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Variants of vasoactive intestinal peptide in mouse mast cells and rat basophilic leukemia cells
B K Wershil1, C W Turck, S P Sreedharan
1Department of Pathology, Beth Israel Hospital, Boston, Massachusetts.
Abstract:
Radioimmunoassays for neuroendocrine vasoactive intestinal peptide (VIP1-28) detected 30-120 fmol of structurally related peptides in extracts of 10(7) mouse peritoneal mast cells, bone marrow-derived mast cells, cultured PT-18 and C1.MC/C57.1 lines of mast cells, and rat basophilic leukemia (RBL) cells. No VIP was found in peritoneal cells of mast cell-deficient WBB6F1-W/Wv mice, whereas the amounts extracted from peritoneal cells of the congenic normal (WBB6F1-+/+) mice were similar to those from cultured mouse mast cells. Sephadex G-25 gel filtration resolved two different-sized variants of VIP from mouse mast cells and RBL cells. Amino acid sequence analyses showed that the smaller variant is VIP10-28. The principal amino-terminally larger variant of VIP from C1.MC/C57.1 mouse mast cells and RBL cells exhibited amino acid sequence homology with VIP(-6)-28, and this sequence was established for the corresponding larger VIP from PT-18 mast cells. Polymerase chain reaction amplification of two different substituent sequences of prepro VIP in RBL cell RNA identified the VIP message. VIP10-28 was released from mouse mast cells concurrently with histamine by IgE-dependent stimulation. Rodent mast cell-derived VIP thus consists of both the truncated VIP10-28 and amino-terminally larger forms that appear to be generated by peptidolysis of a preproVIP similar to that found in neural cells.
Insights
Vasoactive intestinal peptide (VIP) is present in rodent mast cells, with two variants identified: VIP10-28 and larger N-terminal forms. These VIP forms are released with histamine upon IgE-dependent stimulation.
Area of Science:
- Neuroendocrinology
- Immunology
- Cell Biology
Background:
- Vasoactive intestinal peptide (VIP) is a neuroendocrine peptide with diverse physiological roles.
- Mast cells are immune cells involved in allergic reactions and inflammation.
- The presence and forms of VIP in mast cells have not been fully elucidated.
Purpose of the Study:
- To investigate the presence and characterization of VIP in rodent mast cells.
- To determine the relationship between VIP and mast cell activation.
- To identify the molecular forms of VIP produced by mast cells.
Main Methods:
- Radioimmunoassays (RIAs) were used to quantify VIP levels.
- Sephadex G-25 gel filtration was employed for size variant analysis.
- Amino acid sequencing and polymerase chain reaction (PCR) were utilized for structural and genetic identification.
- IgE-dependent stimulation was used to assess VIP release.
Main Results:
- VIP was detected in various mouse and rat mast cell lines, as well as primary mast cells.
- Two distinct VIP variants were identified: VIP10-28 and larger N-terminal forms.
- VIP10-28 and histamine were co-released from mast cells upon IgE-dependent stimulation.
- The VIP message (preproVIP) was identified in RBL cells via PCR.
Conclusions:
- Rodent mast cells contain and produce vasoactive intestinal peptide (VIP).
- Mast cell-derived VIP exists as at least two forms, VIP10-28 and N-terminally extended variants.
- These VIP forms are likely generated through peptidolysis of preproVIP and released during mast cell activation.