Report
Teaser, summary, work performed and final results
Periodic Reporting for period 2 - STEMBAR (Mechanisms and functional significance of diffusion barriers for asymmetric segregation of age in neural stem cells)
Teaser
\"Neural stem cells (NSCs) generate new neurons in distinct areas of the mammalian brain throughout life. Newborn neurons have been linked to certain forms of learning and memory. Moreover, failing or altered neurogenesis has been associated with a number of neuro-psychiatric...
Summary
\"Neural stem cells (NSCs) generate new neurons in distinct areas of the mammalian brain throughout life. Newborn neurons have been linked to certain forms of learning and memory. Moreover, failing or altered neurogenesis has been associated with a number of neuro-psychiatric diseases, among others cognitive aging, Alzheimer\'s disease, and epilepsy. Thus, understanding the principles allowing for life-long neurogenesis may be the prerequisite for future therapeutic attempts to harness the regenerative potential of the adult mammalian brain. In contrast to many other proliferative cells in the adult organism that only show restricted numbers of cell divisions, it appears that stem cells are capable to generate \"\"young\"\" daughter cells throughout life. These findings suggest that accumulating damage (i.e., age) may not be symmetrically segregated between the mother stem cell and the differentiating daughter cell (e.g., Moore and Jessberger, 2017 TiCB). Thus, the aim of our project is to understand how age is asymmetrically segregated during NSC divisions.
We anticipate to define mechanisms that regulate the segregation of cellular damage factors and to use this knowledge to rejuvenate stem cells in old age or in the context of neuro-psychiatric disease.
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Work performed
Since the last reporting period we made substantial progress to reach our challenging aims. We heavily invested into technology development and are now able to track previous cell division histories (e.g., the iCOUNT and modified miCOUNT mice), follow cell divisions long term in vivo using 2-photon microscopy (e.g., Pilz et al., 2018 Science), and generated novel mice analyzing the effects of age on the strength of the barrier in the endoplasmic reticulum (ER; e.g., Moore et al., 2015 Science).
We successfully visualized damaged protein segregation in dividing neural stem cells (NSCs) and continued long-term imaging approaches (over 14 days in vitro) to study segregation of cellular components in cultures of human and mouse somatic stem cells. Parts of the data were published (Moore et al., 2015 Science). Further, we established long-term imaging of NSCs in embryonic slice cultures and in vivo (e.g., Pilz et al., 2018 Science). We started to correlate cellular behavior and fate with the strength of the diffusion barrier. Currently, we collect and analyze our data using modern bioinformatic tools. We have also successfully tested genetic approaches to analyze individual cell division history in vitro and generated transgenic iCOUNT mice using CRISPR/Cas9 technology. iCOUNT mice (and modified miCOUNT mice) are currently analyzed using a series of complementary approaches including imaging technology and single cell molecular analyses. We finished the analyses of age-induced protein expression (using immunhistochemical approaches and knock-in strategies in mouse NSCs) and confirmed the anticipated age-dependent regulation of these proteins. We have obtained conditional mutant mice that are currently bred with a number of different Cre driver lines. First analyses suggest exciting effects of age-induced protein deletion on NSC behavior in the murine brain. Our results have been partially published and disseminated in an number of lectures and international conferences and seminar series.
Final results
During our project we developed novel and unique genetic tools, allowing for the analysis of previous cell division events (iCOUNT). This tool will be soon made available to the scientific community. Furthermore, we have established first intravital imaging approaches of neural stem cells in the adult brain (e.g., Pilz et al., 2018 Science). We currently make use of this breakthrough technology and expect to provide major advancements to the field within the funding period.