Novel regulatory mechanisms of D1 dopamine receptor maturation and internalization.
Bibliographic record
Abstract
Novel Regulatory Mechanisms of D1 Dopamine Receptor Maturation and Internalization\n\n\nMichael Ming Chuen Kong\nDegree of Doctor of Philosophy, 2008\nDepartment of Pharmacology\nUniversity of Toronto\n\n\n\nABSTRACT\n\n\tDopamine is the most abundant catecholamine neurotransmitter in the mammalian brain and controls various physiological processes. The D1 dopamine receptor (D1DR) is the predominant dopamine receptor in the brain and traditionally couples to stimulatory G proteins, such as Gs, to activate adenylyl cyclase and generate cAMP.\n\tAlthough the trafficking itinerary of ER/Golgi maturation, agonist-induced internalization, and recycling/degradation are features common to many G protein-coupled receptors (GPCRs), the molecular regulation of these individual processes for the D1DR is not fully elucidated. Many GPCRs have been shown to form homo-oligomers; the work presented in this thesis explores how multimerization of D1DR has a role in regulating how these receptors are trafficked to the plasma membrane. In addition, the regulation of D1DR internalization is investigated in the context of emerging evidence highlighting the importance of lipid rafts.\n\tUsing strategically designed point mutations of the D1DR, specific receptor mutants were found to intracellularly sequester the wild-type receptor by oligomerization. This level of scrutiny by the quality control machinery in the cell could be circumvented by treatment with cell permeable dopaminergic agonists, but not antagonists or inverse agonists. This finding suggests that specific conformational requirements must be achieved before full maturation and anterograde trafficking of the D1DR can proceed. Furthermore, it was determined that cell surface bound D1DRs could internalize through a novel clathrin independent pathway that required binding to the scaffolding protein, caveolin-1. This interaction with caveolin-1 was identified in whole rat brain and was found to require a putative caveolin binding motif in transmembrane domain 7. Palmitoylation of D1DR was found to regulate the rate of agonist-induced caveolae mediated internalization. Finally, we determined that the integrity of caveolae was important in regulating cAMP signaling through D1DR.\n\tThese findings provide novel insight into the trafficking requirements of newly synthesized D1DRs as well as alternative mechanisms of regulation of receptors after agonist activation. The oligomerization of GPCRs and the localization of GPCRs in lipid rafts represent two emerging concepts important to many aspects of GPCR function. Future work aimed at integrating these overlapping processes will further our understanding of this important group of cell surface receptors.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".