BMP9 Protects Septal Neurons from Axotomy-Evoked Loss of Cholinergic Phenotype

Cholinergic projection from the septum to the hippocampus is crucial for normal cognitive function and degeneration of cells and nerve fibers within the septohippocampal pathway contributes to the pathophysiology of Alzheimer's disease. Bone morphogenetic protein (BMP) 9 is a cholinergic differentiating factor during development both in vivo and in vitro.To determine whether BMP9 could protect the adult cholinergic septohippocampal pathway from axotomy-evoked loss of the cholinergic phenotype, we performed unilateral fimbria-fornix transection in mice and treated them with a continuous intracerebroventricular infusion of BMP9 for six days. The number of choline acetyltransferase (CHAT)-positive cells was reduced by 50% in the medial septal nucleus ipsilateral to the lesion as compared to the intact, contralateral side, and BMP9 infusion prevented this loss in a dose-dependent manner. Moreover, BMP9 prevented most of the decline of hippocampal acetylcholine levels ipsilateral to the lesion, and markedly increased CHAT, choline transporter CHT, NGF receptors p75 (NGFR-p75) and TrkA (NTRK1), and NGF protein content in both the lesioned and unlesioned hippocampi. In addition, BMP9 infusion reduced bilaterally hippocampal levels of basic FGF (FGF2) protein.These data indicate that BMP9 administration can prevent lesion-evoked impairment of the cholinergic septohippocampal neurons in adult mice and, by inducing NGF, establishes a trophic environment for these cells

The modular systems biology approach to investigate the control of apoptosis in Alzheimer's disease neurodegeneration

Apoptosis is a programmed cell death that plays a critical role during the development of the nervous system and in many chronic neurodegenerative diseases, including Alzheimer's disease (AD). This pathology, characterized by a progressive degeneration of cholinergic function resulting in a remarkable cognitive decline, is the most common form of dementia with high social and economic impact. Current therapies of AD are only symptomatic, therefore the need to elucidate the mechanisms underlying the onset and progression of the disease is surely needed in order to develop effective pharmacological therapies. Because of its pivotal role in neuronal cell death, apoptosis has been considered one of the most appealing therapeutic targets, however, due to the complexity of the molecular mechanisms involving the various triggering events and the many signaling cascades leading to cell death, a comprehensive understanding of this process is still lacking. Modular systems biology is a very effective strategy in organizing information about complex biological processes and deriving modular and mathematical models that greatly simplify the identification of key steps of a given process. This review aims at describing the main steps underlying the strategy of modular systems biology and briefly summarizes how this approach has been successfully applied for cell cycle studies. Moreover, after giving an overview of the many molecular mechanisms underlying apoptosis in AD, we present both a modular and a molecular model of neuronal apoptosis that suggest new insights on neuroprotection for this disease

Genomic reconstruction of the SARS-CoV-2 epidemic in England.

The evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus leads to new variants that warrant timely epidemiological characterization. Here we use the dense genomic surveillance data generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of subepidemics that peaked in early autumn 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. The Alpha variant grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed the Alpha variant and eliminated nearly all other lineages in early 2021. Yet a series of variants (most of which contained the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. However, by accounting for sustained introductions, we found that the transmissibility of these variants is unlikely to have exceeded the transmissibility of the Alpha variant. Finally, B.1.617.2/Delta was repeatedly introduced in England and grew rapidly in early summer 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on 26 June 2021

Endophilin B1 as a novel regulator of nerve growth factor/TrkA trafficking and neurite outgrowth

Neurotrophins and their cognate receptors Trks are important regulators of neuronal survival and differentiation. Recent studies reveal that internalization and trafficking of Trks play a critical role in neurotrophin-mediated signaling. At present, little is known of the molecular events that mediate this process. In the current study, we show that endophilin B1 is a novel regulator of nerve growth factor (NGF) trafficking.Wefound that endophilin B1 interacts with both TrkA and early endosome marker EEA1. Interestingly, knockdown of endophilin B1 results in enlarged EEA1-positive vesicles in NGF-treated PC12 cells. This is accompanied by increased lysosomal targeting of NGF/TrkA and TrkA degradation, and reduced total TrkA levels. In addition, knockdown of endophilin B1 attenuates Erk1/2 activation in the endosomal fraction after NGF treatment. This is accompanied by a marked inhibition of NGF-induced gene transcription and neurite outgrowth in endophilin B1-knocked down cells. Our observations implicate endophilin B1 as a novel regulator of NGF trafficking, thereby affecting TrkA levels and downstream signaling on endosomes to mediate biological functions of NGF. Copyright © 2008 Society for Neuroscience.link_to_subscribed_fulltex