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Investigating Mast Cell Secretory Granules; from Biosynthesis to Exocytosis
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Expression of pro-Muclin in pancreatic AR42J cells induces functional regulated secretory granules

Robert C De Lisle1, Oxana Norkina, Eileen Roach

  • 1Anatomy and Cell Biology, MS 3038, University of Kansas School of Medicine, 3901 Rainbow Blvd., Kansas City, KS 66160, USA. rdelisle@kumc.edu

American Journal of Physiology. Cell Physiology
|July 1, 2005
PubMed

Insights

Pro-Muclin protein acts as a sorting receptor to induce regulated secretory granules (RSG) formation. Its cytosolic tail is crucial for efficient RSG formation and regulated secretion.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Protein sorting and retention in regulated secretory granules (RSG) remain unclear.
  • The AR42J cell line expresses RSG content proteins but lacks granule formation.

Purpose of the Study:

  • To investigate the role of sulfated mucin-type glycoprotein pro-Muclin in inducing RSG formation.
  • To determine the importance of pro-Muclin's cytosolic tail in RSG biogenesis and secretion.

Main Methods:

  • Adenovirus-mediated expression of pro-Muclin in AR42J cells.
  • Assessing amylase storage, RSG accumulation, and hormonal secretion response.
  • Comparing full-length pro-Muclin with a construct lacking the cytosolic tail.

Main Results:

  • Pro-Muclin expression induced RSG formation and amylase storage in AR42J cells.
  • Pro-Muclin enhanced regulated secretion efficiency and decreased constitutive secretion.
  • The cytosolic tail of pro-Muclin was essential for its full effect on regulated secretion.

Conclusions:

  • Pro-Muclin functions as a sorting receptor that induces RSG formation.
  • The cytosolic tail domain of pro-Muclin plays a critical role in this process.
  • Pro-Muclin's effect may also involve increased cargo protein expression.

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