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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

Spectrosome Knockout minimally affects centrosome orientation, spindle orientation, mitosis duration, and stem cell numbers in male GSCs.(A) Centrosome misorientation during interphase was analyzed from time lapse image sequences, and there is no significant difference between the hts-mut and the wild type. (B) There is minimal change in the spindle orientation between the hts-mut and the wild type. (C) Mitosis duration is not affected in hts-mut compared to the wild type when measured from nuclear envelope breakdown time to anaphase. (D) There is no significant difference for GSC number per testis in hts-mut and wild type flies.
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pone.0123294.g004: Spectrosome Knockout minimally affects centrosome orientation, spindle orientation, mitosis duration, and stem cell numbers in male GSCs.(A) Centrosome misorientation during interphase was analyzed from time lapse image sequences, and there is no significant difference between the hts-mut and the wild type. (B) There is minimal change in the spindle orientation between the hts-mut and the wild type. (C) Mitosis duration is not affected in hts-mut compared to the wild type when measured from nuclear envelope breakdown time to anaphase. (D) There is no significant difference for GSC number per testis in hts-mut and wild type flies.

Mentions: Utilizing time-lapse live-cell imaging, we investigated the centrosome and spindle orientation when spectrosome was knocked out. Firstly, consistent with reported results based on fixed sample studies, hts-mut does not affect either the interphase centrosome orientation (p>0.5) (Fig 4A) or the mitotic spindle orientation, as 95% spindles in hts-mut were still properly oriented (Fig 4B). Moreover, the hts-mut does not significantly affect mitosis duration either (Fig 4C: from nuclear envelope break time to the onset of anaphase, p>0.06); wild type GSCs were 9.5±1.5min (n = 21) and hts-mut GSCs were 8.5±1.7min (n = 21). We found that wild type GSC count per testis (8.3±0.9 GSCs, n = 20 testes) and hts-mut GSC counts per testis (7.9±0.6 GSCs, n = 18 testes) were not significantly different (p>0.23), (Fig 4D). These results demonstrate that the spectrosome does not affect the centrosome and spindle orientation.


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

Bang C, Cheng J - PLoS ONE (2015)

Spectrosome Knockout minimally affects centrosome orientation, spindle orientation, mitosis duration, and stem cell numbers in male GSCs.(A) Centrosome misorientation during interphase was analyzed from time lapse image sequences, and there is no significant difference between the hts-mut and the wild type. (B) There is minimal change in the spindle orientation between the hts-mut and the wild type. (C) Mitosis duration is not affected in hts-mut compared to the wild type when measured from nuclear envelope breakdown time to anaphase. (D) There is no significant difference for GSC number per testis in hts-mut and wild type flies.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123294.g004: Spectrosome Knockout minimally affects centrosome orientation, spindle orientation, mitosis duration, and stem cell numbers in male GSCs.(A) Centrosome misorientation during interphase was analyzed from time lapse image sequences, and there is no significant difference between the hts-mut and the wild type. (B) There is minimal change in the spindle orientation between the hts-mut and the wild type. (C) Mitosis duration is not affected in hts-mut compared to the wild type when measured from nuclear envelope breakdown time to anaphase. (D) There is no significant difference for GSC number per testis in hts-mut and wild type flies.
Mentions: Utilizing time-lapse live-cell imaging, we investigated the centrosome and spindle orientation when spectrosome was knocked out. Firstly, consistent with reported results based on fixed sample studies, hts-mut does not affect either the interphase centrosome orientation (p>0.5) (Fig 4A) or the mitotic spindle orientation, as 95% spindles in hts-mut were still properly oriented (Fig 4B). Moreover, the hts-mut does not significantly affect mitosis duration either (Fig 4C: from nuclear envelope break time to the onset of anaphase, p>0.06); wild type GSCs were 9.5±1.5min (n = 21) and hts-mut GSCs were 8.5±1.7min (n = 21). We found that wild type GSC count per testis (8.3±0.9 GSCs, n = 20 testes) and hts-mut GSC counts per testis (7.9±0.6 GSCs, n = 18 testes) were not significantly different (p>0.23), (Fig 4D). These results demonstrate that the spectrosome does not affect the centrosome and spindle orientation.

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