Bacopa monnieri Attenuates Alzheimer's Pathology by Modulating RNA Metabolism, Cellular Stress Responses, and Rho GTPase Signaling: Phosphoproteomic Insights from a Cellular Model of Alzheimer's Disease.

Alzheimer's disease is a multifactorial disease characterized by proteinopathy caused by senile plaques and neurofibrillary tangles, leading to neuroinflammation and neuronal damage. Bacopa monnieri, with its extensive usage in the Indian traditional medicinal system, Ayurveda, holds promise in enhancing memory and improving neuronal functions. We performed quantitative phosphoproteomics analysis to understand the temporal dynamics of protein phosphorylation involved in Bacopa monnieri-mediated neuroprotection in the Alzheimer's disease model of IMR-32 cells. The quantitative phosphoproteomics analysis identified 5488 phosphopeptides corresponding to 1427 phosphoproteins. Among the dysregulated peptides in the Aβ42 treatment group, 430 were significantly hyperphosphorylated, and 540 were significantly hypophosphorylated. In contrast, the Bacopa monnieri co-treatment group exhibited 64 significantly hyperphosphorylated peptides and 69 significantly hypophosphorylated peptides. The phosphoproteins altered by Aβ42 were involved in biological functions such as RNA splicing, neuron axonogenesis in the central nervous system, and positive regulation of tau-protein kinase activity. Bacopa monnieri restored key pathways altered by Aβ42, including RNA metabolism, cellular response to stress, signaling by Rho GTPases, and RHOBTB2 GTPase cycle. Kinase mapping of differentially expressed phosphoproteins using the KinMap tool identified CDK11B, CDK12, PRKAA1, PRPF4B, STK10, ROCK1 and ROCK2 as downstream effectors of Bacopa monnieri. The network analysis of restored proteins revealed tight interactions between proteins associated with splicing regulation and stress response. This study offers a comprehensive understanding of phosphoproteome alterations involved in Alzheimer's disease in response to neuroprotection by Bacopa monnieri, which may pave the way for developing therapeutic strategies.