TY - JOUR
T1 - The mixed-lineage kinase 3 inhibitor URMC-099 facilitates microglial amyloid-β degradation
AU - Dong, Weiguo
AU - Embury, Christine M.
AU - Lu, Yaman
AU - Whitmire, Sarah M.
AU - Dyavarshetty, Bhagyalaxmi
AU - Gelbard, Harris A.
AU - Gendelman, Howard E.
AU - Kiyota, Tomomi
N1 - Publisher Copyright:
© 2016 The Author(s).
PY - 2016/7/11
Y1 - 2016/7/11
N2 - Background: Amyloid-β (Aβ)-stimulated microglial inflammatory responses engage mitogen-activated protein kinase (MAPK) pathways in Alzheimer's disease (AD). Mixed-lineage kinases (MLKs) regulate upstream MAPK signaling that include p38 MAPK and c-Jun amino-terminal kinase (JNK). However, whether MLK-MAPK pathways affect Aβ-mediated neuroinflammation is unknown. To this end, we investigated if URMC-099, a brain-penetrant small-molecule MLK type 3 inhibitor, can modulate Aβ trafficking and processing required for generating AD-associated microglial inflammatory responses. Methods: Aβ1-42 (Aβ42) and/or URMC-099-treated murine microglia were investigated for phosphorylated mitogen-activated protein kinase kinase (MKK)3, MKK4 (p-MKK3, p-MKK4), p38 (p-p38), and JNK (p-JNK). These pathways were studied in tandem with the expression of the pro-inflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. Gene expression of the anti-inflammatory cytokines, IL-4 and IL-13, was evaluated by real-time quantitative polymerase chain reaction. Aβ uptake and expression of scavenger receptors were measured. Protein trafficking was assessed by measures of endolysosomal markers using confocal microscopy. Results: Aβ42-mediated microglial activation pathways were shown by phosphorylation of MKK3, MKK4, p38, and JNK and by expression of IL-1β, IL-6, and TNF-α. URMC-099 modulated microglial inflammatory responses with induction of IL-4 and IL-13. Phagocytosis of Aβ42 was facilitated by URMC-099 with up-regulation of scavenger receptors. Co-localization of Aβ and endolysosomal markers associated with enhanced Aβ42 degradation was observed. Conclusions: URMC-099 reduced microglial inflammatory responses and facilitated phagolysosomal trafficking with associated Aβ degradation. These data demonstrate a new immunomodulatory role for URMC-099 to inhibit MLK and to induce microglial anti-inflammatory responses. Thus, URMC-099 may be developed further as a novel disease-modifying AD therapy.
AB - Background: Amyloid-β (Aβ)-stimulated microglial inflammatory responses engage mitogen-activated protein kinase (MAPK) pathways in Alzheimer's disease (AD). Mixed-lineage kinases (MLKs) regulate upstream MAPK signaling that include p38 MAPK and c-Jun amino-terminal kinase (JNK). However, whether MLK-MAPK pathways affect Aβ-mediated neuroinflammation is unknown. To this end, we investigated if URMC-099, a brain-penetrant small-molecule MLK type 3 inhibitor, can modulate Aβ trafficking and processing required for generating AD-associated microglial inflammatory responses. Methods: Aβ1-42 (Aβ42) and/or URMC-099-treated murine microglia were investigated for phosphorylated mitogen-activated protein kinase kinase (MKK)3, MKK4 (p-MKK3, p-MKK4), p38 (p-p38), and JNK (p-JNK). These pathways were studied in tandem with the expression of the pro-inflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. Gene expression of the anti-inflammatory cytokines, IL-4 and IL-13, was evaluated by real-time quantitative polymerase chain reaction. Aβ uptake and expression of scavenger receptors were measured. Protein trafficking was assessed by measures of endolysosomal markers using confocal microscopy. Results: Aβ42-mediated microglial activation pathways were shown by phosphorylation of MKK3, MKK4, p38, and JNK and by expression of IL-1β, IL-6, and TNF-α. URMC-099 modulated microglial inflammatory responses with induction of IL-4 and IL-13. Phagocytosis of Aβ42 was facilitated by URMC-099 with up-regulation of scavenger receptors. Co-localization of Aβ and endolysosomal markers associated with enhanced Aβ42 degradation was observed. Conclusions: URMC-099 reduced microglial inflammatory responses and facilitated phagolysosomal trafficking with associated Aβ degradation. These data demonstrate a new immunomodulatory role for URMC-099 to inhibit MLK and to induce microglial anti-inflammatory responses. Thus, URMC-099 may be developed further as a novel disease-modifying AD therapy.
KW - Alzheimer's disease
KW - Amyloid-β
KW - Endolysosomal pathway
KW - Microglia
KW - Mixed-lineage kinase 3
KW - Phagocytosis
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U2 - 10.1186/s12974-016-0646-z
DO - 10.1186/s12974-016-0646-z
M3 - Article
C2 - 27401058
AN - SCOPUS:84978998200
SN - 1742-2094
VL - 13
JO - Journal of Neuroinflammation
JF - Journal of Neuroinflammation
IS - 1
M1 - 184
ER -