Page 355 - 53rd Annual Drosophila Research Conference

Poster Full Abstracts - Stem Cells
Poster board number is above title. The first author is the presenter
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828C
Examining the role of the fat body in the ovarian response to diet. Alissa R Armstrong1, Leesa LaFever 2, Kaitlin Laws1, Robert Cole3, Daniela
Drummond-Barbosa1. 1) Biochemistry and Molecular Biology, Bloomberg School of Public Health, Baltimore, MD; 2) Division of Experimental
Hematology and Cancer Biology, Children's Hospital Research Foundation, University of Cincinnati, Cincinnati, OH; 3) Mass Spectrometry and Proteomics
Facility, Johns Hopkins School of Medicine, Baltimore, MD.
Nutritional status is sensed by many tissues and must be coordinated properly for appropriate cellular responses. In many organisms, modulation of fertility
by diet ensures that energy and building blocks used to generate gametes are not expended when resources are limited. Our past work showed that
Drosophila females fed a yeast-free diet have reduced proliferation rates of germline stem cells (GSCs), follicle stem cells (FSCs) and their progeny,
increased early cyst death and a block in vitellogenesis. We also showed that insulin, Target of rapamycin (TOR) and ecdysone signaling act in the ovary to
mediate these effects. However, it remains largely unclear how the fat body, a nutrient sensitive tissue with storage and endocrine roles, modulates the
ovarian response to diet. Preliminary data from our lab revealed that altered TOR signaling or amino acid transport in the fat body affects egg production
rates, and we are currently expanding these analyses. We also performed a quantitative iTRAQ proteomics comparison between the fat body from flies fed a
yeast-rich versus switched for 12 hours to a yeast-free diet, and identified 27 putative secreted proteins that were either down-regulated or up-regulated. We
are currently performing a functional screen of these candidates for a potential role in oogenesis. These studies will shed light on the interaction between the
fat body and ovary during the response to diet and may identify specific factors secreted by the fat body that help transmit dietary information to the ovary.
829A
The LEM-D protein Otefin regulates niche signaling cascades to maintain female germline stem cell homeostasis. Lacy J. Barton1, Belinda S. Pinto2 ,
Pamela K. Geyer1. 1) Dept Biochemistry, Univ Iowa, Iowa City, IA; 2) Whitehead Institute, MIT, Cambridge, MA.
Adult stem cell populations are supported by a specialized microenvironment or niche. The Drosophila female germline stem cells (GSCs) niche balances
GSC maintenance and differentiation by tightly regulating the Bone-Morphogenetic-Protein (BMP) pathway. Production of the dominant BMP ligand,
Decapentaplegic (Dpp), is transcriptionally controlled by Janus Kinase/Signal Transducer and Activator of Transcription (Jak/Stat) signaling. The LEM
Domain (LEM-D) protein, Otefin, is required for both female GSC maintenance and germline differentiation; however the dual nature of these requirements
remains poorly understood. Here we show that loss of Otefin results in over-expression of genes encoding Jak/Stat and BMP ligands, despite premature loss
of the niche cells which normally produce Dpp. As a result, BMP signaling is activated in germline and somatic cells located far from the GSC niche. These
effects block germline differentiation, generating small tumors of ten to fifty GSC-like cells. Further, restricted expression of otefin in somatic cells restores
Jak/Stat and BMP ligand expression and rescues the block in germline differentiation. Together, these data suggest that Otefin regulates the somatic
signaling pathways required for proper niche function. Otefin and other LEM-D proteins are part of an extensive nuclear lamina network that lies beneath the
nuclear envelope. Mutations in genes encoding LEM-D proteins cause a collection of age-enhanced diseases which affect the mesenchymal tissues that
depend upon resident adult stem cells. Our findings are consistent with emerging evidence indicating that nuclear lamina proteins have important roles in
maintaining the homeostasis of adult stem cell populations.
830B
Investigating the Role of Hr39 in the Germline Stem Cell Lineage. Grace H. Hwang, Elizabeth T. Ables, Daniela Drummond-Barbosa. Dept. of
Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD.
Proper regulation of stem cell maintenance and division coordinated with organismal physiology is important for tissue homeostasis. Steroid hormones, by
binding to conserved nuclear hormone receptors, are important systemic regulators of cellular activity in diverse cell types in response to nutrient intake, but
little is known about their direct effects on adult stem cells. The steroid hormone ecdysone regulates Drosophila ovarian germline stem cell (GSC)
maintenance and proliferation via the ecdysone signaling target E74; however, additional targets likely also mediate this response. Nuclear hormone
receptors, downstream of the ecdysone receptor, are potential candidate targets of ecdysone signaling, but whether ecdysone controls GSC activity through
these hormone receptors is unclear. Hr39 is a nuclear hormone receptor that is a target of ecdysone in larval tissues and has reported roles in the reproductive
tract. We have obtained a collection of Hr39 mutant alleles and are currently testing whether Hr39 regulates the GSC lineage downstream of ecdysone
signaling.
831C
in vitro analyses of cellular interactions among germline stem cells, cap cells and escort cells in Drosophila. Yuzo Niki, Takuya Sato, Yusuke Iizumi.
Dept. Biology, Faculty of Science, Ibaraki University, Mito, Ibaraki, Japan.
Drosophila germline stem cells (GSCs) and their niche cells comprise one of the best-characterized stem cell systems and are well suited to study of stem
cell biology. The elucidation of the cellular and molecular mechanisms responsible for GSC behavior is hindered by the lack of suitable culture systems.
Recently, we succeeded in establishing Drosophila larval ovarian cell lines of which primordial germ cells (PGCs) and niche cells are coexisted. In addition,
we cloned stable cell lines originated from terminal filament and cap cells (named TCAP cells) from these cell lines. We analyzed self-renewal divisions
under the living conditions and signal pathways occurring between TCAP and germ cells after co-culturing PGCs or GSCs with TCAP cells. We found that
PGCs and GSCs proliferated stably for a long term, while their differentiation was suppressed. The Dpp signal pathway occurs normally as seen GSC/niche
in vivo , which indicating that TCAP cells retains functional ability of niche cells. TCAP cells express wingless and hedgehog as do cap cells. Furthermore,
we analyzed functional ability of escort cell lines (ESC) that we have established. Interestingly, ESC can differentiate male PGCs and GSCs as well as
female GSCs in vitro . This in vitro reconstituted niche system will facilitate further elucidation of the molecular mechanisms responsible for the construction
and maintenance of GSCs/niche system during normal development.
832A
PointedP1 connects the establishment and maintenance of intermediate neural progenitor cell fate in Drosophila neural stem cell lineages. Derek H
Janssens1,4, Hideyuki Komori4 , Xiao Qi2,4, Cheng-Yu Lee1,2,3,4. 1) Cellular and Molecular Biology Graduate Program; 2) Department of Cell and
Developmental Biology; 3) Division of Molecular Medicine and Genetics, Department of Internal Medicine; 4) Center for Stem Cell Biology, Life Sciences