Date Approved
8-2018
Document Type
Dissertation
Degree Name
PhD in Cell & Molecular Biology
Department
Molecular Biology
College
Graduate School of Biomedical Sciences
First Advisor
Eric Moss, PhD
Committee Member 1
Jeremy Francis, PhD
Committee Member 2
Ronald Ellis, PhD
Committee Member 3
Hristo Houbaviy, PhD
Committee Member 4
Nathaniel Hartman, PhD
Subject(s)
RNA-Binding Proteins, Mammals, Neurogenesis, Cell Physiological Phenomena, Neurobiology
Disciplines
Cell Biology | Cellular and Molecular Physiology | Laboratory and Basic Science Research | Life Sciences | Medical Cell Biology | Medical Neurobiology | Medicine and Health Sciences | Molecular and Cellular Neuroscience | Molecular Biology
Abstract
Developmental timing is a key aspect of tissue and organ formation in which distinct cell types are generated through a series of steps from common progenitors. These progenitors undergo specific changes in gene expression that signifies both a distinct progenitor type and developmental time point that thereby specifies a particular cell fate at that stage of development. The nervous system is an important setting for understanding developmental timing because different cell types are produced in a certain order and the switch from stem cells to progenitors requires precise timing and regulation. Notable examples of such regulatory molecules include the RNA-binding protein LIN28, and its downstream target, miRNA let-7. Although LIN28 is known to regulate both cell fate and tissue growth, and at times to promote an undifferentiated state, thus far a unified understanding of LIN28’s biological role at the cellular level has not been attained. Here I address LIN28’s activity in mammalian postnatal neurogenesis. Constitutive expression of LIN28 in cells derived from the subventricular zone of the mouse caused several distinct effects: (1) the number of differentiated neurons was dramatically reduced while the relative abundance of two neuronal sub-types was significantly altered; (2) the population of proliferating neural progenitors in the SVZ was reduced while the proportion of neuroblasts was increased, (3) neuro-blast exit from the SVZ increased, and (4) the number of astrocytes was reduced while occasionally causing them to appear early. Thus, LIN28 acts at a post-stem cell/pre-differentiation step, and its continuous expression caused a precocious, not a reiterative phenotype, as is seen in other experimental systems. I made use of a circular RNA sponge that effectively inhibits let-7 activity to address the degree to which LIN28’s effects are due to its inhibition of let-7. Moreover, since LIN41 contributes to a subset of LIN28’s function in C. elegans, I explored whether LIN41 played a role in mammalian neurogenesis. I found that although LIN28 has a multifaceted role in the number and types of cells produced during postnatal neurogenesis, it appears that its action through let-7 accounts for only a fraction of these effects.
Recommended Citation
Romer-Seibert, Jennifer S., "The Role of Developmental Timing Regulators in Progenitor Proliferation and Cell Fate Specification During Mammalian Neurogenesis" (2018). Graduate School of Biomedical Sciences Theses and Dissertations. 38.
https://rdw.rowan.edu/gsbs_etd/38
Included in
Cell Biology Commons, Cellular and Molecular Physiology Commons, Laboratory and Basic Science Research Commons, Medical Cell Biology Commons, Medical Neurobiology Commons, Molecular and Cellular Neuroscience Commons, Molecular Biology Commons