mastermind
            regulates niche ageing independently of the
            Notch
            pathway in the
            Drosophila
            ovary

Proper stem cell activity in tissues ensures the correct balance between proliferation and differentiation, thus allowing tissue homeostasis and repair. The Drosophila ovary develops well-defined niches that contain on average 2–4 germline stem cells (GSCs), whose maintenance depends on systemic signals and local factors. A known player in the decline of tissue homeostasis is ageing, which correlates with the waning of resident stem cell populations. In Drosophila , ovaries from old females contain fewer GSCs than those from young flies. We isolated niche cells of aged ovaries, performed a transcriptomic analysis and identified mastermind (mam) as a factor for Drosophila ovarian niche functionality during ageing. We show that mam is upregulated in aged niche cells and that we can induce premature GSC loss by overexpressing mam in otherwise young niche cells. High mam levels in niche cells induce reduced Hedgehog amounts, a decrease in cadherin levels and a likely increase in reactive oxygen species, three scenarios known to provoke GSC loss. Mam is a canonical co-activator of the Notch pathway in many Drosophila tissues. However, we present evidence to support a Notch-independent role for mam in the ovarian germline niche.

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Maintaining Tissue Homeostasis: Dynamic Control of Somatic Stem Cell Activity

Cell Stem Cell ◽

10.1016/j.stem.2011.10.004 ◽

2011 ◽

Vol 9 (5) ◽

pp. 402-411 ◽

Cited By ~ 171

Author(s):

Benoit Biteau ◽

Christine E. Hochmuth ◽

Heinrich Jasper

Keyword(s):

Stem Cell ◽

Dynamic Control ◽

Cell Activity ◽

Tissue Homeostasis ◽

Somatic Stem Cell ◽

Stem Cell Activity

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Gilgamesh (Gish)/CK1γ regulates tissue homeostasis and aging in adult Drosophila midgut

The Journal of Cell Biology ◽

10.1083/jcb.201909103 ◽

2020 ◽

Vol 219 (4) ◽

Author(s):

Shuangxi Li ◽

Aiguo Tian ◽

Shuang Li ◽

Yuhong Han ◽

Bing Wang ◽

...

Keyword(s):

Stem Cell ◽

Cell Activity ◽

Adult Life ◽

Small Gtpase ◽

Tissue Homeostasis ◽

Jnk Pathway ◽

Pathway Activation ◽

Stem Cell Activity ◽

Resident Stem Cells ◽

Jnk Activation

Adult tissues and organs rely on resident stem cells to generate new cells that replenish damaged cells. To maintain homeostasis, stem cell activity needs to be tightly controlled throughout the adult life. Here, we show that the membrane-associated kinase Gilgamesh (Gish)/CK1γ maintains Drosophila adult midgut homeostasis by restricting JNK pathway activity and that Gish is essential for intestinal stem cell (ISC) maintenance under stress conditions. Inactivation of Gish resulted in aberrant JNK pathway activation and excessive production of multiple cytokines and growth factors that drive ISC overproliferation. Mechanistically, Gish restricts JNK activation by phosphorylating and destabilizing a small GTPase, Rho1. Interestingly, we find that Gish expression is down-regulated in aging guts and that increasing Gish activity in aging guts can restore tissue homeostasis. Hence, our study identifies Gish/CK1γ as a novel regulator of Rho1 and gatekeeper of tissue homeostasis whose activity is compromised in aging guts.

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Positional information specifies the site of organ regeneration and not tissue maintenance in planarians

eLife ◽

10.7554/elife.33680 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 8

Author(s):

Eric M Hill ◽

Christian P Petersen

Keyword(s):

Stem Cell ◽

Cell Activity ◽

Positional Information ◽

Tissue Homeostasis ◽

Target Site ◽

Maintenance And Repair ◽

Organ Regeneration ◽

Stem Cell Activity ◽

Factor Expression

Most animals undergo homeostatic tissue maintenance, yet those capable of robust regeneration in adulthood use mechanisms significantly overlapping with homeostasis. Here we show in planarians that modulations to body-wide patterning systems shift the target site for eye regeneration while still enabling homeostasis of eyes outside this region. The uncoupling of homeostasis and regeneration, which can occur during normal positional rescaling after axis truncation, is not due to altered injury signaling or stem cell activity, nor specific to eye tissue. Rather, pre-existing tissues, which are misaligned with patterning factor expression domains, compete with properly located organs for incorporation of migratory progenitors. These observations suggest that patterning factors determine sites of organ regeneration but do not solely determine the location of tissue homeostasis. These properties provide candidate explanations for how regeneration integrates pre-existing tissues and how regenerative abilities could be lost in evolution or development without eliminating long-term tissue maintenance and repair.

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Positional information specifies the site of organ regeneration and not tissue maintenance in planarians

10.1101/282657 ◽

2018 ◽

Author(s):

Eric M. Hill ◽

Christian P. Petersen

Keyword(s):

Stem Cell ◽

Cell Activity ◽

Positional Information ◽

Tissue Homeostasis ◽

Target Site ◽

Maintenance And Repair ◽

Organ Regeneration ◽

Stem Cell Activity ◽

Factor Expression

AbstractMost animals undergo homeostatic tissue maintenance, yet those capable of robust regeneration in adulthood use mechanisms significantly overlapping with homeostasis. Here we show in planarians that modulations to body-wide patterning systems shift the target site for eye regeneration while still enabling homeostasis of eyes outside this region. The uncoupling of homeostasis and regeneration, which can occur during normal positional rescaling after axis truncation, is not due to altered injury signaling or stem cell activity, nor specific to eye tissue. Rather, pre-existing tissues, which are misaligned with patterning factor expression domains, compete with properly located organs for incorporation of migratory progenitors. These observations suggest that patterning factors determine sites of organ regeneration but do not solely determine the location of tissue homeostasis. These properties provide candidate explanations for how regeneration integrates pre-existing tissues and how regenerative abilities could be lost in evolution or development without eliminating long-term tissue maintenance and repair.One Sentence SummaryHomeostatic tissue maintenance can occur independent of precise positional information in planarians.

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The Dynamics of Cambial Stem Cell Activity

Annual Review of Plant Biology ◽

10.1146/annurev-arplant-050718-100402 ◽

2019 ◽

Vol 70 (1) ◽

pp. 293-319 ◽

Cited By ~ 20

Author(s):

Urs Fischer ◽

Melis Kucukoglu ◽

Ykä Helariutta ◽

Rishikesh P. Bhalerao

Keyword(s):

Stem Cell ◽

Current Knowledge ◽

Secondary Growth ◽

Cell Activity ◽

Cambial Activity ◽

Stress Factors ◽

Cell Populations ◽

Plant Body ◽

Stem Cell Activity ◽

Stem Cell Populations

Stem cell populations in meristematic tissues at distinct locations in the plant body provide the potency of continuous plant growth. Primary meristems, at the apices of the plant body, contribute mainly to the elongation of the main plant axes, whereas secondary meristems in lateral positions are responsible for the thickening of these axes. The stem cells of the vascular cambium—a secondary lateral meristem—produce the secondary phloem (bast) and secondary xylem (wood). The sites of primary and secondary growth are spatially separated, and mobile signals are expected to coordinate growth rates between apical and lateral stem cell populations. Although the underlying mechanisms have not yet been uncovered, it seems likely that hormones, peptides, and mechanical cues orchestrate primary and secondary growth. In this review, we highlight the current knowledge and recent discoveries of how cambial stem cell activity is regulated, with a focus on mobile signals and the response of cambial activity to environmental and stress factors.

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