Immunohistochemical localization and mRNA detection of Rab3D and/or Rab3B in rat von Ebner's glands, parotid gland, pancreas, and liver.
In examining the secretory mechanism of exocrine glands, we focused on the small GTP-binding proteins, Rab3D and Rab3B, which function in the final steps of exocytosis in non-neuronal tissues. These proteins were observed in von Ebner's glands by 32P-GTP overlay. mRNA isolated from von Ebner's glands, the pancreas, parotid glands, and liver was subjected to reverse transcription PCR and probed with primers and nested primers for Rab3D and Rab3B. Rab3D was found in all three exocrine glands and the liver, while Rab3B was found in the liver. Utilizing immunofluorescence histochemistry, Rab3D was localized to hepatocytes of the liver and to secretory granules of the exocrine glands, and Rab3B to liver and pancreatic islets. Isoproterenol evoked decreases in alpha-amylase- and Rab3D-labelled parotid secretory granules, and pilocarpine stimulated decreases in secretory granules labelled for lingual lipase and Rab3D from von Ebner's glands, and amylase and Rab3D from pancreas. Neither secretagogue affected Rab3B in pancreatic islets. These observed parallel decreases in response to beta-adrenergic (parotid) or cholinergic (von Ebner's and pancreas) secretagogues indicate that the function of Rab3D in exocytosis in these exocrine organs is similar and that the type of secretagogue does not determine the function.
Field
R B
RB
Oral Pathology Research Laboratory, Department of Veterans Affairs Medical Center, Washington, DC 20422, USA.
Kruse
D H
DH
Redman
R S
RS
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D005088:Exocrine Glands / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism; D010179:Pancreas / Q000378:metabolism; D010306:Parotid Gland / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012470:Salivary Glands, Minor / Q000378:metabolism; D020692:rab3 GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism*
D017931:DNA Primers; D012333:RNA, Messenger; C492132:Rab3b protein, rat; C492133:Rab3d protein, rat; D020692:rab3 GTP-Binding Proteins