Brain specific kinase-1 BRSK1/SAD-B associates with lipid rafts: modulation of kinase activity by lipid environment.
Biochim Biophys Acta
; 1811(12): 1124-35, 2011 Dec.
Article
en En
| MEDLINE
| ID: mdl-22020259
ABSTRACT
Brain specific kinases 1 and 2 (BRSK1/2, also named SAD kinases) are serine-threonine kinases specifically expressed in the brain, and activated by LKB1-mediated phosphorylation of a threonine residue at their T-loop (Thr189/174 in human BRSK1/2). BRSKs are crucial for establishing neuronal polarity, and BRSK1 has also been shown to regulate neurotransmitter release presynaptically. How BRSK1 exerts this latter function is unknown, since its substrates at the synaptic terminal and the mechanisms modulating its activity remain to be described. Key regulators of neurotransmitter release, such as SNARE complex proteins, are located at membrane rafts. Therefore we initially undertook this work to check whether BRSK1 also locates at these membrane microdomains. Here we show that brain BRSK1, but not BRSK2, is palmitoylated, and provide biochemical and pharmacological evidences demonstrating that a pool of BRSK1, but not BRSK2 or LKB1, localizes at membrane lipid rafts. We also show that raft-associated BRSK1 has higher activity than BRSK1 from non-raft environment, based on a higher T-loop phosphorylation at Thr-189. Further, recombinant BRSK1 activity increased 3-fold when assayed with small multilamellar vesicles (SMV) generated with lipids extracted from synaptosomal raft fractions. A similar BRSK1-activating effect was obtained with synthetic SMV made with phosphatidylcholine, cholesterol and sphingomyelin, mixed in the same molar ratio at which these three major lipids are present in rafts. Importantly, SMV also enhanced the activity of a constitutively active BRSK1 (T189E), underpinning that interaction with lipid rafts represents a new mechanism of BRSK1 activity modulation, additional to T-loop phosphorylation.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Sinaptosomas
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Encéfalo
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Proteínas Recombinantes
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Transducción de Señal
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Proteínas Serina-Treonina Quinasas
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Transmisión Sináptica
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Microdominios de Membrana
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Péptidos y Proteínas de Señalización Intracelular
Tipo de estudio:
Risk_factors_studies
Límite:
Animals
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Humans
Idioma:
En
Revista:
Biochim Biophys Acta
Año:
2011
Tipo del documento:
Article
País de afiliación:
España