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Southard, S.

Publications and source records attributed to Southard, S..

2 recordsLinked to original sources

Pancreatic endocrine cell clusters derived from a non-pluripotent stem cell capable of regulating blood glucose in animal models of diabetes

This article describes a stem cell line derived by reprogramming of native human islet cells that consistently generates pure populations of endocrine pancreatic clusters following a simple differentiation protocol. Surprisingly, the population of stem cell derived pancreatic endocrine clusters that was most consistently capable of regulating blood glucose in rodent models of diabetes lacked robust expression of the key beta cell maturation-associated factor NKX6-1 but did manifest high expression of other key drivers of endocrine cell specification and maturation, ISL1 and MAFA. These data support the hypothesis that multiple pancreatic profiles can be identified in stem cell derived cultures and that these have disparate in vivo potency. The population with low NKX6-1 and high in vivo potency was further characterized by transcriptome profiling as an endocrine-committed population progressively maturing in vitro to a state proximal to the native islet.

bioengineering↗

Germline Sex Determination regulates sex-specific signaling between germline stem cells and their niche

The establishment of sexual identity in germ cells is critical for the development of male and female germline stem cells (GSCs) and production of sperm vs. eggs. Thus, this process is essential for sexual reproduction and human fertility. Germ cells depend on signals from the somatic gonad to determine their sex, but in organisms such as flies, mice and humans, the sex chromosome genotype of the germ cells is also important for germline sexual development. How somatic signals and germ cell-intrinsic cues act together to regulate germline sex determination is a key question about which little is known. We have found that JAK/STAT signaling in the GSC niche promotes male identity in germ cells and GSCs, in part by activating expression of the epigenetic reader Phf7. We have also found that JAK/STAT signaling is blocked in XX (female) germ cells through the intrinsic action of the sex determination gene Sex lethal, which preserves female identity. Thus, an important function of germline sexual identity is to control how GSCs respond to signals in their niche environment.

developmental biology↗