Journal article
Remodeling the exocrine pancreas at metamorphosis in Xenopus laevis
Proceedings of the National Academy of Sciences - PNAS, Vol.105(26), pp.8962-8967
06/23/2008
DOI: 10.1073/pnas.0803569105
PMCID: PMC2449347
PMID: 18574144
Abstract
At metamorphosis the
Xenopus laevis
tadpole exocrine pancreas remodels in two stages. At the climax of metamorphosis thyroid hormone (TH) induces dedifferentiation of the entire exocrine pancreas to a progenitor state. The organ shrinks to 20% of its size, and ≈40% of its cells die. The acinar cells lose their zymogen granules and ≈75% of their RNA. The mRNAs that encode exocrine-specific proteins (including the transcription factor Ptf1a) undergo almost complete extinction at climax, whereas
PDX-1
,
Notch-1
, and
Hes-1
, genes implicated in differentiation of the progenitor cells, are activated. At the end of spontaneous metamorphosis when the endogenous TH has reached a low level, the pancreas begins to redifferentiate. Exogenous TH induces the dedifferentiation phase but not the redifferentation phase. The tadpole pancreas lacks the mature ductal system that is found in adult vertebrate pancreases, including the frog. Exocrine pancreases of transgenic tadpoles expressing a dominant negative form of the TH receptor controlled by the elastase promoter are resistant to TH. They do not shrink when subjected to TH. Their acinar cells do not dedifferentiate at climax, nor do they down-regulate exocrine-specific genes or activate
Notch-1
and
Hes-1
. Even 2 months after metamorphosis these frogs have not developed a mature ductal system and the acinar cells are abnormally arranged. The TH-dependent dedifferentiation of the tadpole acinar cells at climax is a necessary step in the formation of a mature frog pancreas.
Details
- Title: Subtitle
- Remodeling the exocrine pancreas at metamorphosis in Xenopus laevis
- Creators
- Sandeep Mukhi - Department of EmbryologyJinzhe Mao - Center for Neuroscience Research, Children's National Medical Center, Washington, DC 20010Donald D. Brown
- Resource Type
- Journal article
- Publication Details
- Proceedings of the National Academy of Sciences - PNAS, Vol.105(26), pp.8962-8967
- DOI
- 10.1073/pnas.0803569105
- PMID
- 18574144
- PMCID
- PMC2449347
- NLM abbreviation
- Proc Natl Acad Sci U S A
- ISSN
- 0027-8424
- eISSN
- 1091-6490
- Publisher
- National Academy of Sciences
- Language
- English
- Date published
- 06/23/2008
- Academic Unit
- Cardiovascular Medicine; Internal Medicine
- Record Identifier
- 9984361732402771
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