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Dynamic interplay of spectrosome and centrosome organelles in asymmetric stem cell divisions.

Bang C, Cheng J - PLoS ONE (2015)

Bottom Line: Utilizing time-lapse live cell imaging, customized tracking, and image processing programs, we found that most acentrosomal GSCs have the spectrosomes reposition from the basal end (wild type) to the apical end close to hub-GSC interface (acentrosomal GSCs).For acentrosomal GSCs, their mitotic spindles were still highly oriented and divided asymmetrically with longer mitosis duration, resulting in asymmetric divisions.Moreover, when the spectrosome was knocked out, the centrosomes velocity decreased and centrosomes located closer to hub-GSC interface.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, The University of Illinois at Chicago, Chicago, Illinois, United States of America.

ABSTRACT
Stem cells have remarkable self-renewal ability and differentiation potency, which are critical for tissue repair and tissue homeostasis. Recently it has been found, in many systems (e.g. gut, neurons, and hematopoietic stem cells), that the self-renewal and differentiation balance is maintained when the stem cells divide asymmetrically. Drosophila male germline stem cells (GSCs), one of the best characterized model systems with well-defined stem cell niches, were reported to divide asymmetrically, where centrosome plays an important role. Utilizing time-lapse live cell imaging, customized tracking, and image processing programs, we found that most acentrosomal GSCs have the spectrosomes reposition from the basal end (wild type) to the apical end close to hub-GSC interface (acentrosomal GSCs). In addition, these apically positioned spectrosomes were mostly stationary while the basally positioned spectrosomes were mobile. For acentrosomal GSCs, their mitotic spindles were still highly oriented and divided asymmetrically with longer mitosis duration, resulting in asymmetric divisions. Moreover, when the spectrosome was knocked out, the centrosomes velocity decreased and centrosomes located closer to hub-GSC interface. We propose that in male GSCs, the spectrosome recruited to the apical end plays a complimentary role in ensuring proper spindle orientation when centrosome function is compromised.

No MeSH data available.


Related in: MedlinePlus

Most spindle orientation at anaphase and stem cell number are maintained in GSCs without centrosomes.(A) Live imaging reveals that most DSas4-mut GSCs maintain their spindle orientation compared to the wild type. (B) There is no significant difference of GSC number per testes in DSas4-mut and wild type flies. (C) The mitosis duration from pro-metaphase to anaphase in DSas4-mut GSCs is significantly longer than that in wild type.
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pone.0123294.g001: Most spindle orientation at anaphase and stem cell number are maintained in GSCs without centrosomes.(A) Live imaging reveals that most DSas4-mut GSCs maintain their spindle orientation compared to the wild type. (B) There is no significant difference of GSC number per testes in DSas4-mut and wild type flies. (C) The mitosis duration from pro-metaphase to anaphase in DSas4-mut GSCs is significantly longer than that in wild type.

Mentions: Previous literature has reported that centrosomes in Drosophila appear to have mixed roles for some types of stem cells in maintaining asymmetric stem cell divisions. A neuroblast without centrosome due to DSas4-mut displays asymmetric division defects [27], but most male and female GSCs in DSas4-mut can still maintain asymmetric stem cell division with proper spindle alignment [21, 22]. Consistently, we found that most acentrosomal GSCs with DSas4-mut maintained proper orientation (Fig 1A: 63% at 0–30 degrees, 20% at 30–60 degrees, and 17% at 60–90 degrees) compared to wild type (83% at 0–30 degrees, 17% at 30–60 degrees, and 0% at 60–90 degrees). Additionally, by counting the GSC numbers per testis, we found that there is no significant difference (p>0.69) of GSC number per testis in DSas4-mut (8.8±1.2 GSCs, n = 26 testes) and wild type (8.8±1.0 GSCs, n = 25 testes) (Fig 1B).


Dynamic interplay of spectrosome and centrosome organelles in asymmetric stem cell divisions.

Bang C, Cheng J - PLoS ONE (2015)

Most spindle orientation at anaphase and stem cell number are maintained in GSCs without centrosomes.(A) Live imaging reveals that most DSas4-mut GSCs maintain their spindle orientation compared to the wild type. (B) There is no significant difference of GSC number per testes in DSas4-mut and wild type flies. (C) The mitosis duration from pro-metaphase to anaphase in DSas4-mut GSCs is significantly longer than that in wild type.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388834&req=5

pone.0123294.g001: Most spindle orientation at anaphase and stem cell number are maintained in GSCs without centrosomes.(A) Live imaging reveals that most DSas4-mut GSCs maintain their spindle orientation compared to the wild type. (B) There is no significant difference of GSC number per testes in DSas4-mut and wild type flies. (C) The mitosis duration from pro-metaphase to anaphase in DSas4-mut GSCs is significantly longer than that in wild type.
Mentions: Previous literature has reported that centrosomes in Drosophila appear to have mixed roles for some types of stem cells in maintaining asymmetric stem cell divisions. A neuroblast without centrosome due to DSas4-mut displays asymmetric division defects [27], but most male and female GSCs in DSas4-mut can still maintain asymmetric stem cell division with proper spindle alignment [21, 22]. Consistently, we found that most acentrosomal GSCs with DSas4-mut maintained proper orientation (Fig 1A: 63% at 0–30 degrees, 20% at 30–60 degrees, and 17% at 60–90 degrees) compared to wild type (83% at 0–30 degrees, 17% at 30–60 degrees, and 0% at 60–90 degrees). Additionally, by counting the GSC numbers per testis, we found that there is no significant difference (p>0.69) of GSC number per testis in DSas4-mut (8.8±1.2 GSCs, n = 26 testes) and wild type (8.8±1.0 GSCs, n = 25 testes) (Fig 1B).

Bottom Line: Utilizing time-lapse live cell imaging, customized tracking, and image processing programs, we found that most acentrosomal GSCs have the spectrosomes reposition from the basal end (wild type) to the apical end close to hub-GSC interface (acentrosomal GSCs).For acentrosomal GSCs, their mitotic spindles were still highly oriented and divided asymmetrically with longer mitosis duration, resulting in asymmetric divisions.Moreover, when the spectrosome was knocked out, the centrosomes velocity decreased and centrosomes located closer to hub-GSC interface.

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering, The University of Illinois at Chicago, Chicago, Illinois, United States of America.

ABSTRACT
Stem cells have remarkable self-renewal ability and differentiation potency, which are critical for tissue repair and tissue homeostasis. Recently it has been found, in many systems (e.g. gut, neurons, and hematopoietic stem cells), that the self-renewal and differentiation balance is maintained when the stem cells divide asymmetrically. Drosophila male germline stem cells (GSCs), one of the best characterized model systems with well-defined stem cell niches, were reported to divide asymmetrically, where centrosome plays an important role. Utilizing time-lapse live cell imaging, customized tracking, and image processing programs, we found that most acentrosomal GSCs have the spectrosomes reposition from the basal end (wild type) to the apical end close to hub-GSC interface (acentrosomal GSCs). In addition, these apically positioned spectrosomes were mostly stationary while the basally positioned spectrosomes were mobile. For acentrosomal GSCs, their mitotic spindles were still highly oriented and divided asymmetrically with longer mitosis duration, resulting in asymmetric divisions. Moreover, when the spectrosome was knocked out, the centrosomes velocity decreased and centrosomes located closer to hub-GSC interface. We propose that in male GSCs, the spectrosome recruited to the apical end plays a complimentary role in ensuring proper spindle orientation when centrosome function is compromised.

No MeSH data available.


Related in: MedlinePlus