Immaturity of the immune system of human fetuses and neonates is often invoked to explain their increased susceptibility to infection; however, the development of the fetal innate immune system in early life remains incompletely explored. We now show that the most mature NK cells found in adult (or postnatal) human circulation (CD94–CD16+) are absent during ontogeny. Human fetal NK cells were found to express the 2 signature T-box transcription factors essential for the development of all murine NK and NK-like cells, eomesodermin (Eomes) and T-bet. The single-cell pattern of Eomes and T-bet expression during ontogeny, however, revealed a stereotyped pattern of reciprocal dominance, with immature NK cells expressing higher amounts of Eomes and more mature NK cells marked by greater abundance of T-bet. We also observed a stereotyped pattern of tissue-specific NK cell maturation during human ontogeny, with fetal liver being more restrictive to NK cell maturity than fetal bone barrow, spleen, or lung. These results support the hypothesis that maturation of human NK cells has a discrete restriction until postnatal life, and provide a framework to better understand the increased susceptibility of fetuses and newborns to infection.
Amélie Collins, Nyanza Rothman, Kang Liu, Steven L. Reiner
It remains unclear how perturbations in cardiomyocyte sarcomere function alter postnatal heart development. We utilized murine models that allowed manipulation of cardiac myosin-binding protein C (MYBPC3) expression at critical stages of cardiac ontogeny to study the response of the postnatal heart to disrupted sarcomere function. We discovered that the hyperplastic to hypertrophic transition phase of mammalian heart development was altered in mice lacking MYBPC3 and this was the critical period for subsequent development of cardiomyopathy. Specifically, MYBPC3-null hearts developed evidence of increased cardiomyocyte endoreplication, which was accompanied by enhanced expression of cell cycle stimulatory cyclins and increased phosphorylation of retinoblastoma protein. Interestingly, this response was self-limited at later developmental time points by an upregulation of the cyclin-dependent kinase inhibitor p21. These results provide valuable insights into how alterations in sarcomere protein function modify postnatal heart development and highlight the potential for targeting cell cycle regulatory pathways to counteract cardiomyopathic stimuli.
Benjamin R. Nixon, Alexandra F. Williams, Michael S. Glennon, Alejandro E. de Feria, Sara C. Sebag, H. Scott Baldwin, Jason R. Becker
The neonatal mouse kidney retains nephron progenitor cells in a nephrogenic zone for 3 days after birth. We evaluated whether de novo nephrogenesis can be induced postnatally beyond 3 days. Given the long-term implications of nephron number for kidney health, it would be useful to enhance nephrogenesis in the neonate. We induced nephron reduction by cryoinjury with or without contralateral nephrectomy during the neonatal period or after 1 week of age. There was no detectable compensatory de novo nephrogenesis, as determined by glomerular counting and lineage tracing. Contralateral nephrectomy resulted in additional adaptive healing, with little or no fibrosis, but did not also stimulate de novo nephrogenesis. In contrast, injury initiated at 1 week of age led to healing with fibrosis. Thus, despite the presence of progenitor cells and ongoing nephron maturation in the newborn mouse kidney, de novo nephrogenesis is not inducible by acute nephron reduction. This indicates that additional nephron progenitors cannot be recruited after birth despite partial renal ablation providing a reparative stimulus and suggests that nephron number in the mouse is predetermined at birth.
Florian Tögel, M. Todd Valerius, Benjamin S. Freedman, Rossella Latrino, Mor Grinstein, Joseph V. Bonventre
Functional intestines are composed of cell types from all 3 primary germ layers and are generated through a highly orchestrated and serial developmental process. Directed differentiation of human pluripotent stem cells (hPSCs) has been shown to yield gut-specific cell types; however, these structures do not reproduce critical functional interactions between cell types of different germ layers. Here, we developed a simple protocol for the generation of mature functional intestinal organoids from hPSCs under xenogeneic-free conditions. The stem cell–derived gut organoids produced here were found to contain distinct types of intestinal cells, including enterocytes, goblet cells, Paneth cells, and enteroendocrine cells, that were derived from all 3 germ layers; moreover, they demonstrated intestinal functions, including peptide absorption, and showed innervated bowel movements in response to stimulation with histamine and anticholinergic drugs. Importantly, the gut organoids obtained using this xenogeneic-free system could be stably maintained in culture for prolonged periods and were successfully engrafted in vivo. Our xenogeneic-free approach for generating gut organoids from hPSCs provides a platform for studying human intestinal diseases and for pharmacological testing.
Hajime Uchida, Masakazu Machida, Takumi Miura, Tomoyuki Kawasaki, Takuya Okazaki, Kengo Sasaki, Seisuke Sakamoto, Noriaki Ohuchi, Mureo Kasahara, Akihiro Umezawa, Hidenori Akutsu
Studies in rodents and newborn humans demonstrate the influence of brown adipose tissue (BAT) in temperature control and energy balance and a critical role in the regulation of body weight. Here, we obtained samples of epicardial adipose tissue (EAT) from neonates, infants, and children in order to evaluate changes in their transcriptional landscape by applying a systems biology approach. Surprisingly, these analyses revealed that the transition to infancy is a critical stage for changes in the morphology of EAT and is reflected in unique gene expression patterns of a substantial proportion of thermogenic gene transcripts (~10%). Our results also indicated that the pattern of gene expression represents a distinct developmental stage, even after the rebound in abundance of thermogenic genes in later childhood. Using weighted gene coexpression network analyses, we found precise anthropometric-specific correlations with changes in gene expression and the decline of thermogenic capacity within EAT. In addition, these results indicate a sequential order of transcriptional events affecting cellular pathways, which could potentially explain the variation in the amount, or activity, of BAT in adulthood. Together, these results provide a resource to elucidate gene regulatory mechanisms underlying the progressive development of BAT during early life.
Shalini Ojha, Hernan P. Fainberg, Victoria Wilson, Giuseppe Pelella, Marcos Castellanos, Sean T. May, Attilio A. Lotto, Harold Sacks, Michael E. Symonds, Helen Budge
The deubiquitinase-encoding gene
Yingai Jane Jin, Sally Wang, Joshua Cho, M. Angelica Selim, Tim Wright, George Mosialos, Jennifer Y. Zhang
Noelia Escobedo, Steven T. Proulx, Sinem Karaman, Miriam E. Dillard, Nicole Johnson, Michael Detmar, Guillermo Oliver
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