Retinoblastoma protein prevents enteric nervous system defects and intestinal pseudo-obstruction
Ming Fu, … , J. William Harbour, Robert O. Heuckeroth
Ming Fu, … , J. William Harbour, Robert O. Heuckeroth
Published November 1, 2013
Citation Information: J Clin Invest. 2013;123(12):5152-5164. https://doi.org/10.1172/JCI67653.
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Research Article Gastroenterology

Retinoblastoma protein prevents enteric nervous system defects and intestinal pseudo-obstruction

Abstract

The retinoblastoma 1 (RB1) tumor suppressor is a critical regulator of cell cycle progression and development. To investigate the role of RB1 in neural crest–derived melanocytes, we bred mice with a floxed Rb1 allele with mice expressing Cre from the tyrosinase (Tyr) promoter. TyrCre+;Rb1fl/fl mice exhibited no melanocyte defects but died unexpectedly early with intestinal obstruction, striking defects in the enteric nervous system (ENS), and abnormal intestinal motility. Cre-induced DNA recombination occurred in all enteric glia and most small bowel myenteric neurons, yet phenotypic effects of Rb1 loss were cell-type specific. Enteric glia were twice as abundant in mutant mice compared with those in control animals, while myenteric neuron number was normal. Most myenteric neurons also appeared normal in size, but NO-producing myenteric neurons developed very large nuclei as a result of DNA replication without cell division (i.e., endoreplication). Parallel studies in vitro found that exogenous NO and Rb1 shRNA increased ENS precursor DNA replication and nuclear size. The large, irregularly shaped nuclei in NO-producing neurons were remarkably similar to those in progeria, an early-onset aging disorder that has been linked to RB1 dysfunction. These findings reveal a role for RB1 in the ENS.

Authors

Ming Fu, Solange Landreville, Olga A. Agapova, Luke A. Wiley, Michael Shoykhet, J. William Harbour, Robert O. Heuckeroth

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Figure 7

RB1 family members p107 and p130 in the DSI of P30 WT and Rb1 cKO mice were evaluated by immunohistochemistry.

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RB1 family members p107 and p130 in the DSI of P30 WT and Rb1 cKO mice w...
(A) p107 immunoreactivity was detected in neurites at a low level but not in neuron cell bodies. (B) p130 immunoreactivity was easily detected in all myenteric neurons of the Rb1 cKO mouse but was difficult to detect in the WT mouse. The white arrows show a myenteric neuron (HuC/D+) that expresses p130 but is not stained with NADPH-d histochemistry. Arrowheads show an NADPH-d histochemistry positive NO-producing neuron that also expresses p130. Scale bar: 50 μm (A and B, lower right), 20 μm.