Caveolae, CD109, and endothelial cells as targets for treating Alzheimer's disease

Novel brain-penetrant inhibitor of G9a methylase blocks Alzheimer's disease proteopathology for precision medication

Current amyloid beta-targeting approaches for Alzheimer's disease (AD) therapeutics only slow cognitive decline for small numbers of patients. This limited efficacy exists because AD is a multifactorial disease whose pathological mechanism(s) and diagnostic biomarkers are largely unknown. Here we report a new mechanism of AD pathogenesis in which the histone methyltransferase G9a noncanonically regulates translation of a hippocampal proteome that defines the proteopathic nature of AD. Accordingly, we developed a novel brain-penetrant inhibitor of G9a, MS1262, across the blood-brain barrier to block this G9a-regulated, proteopathologic mechanism. Intermittent MS1262 treatment of multiple AD mouse models consistently restored both cognitive and noncognitive functions to healthy levels. Comparison of proteomic/phosphoproteomic analyses of MS1262-treated AD mice with human AD patient data identified multiple pathological brain pathways that elaborate amyloid beta and neurofibrillary tangles as well as blood coagulation, from which biomarkers of early stage of AD including SMOC1 were found to be affected by MS1262 treatment. Notably, these results indicated that MS1262 treatment may reduce or avoid the risk of blood clot burst for brain bleeding or a stroke. This mouse-to-human conservation of G9a-translated AD proteopathology suggests that the global, multifaceted effects of MS1262 in mice could extend to relieve all symptoms of AD patients with minimum side effect. In addition, our mechanistically derived biomarkers can be used for stage-specific AD diagnosis and companion diagnosis of individualized drug effects.

Smooth muscle αv integrins regulate vascular fibrosis via CD109 downregulation of TGF-β signalling

Aims

α_v integrins are implicated in fibrosis in a number of organs through their ability to activate TGF-β. However their role in vascular fibrosis and collagen accumulation is only partially understood. Here we have used α_v conditional knockout mice and cell lines to determine how α_v contributes to vascular smooth muscle cell (VSMC) function in vascular fibrosis and the role of TGF-β in that process.

Methods and results

Angiotensin II (Ang II) treatment causes upregulation of α_v and β₃ expression in the vessel wall, associated with increased collagen deposition. We found that deletion of α_v integrin subunit from VSMCs (α_v ^SMKO) protected mice against angiotensin II-induced collagen production and assembly. Transcriptomic analysis of the vessel wall in α_v ^SMKO mice and controls identified a significant reduction in expression of fibrosis and related genes in α_v ^SMKO mice. In contrast, α_v ^SMKO mice showed prolonged expression of CD109, which is known to affect TGF-β signalling. Using cultured mouse and human VSMCs, we showed that overexpression of CD109 phenocopied knockdown of α_v integrin, attenuating collagen expression, TGF-β activation, and Smad2/3 signalling in response to angiotensin II or TGF-β stimulation. CD109 and TGF-β receptor were internalized in early endosomes.

Conclusion

We identify a role for VSMC α_v integrin in vascular fibrosis and show that α_v acts in concert with CD109 to regulate TGF-β signalling.

WWOX and Its Binding Proteins in Neurodegeneration

WW domain-containing oxidoreductase (WWOX) is known as one of the risk factors for Alzheimer's disease (AD), a neurodegenerative disease. WWOX binds Tau via its C-terminal SDR domain and interacts with Tau phosphorylating enzymes ERK, JNK, and GSK-3β, and thereby limits AD progression. Loss of WWOX in newborns leads to severe neural diseases and early death. Gradual loss of WWOX protein in the hippocampus and cortex starting from middle age may slowly induce aggregation of a protein cascade that ultimately causes accumulation of extracellular amyloid beta plaques and intracellular tau tangles, along with reduction in inhibitory GABAergic interneurons, in AD patients over 70 years old. Age-related increases in pS14-WWOX accumulation in the brain promotes neuronal degeneration. Suppression of Ser14 phosphorylation by a small peptide Zfra leads to enhanced protein degradation, reduction in NF-κB-mediated inflammation, and restoration of memory loss in triple transgenic mice for AD. Intriguingly, tumor suppressors p53 and WWOX may counteract each other in vivo, which leads to upregulation of AD-related protein aggregation in the brain and lung. WWOX has numerous binding proteins. We reported that the stronger the binding between WWOX and its partners, the better the suppression of cancer growth and reduction in inflammation. In this regard, the stronger complex formation between WWOX and partners may provide a better blockade of AD progression. In this review, we describe whether and how WWOX and partner proteins control inflammatory response and protein aggregation and thereby limit AD progression.