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The repopulation and regulation of t...

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The repopulation and regulation of two different stem cell lineages in one stem cell niche: The germline and somatic stem cells in the Drosophila testis.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	The repopulation and regulation of two different stem cell lineages in one stem cell niche: The germline and somatic stem cells in the Drosophila testis./
Author:	Brawley, Crista M.
Description:	129 p.
Notes:	Adviser: Erika Matunis.
Contained By:	Dissertation Abstracts International68-11B.
Subject:	Biology, Cell. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoeng/servlet/advanced?query=3288435
ISBN:	9780549311706

The repopulation and regulation of two different stem cell lineages in one stem cell niche: The germline and somatic stem cells in the Drosophila testis.
Brawley, Crista M.

The repopulation and regulation of two different stem cell lineages in one stem cell niche: The germline and somatic stem cells in the Drosophila testis. - 129 p.

Adviser: Erika Matunis.

Thesis (Ph.D.)--The Johns Hopkins University, 2008.

Stem cells are functionally defined by their ability to regenerate lost stem cells, and thereby entire tissues, upon engraftment. However, the molecular mechanisms underlying tissue regeneration are not understood. In the Drosophila testis, two types of stem cells exist, germline stem cells (GSCs) and somatic stem cells (SSCs). The signal transducer and activator of transcription gene, Stat92E, was found previously to be directly required in the GSCs to prevent their differentiation. Here we find that Jak-STAT signaling is also directly required in the SSCs for their maintenance. Therefore, two stem cell populations directly receive one signal, and this signal ensures that each population is maintained within the same niche. Removal of the signal causes GSCs to differentiate into spermatogonia without self-renewal, while we also find that SSCs lacking Jak-STAT signaling differentiate into cyst cells (CCs). Even though both populations receive the same signal and differentiate when the signal is removed, these two populations are actually maintained independently of each other. This independence becomes evident when the SSCs are lost from the niche by conditionally removing Jak-STAT from only them. In this situation the GSCs are maintained autonomously and divide reminiscent of wild type even though their neighboring SSCs have been lost. Although, the level of Stat92E received in the GSCs is very important for their maintenance because if the amount received is altered, either GSCs are not maintained or the niche becomes affected. Since the level is important, we determined if restoring the signal after removal would have repercussions. Interestingly, a mechanism of stem cell regeneration was found. By conditionally removing and restoring Jak-STAT signaling, testes lacking GSCs but containing spermatogonia regain normal numbers of functional GSCs. Thus, spermatogonial cells (precursors to sperm) dedifferentiate into GSCs, indicating that in the admissible environment, dedifferentiation repopulates functional GSCs during tissue regeneration. SSCs also return to the niche during the restoration of Jak-STAT signaling although their mechanism of repopulation has yet to be determined. Repopulation of the GSCs can also occur when SSCs are not lost from the niche, again indicating that each stem cell population is controlled independently in same niche.

ISBN: 9780549311706Subjects--Topical Terms:

1017686
Biology, Cell.

The repopulation and regulation of two different stem cell lineages in one stem cell niche: The germline and somatic stem cells in the Drosophila testis.
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100 1 $a Brawley, Crista M. $3 1023402
245 1 4 $a The repopulation and regulation of two different stem cell lineages in one stem cell niche: The germline and somatic stem cells in the Drosophila testis.
300 $a 129 p.
500 $a Adviser: Erika Matunis.
500 $a Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7056.
502 $a Thesis (Ph.D.)--The Johns Hopkins University, 2008.
520 $a Stem cells are functionally defined by their ability to regenerate lost stem cells, and thereby entire tissues, upon engraftment. However, the molecular mechanisms underlying tissue regeneration are not understood. In the Drosophila testis, two types of stem cells exist, germline stem cells (GSCs) and somatic stem cells (SSCs). The signal transducer and activator of transcription gene, Stat92E, was found previously to be directly required in the GSCs to prevent their differentiation. Here we find that Jak-STAT signaling is also directly required in the SSCs for their maintenance. Therefore, two stem cell populations directly receive one signal, and this signal ensures that each population is maintained within the same niche. Removal of the signal causes GSCs to differentiate into spermatogonia without self-renewal, while we also find that SSCs lacking Jak-STAT signaling differentiate into cyst cells (CCs). Even though both populations receive the same signal and differentiate when the signal is removed, these two populations are actually maintained independently of each other. This independence becomes evident when the SSCs are lost from the niche by conditionally removing Jak-STAT from only them. In this situation the GSCs are maintained autonomously and divide reminiscent of wild type even though their neighboring SSCs have been lost. Although, the level of Stat92E received in the GSCs is very important for their maintenance because if the amount received is altered, either GSCs are not maintained or the niche becomes affected. Since the level is important, we determined if restoring the signal after removal would have repercussions. Interestingly, a mechanism of stem cell regeneration was found. By conditionally removing and restoring Jak-STAT signaling, testes lacking GSCs but containing spermatogonia regain normal numbers of functional GSCs. Thus, spermatogonial cells (precursors to sperm) dedifferentiate into GSCs, indicating that in the admissible environment, dedifferentiation repopulates functional GSCs during tissue regeneration. SSCs also return to the niche during the restoration of Jak-STAT signaling although their mechanism of repopulation has yet to be determined. Repopulation of the GSCs can also occur when SSCs are not lost from the niche, again indicating that each stem cell population is controlled independently in same niche.
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