Dr. Matunis studies the stem cells that sustain spermatogenesis in the fruit fly Drosophila melanogaster to understand how signals from neighboring cells control stem cell renewal or differentiation. In the fruit fly testes, germ line stem cells attach to a cluster of non-dividing somatic cells called the hub. When a germ line stem cell divides, its daughter is pushed away from the hub and differentiates into a gonialblast. The germ line stem cells receive a signal from the hub that allows it to remain a stem cell, while the daughter displaced away from the hub loses the signal, and differentiates. Researchers in the Matunis lab have found key regulatory signals involved in this process.
Using genetic and genomic approaches, the Matunis lab continues to identify more genes that define the germ line stem cells' fate. She and her team are also investigating how spermatogonia reverse differentiation to become germ line stem cells again.
By studying stem cells that sustain spermatogenesis in the fruit fly Drosophila melanogaster, Dr. Matunis' lab has begun to understand stem cell regulation. Germ line stem cell (GSC) divisions produce two cells with different fates: gonialblasts (GB) and cyst progenitor cells. Her team has found that the hub secretes a ligand (called Unpaired) that activates the Janus kinase-Signal transducer and activator of transcription (Jak-Stat) signaling pathway within GSCs. Activation of Jak-Stat within GSCs ensures that they remain stem cells; GB do not receive enough Upd to activate Jak-Stat, and instead differentiate.
Currently, the lab is using genetic and genomic approaches to identify targets of Stat within GSCs, since these genes molecularly define the GSC fate. They are also determining if the hub directly activates Stat in somatic stem cells, or if a different mechanism is operating to ensure their renewal, since little is known of how two stem cell populations are regulated within one niche. They are also asking how the stem cell niche is established during development.
Finally, they have recently found that spermatogonia that have begun to differentiate can reverse their path and de-differentiate to become GSCs. They are very interested in understanding the mechanisms controlling de-differentiation.
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Hetie P, de Cuevas M, Matunis E. "Conversion of quiescent niche cells to somatic stem cells causes ectopic niche formation in the Drosophila testis." Cell Rep. 2014 May 8;7(3):715-21. doi: 10.1016/j.celrep.2014.03.058. Epub 2014 Apr 18.
Stine RR, Matunis EL. "JAK-STAT signaling in stem cells." Adv Exp Med Biol. 2013;786:247-67. doi: 10.1007/978-94-007-6621-1_14.
Stine RR, Matunis EL. "Stem cell competition: finding balance in the niche." Trends Cell Biol. 2013 Aug;23(8):357-64. doi: 10.1016/j.tcb.2013.03.001. Epub 2013 Apr 16. Review.
Matunis EL, Stine RR, de Cuevas M. "Recent advances in Drosophila male germline stem cell biology." Spermatogenesis. 2012 Jul 1;2(3):137-144.
Sinden D, Badgett M, Fry J, Jones T, Palmen R, Sheng X, Simmons A, Matunis E, Wawersik M. "Jak-STAT regulation of cyst stem cell development in the Drosophila testis." Dev Biol. 2012 Dec 1;372(1):5-16. doi: 10.1016/j.ydbio.2012.09.009. Epub 2012 Sep 23.