhibited FSH- and forskolin-stimulated progesterone secretion. The reduced progesterone production was accompanied by marked elevations of pregnenolone concentrations, suggesting inhibition of 3beta-hydroxysteroid dehydrogenase (3beta-HSD). The activity of 3beta-HSD in troglitazone-treated granulosa cells was decreased by more than 60%, compared with controls after 24 h. Troglitazone did not affect aromatase activity in porcine granulosa cells. In summary, troglitazone has direct effects on porcine granulosa cell steroidogenesis. The drug specifically inhibits 3beta-HSD activity, resulting in impaired progesterone production. The clinical relevance of this direct in vitro effect on steroidogenesis needs further investigation.

Transcriptional activation of the porcine P450 11A insulin-like growth factor response element in MCF-7 breast cancer cells.

Insulin-like growth factor-I (IGF-I) stimulates the growth of MCF-7 breast cancer cells. This study determined the transcriptional activity of an IGF-I-responsive region (IGFRE) of porcine P450 11A (P450scc) after transfection into MCF-7 cells. IGF-I induced transcriptional activity of a porcine P450scc core promoter luciferase construct containing the IGFRE transfected in MCF-7 cells. Electrophoretic mobility shift assay with nuclear protein extract from MCF-7 cells showed two transcription factors binding to the IGFRE. Supershift assay determined that one transcription factor was Sp1. Electrophoretic mobility shift assay and transfection experiments with selected mutations to the IGFRE found that binding of both transcription factors was necessary to confer an IGF-I response. The binding activity of both transcription factors was increased with IGF-I treatment. In conclusion, MCF-7 cells contain Sp1 and another unknown transcription factor, P2, that bind to a known IGFRE (porcine P450scc) and induce reporter gene transcriptional activity with IGF-I treatment. Because Sp1 is a ubiquitous transcription factor, determining the identity of P2 may lead to cell-specific methods to impair breast cancer cell growth as mediated by IGF-I.

Tumor necrosis factor alpha inhibits transcriptional activity of the porcine P-45011A insulin-like growth factor response element.

We investigated the effects of tumor necrosis factor alpha (TNFalpha) on the transcriptional activity of the porcine P-45011A (P450scc) insulin-like growth factor response element (IGFRE). TNFalpha inhibited insulin-like growth factor-I (IGF-I)-stimulated P450scc mRNA concentrations in cultures of porcine granulosa cells. Transient transfection experiments in granulosa cells with deletion P450scc/luciferase constructs showed that TNFalpha inhibited the transcriptional activity of the IGFRE. IGF-I binding and IGF-I receptor mRNA concentrations in porcine granulosa cells were not inhibited by TNFalpha. Electrophoretic mobility shift assay with nuclear extract protein from porcine granulosa cells treated with IGF-I and TNFalpha showed that Sp1 and a second transcription factor, P2, bound to the IGFRE. While IGF-I treatment increased the binding activity of both factors, TNFalpha specifically inhibited the IGF-I-stimulated binding activity of P2. Transient transfection studies done in mouse fibroblasts overexpressing the IGF-I receptor (NWTb3) with the porcine IGFRE (three repeats) in an SV40/luciferase construct also showed TNFalpha inhibited IGF-I-stimulated reporter gene expression. We conclude that TNFalpha inhibits the transcriptional activity of the porcine P450scc IGFRE by preventing IGF-I-stimulated binding of P2.

Testosterone administration to elderly men increases skeletal muscle strength and protein synthesis.

Aging men develop a significant loss of muscle strength that occurs in conjunction with a decline in serum testosterone concentrations. We investigated the effects of testosterone administration to six healthy men [67 +/- 2 (SE) yr] on skeletal muscle protein synthesis, strength, and the intramuscular insulin-like growth factor I (IGF-I) system. Elderly men with serum testosterone concentrations of 480 ng/dl or less were given testosterone injections for 4 wk to produce serum concentrations equal to those of younger men. During testosterone administration muscle strength (isokinetic dynamometer) increased in both right and left hamstring and quadricep muscles as did the fractional synthetic rate of muscle protein (stable-isotope infusion). Ribonuclease protection assays done on total RNA from muscle showed that testosterone administration increased mRNA concentrations of IGF-I and decreased mRNA concentrations of insulin-like growth factor binding protein-4. We conclude that increasing testosterone concentrations in elderly men increases skeletal muscle protein synthesis and strength. This increase may be mediated by stimulation of the intramuscular IGF-I system.

Insulin-like growth factor-I increases expression of the porcine P-450 cholesterol side chain cleavage gene through a GC-rich domain.

The promoter/regulatory region of the porcine P-450 cholesterol side chain cleavage (P450scc) gene was cloned from a porcine genomic library. This gene contains a GC-rich region (-130-100) that mediates insulin-like growth factor I (IGF-I) and cAMP stimulation of gene expression in porcine granulosa cells. Stimulation of gene expression by cAMP occurs in 6 h, while IGF-I stimulation occurs in 24-48 h. This region is also responsive to insulin but not fibroblast growth factor. The effects of IGF-I and cAMP on gene expression in porcine granulosa cells are additive. In Y1 adrenal cells, the same region is responsive to cAMP but not to IGF-I. Gel shift assays using an oligonucleotide of this region and nuclear extract protein from porcine granulosa and Y1 adrenal cells identified three DNA-protein complexes (C1-C3). The binding activity of the complexes did not change with IGF-I or forskolin treatment of granulosa cells. Mutational analysis results were consistent with IGF-I regulating gene expression through the C2 DNA protein complex. Moreover, this complex binds differently in gel shift assay to mutant oligonucleotides with porcine and Y1 and nuclear extract protein. We conclude that IGF-I stimulates porcine P450scc gene expression through a distinct, cell-specific protein complex binding to a GC-rich domain.

Dexamethasone potentiates IGF-I actions in porcine granulosa cells.

To understand better interactions between glucocorticoids and insulin-like growth factor I (IGF-I) in the ovary, we studied the effects of dexamethasone on IGF-I stimulation of P-450 cholesterol side-chain cleavage enzyme (P-450scc) mRNA concentrations in porcine granulosa cells. Dexamethasone potentiated IGF-I-stimulated P-450scc mRNA concentrations and progesterone production in granulosa cell cultures. Time-course and dose-response studies showed that maximal enhancement occurred at a 1-microM dexamethasone concentration after 48 h of treatment. This potentiation was prevented by the glucocorticoid receptor antagonist RU-38486, 17 beta-hydroxy-11 beta-[-4-dimethyl-aminophenyl]estra-4,9,-dien-3-one (RU-486). We investigated mechanisms for this potentiation by performing IGF-I binding studies in porcine granulosa cells. Dexamethasone increased IGF-I binding, and Scatchard analysis showed this enhanced binding was caused by an increase in receptor concentration. Northern blot hybridization using a rat type I IGF-I receptor gene riboprobe showed that although dexamethasone alone did not increase IGF-I receptor mRNA concentrations, it did prevent a decrease in receptor mRNA concentrations caused by IGF-I. In addition, we used synthetic primers from conserved regions of the rat type I IGF-I receptor gene with total RNA from porcine granulosa cells and polymerase chain reaction to isolate a 615-base pair porcine type I IGF-I receptor cDNA clone. Ribonuclease protection assay results were similar to those found with the rat IGF-I receptor riboprobe. We conclude that dexamethasone potentiates IGF-I actions on steroidogenesis in the porcine ovary.