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Title:Somatic regulation of germ cell development in the planarian Schmidtea mediterranea: the role of systemic and local factors
Author(s):Saberi, Amir
Director of Research:Newmark, Phillip A
Doctoral Committee Chair(s):Freeman, Brian C
Doctoral Committee Member(s):Chen, Jie; Smith-Bolton, Rachel; Raetzman, Lori T.
Department / Program:Cell & Developmental Biology
Discipline:Cell and Developmental Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):planarian
schmidtea mediterranea
germline
germ cell
germline development
germ cell development
reproductive development
neuropeptide
neuropeptide Y
NPY
NPY-8
prohormone convertase
monooxygenase
amidation
peptide processing
G protein-coupled receptor
GPCR
NPY receptor
NPYR
ophis
chemoreceptor
clustering
receptor assay
peptide internalization
reproductive phenotype
Abstract:Germline development in animals is closely coordinated with those aspects of physiology that are influenced by environmental conditions. The soma acts as a vehicle for the germline and plays a critical role in regulating its development and maintenance by providing systemic and local instructive signals. Investigating the relationship between soma and germline is essential for understanding the mechanisms of germline development across animals and, in particular, in the context of human reproductive physiology. Planarians provide a unique system for studying somatic regulation of germline development: they display remarkable plasticity in maintenance of their germline, with the ability to develop or dismantle reproductive tissues in response to systemic and environmental cues. The planarian nervous system plays a key role in systemic regulation of germ cell development through signaling molecules such as neuropeptide Y-8 (NPY-8). In this study, we explored different aspects of NPY-8 biosynthesis and signaling in planarians and expanded our work to examine the role of G protein-coupled receptors (GPCRs) in systemic and local regulation of germ cell differentiation. First, we revealed the expression of NPY-8 in central and peripheral nervous systems of the planarian and used mass spectrometric methods to deduce the structure of endogenous NPY-8. We demonstrated that two neuropeptide processing enzymes, prohormone convertase 2 and peptidylglycine alpha-hydroxylating monooxygenase, are essential for planarian reproductive development, likely through post-translational modification of NPY-8. Next, we sought to identify the NPY-8 receptor by genome-wide analysis of planarian GPCRs. We identified 566 putative planarian GPCR genes and classified them into conserved and phylum-specific subfamilies. By functional analysis of a subset these genes, we found that neurally expressed neuropeptide y receptor-1 is the NPY-8 receptor and required for reproductive maturation of the planarian. Additionally, we screened the complement of GPCRs with enriched expression in sexual planarians and identified a chemoreceptor family member, ophis, that is required for germ cell differentiation. ophis is expressed in somatic cells of male and female gonads, as well as in accessory reproductive tissues. We have previously shown that somatic gonadal cells are required for male germline specification and maintenance in planarians. However, ophis is not essential for germline specification or maintenance, and therefore, defines a secondary role for planarian gonadal niche cells in promoting germ cell differentiation. In addition to characterization of NPY-8 expression and biosynthesis, our studies uncover the complement of planarian GPCRs and reveal previously unappreciated roles for these receptors in systemic and local control of germ cell development.
Issue Date:2016-07-13
Type:Thesis
URI:http://hdl.handle.net/2142/93054
Rights Information:Copyright 2016 Amir Saberi
Date Available in IDEALS:2016-11-10
Date Deposited:2016-08


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