Document Type

Honors Thesis

Major

Molecular and Cellular Biology and Biochemistry

Advisor(s)

Kristy Townsend

Committee Members

Lynn Atkins, Gabriel Jensen, Margaret Killinger, Melissa Maginnis

Graduation Year

May 2021

Publication Date

2025

Abstract

Until the turn of the 21st century, the scientific community believed the adult mammalian brain did not create newborn neurons via the process of neurogenesis after development. It is now widely accepted that adult neurogenesis continues throughout life in both basal conditions and as a response to injury or other stimuli. In the field of adult neurogenesis, researchers identify adult neural stem cells (NSCs) by their capacity to self-renew, differentiate into mature neurons and glial cells, and maintain an immature state over a long duration. However, there has been lacking a specific and unique marker of quiescent adult stem cells in the brain, forcing researchers to rely on nonspecific stem cell markers, label-retention/lineage tracing studies, and proliferation markers to identify these cells. These methods led to non-specific labeling of stem cells in the adult brain. Mouse Telomerase Reverse Transcriptase (mTert) is the rate limiting component of the telomerase holoenzyme complex in mice that is required for stem cells to avoid senescence and has been shown to mark adult stem cells in other adult tissues but has never been described as a marker of quiescent, slowly cycling adult brain stem cells until now. Using a direct reporter mouse line, we have mapped mTert-expressing cells to novel and well-described stem cell niches in the brain. By comparing mTert+ cells in young-adult to aged mice, we have also been able to visualize and quantify these cells at different stages of the mouse’s lifespan. Finally, co-immunostaining has identified cell types that express mTert within the adult mouse brain and has identified several markers that colocalize with mTert. These data support the use of mTert as a much-needed unique and specific cellular marker to identify adult stem cells in the brain for the study of adult neurogenesis.

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