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Oral administration of a GSK3 inhibitor increases brain insulin-like growth factor I levels

journal contribution
posted on 2023-05-17, 20:37 authored by Bolos, M, Fernandez, S, Torres-Aleman, I
Reduced brain input of serum insulin-like growth factor I (IGF-I), a potent neurotrophic peptide, may be associated with neurodegenerative processes. Thus, analysis of the mechanisms involved in passage of blood-borne IGF-I into the brain may shed light onto pathological mechanisms in neurodegeneration and provide new drug targets. A site of entrance of serum IGF-I into the brain is the choroid plexus. The transport mechanism for IGF-I in this specialized epithelium involves the IGF-I receptor and the membrane multicargo transporter megalin/LRP2. We have now analyzed this process in greater detail and found that the IGF-I receptor interacts with the transmembrane region of megalin, whereas the perimembrane domain of megalin is required for IGF-I internalization. Furthermore, a GSK3 site within the Src homology 3 domain of the C-terminal region of megalin is a key regulator of IGF-I transport. Thus, inhibition of GSK3 markedly increased internalization of IGF-I, whereas mutation of this GSK3 site abrogated this increase. Notably, oral administration of a GSK3 inhibitor to adult wild-type mice or to amyloid precursor protein/presenilin 1 mice modeling Alzheimer amyloidosis significantly increased brain IGF-I content. These results indicate that pharmacological modulation of IGF-I transport by megalin may be used to increase brain availability of serum IGF-I. Interestingly, GSK3 inhibitors such as those under development to treat Alzheimer disease may show therapeutic efficacy in part by increasing brain IGF-I levels, an effect already reported for other neuroprotective compounds.

History

Publication title

Journal of Biological Chemistry

Volume

285

Issue

23

Pagination

17693-17700

ISSN

0021-9258

Department/School

Menzies Institute for Medical Research

Publisher

Amer Soc Biochemistry Molecular Biology Inc

Place of publication

9650 Rockville Pike, Bethesda, USA, Md, 20814-3996

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the biological sciences

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