In the present study, we identified an additional member of the human high-temperature requirement factor A (HtrA) protein family, called pregnancy-related serine protease or HtrA3, which was most highly expressed in the heart and placenta. We cloned the full-length sequences of two forms (long and short) of human HtrA3 mRNA, located the gene on chromosome 4p16.1, determined its genomic structure and revealed how the two mRNA variants are produced through alternative splicing. The alternative splicing was also verified by Northern blotting. Four distinct domains were found for the long form HtrA3 protein: (i) an insulin/insulin-like growth factor binding domain, (ii) a Kazal-type S protease-inhibitor domain, (iii) a trypsin protease domain and (iv) a PDZ domain. The short form is identical to the long form except it lacks the PDZ domain. Comparison of all members of human HtrA proteins, including their isoforms, suggests that both isoforms of HtrA3 represent active serine proteases, that they may have different substrate specificities and that HtrA3 may have similar functions to HtrA1. All three HtrA family members showed very different mRNA-expression patterns in 76 human tissues, indicating a specific function for each. Interestingly, both HtrA1 and HtrA3 are highly expressed in the placenta. Identification of the tissue-specific function of each HtrA family member is clearly of importance.

The human endometrium is a highly dynamic tissue that is cyclically shed, repaired, regenerated and remodelled, primarily under the orchestration of oestrogen and progesterone, in preparation for embryo implantation. Humans are among the very few species that menstruate and that, consequently, are equipped with unique cellular and molecular mechanisms controlling these cyclic processes. Many reproductive pathologies are specific to menstruating species, and studies in animal models rarely translate to humans. Abnormal remodelling and regeneration of the human endometrium leads to a range of reproductive complications. Furthermore, the processes regulating endometrial remodelling and implantation, including those controlling hormonal impact, breakdown and repair, stem/progenitor cell activation, inflammation and cell invasion have broad applications to other fields. This Review presents current knowledge regarding the normal and abnormal function of the human endometrium. The development of biomarkers for prediction of uterine diseases and pregnancy disorders and future avenues of investigation to improve fertility and enhance endometrial function are also discussed.

BACKGROUND The actions of the extracellular‐matrix degrading enzymes, matrix metalloproteinases (MMPs), are implicated in tumorigenesis. The cellular localization of MMP‐2, MMP‐9, membrane type 1 (MT1)‐MMP, tissue inhibitors of metalloproteinases (TIMPs) 1‐3, and the presence of active gelatinases were investigated in endometrial carcinoma. METHODS Endometrial carcinomas were grouped according to histologic grade (Grades 1‐3), depth of myometrial invasion (0, < 50%, > 50%) and the presence of vascular/lymphatic invasion. Twenty‐nine endometrial carcinoma biopsies were investigated immunohistochemically to determine the tissue localization of MMP‐2 (gelatinase A), MMP‐9 (gelatinase B), MT1‐MMP, and TIMPs 1‐3. In situ hybridization was performed to localize MMP‐2 and MMP‐9 mRNA. The presence of active gelatinases was assessed using in situ zymography. RESULTS Epithelial tumor cells were the main site of MMP‐2, MMP‐9, and MT1‐MMP protein. Variable stromal cell localization was also observed, particularly in areas adjacent to tumor nests. Semiquantitative analysis revealed increases in MMP‐9 and MMP‐2 but not MT1‐MMP staining scores in tumor epithelial cells in the transition from histologic Grade 1 to Grades 2 and 3. Matrix metalloproteinase‐9 and MT1‐MMP staining scores in tumor cells were significantly associated with the presence of myometrial invasion and vascular/lymphatic invasion, while MMP‐2 did not correlate with these factors. In addition, MT1‐MMP was co‐localized with MMP‐2, supporting its role in the activation of proMMP‐2. Tumor cells from all histologic grades stained intensely for TIMP‐2 and TIMP‐3 proteins, while variable stromal staining was observed. In Grade 1 carcinomas TIMP‐1 was predominantly immunolocalized to the stromal compartment with variable tumor cell localization being observed in Grades 2 and 3 carcinomas. Matrix metalloproteinase‐9 and MMP‐2 mRNAs were predominantly observed in tumor epithelial cells as well as in the stroma to varying degrees. In situ zymography revealed active forms of gelatinases at the cellular surface and in association with tumor epithelial cells within endometrial carcinoma tissues. CONCLUSIONS These data suggest that increasing expression of MMPs and endometrial carcinoma progression are closely related. Active gelatinases are present in endometrial carcinoma, resulting in alterations to the microenvironment that promote tumor invasion and metastasis. Cancer 2002;94:1466–75. © 2002 American Cancer Society. DOI 10.1002/cncr.10355

In this review we discuss how the photosynthetic apparatus, particularly Rubisco, acclimates to rising atmospheric CO2 concentrations (ca). Elevated ca alters the control exerted by different enzymes of the Calvin cycle on the overall rate of photosynthetic CO2 assimilation, so altering the requirement for different functional proteins. A decreased flux of carbon through the photorespiratory pathway will decrease requirements for these enzymes. From modeling of the response of CO2 uptake (A) to intracellular CO2 concentration (ci) it is shown that the requirement for Rubisco is decreased at elevated ca, whilst that for proteins limiting ribulose 1,5 bisphosphate regeneration may be increased. This balance may be altered by other interactions, in particular plasticity of sinks for photoassimilate and nitrogen supply; hypotheses on these interactions are presented. It is speculated that increased accumulation of carbohydrate in leaves developed at elevated ca may signal the 'down regulation' of Rubisco. The molecular basis of this 'down regulation' is discussed in terms of the repression of photosynthetic gene expression by the elevated carbohydrate concentrations. This molecular model is then used to predict patterns of acclimation of perennials to long term growth in elevated ca.