read_status: read
type: paper
title: "Myosin Vb Traffics P-Glycoprotein to the Apical Membrane of Intestinal Epithelial Cells"
year: 2025
authors:
- "Dooley, Sarah A."
- "Kolobova, Elena"
- "Burman, Andreanna"
- "Kaji, Izumi"
- "Digrazia, Jessica R."
- "Stubler, Rachel"
- "Goldstein, Anna"
- "Packirisamy, Charulekha"
- "Coutts, Alexander W."
- "Saqui-Salces, Milena"
- "Gao, Nan"
- "Engevik, Melinda A."
- "Shub, Mitchell D."
- "Goldenring, James R."
- "Engevik, Amy C."
journal: "Gastroenterology"
doi: "10.1053/j.gastro.2024.09.007"
url: "https://linkinghub.elsevier.com/retrieve/pii/S0016508524054593"
project:
- EpPathbio
system:
- intestinal_epithelium
- enterocytes
- apical_domain
- brush_border
disease:
- microvillus_inclusion_disease
- inflammatory_bowel_disease
- colorectal_cancer
genes:
- myo5b
- rab11a
- abcb1
processes:
- apical_membrane_trafficking
- vesicle_recycling
- xenobiotic_efflux
- epithelial_polarity_maintenance
methods:
- conditional_gene_knockout
- intestinal_organoid_culture
- immunofluorescence_colocalization
- xenobiotic_efflux_assay
key_findings:
- myo5b_required_for_apical_targeting
- rab11a_mediates_recycling_vesicles
- loss_of_apical_efflux_function
- transporter_specific_trafficking
limitations:
- alternative_trafficking_pathways_unresolved
- partial_translational_validation
relevance:
- mechanism_of_drug_resistance
- epithelial_trafficking_framework
- therapeutic_target_identification
concepts:
- Myosin_Vb_Dependent_Apical_Trafficking
- Transporter_Specific_Recycling_Pathways
- Xenobiotic_Efflux_and_Epithelial_Defense
tags:
- gi_epithelium
- trafficking
- drug_resistance
- apical_recycling
BACKGROUND & AIMS: The xenobiotic efflux pump P-glycoprotein is highly expressed on the apical membrane of the gastrointestinal tract, where it regulates the levels of intracellular substrates. P-glycoprotein is altered in disease, but the mechanisms that regulate the levels of P-glycoprotein are still being explored. The molecular motor myosin Vb (Myo5b) traffics diverse cargo to the apical membrane of intestinal epithelial cells. We hypothesized that Myo5b was responsible for the delivery of P-glycoprotein to the apical membrane of enterocytes. METHODS: We used multiple murine models that lack functional Myo5b or the myosin binding partner Rab11a to analyze P-glycoprotein localization. Pig and human tissue were analyzed to determine P-glycoprotein localization in the setting of MYO5B mutations. Intestinal organoids were used to examine P-glycoprotein trafficking and to assay P-glycoprotein function when MYO5 is inhibited. RESULTS: In mice lacking Myo5b or the binding partner Rab11a, P-glycoprotein was improperly trafficked and had decreased presence in the brush border of enterocytes. Immunostaining of a pig model lacking functional Myo5b and human biopsies from a patient with an inactivating mutation in Myo5b also showed altered localization of intestinal P-glycoprotein. Human intestinal organoids expressing the motorless MYO5B tail domain had colocalization with P-glycoprotein, confirming that P-glycoprotein was trafficked by MYO5B in human enterocytes. Inhibition of MYO5 in human intestinal cell lines and organoids resulted in decreased P-glycoprotein capacity. Additionally, inhibition of MYO5 in human colon cancer cells diminished P-glycoprotein activity and increased cell death in response to a chemotherapeutic drug. CONCLUSIONS: Collectively, these data demonstrate that Myo5b is necessary for the apical delivery of P-glycoprotein.
MYO5B is necessary for apical localization of P-glycoprotein in enterocytes in vivo and in vitro
Rab11a-positive recycling vesicles mediate transporter delivery
Loss of MYO5B causes subapical retention and functional loss of P-glycoprotein
MYO5 inhibition reduces xenobiotic efflux capacity without broadly disrupting viability
Not all ABC transporters share this dependency (e.g., ABCG2 is MYO5B-independent)
Germline and inducible intestinal-specific Myo5b knockout mice
Rab11a and Rab8a deletion models
Human and murine intestinal organoids (3D + ALI monolayers)
Motorless MYO5B-tail cargo-trapping strategy
Rhodamine-123 efflux assays for transporter function
MYO5 inhibition using MyoVin-1
Establishes motor-based trafficking, not transcription, as a limiting step for efflux capacity
Reframes MYO5B as a gatekeeper of epithelial chemical defense
Provides mechanistic separation between brush-border structure vs transporter delivery
Connects MVID, IBD, and cancer drug resistance through a shared trafficking axis
Figure 1–2: Loss of apical P-gp in Myo5b- and Rab11a-deficient intestine
Figure 3: Conservation in pig and human MVID tissue
Figure 4: Reduced MYO5B and P-gp in IBD and colorectal cancer
Figure 5: MYO5B-tail colocalization with P-gp in human organoids
Figure 6: Functional loss of efflux and increased chemosensitivity
Figure 7: Model of MYO5B-Rab11-dependent transporter trafficking
Relative contribution of alternative apical trafficking routes unresolved
Long-term in vivo pharmacologic targeting not tested
Functional consequences of partial mislocalization remain unclear