Dataset Information

Counting human somatic cell replications: methylation mirrors endometrial stem cell divisions.

ABSTRACT: Cell proliferation may be altered in many diseases, but it is uncertain exactly how to measure total numbers of divisions. Although it is impossible to count every division directly, potentially total numbers of stem cell divisions since birth may be inferred from numbers of somatic errors. The idea is that divisions are surreptitiously recorded by random errors that occur during replication. To test this "molecular clock" hypothesis, epigenetic errors encoded in certain methylation patterns were counted in glands from 30 uteri. Endometrial divisions can differ among women because of differences in estrogen exposures or numbers of menstrual cycles. Consistent with an association between mitotic age and methylation, there was an age-related increase in methylation with stable levels after menopause, and significantly less methylation was observed in lean or older multiparous women. Methylation patterns were diverse and more consistent with niche rather than immortal stem cell lineages. There was no evidence for decreased stem cell survival with aging. An ability to count lifetime numbers of stem cell divisions covertly recorded by random replication errors provides new opportunities to link cell proliferation with aging and cancer.

SUBMITTER: Kim JY

PROVIDER: S-EPMC1308885 | biostudies-other | 2005 Dec

REPOSITORIES: biostudies-other

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Counting human somatic cell replications: methylation mirrors endometrial stem cell divisions.

Kim Jung Yeon JY Tavaré Simon S Shibata Darryl D

Proceedings of the National Academy of Sciences of the United States of America 20051128 49

Cell proliferation may be altered in many diseases, but it is uncertain exactly how to measure total numbers of divisions. Although it is impossible to count every division directly, potentially total numbers of stem cell divisions since birth may be inferred from numbers of somatic errors. The idea is that divisions are surreptitiously recorded by random errors that occur during replication. To test this "molecular clock" hypothesis, epigenetic errors encoded in certain methylation patterns wer ...[more]

PMID: 16314580

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Project description:Successful maintenance of cellular lineages critically depends on the fate decision dynamics of stem cells (SCs) upon division. There are three possible strategies with respect to SC fate decision symmetry: (a) asymmetric mode, when each and every SC division produces one SC and one non-SC progeny; (b) symmetric mode, when 50% of all divisions produce two SCs and another 50%-two non-SC progeny; (c) mixed mode, when both the asymmetric and two types of symmetric SC divisions co-exist and are partitioned so that long-term net balance of the lineage output stays constant. Theoretically, either of these strategies can achieve lineage homeostasis. However, it remains unclear which strategy(s) are more advantageous and under what specific circumstances, and what minimal control mechanisms are required to operate them. Here we used stochastic modeling to analyze and quantify the ability of different types of divisions to maintain long-term lineage homeostasis, in the context of different control networks. Using the example of a two-component lineage, consisting of SCs and one type of non-SC progeny, we show that its tight homeostatic control is not necessarily associated with purely asymmetric divisions. Through stochastic analysis and simulations we show that asymmetric divisions can either stabilize or destabilize the lineage system, depending on the underlying control network. We further apply our computational model to biological observations in the context of a two-component lineage of mouse epidermis, where autonomous lineage control has been proposed and notable regional differences, in terms of symmetric division ratio, have been noted-higher in thickened epidermis of the paw skin as compared to ear and tail skin. By using our model we propose a possible explanation for the regional differences in epidermal lineage control strategies. We demonstrate how symmetric divisions can work to stabilize paw epidermis lineage, which experiences high level of micro-injuries and a lack of hair follicles as a back-up source of SCs.

Project description:Study questionCan endometrial stromal stem/progenitor cell markers, SUSD2 and CD146/CD140b, enrich for human myometrial and fibroid stem/progenitor cells?Summary answerSUSD2 enriches for myometrial and fibroid cells that have mesenchymal stem cell (MSC) characteristics and can also be induced to decidualise.What is known alreadyMesenchymal stem-like cells have been separately characterised in the endometrial stroma and myometrium and may contribute to diseases in their respective tissues.Study design, size, durationNormal myometrium, fibroids and endometrium were collected from hysterectomies with informed consent. Primary cells or tissues were used from at least three patient samples for each experiment.Participants/materials, setting, methodsFlow cytometry, immunohistochemistry and immunofluorescence were used to characterise tissues. In vitro colony formation in normoxic and hypoxic conditions, MSC lineage differentiation (osteogenic and adipogenic) and decidualisation were used to assess stem cell activity. Xenotransplantation into immunocompromised mice was used to determine in vivo stem-like activity. Endpoint measures included quantitative PCR, colony formation, trichrome, Oil Red O and alkaline phosphatase activity staining.Main results and the role of chanceCD146+CD140b+ and/or SUSD2+ myometrial and fibroid cells were located in the perivascular region and formed more colonies in vitro compared to control cells and differentiated down adipogenic and osteogenic mesenchymal lineages in vitro. SUSD2+ myometrial cells had greater in vitro decidualisation potential, and SUSD2+ fibroid cells formed larger tumours in vivo compared to control cells.Large-scale dataN/A.Limitations, reasons for cautionMarkers used in this study enrich for cells with stem/progenitor cell activity; however, they do not distinguish stem from progenitor cells. SUSD2+ myometrial cells express markers of decidualisation when treated in vitro, but in vivo assays are needed to fully demonstration their ability to decidualise.Wider implications of the findingsThese results suggest a possible common MSC for the endometrial stroma and myometrium, which could be the tumour-initiating cell for uterine fibroids.Study funding/competing interest(s)These studies were supported by NIH grants to JMT (R01OD012206) and to ALP (F32HD081856). The authors certify that we have no conflicts of interest to disclose.

Dataset Information

Counting human somatic cell replications: methylation mirrors endometrial stem cell divisions.

Publications

Counting human somatic cell replications: methylation mirrors endometrial stem cell divisions.

Similar Datasets

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