Expression and functional studies of the GDNF family receptor alpha 3 in the pancreas
Laure Nivlet1, Joel Herrmann1, Delia Esteban Martin1
1Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC)Institut National de la Santé et de la Recherche Médicale (INSERM) U964, Centre National de Recherche Scientifique (CNRS) UMR 7104, Université de Strasbourg (UdS), 1 Rue Laurent Fries, 67404 Illkirch, France.
Abstract:
The generation of therapeutic β-cells from human pluripotent stem cells relies on the identification of growth factors that faithfully mimic pancreatic β-cell development in vitro. In this context, the aim of the study was to determine the expression and function of the glial cell line derived neurotrophic factor receptor alpha 3 (GFRα3) and its ligand artemin (Artn) in islet cell development and function. GFRα3 and Artn expression were characterized by in situ hybridization, immunochemistry, and qRT-PCR. We used GFRα3-deficient mice to study GFRα3 function and generated transgenic mice overexpressing Artn in the embryonic pancreas to study Artn function. We found that GFRα3 is expressed at the surface of a subset of Ngn3-positive endocrine progenitors as well as of embryonic α- and β-cells, while Artn is found in the pancreatic mesenchyme. Adult β-cells lack GFRα3 but α-cells express the receptor. GFRα3 was also found in parasympathetic and sympathetic intra-islet neurons as well as in glial cells in the embryonic and adult pancreas. The loss of GFRα3 or overexpression of Artn has no impact on Ngn3 and islet cell formation and maintenance in the embryo. Islet organization and innervation as well as glucose homeostasis is normal in GFRα3-deficient mice suggesting functional redundancy.
Insights
Glial cell line derived neurotrophic factor receptor alpha 3 (GFRα3) and artemin (Artn) are not essential for pancreatic islet development or function. Loss of GFRα3 or Artn overexpression did not affect islet formation, maintenance, or glucose homeostasis in mice.
Area of Science:
- Endocrinology
- Developmental Biology
- Neuroscience
Background:
- Generating therapeutic beta-cells requires understanding factors mimicking pancreatic development.
- Glial cell line derived neurotrophic factor receptor alpha 3 (GFRα3) and its ligand artemin (Artn) are implicated in neurotrophic signaling.
- Their role in pancreatic islet development and function requires elucidation.
Purpose of the Study:
- To determine the expression and function of GFRα3 and Artn in pancreatic islet cell development and function.
- To investigate the potential of GFRα3 and Artn in therapeutic beta-cell generation.
Main Methods:
- In situ hybridization, immunochemistry, and qRT-PCR were used to characterize GFRα3 and Artn expression.
- GFRα3-deficient mice and transgenic mice overexpressing Artn were utilized to study their functions.
- Analysis included Ngn3 expression, islet cell formation, maintenance, organization, innervation, and glucose homeostasis.
Main Results:
- GFRα3 is expressed on Ngn3-positive progenitors, embryonic alpha- and beta-cells, adult alpha-cells, and intra-islet neurons/glial cells.
- Artn is localized in the pancreatic mesenchyme.
- Loss of GFRα3 or Artn overexpression did not impact embryonic islet cell development or adult glucose homeostasis, suggesting functional redundancy.
Conclusions:
- GFRα3 and Artn are expressed in various pancreatic cell types, including neurons and endocrine progenitors.
- These factors do not appear to play a critical role in islet cell formation, maintenance, or function.
- Functional redundancy may explain the lack of phenotype in GFRα3-deficient or Artn-overexpressing mice.
