Control of β-Site Amyloid Precursor Protein-Cleaving Enzyme-1 Expression by Protein Kinase C-λ/ι and Nuclear Factor κ-B

Title:Control of β-Site Amyloid Precursor Protein-Cleaving Enzyme-1 Expression by Protein Kinase C-λ/ι and Nuclear Factor κ-B

Volume: 18 Issue: 12

Author(s): Mini P. Sajan, Michael Leitges, Colin Park, David M. Diamond, Jin Wu, Barbara C. Hansen, Mildred A. Duncan, Christopher A. Apostolatos, Andre H. Apostolatos, Mark Kindy and Robert V. Farese*

Affiliation:

• Department of Internal Medicine, University of South Florida College of Medicine, Tampa, Florida, FL, USA
• Research Service, James A. Haley Veterans Medical Center, Tampa, Florida, FL, USA

Keywords: BACE1, atypical PKC, PKC-lambda/iota, brain, liver, A-beta, Alzheimer’s disease, dementia, type 2 diabetes mellitus.

Abstract:

Βackground: β-Amyloid precursor protein-cleaving enzyme-1 (BACE1) initiates the production of Aβ-peptides that form Aβ-plaque in Alzheimer’s disease.

Methods: Reportedly, acute insulin treatment in normal mice, and hyperinsulinemia in high-fat-fed (HFF) obese/diabetic mice, increase BACE1 activity and levels of Aβ-peptides and phospho- -thr-231-tau in the brain; moreover, these effects are blocked by PKC-λ/ι inhibitors. However, as chemical inhibitors may affect unsuspected targets, we presently used knockout methodology to further examine PKC-λ/ι requirements. We found that total-body heterozygous PKC-λ knockout reduced acute stimulatory effects of insulin and chronic effects of hyperinsulinemia in HFF/obese/diabetic mice, on brain PKC-λ activity and production of Aβ_1-40/42 and phospho-thr-231-tau. This protection in HFF mice may reflect that hepatic PKC-λ haploinsufficiency prevents the development of glucose intolerance and hyperinsulinemia.

Results: On the other hand, heterozygous knockout of PKC-λ markedly reduced brain levels of BACE1 protein and mRNA, and this may reflect diminished activation of nuclear factor kappa-B (NFκB), which is activated by PKC-λ and increases BACE1 and proinflammatory cytokine transcription. Accordingly, whereas intravenous administration of aPKC inhibitor diminished aPKC activity and BACE1 levels by 50% in the brain and 90% in the liver, nasally-administered inhibitor reduced aPKC activity and BACE1 mRNA and protein levels by 50-70% in the brain while sparing the liver. Additionally, 24-hour insulin treatment in cultured human-derived neurons increased NFκB activity and BACE1 levels, and these effects were blocked by various PKC-λ/ι inhibitors.

Conclusion: PKC-λ/ι controls NFκB activity and BACE1 expression; PKC-λ/ι inhibitors may be used nasally to target brain PKC-λ/ι or systemically to block both liver and brain PKC-λ/ι, to regulate NFκB-dependent BACE1 and proinflammatory cytokine expression.

Cite this article as:

Sajan P. Mini , Leitges Michael , Park Colin , Diamond M. David , Wu Jin , Hansen C. Barbara , Duncan A. Mildred, Apostolatos A. Christopher, Apostolatos H. Andre , Kindy Mark and Farese V. Robert *, Control of β-Site Amyloid Precursor Protein-Cleaving Enzyme-1 Expression by Protein Kinase C-λ/ι and Nuclear Factor κ-B, Current Alzheimer Research 2021; 18 (12) . https://dx.doi.org/10.2174/1567205019666211222120448