p63 Coordinates anogenital modeling and epithelial cell differentiation in the developing female urogenital tract

The exstrophy-epispadias complex

Exstrophy-epispadias complex (EEC) represents a spectrum of genitourinary malformations ranging in severity from epispadias (E) to classical bladder exstrophy (CEB) and exstrophy of the cloaca (EC). Depending on severity, EEC may involve the urinary system, musculoskeletal system, pelvis, pelvic floor, abdominal wall, genitalia, and sometimes the spine and anus. Prevalence at birth for the whole spectrum is reported at 1/10,000, ranging from 1/30,000 for CEB to 1/200,000 for EC, with an overall greater proportion of affected males. EEC is characterized by a visible defect of the lower abdominal wall, either with an evaginated bladder plate (CEB), or with an open urethral plate in males or a cleft in females (E). In CE, two exstrophied hemibladders, as well as omphalocele, an imperforate anus and spinal defects, can be seen after birth. EEC results from mechanical disruption or enlargement of the cloacal membrane; the timing of the rupture determines the severity of the malformation. The underlying cause remains unknown: both genetic and environmental factors are likely to play a role in the etiology of EEC. Diagnosis at birth is made on the basis of the clinical presentation but EEC may be detected prenatally by ultrasound from repeated non-visualization of a normally filled fetal bladder. Counseling should be provided to parents but, due to a favorable outcome, termination of the pregnancy is no longer recommended. Management is primarily surgical, with the main aims of obtaining secure abdominal wall closure, achieving urinary continence with preservation of renal function, and, finally, adequate cosmetic and functional genital reconstruction. Several methods for bladder reconstruction with creation of an outlet resistance during the newborn period are favored worldwide. Removal of the bladder template with complete urinary diversion to a rectal reservoir can be an alternative. After reconstructive surgery of the bladder, continence rates of about 80% are expected during childhood. Additional surgery might be needed to optimize bladder storage and emptying function. In cases of final reconstruction failure, urinary diversion should be undertaken. In puberty, genital and reproductive function are important issues. Psychosocial and psychosexual outcome depend on long-term multidisciplinary care to facilitate an adequate quality of life.

Distribution pattern and marker profile show two subpopulations of reserve cells in the endocervical canal

SUMMARY

A previous immunophenotyping study in the fetal uterine cervix provided evidence for the existence of 2 subpopulations of reserve cells, one giving rise to glandular epithelium and the other to squamous epithelium (5). In this study, we investigated whether the adult uterine cervix also harbors different populations of reserve cells on the basis of their marker profile and distribution pattern. Sagittal sections from 10 normal uteri, comprising the region from ectocervix to lower uterine cavity, were histologically examined and immunostained for p63, bcl-2 and cytokeratins (CKs) 5, 7, 8, and 17. The endocervical canal consists of three regions, that is, a part lined with squamous epithelium, a part lined with endocervical cells and a part lined with tubal type epithelial cells. Histologically, we found reserve cells in all 10 investigated cervices, with an abundancy in the area beneath the endocervical columnar epithelium close to the squamo-columnar junction, and high in the endocervical canal where the invaginations consist of tubal type epithelium. In between, an area lined with endocervical columnar cells without reserve cells was identified. No reserve cells were detected in the endometrial epithelium. We defined the end of the endocervix as the point where the surface of the cervical canal and the invaginations are completely lined with tubal type epithelium. From this point, reserve cells were no longer found. Reserve cells show strong expression for p63, CKs 5 and 7, and moderate expression for bcl-2. CK17 is strongly expressed in the reserve cells at the squamo-columnar junction and to a lesser extent in the reserve cells close to the endometrium. Endocervical columnar cells usually express CKs 7 and 8 and sporadically also p63 and CK5. CK17 was only found in endocervical cells in the vicinity of CK17-positive subcolumnar reserve cells. Tubal-type epithelium was present in all samples and contained bcl-2, along with CKs 5, 7, and 8. As a result, bcl-2 and CK5 expression distinguishes tubal epithelium from endocervical columnar cells. We conclude that reserve cells are present in all investigated cervices along the entire cervical canal. The concentration of subglandular reserve cells is highest close to the squamo-columnar junction and in the upper third of the cervix. The marker profile of reserve cells is the same in all parts of the cervix, except for CK17, which shows a decreasing gradient from distal to proximal, indicating a subpopulation of distal reserve cells as progenitor for squamous and columnar epithelium, and proximal reserve cells that can serve as progenitor cells for columnar epithelium.

Expression of EphB2 in the development of anorectal malformations in fetal rats

PURPOSE

The receptor tyrosine kinase of the Eph family is a large group of highly conserved molecules that function in diverse intercellular recognition events. It has been reported that EphB2 is related to caudal remodeling events. The aim of this study is to investigate EphB2 expression in anorectal development in normal and rat embryos with anorectal malformations (ARMs) and attempt to define its role in anorectal morphogenesis.

METHODS

The ethylenethiourea (ETU) rat model of the ARMs was used in this study. Immunohistochemical analyses and real time quantitative polymerase chain reaction (PCR) were carried out to investigate EphB2 protein localizations and messenger RNA (mRNA) expression levels. (1) Rat embryos with ARMs were obtained by treating pregnant rats (n = 24) with administration of ETU on gestation day (Gd) 10. Normal rat embryos (n = 111) and embryos treated by ETU without ARMs (n = 90) were the control groups, and embryos with ARMs (n = 108) from Gd13 to Gd16 were divided according to the sections taken from specimens. (2) Embryos were sequentially sectioned in the sagittal and transversal planes before staining with a specific antibody to EphB2. Spatiotemporal study was carried out on EphB2 expression. (3) Individual frozen sections were used to manually microdissect the cloaca and anorectal specimens for total RNA extraction. EphB2 expression was evaluated by real time quantitative PCR.

RESULTS

On the immunologic labeling study, EphB2 expression was confined to the cloaca in control groups, whereas EphB2 expression was mainly located at the urorectal septum (URS) and cloacal membrane on Gd13 and Gd14. The increased positive expression was observed in the fused tissue of the URS and cloacal membrane on Gd15. On Gd16, the anal membrane broke down, and the rectum was able to be in contact with the anus, and EphB2 expression was then noted in mucous membrane of rectum. EphB2 expression was seen in the cloacal and anorectal tissues of embryos with ARMs. By integrated optical density (IOD) measurement, IOD value of EphB2 protein was significantly lower in the ARM group than that in the control groups on Gd13 to Gd16 (P < .05), respectively. As shown by real time quantitative PCR, EphB2 expression was detected in 3 groups. EphB2 mRNA level increased on Gd13 to Gd16 but gradually decreased after Gd16. The expression level of EphB2 mRNA in the ARM embryos was lower on Gd13 to Gd16 than that in control groups (P < .05).

CONCLUSIONS

EphB2 expression decreased in the ARM embryos and was confined to URS and cloaca, whereas it was higher in control group. Our data thus indicated that EphB2 molecules possibly contributed to the anorectal morphogenesis and the decreased expression of EphB2 might be related to the development of ARMs.

Investigation of FGF10 as a candidate gene in patients with anorectal malformations and exstrophy of the cloaca

The spectrum of anorectal malformations (ARM) comprises anal stenosis, ectopic anus, recto-urogenital fistula, persistent cloaca, multisystem VACTERL (VATER associations including cardiac and limb anomalies) associations, and exstrophy of the cloaca (CE). The latter also constitutes the most severe form of the bladder exstrophy epispadias complex. Since recent data revealed that fibroblast growth factor 10 (fgf-10) invalidation in mice resulted in a genetically reproducible urorectal defect, we considered FGF10 a suitable candidate gene for ARM and CE, as the protein seems to be involved in the development of this primary developmental field. A total of 20 patients (ten with ARM and VACTERL association, respectively, and ten with CE) were analysed for genomic mutations in the coding regions and exon-intron boundaries of FGF10. Aside from a common FGF10 variant no deviation from the wild-type sequence could be detected and data obtained is not supportive of FGF10 as a genetic cause of ARMs or CE in the patients investigated. Nonetheless, mutations in possibly further upstream located promoter regions and/or unknown regulatory sequences or non-coding regions cannot be excluded. Furthermore, it cannot be ruled out that other genes involved in the signalling pathway of FGF10 may contribute to the formation of these congenital malformations.

Transcriptional profiling of the megabladder mouse: a unique model of bladder dysmorphogenesis

Recent studies in our lab identified a mutant mouse model of obstructive nephropathy designated mgb for megabladder. Homozygotic mgb mice (mgb-/-) develop lower urinary tract obstruction in utero due to a lack of bladder smooth muscle differentiation. This defect is the result of a random transgene insertion/translocation into chromosomes 11 and 16. Transcriptional profiling identified a significantly over-expressed cluster of gene products located on the translocated fragment of chromosome 16 including urotensin II-related peptide (Urp), which was shown to be preferentially over-expressed in developing mgb-/- bladders. Pathway analysis of mgb microarray data indicated dysregulation of at least 60 gene products associated with smooth muscle development. In conclusion, the results of this study indicate that the molecular pathways controlling normal smooth muscle development are severely altered in mgb-/- bladders, and provide the first evidence that Urp may play a critical role in bladder smooth muscle development.

Cell lineage analysis demonstrates an endodermal origin of the distal urethra and perineum

Congenital malformations of anorectal and genitourinary (collectively, anogenital) organs occur at a high frequency in humans, however the lineage of cells that gives rise to anogenital organs remains poorly understood. The penile urethra has been reported to develop from two cell populations, with the proximal urethra developing from endoderm and the distal urethra forming from an apical ectodermal invagination, however this has never been tested by direct analysis of cell lineage. During gut development, endodermal cells express Sonic hedgehog (Shh), which is required for normal patterning of digestive and genitourinary organs. We have taken advantage of the properties of Shh expression to genetically label and follow the fate of posterior gut endoderm during anogenital development. We report that the entire urethra, including the distal (glandar) region, is derived from endoderm. Cloacal endoderm also gives rise to the epithelial linings of the bladder, rectum and anterior region of the anus. Surprisingly, the lineage map also revealed an endodermal origin of the perineum, which is the first demonstration that endoderm differentiates into skin. In addition, we fate mapped genital tubercle ectoderm and show that it makes no detectable contribution to the urethra. In males, formation of the urethral tube involves septation of the urethral plate by continued growth of the urorectal septum. Analysis of cell lineage following disruption of androgen signaling revealed that the urethral plate of flutamide-treated males does not undergo this septation event. Instead, urethral plate cells persist to the ventral margin of the tubercle, mimicking the pattern seen in females. Based on these spatial and temporal fate maps, we present a new model for anogenital development and suggest that disruptions at specific developmental time points can account for the association between anorectal and genitourinary defects.

Reserve Cells in Human Uterine Cervical Epithelium Are Derived from Müllerian Epithelium at Midgestational Age

The role of endocervical reserve cells in squamous metaplasia and neoplasia is still debated. Their origin in the cervix is open to speculation and it is unclear how they are targeted during carcinogenesis. To further understand the primary characteristics of reserve cells, we phenotyped them in the developing human cervix. In 13 perinatal autopsies of fetuses between 16 and 40 weeks of gestation, the human fetal cervix was evaluated in serial sections. Immunostaining comprised a panel of antibodies for cytokeratins, p63, and bcl-2; then, the sections were stained with Alcian blue and periodic acid-Schiff before and after diastase treatment. Reserve cells are first identified at approximately 20 weeks of gestation. They are first noted under müllerian-type columnar cells lining the developing uterine cavity. There is considerable overlap in the expression profiles of müllerian cells and reserve cells for p63, bcl-2, and cytokeratins 5, 8, and 18 at this stage of development, with increasing gestational age expression localized to respective cell compartments. Eventually, the phenotype of these cells correspond fully with that described for adult reserve cells and endocervical cells. Müllerian epithelial cells are the stem cell for endocervical reserve cells and endocervical columnar cells. They have the capacity to transform into both endocervical columnar and squamous-type epithelium in the endocervix during early cervical development.

EEC syndrome, Arg227Gln TP63 mutation and micturition difficulties: Is there a genotype-phenotype correlation?

We report on two unrelated families with EEC syndrome (ectrodactyly, ectodermal dysplasia, cleft lip/palate), each with an Arg227Gln TP63 gene mutation, where the phenotype overlapped extensively with the allelic disorder, limb-mammary syndrome (LMS). Features common to both families were an ectodermal dysplasia principally affecting tooth, breast and nipple development, dacryostenosis and severe micturition difficulties. Additional findings included post-axial digital hypoplasia, cleft uvula, anal stenosis, hypoplasia of the perineal body and biopsy-proven interstitial cystitis. No individual had cleft lip. Split hand-split foot malformation (SHFM) occurred in one child-born after the molecular diagnosis was established. Unlike previous reports, the urinary symptoms were refractory to treatment with oral Fibrase and persisted into adulthood. Of the six cases/families now reported with EEC syndrome and Arg227Gln TP63 mutation, four have manifested this distinct urological abnormality, indicative of a genotype-phenotype correlation.

A unifying concept of trophoblastic differentiation and malignancy defined by biomarker expression

Several trophoblast phenotypes, including cytotrophoblast, syncytiotrophoblast, and extravillous trophoblast, emerge during gestation. To clarify the lineage relationship between these subtypes, we profiled p63 localization in developing and term placental tissue, as well as in trophoblastic tumors, using antibodies specific to full-length (TAp63) and one against all p63 isoforms (TAp63 and DeltaNp63). Localization of p63 was compared with that of biomarkers of proliferation and trophoblastic differentiation, including mib-1, inhibin, and MelCAM. In early gestation, p63 was localized principally to villous cytotrophoblast after contact with the villous mesenchyme, absent in the trophoblast columns, and early implantation trophoblast. In the maturing placenta, intraplacental perivillous fibrin correlated with the emergence of a p63-positive "transitional" (vacuolated) extravillous trophoblast from cytotrophoblast, which differentiated further into a "mature" p63-negative extravillous trophoblast. The same lineage pathway emerged from entrapped villi on the chorionic membrane. Virtually all p63 immunopositivity was attributed to dominant-negative p63. The immunophenotypic patterns seen in the immature and mature placenta permit the resolution of all trophoblastic phenotypes within 3 lineage pathways of cytotrophoblast differentiation, including cytotrophoblast-to-trophoblast column/implantation site, cytotrophoblast-to-syncytiotrophoblast, and cytotrophoblast-to-mature extravillous trophoblast. In the latter pathway, a transitional (vacuolated) p63-positive extravillous trophoblast emerges from and links cytotrophoblast to mature extravillous trophoblast in intraplacental fibrin, chorionic membrane, and basal plate. The placental trophoblast is thus resolved within this continuum of differentiation. Terms such as transitional and mature extravillous trophoblast are proposed to reflect the differentiation phases of this unique epithelium. p63 staining patterns in trophoblastic tumors reflect timing of neoplastic transformation during trophoblastic differentiation.

DeltaNp63alpha promotes apoptosis of human epidermal keratinocytes

In this study we show that deltaNp63alpha overexpression in primary human epidermal keratinocytes causes decreased cell proliferation and increased apoptosis. These changes are associated with increased levels of p21 and p27, decreased cyclin D1 and cyclin E levels, reduced mitochondrial membrane potential, and enhanced procaspase and poly(ADP-ribose) polymerase cleavage. Bcl-xS and Bax levels are increased and Bcl-xL level is reduced. p53 levels are increased in the deltaNp63alpha-expressing cells and p53 overexpression reproduces features of the deltaNp63alpha phenotype. Increased p53 expression results in reduced deltaNp63alpha, suggesting that p53 may negatively regulate deltaNp63alpha level. DeltaNp63alpha also induces apoptosis in HaCaT and SCC-13 cells, which encode inactive p53 genes, suggesting that the response is p53 independent in these cell lines. Both deltaNp63alpha and TAp63alpha reduce SCC-13 cell survival. These studies indicate that both deltaNp63alpha and TAp63alpha can negatively regulate keratinocyte survival.

The role of Shh transcription activator Gli2 in chick cloacal development

Patterning and differentiation along the dorsal-ventral (D-V) axis lead to cloacal partitioning into ventral urinary and dorsal alimentary tracts in most mammals, but not birds and fish. We previously reported that the major activator of Sonic hedgehog (Shh) signaling transcription factor Gli2 plays an essential role in cloacal partitioning along the D-V axis in a mouse model. Here, we report that chick cloacal patterning and differentiation is along the anterior-posterior axis. During chick cloacal formation, Shh is expressed strongly in hindgut endoderm; Gli2 is very weakly detected in the surrounding hindgut mesoderm. In the mesoderm of the cloacal region, the over-expression of the constitutively active form of mouse Gli2 has been shown to: not induce cloacal partitioning along the D-V axis; induce expression of Ptch1, Gli2, bmp4, wnt5a, and hoxd-13, which have been previously shown to play a role in hindgut patterning; increase cell proliferation; and reduce apoptosis. Interestingly, p63 expression in the cloacal endoderm is also up-regulated, suggesting an interaction between the Shh and p63 pathways. In conclusion, Gli2 alone is insufficient to induce partitioning along the D-V axis in the chick embryo. However, Gli2 regulates both epithelial and mesenchymal cell proliferation and apoptosis during cloacal development.

DeltaNp63 plays an anti-apoptotic role in ventral bladder development

The bladder, the largest smooth-muscle organ in the human body, is responsible for urine storage and micturition. P63, a homolog of the p53 tumor-suppressor gene, is essential for the development of all stratified epithelia, including the bladder urothelium. The N-terminal truncated isoform of p63, DeltaNp63, is known to have anti-apoptotic characteristics. We have established that DeltaNp63 is not only the predominant isoform expressed throughout the bladder, but is also preferentially expressed in the ventral bladder urothelium during early development. We observed a host of ventral defects in p63-/- embryos, including the absence of the abdominal and ventral bladder walls. This number of ventral defects is identical to bladder exstrophy, a congenital anomaly exhibited in human neonates. In the absence of p63, the ventral urothelium was neither committed nor differentiated, whereas the dorsal urothelium was both committed and differentiated. Furthermore, in p63-/- bladders, apoptosis in the ventral urothelium was significantly increased. This was accompanied by the upregulation of mitochondrial apoptotic mediators Bax and Apaf1, and concurrent upregulation of p53. Overexpression of DeltaNp63gamma and DeltaNp63beta in p63-/- bladder primary cell cultures resulted in a rescue, evidenced by significantly reduced expressions of Bax and Apaf1. We conclude that DeltaNp63 plays a crucial anti-apoptotic role in normal bladder development.

Cellular proliferation in the urorectal septation complex of the human embryo at Carnegie stages 13-18: a nuclear area-based morphometric analysis

In order to analyse the patterns of cellular proliferation both in the mesenchyme of the urorectal septum (URS) and in the adjacent territories (posterior urogenital mesenchyme, anterior intestinal mesenchyme and cloacal folds mesenchyme), as well as their contribution to the process of cloacal division, a computer-assisted method was used to obtain the nuclear area of 3874 mesenchymal cells from camera lucida drawings of nuclear contours of selected sections of human embryos [Carnegie stages (CSs) 13-18]. Based on changes in the size of the nucleus during the cellular cycle, we considered proliferating cells in each territory to be those with a nuclear area over the 75th percentile. The URS showed increasing cell proliferation, with proliferation patterns that coincided closely with cloacal folds mesenchyme, and with less overall proliferation than urogenital and intestinal mesenchymes. Furthermore, at CS 18, we observed the beginning of the rupture in the cloacal membrane; however, no fusion has been demonstrated either between the URS and the cloacal membrane or between the cloacal folds. The results suggest that cloacal division depends on a morphogenetic complex where the URS adjacent territories could determine septal displacement at the time that their mesenchymes could be partially incorporated within the proliferating URS.

P63 deficiency: a failure of lineage commitment or stem cell maintenance?

A critical role for p63 in the development of stratified epithelia, such as the epidermis, has been recognized since the generation of mice lacking p63 expression. The molecular role of p63 in epidermal morphogenesis, however, remained controversial. The epidermal phenotype of p63-/- mice, which are born with a single-layered surface epithelium instead of a fully stratified epidermis, suggested that p63 could have a role in stem cell maintenance or in the commitment to stratification. In this review, we discuss evidence suggesting that p63 is required for the commitment to stratification, making p63 the earliest known gene expressed in the developing epidermis that is specific for the keratinocyte lineage.

Cytoarchitecture modifications of the human uterine endocervical mucosa in long-term three-dimensional organotypic culture

We assayed the effects of phenol red (pr), estrogen (Es), and progesterone (Pg) in three-dimensional organotypic cultures of human uterine endocervix. Small intact fragments deposited on sponges submerged in DMEM with 10% fetal bovine serum were cultured in three different conditions: with pr (DMEM(pr+)), without pr (DMEM(pr-)), and without pr but with the addition of physiological concentrations of Es and Pg [DMEM(pr-)(Es+Pg)]. Cell viability and cellular responses were assayed after 4, 10, and 21 days using immunohistochemistry for the expression and distribution of the following markers: mucins and mucopolysaccharides (PAS staining), pan-cytokeratins (AE1/AE3), CK19, p63, Ki-67, vimentin, estrogen receptor-alpha (ER-alpha), and progesterone receptor (PR). The fragments cultivated in DMEM(pr+) showed a cuboidal, poorly differentiated epithelial phenotype and signs of stroma degeneration. In DMEM(pr-), both tissue architecture and cellular heterogeneity were much better preserved: epithelial cells showed a more columnar shape, and stroma was very well conserved, maintaining cell density. The addition of Es and Pg further improved the histology and physiology of the fragments: in DMEM(pr-)(Es+Pg), epithelial cells retained a columnar shape, secreted mucins, and formed areas of squamous hyperplasia.

Development of the mammalian female reproductive tract

The female reproductive tract (FRT), which includes the oviduct, uterus, cervix and vagina, is critical for mammalian reproduction. Recent research using knockout mice has contributed substantially to our understanding of the molecular mechanisms governing FRT development. Aside from satisfying our curiosities about the origin of life, these studies have provided us with a better understanding of FRT disorders and ways to improve female fertility. Here we review genes that are involved in various stages of sexual duct formation and development in mammals. In addition, the effect of exogenous estrogen such as DES on FRT development is also discussed.

Neonatal treatment of rats with diethylstilboestrol (DES) induces stromal-epithelial abnormalities of the vas deferens and cauda epididymis in adulthood following delayed basal cell development

This study investigated whether transient, neonatal (days 2-12) treatment of rats with the potent oestrogen, diethylstilboestrol (DES), altered the structure of the cauda epididymis/vas deferens in adulthood, and if the changes observed related to altered development of basal cells in early puberty. Neonatal treatment with 10 microg DES resulted in the following during adulthood: (a) coiling of the normally straight initial vas deferens, (b) gross epithelial abnormalities, (c) 4-fold widening of the periductal non-muscle layer, (d) infiltration of immune cells across the epithelium into the lumen, and (e) reduction/absence of sperm from the vas deferens lumen. Amongst affected animals>75% exhibited reduced epithelial immunoexpression of androgen receptor and aberrant oestrogen receptor-alpha immunoexpression and 63% exhibited multi-layering of basal cells coincident with increased epithelial cell proliferation. None of the aforementioned changes occurred in rats treated neonatally with 0.1 microg DES. As basal cells play a key role in the development of epithelia such as that in the epididymis and vas deferens, we went on to investigate if neonatal DES treatment affected basal cell development. In controls, basal cells were first evident at day 10 (vas deferens) or day 18 (cauda). Rats treated with 10 microg, but not those treated with 0.1 microg, DES, showed approximately 90% reduction (P<0.001) in basal cell numbers at day 15 and day 18. This decrease coincided with gross suppression of testosterone levels; co-treatment of rats with 10 microg DES+testosterone maintained basal cell numbers at control levels at day 18. However, suppression of testosterone production (GnRH antagonist treatment) or action (flutamide treatment) did not alter basal cell numbers. It is concluded that neonatal exposure to high oestrogen levels coincident with reduced testosterone action results in abnormal changes in the adult cauda/vas deferens that are preceded by delayed differentiation of basal cells. These findings imply a role for androgens and oestrogens in basal cell development and suggest that this may be pivotal in determining normal epithelial (and stromal) development of the cauda/vas deferens.

Molecular, cellular and developmental biology of urothelium as a basis of bladder regeneration

Urinary bladder malfunction and disorders are caused by congenital diseases, trauma, inflammation, radiation, and nerve injuries. Loss of normal bladder function results in urinary tract infection, incontinence, renal failure, and end-stage renal dysfunction. In severe cases, bladder augmentation is required using segments of the gastrointestinal tract. However, use of gastrointestinal mucosa can result in complications such as electrolyte imbalance, stone formation, urinary tract infection, mucous production, and malignancy. Recent tissue engineering techniques use acellular grafts, cultured cells combined with biodegradable scaffolds, and cell sheets. These techniques are not all currently applicable for human bladder reconstruction. However, new avenues for bladder reconstruction maybe facilitated by a better understanding of urogenital development, the cellular and molecular biology of urothelium, and cell-cell interactions, which modulate tissue repair, homeostasis, and disease progression.

Rubella virus infection dysregulates the pattern of p63 expression

The effect of rubella virus (RV) on the expression of the p63 isoforms was investigated in Vero cells. The levels of all the TAp63 isoforms were elevated, while the expression of a approximately 73 kDa isoform corresponding to DeltaNp63alpha was downregulated in Vero cells infected with the To-336 strain of RV. A approximately 66 kDa isoform corresponding to TAp63beta was the predominant protein species in RV-infected cells. Semi-quantitative end-point dilution RT-PCR analysis, with TAp63beta isoform-specific primers, detected a 4-fold rise in the TAp63beta mRNA level following virus infection. Taken together, our data demonstrate that RV infection alters the stoichiometric ratio of the p63 isoforms. The dysregulated pattern of p63 expression observed in RV-infected cells may represent a mechanism whereby RV exerts its pro-apoptotic effect.

Microglandular hyperplasia: a model for the de novo emergence and evolution of endocervical reserve cells

BACKGROUND

Microglandular hyperplasia (MGH) of the cervix in human beings is associated early with gland proliferation and terminates in mature squamous metaplasia. Using antibodies to basal cell markers, we analyzed biopsies with MGH to profile the distribution and evolution of reserve cells and their relationship to these epithelial components.

DESIGN

Serial sections of 24 MGHs were subdivided into (1) early MGH with microacinar proliferation, abundant subnuclear vacuoles, and a paucity of supporting stroma and (2) late MGH with more prominent supporting stroma and/or squamous metaplasia. Serial sections were stained with antibodies to p63, bcl-2, and keratin-5.

RESULTS

Three patterns of p63 staining were observed corresponding to the age of the MGH: (1) scattered staining of columnar cells, (2) focal subcolumnar staining in a reserve cell distribution, and (3) linear subcolumnar arrays of p63-positive reserve cells that in some MGHs expanded into a squamous metaplasia. Early acinar proliferations showed weak and focal columnar cell staining followed by focal subcolumnar p63-positive cells. In late lesions, p63 staining was compartmentalized to the extraglandular (or subcolumnar) areas. Stainings of p63, bcl-2, and keratin-5 were concordant. Staining for keratin 14, which localizes to squamous cells, was variable.

CONCLUSIONS

The immunohistochemical profile in MGH indicates that reserve cells are created in adulthood during specialized columnar proliferations. This columnar to reserve cell transition may produce a stable population of reserve cells or a transition to squamous metaplasia. Similar patterns are seen in cervical neoplasia, suggesting a link between benign and neoplastic cervical epithelial differentiation.

p63 and epithelial appendage development

Abstract Epithelial appendages share a common developmental program that relies on extensive interactions between epithelia and adjacent mesenchyme. The transcription factor p63 has a critical role in epithelial appendage development in both vertebrates and non-vertebrates. Both mice and zebrafish lacking p63 expression fail to develop epithelial appendages and other structures that develop as a result of epithelial-mesenchymal interactions. Furthermore, dominantly inherited mutations in p63 are the cause of a subset of human ectodermal dysplasias, which are characterized by developmental abnormalities in epithelia and epithelial appendages. While the importance of p63 for epithelial appendage development is evident, the molecular mechanisms by which p63 functions are largely unknown. In this review, we will discuss the current knowledge of the developmental role of p63 and the implications for epithelial appendage development.

p63 Expression in Lung Carcinoma

p63 is a recently discovered member of the p53 family that has been shown to be important in the development of epithelial tissues. p63 may also play a role in squamous cell carcinomas of the lung, head and neck, and cervix, and its expression is increased in these tumors. The purpose of this study was to investigate the expression of p63 in a broad spectrum of histologic types of lung tumors. A total of 441 cases of primary lung tumors with follow-up data were identified, and the paraffin-embedded tissue blocks were used to construct a duplicate core tissue microarray. After review of the tissue cores, 408 cases, consisting of 123 squamous cell carcinomas, 93 adenocarcinomas, 68 large cell carcinomas, 68 classic carcinoids, 31 atypical carcinoids, 11 large cell neuroendocrine carcinomas, and 14 small cell carcinomas, were adequate for analysis. Immunohistochemistry was performed at 2 different laboratories using monoclonal antibody 4A4 to detect the expression of p63, using different staining protocols. p53 expression was also studied with immunohistochemistry using monoclonal antibody DO-7. Kaplan-Meier curves were plotted to compare the survival of p63-expressing versus nonexpressing tumors. A large proportion of squamous cell carcinomas expressed p63 (96.9%), most showing strong positive nuclear immunoreactivity. Expression in other nonsmall cell lung cancers was also present. Thirty percent of adenocarcinomas and 37% of large cell carcinomas showed p63 expression. In the neuroendocrine tumors, an increasing proportion of tumors stained for p63 as tumor grade increased; 1.9% of classic carcinoids, 30.8% of atypical carcinoids, 50% of large cell neuroendocrine carcinomas, and 76.9% of small cell carcinomas were positive. Approximately half of the positively staining neuroendocrine cases showed strong staining. Expression of p63 was of prognostic significance in neuroendocrine tumors (P < 0.0001), with higher-grade tumors more likely to express p63. Correlation between p63 and p53 expression was not observed (P = 0.18) in nonsmall cell lung cancer; however, a significant correlation between the 2 markers was found in neuroendocrine tumors (P < 0.0001). p63 staining was repeated with a different staining protocol, yielding similar results overall but a lower percentage of positive cases (34.2% vs. 48.4% of tumors positive). In conclusion, p63 expression is consistently expressed in squamous cell carcinoma in the lung, but is also expressed in a subset of adenocarcinomas and large cell carcinomas. Pulmonary neuroendocrine tumors also show p63 staining in some instances, particularly in higher-grade tumors, and the majority of small cell carcinomas are p63-positive. These results suggest that p63 may be involved in oncogenesis in a broader range of tumors than was previously thought.

A three-dimensional organotypic culture of the human uterine exocervix for studying mucosal epithelial differentiation and migrating leukocytes

We report on a three-dimensional organotypic culture in vitro of explants from the human uterine exocervix. Exocervical fragments (2-3 mm3) from pre-menopausal women were cultured on sponges submerged in Dulbecco's Modified Eagle's Medium containing p-nonylphenol and 10% fetal bovine serum for up to 3 weeks and the viability and cellular responses were assayed. The fragments were analyzed by immunohistochemistry for the expression and distribution of a broad spectrum of cellular markers: p63, Ki-67, involucrin, high molecular weight cytokeratins, estrogen receptor-alpha, vimentin, CD45, and CD31. The fragments preserved their tissue architecture and cellular heterogeneity comparable to that observed in exocervical tissue in vivo. Prior to culture, the original epithelium was composed of stratified multilayered keratinocytes with integrated monocyte/dendritic-like cells in the basal and suprabasal layers. The epithelium began to exfoliate in culture and within 4 days appeared to have lost its differentiated high-zone layers of keratinocytes. After 10 days a new epithelium, slightly different from the original one, was formed; it displayed an increasing prominence of basal and suprabasal keratinocyte layers, containing infiltrating leukocytes that had probably migrated from the submucosa. The epithelium subsequently lost its organization, concomitant with a progressive involution of the stroma. Subepithelial capillaries appeared to be well maintained throughout the culture period. Aside from the maintenance of cellular heterogeneity within the fragments of exocervix, these culture systems are a valuable tool for studying the mechanisms of epithelial regeneration, and may prove to be a useful model for studying mucosal immunity.

Cellular and molecular mechanisms of development of the external genitalia

The limb and external genitalia are appendages of the body wall. Development of these structures differs fundamentally in that masculine development of the external genitalia is androgen dependent, whereas development of the limb is not. Despite this fundamental difference in developmental regulation, epithelial-mesenchymal interactions play key roles in the development of both structures, and similar regulatory molecules are utilized as mediators of morphogenetic cell-cell interactions during development of both the limb and external genitalia. Given the relatively high incidence of hypospadias, a malformation of penile development, it is appropriate and timely to review the morphological, endocrine, and molecular mechanisms of development of the genital tubercle (GT), the precursor of the penis in males and the clitoris in females. Morphological observations comparing development of the GT in humans and mouse emphasize the validity of the mouse as an animal model of GT development and validate the results of experimental studies. Accordingly, the use of mutant mice provides important insights into the roles of specific regulatory molecules in development of the external genitalia. While our current understanding of the morphological and molecular mechanisms of mammalian external genitalia development is still rudimentary, this review summarizes the current state of our knowledge and whenever possible draws from the rich experimental embryology literature on other relevant organs such as the developing limb. Future research on the hormonal and molecular mechanisms of GT development may yield strategies to prevent or reduce the incidence of hypospadias and to elucidate the molecular genetic mechanisms of GT morphogenesis, especially in relation to common organogenetic pathways utilized in other organ systems.

In vivo and in vitro evidence for hydrogen peroxide (H2O2) accumulation in the epidermis of patients with vitiligo and its successful removal by a UVB-activated pseudocatalase

To date there is compelling in vitro and in vivo evidence for epidermal H2O2 accumulation in vitiligo. This paper reviews the literature and presents new data on oxidative stress in the epidermal compartment of this disorder. Elevated H2O2 levels can be demonstrated in vivo in patients compared with healthy controls by utilizing Fourier-Transform Raman spectroscopy. H2O2 accumulation is associated with low epidermal catalase levels. So far, four potential sources for epidermal H2O2 generation in vitiligo have been identified: (i) perturbed (6R)-L-erythro 5,6,7,8 tetrahydrobiopterin (6BH4) de novo synthesis/recycling/regulation; (ii) impaired catecholamine synthesis with increased monoamine oxidase A activities; (iii) low glutathione peroxidase activities; and (iv) "oxygen burst" via NADPH oxidase from a cellular infiltrate. H2O2 overproduction can cause inactivation of catalase as well as vacuolation in epidermal melanocytes and keratinocytes. Vacuolation was also observed in vitro in melanocytes established from lesional and nonlesional epidermis of patients (n = 10) but was reversible upon addition of catalase. H2O2 can directly oxidize 6BH4 to 6-biopterin, which is cytotoxic to melanocytes in vitro. Therefore, we substituted the impaired catalase with a "pseudocatalase". Pseudocatalase is a bis-manganese III-EDTA-(HCO3-)2 complex activated by UVB or natural sun. This complex has been used in a pilot study on 33 patients, showing remarkable repigmentation even in long lasting disease. Currently this approach is under worldwide clinical investigation in an open trial. In conclusion, there are several lines of evidence that the entire epidermis of patients with vitiligo is involved in the disease process and that correction of the epidermal redox status is mandatory for repigmentation.