George T.C. Chen

Regulated expression of cadherin‐6 and cadherin‐11 in the glandular epithelial and stromal cells of the human endometrium

The cadherins are key morphoregulators. A switch in the cadherin subtype(s) expressed by a population of cells has been associated with the differentiation and formation of tissues during embryonic development. To date, the role(s) of the cadherins in the highly regulated remodeling processes which occur in the human endometrium in preparation for the implanting embryo remain poorly characterized. Here we report that two atypical cadherins, known as cadherin‐6 and cadherin‐11, are spatiotemporally expressed in the human endometrium during the menstrual cycle. Cadherin‐6 levels are high in both the glandular epithelium and stroma of the endometrium during the follicular phase and decline as the cycle enters the luteal phase. The down‐regulation of cadherin‐6 in the glandular epithelium during the luteal phase does not effect the levels of cadherin‐11 in this cell type. In contrast, the loss of cadherin‐6 expression in endometrial stroma cells is concomitant with an increase in the levels of cadherin‐11. Collectively, these observations suggest that multiple factors regulate the expression of these two endometrial cadherins. As a first step in identifying these factors, we examined the effects of progesterone on cadherin‐6 and cadherin‐11 expression in isolated endometrial stromal cells. Progesterone was capable of differentially regulating the expression of these two stromal cell adhesion molecules. These findings lend further support to our hypothesis that steroids are key regulators of cadherin expression in mammalian tissues. Dev. Dyn. 1998;211:238‐247.

Type 2 Cadherins in the Human Endometrium and Placenta: Their Putative Roles in Human Implantation and Placentation

PROBLEM: The Cadherins are a gene superfamily of calcium‐dependent cell adhesion molecules. To date, the role(s) of the Cadherins in human implantation remains poorly defined. METHOD OF STUDY: The spatiotemporal expression of the type 2 Cadherins, known as Cadherin‐11 and cadherin‐6, in the endometrium and placenta was examined using the reverse transcriptase‐polymerase chain reaction.

Cadherin-11 is a hormonally regulated cellular marker of decidualization in human endometrial stromal cells

Cultured human endometrial stromal cells respond to the gonadal steroids, progesterone and 17β‐estradiol, with morphological and biochemical changes that are characteristic of decidualization in vivo. To date, the cellular mechanisms involved in the terminal differentiation of human endometrial stromal cells into decidual cells remain poorly understood. We have recently determined that the novel cadherin subtype, known as cadherin‐11, is expressed by endometrial stromal cells undergoing decidualization during the luteal phase of the menstrual cycle and the decidua of pregnancy. In these studies, we have examined cadherin‐11 mRNA and protein expression levels in human endometrial stromal cells undergoing steroid‐mediated decidualization in vitro. Progesterone or a combination of progesterone and 17β‐estradiol increased stromal cadherin‐11 mRNA and protein expression levels with time in culture. Maximum levels of cadherin‐11 expression in these cell cultures correlated with a marked increase in IGFBP‐1 mRNA levels, a biochemical marker of decidualization. In contrast, 17β‐estradiol had no effect on stromal cad‐11 mRNA and protein expression or the levels of the IGFBP‐1 mRNA transcript. Taken together, these observations demonstrate that cadherin‐11 mRNA and protein expression levels are up‐regulated during the terminal differentiation of endometrial stromal cells—suggesting that this cell adhesion molecule may serve as a useful cellular marker for decidualization. Mol. Reprod. Dev. 52:158–165, 1999.

17BETA -ESTRADIOL POTENTIATES THE STIMULATORY EFFECTS OF PROGESTERONE ON CADHERIN-11 EXPRESSION IN CULTURED HUMAN ENDOMETRIAL STROMAL CELLS

Cadherin-11 (cad-11) is a novel member of the cadherin gene superfamily of calcium-dependent cell adhesion molecules. To date, the factors capable of regulating this cell adhesion molecule remain poorly characterized. We have recently determined that cad-11 expression in the human endometrium is tightly regulated during the menstrual cycle. The spatiotemporal expression of cad-11 in the stromal cells of the human endometrium during the menstrual cycle suggests that gonadal steroids regulate the expression of this endometrial cell adhesion molecule. In view of these observations, we have examined the ability of progestins, estrogens, and androgens, alone or in combination, to regulate cad-11 expression in isolated human endometrial stromal cells using Northern and Western blot analyses. In these studies, we have determined that progesterone, but not 17β-estradiol or dihydrotestosterone, is capable of regulating cad-11 messenger RNA and protein expression levels in isolated endometrial stromal cells. In add...

Antisteroidal compounds and steroid withdrawal down‐regulate cadherin‐11 mRNA and protein expression levels in human endometrial stromal cells undergoing decidualisation in vitro

The cellular mechanisms by which steroids and antisteroidal compounds modulate the function and/or integrity of the human endometrium remain poorly understood. We recently determined that the expression of the novel cadherin subtype, known as cadherin‐11, is tightly regulated in endometrial stromal cells undergoing decidualisation in vivo and in vitro. To determine whether the actions of antisteroids on the endometrium are mediated, at least in part, by their ability to regulate the expression of this cell adhesion molecule, we examined the effects of the antiprogestin RU486 and the antiestrogen ICI 182,780 on cadherin‐11 mRNA and protein expression levels in human endometrial stromal cells undergoing decidualisation in vitro. RU486 decreased the levels of the cadherin‐11 mRNA transcript and protein species present in these cell cultures in a dose‐ and time‐dependent manner. Similarly, ICI 182,780 was capable of reducing stromal cadherin‐11 mRNA and protein expression levels in a dose‐dependent manner, suggesting that the progesterone‐mediated increase in cadherin‐11 expression levels in human endometrial cells undergoing decidualisation in vitro is dependent on the presence of estrogens. Cadherin‐11 expression levels also were reduced in endometrial stromal cell cultures subjected to progesterone withdrawal, an in vitro model for menstrual breakdown. These studies not only give us useful insight into the mechanism(s) by which progesterone regulates stromal cadherin‐11 expression, but they strengthen our hypothesis that this cell adhesion molecule plays a central role in the remodeling processes that occur in the human endometrium in response to fluctuations in the levels of gonadal steroids. Mol. Reprod. Dev. 53:384–393, 1999.

Progesterone regulates β-catenin mRNA levels in human endometrial stromal cells in vitro

Cadherin-catenin complexes mediate cell-cell interactions and may play a central role in intracellular signaling. To date, the factors capable of coordinately regulating cadherin and catenin expression levels within a mammalian cell remain poorly characterized. We have recently determined that progesterone is a key regulator of cadherin-11 mRNA and protein expression levels in cultured human endometrial stromal cells. As a first step in determining whether gonadal steroids are also capable of regulating stromal catenin expression, we have examined the ability of progestins, estrogens, and androgens to regulate β-catenin mRNA levels in these endometrial cell cultures. Here we report that progesterone, but not 17β-estradiol or dihydrotestosterone, increased β-catenin mRNA levels in cultured human endometrial stromal cells. The stimulatory effect of progesterone on the levels of the stromal β-catenin mRNA transcript could not be potentiated by 17β-estradiol. These studies not only demonstrate that gonadal steroids are capable of regulating β-catenin mRNA levels in human endometrial stromal cells, but may also give us useful insight into the cellular mechanisms by which gonadal steroids regulate the cyclic remodeling processes that occur in the human endometrium during each menstrual cycle.

Optimizing guide RNA selection and CRISPR/Cas9 methodology for efficient generation of deletions in C. elegans.

The Caenorhabditis elegans Gene Knockout (KO) Consortium is tasked with obtaining null mutations in each of the more than 20,000 open reading frames (ORFs) of this organism. To date, approximately15,000 ORFs have associated putative null alleles. A directed approach using CRISPR/Cas9 methodology is the most promising technique to complete the task. While there has been substantial success in using CRISPR/Cas9 in C. elegans, there has been little emphasis on optimizing the method for generating large insertions/deletions in this organism. To enhance the efficiency of using CRISPR/Cas9 to generate gene knockouts in C. elegans we have developed an online species-specific guide RNA selection tool (http://genome.sfu.ca/crispr). When coupled with previously developed selection vectors, optimization for homology arm length, and the use of purified Cas9 protein, we demonstrate a robust, efficient and effective protocol for generating deletions. Debate and speculation in the larger scientific community about off- target effects due to non-specific Cas9 cutting has prompted us to investigate through whole genome sequencing the occurrence of single nucleotide variants and indels accompanying targeted deletions. We did not detect any off-site variants above the natural spontaneous mutation rate and therefore conclude this modified protocol does not generate off-target events to any significant degree in C. elegans.