scholarly journals Deficient autophagy drives aging in Hydra

2017 ◽  
Author(s):  
Szymon Tomczyk ◽  
Quentin Schenkelaars ◽  
Nenad Suknovic ◽  
Yvan Wenger ◽  
Kazadi Ekundayo ◽  
...  
Keyword(s):  
Stem Cell ◽  
Aging Effect ◽  
Proteasome Inhibition ◽  
Cell Loss ◽  
Cell Renewal ◽  
Epithelial Stem Cells ◽  
Autophagy Flux ◽  
Stem Cell Renewal ◽  
Negligible Senescence ◽  
Stem Cell Populations

AbstractHydra exhibits a negligible senescence as its epithelial and interstitial stem cell populations continuously divide. Here we identified two H. oligactis strains that respond differently to interstitial stem cell loss. Cold-resistant (Ho_CR) animals adapt and remain healthy while cold-sensitive (Ho_CS) ones die within three months, after their epithelial stem cells lose their selfrenewal potential. In Ho_CS but not in Ho_CR animals, the autophagy flux is deficient, characterized by a low induction upon starvation, proteasome inhibition or Rapamycin treatment, and a constitutively repressed Ulk activity. In the non-aging Hydra vulgaris, WIPI2 silencing suffices to induce aging. Rapamycin can delay aging by sustaining epithelial self-renewal and regeneration, although without enhancing the autophagy flux. Instead Rapamycin promotes engulfment in epithelial cells where p62/SQSTM1-positive phagocytic vacuoles accumulate. This study uncovers the importance of autophagy in the longevity of early-branched eumetazoans by maintaining stem cell renewal, and a novel anti-aging effect of Rapamycin via phagocytosis.

scholarly journals Hydra, a model system for deciphering the mechanisms of aging and resistance to aging

2017 ◽  
Author(s):  
Quentin Schenkelaars ◽  
Szymon Tomczyk ◽  
Yvan Wenger ◽  
Kazadi Ekundayo ◽  
Victor Girard ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Adult Stem Cell ◽  
Distinct Species ◽  
Model System ◽  
Epithelial Stem Cells ◽  
Muscular System ◽  
Autophagy Flux ◽  
Self Renewal ◽  
Stem Cell Populations

ABSTRACTThe freshwater cnidarian polyp named Hydra, which can be mass-cultured in the laboratory, is characterized by a highly dynamic homeostasis with a continuous self-renewal of its three adult stem cell populations, the epithelial stem cells from the epidermis, the epithelial stem cells from the gastrodermis, and the multipotent interstitial stem cells, which provide cells of the nervous system, gland cells and germ cells. Two unusual features characterize these stem cells that cannot replace each other, they all avoid G1 to pause in G2, and the two epithelial populations are concomitantly multifunctional and stem cells. H. vulgaris that does not show any signs of aging over the years, resists to weeks of starvation and adapts to the loss of neurogenesis, providing a unique model system to study the resistance to aging. By contrast some strains of a distinct species named H. oligactis undergo a rapid aging process when undergoing gametogenesis or when placed in stress conditions. The aging phenotype is characterized by the rapid loss of somatic interstitial stem cells, the progressive reduction in epithelial stem cell self-renewal, the loss of regeneration, the disorganization of the neuro-muscular system, the loss of the feeding behavior, and the death of all animals within about three months. We review here the possible mechanisms that help H. vulgaris to sustain stem cell self-renewal and thus bypass aging processes. For this, FoxO seems to act as a pleiotropic actor, regulating stem cell proliferation, stress response and apoptosis. In H. oligactis, the regulation of the autophagy flux differs between aging-sensitive and aging-resistant animals, pointing to a key role for proteostasis in the maintenance of a large pool of active and plastic epithelial stem cells.

scholarly journals Proliferation and differentiation of spermatogonial stem cells

Reproduction ◽  
2001 ◽  
pp. 347-354 ◽  
Author(s):  
DG de Rooij
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Rna Binding ◽  
Single Cells ◽  
Cell Loss ◽  
Spermatogonial Stem Cells ◽  
Cell Renewal ◽  
Stem Cell Renewal ◽  
Factor C ◽  
Almost All

Spermatogonial stem cells (A(s) spermatogonia) are single cells that either renew themselves or produce A(pr) (paired) spermatogonia predestined to differentiate. In turn, the A(pr) divide into chains of A(al) (aligned) spermatogonia that also divide. The ratio between self-renewal and differentiation of the stem cells is regulated by glial cell line-derived neurotrophic factor produced by Sertoli cells, while the receptors are expressed in stem cells. A(s), A(pr) and A(al) spermatogonia proliferate during part of the epithelial cycle forming many A(al) spermatogonia. During epithelial stage VIII, almost all A(al) spermatogonia, few A(pr) and very few A(s) spermatogonia differentiate into A1 spermatogonia. A number of molecules are involved in this differentiation step including the stem cell factor-c-kit system, the Dazl RNA binding protein, cyclin D(2) and retinoic acid. There is no fine regulation of the density of spermatogonial stem cells and consequently, in some areas, many A1 and, in other areas, few A1 spermatogonia are formed. An equal density of spermatocytes is then obtained by the apoptosis of A2, A3 or A4 spermatogonia to remove the surplus cells. The Bcl-2 family members Bax and Bcl-x(L) are involved in this density regulation. Several mechanisms are available to cope with major or minor shortages in germ cell production. After severe cell loss, stem cell renewal is preferred above differentiation and the period of proliferation of A(s), A(pr) and A(al) spermatogonia is extended. Minor shortages are dealt with, at least in part, by less apoptosis among A2-A4 spermatogonia.

scholarly journals miR-200c and GATA binding protein 4 regulate human embryonic stem cell renewal and differentiation

2014 ◽  
Vol 12 (2) ◽  
pp. 338-353 ◽  
Author(s):  
Hsiao-Ning Huang ◽  
Shao-Yin Chen ◽  
Shiaw-Min Hwang ◽  
Ching-Chia Yu ◽  
Ming-Wei Su ◽  
...  
Keyword(s):  
Stem Cell ◽  
Embryonic Stem Cell ◽  
Human Embryonic Stem Cell ◽  
Binding Protein ◽  
Embryonic Stem ◽  
Cell Renewal ◽  
Stem Cell Renewal

scholarly journals MicroRNAs Differentially Regulated by Akt Isoforms Control EMT and Stem Cell Renewal in Cancer Cells

2009 ◽  
Vol 2 (92) ◽  
pp. ra62-ra62 ◽  
Author(s):  
D. Iliopoulos ◽  
C. Polytarchou ◽  
M. Hatziapostolou ◽  
F. Kottakis ◽  
I. G. Maroulakou ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cancer Cells ◽  
Cell Renewal ◽  
Akt Isoforms ◽  
Stem Cell Renewal
Sign in / Sign up

Export Citation Format

Share Document