Related Experiment Videos
Cell type-specific storage of dopamine beta-monooxygenase
1Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2105, USA.
The Journal of Biological Chemistry
|February 1, 2000
Summary
Dopamine beta-monooxygenase (DBM) enzyme maturation is similar across cell types. However, DBM storage in secretory granules requires specific cellular factors, highlighting cell-specific trafficking mechanisms.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Dopamine beta-monooxygenase (DBM) converts dopamine to norepinephrine.
- DBM expression is typically restricted to adrenal chromaffin cells and specific neurons.
Purpose of the Study:
- To investigate the cellular mechanisms governing dopamine beta-monooxygenase (DBM) trafficking and storage.
- To determine if regulated granule storage of DBM is dependent on cell-type specific factors.
Main Methods:
- Stable expression of rat DBM in AtT-20 (with regulated granules) and CHO (without regulated granules) cells.
- Comparison of exogenous DBM behavior with endogenous DBM in adrenal chromaffin cells.
- Pulse-chase experiments and use of conformation-sensitive DBM antiserum to track maturation and folding.
Main Results:
- Active DBM secretion occurred in CHO cells, indicating its production does not require neuroendocrine-specific features.
- Early DBM maturation and acquisition of folded structure proceeded similarly in AtT-20, CHO, and adrenal chromaffin cells.
- DBM was stored in secretory granules of chromaffin cells but not in CHO or AtT-20 cells, despite the presence of regulated granules in the latter.
Conclusions:
- While DBM maturation is conserved across cell types, its efficient storage in secretory granules is mediated by cell type-specific factors.
- This suggests a regulated mechanism controlling DBM localization beyond its enzymatic activity and initial folding.