Flow promotes insulin uptake and transcytosis in microvascular endothelial cells independently of nitric oxide – potential role of the actin cytoskeleton
Notice bibliographique
Résumé
The muscle and adipose microvasculature forms a tight endothelial barrier separating tissues like muscle and adipose from the blood. Transport of circulating insulin out of the microvasculature to reach muscle is a rate‐limiting step to insulin action. Most evidence suggests that this occurs by transport of insulin through individual endothelial cells (transcytosis); however, little is known about how this occurs. We recently developed an assay to measure insulin transcytosis through primary microvascular endothelial cells from human adipose tissue (HAMEC). However, like most in vitro studies of endothelial cells, this was done under static conditions while, in vivo , endothelial cells are constantly exposed to shear stress, a frictional force derived from blood flow. The purpose of this study was to determine whether physiological shear stress induced by flow affects insulin transcytosis by endothelial cells and if so, to determine the mechanism(s). HAMEC were exposed to static conditions or shear stress (0.5 dynes/cm 2 ) for 2h and measured uptake and transcytosis of fluorescently labelled insulin in HAMEC by confocal microscopy and Total Internal Fluorescence Microscopy, respectively. Flow increased insulin transcytosis and uptake in HAMEC by approximately two‐fold compared to static conditions. Since it has been reported that nitric oxide (NO) increases insulin uptake in aortic endothelial cells, and shear stress is known to activate nitric oxide synthase, we hypothesized that the effect of shear stress was mediated through NO. Surprisingly, exposure to the NO‐donor sodium nitroprusside had no effect on insulin uptake by HAMEC; furthermore, treatment with the nitric oxide synthase inhibitor L‐NAME before and during flow did not prevent the induction of insulin transcytosis by flow. To determine if modification to the actin cytoskeleton was involved instead, we treated HAMEC with cytochalasin D (CD), which induces actin depolymerization, or with Jasplakinolide (Jas), which promotes actin polymerization. While incubation with CD or Jas under static conditions had little effect on endothelial insulin uptake, Jas largely abrogated the effect of flow to induce insulin uptake. Conversely, CD significantly enhanced flow‐induced insulin uptake by HAMEC. Together, these findings suggest a likely role for actin dynamics in regulating flow‐induced insulin uptake by microvascular endothelial cells. In summary, flow increases insulin uptake and transcytosis in adipose microvascular endothelial cells in a NO‐independent fashion; this effect is likely mediated by changes in the actin cytoskeleton. These findings may have implications for the development of therapies to enhance insulin transcytosis by the endothelium in obesity/diabetes, in which defective insulin delivery has been recorded. Support or Funding Information Ontario Graduate Scholarship; Canadian Institute of Health Research; Canadian Diabetes Association; Banting and Best Diabetes Centre
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».