An insulin-like peptide regulates size and adult stem cells in planarians

Animal growth depends on nutritional intake during development. In many animals, nutritional status is uncoupled from moderation of adult stature after adult size is achieved. However, some long-lived animals continue to regulate adult size and fertility in a nutrition-dependent manner. For example, the regenerating flatworm Schmidtea mediterranea becomes smaller, or degrows, during periods of starvation. These animals provide an opportunity to readily observe adult stem cell population dynamics in response to nutritional cues. We explore the role of insulin signaling in S. mediterranea. We disrupt insulin signaling via RNA interference and show that animals, despite eating, degrow similarly to starved animals. Utilizing in situ hybridization and immunofluorescence, we assess cellular changes in proliferative populations including the planarian adult stem cell population (neoblasts) and the germline. Both impaired insulin signaling and nutritional deprivation correlate with decreased neoblast proliferation. Additionally, insulin signaling plays a role in supporting spermatogenesis that is distinct from the effects of starvation. In sum, we demonstrate that insulin signaling is responsible for regulation of adult animal size and tissue homeostasis in an organism with plastic adult size. Importantly, insulin signaling continues to affect stem cell and germline populations in a mature organism. Furthermore, we show that adult organisms can differentially regulate specific cell populations as a result of environmental challenges.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Neuroscience

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2012

Author dc:creator

• Miller, Claire

Contributors dc:contributor

• Newmark, Phillip A.
• Ceman, Stephanie S.
• Raetzman, Lori T.

• Planarians
• Insulin
• Adult Stem Cells

Statement dc:rights

• Copyright 2011 Claire Miller

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/29421

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/29421