Benzothiazole Amphiphiles Promote the Formation of Dendritic Spines in Primary Hippocampal Neurons

Abstract

The majority of excitatory synapses in the brain exist on dendritic spines. Accordingly, the regulation of dendritic spine density in the hippocampus is thought to play a central role in learning and memory. The development of novel methods to control spine density could, therefore, have important implications for treatment of a host of neurodegenerative and developmental cognitive disorders. Herein, we report the design and evaluation of a new class of benzothiazole amphiphiles that exhibit a dosedependent response leading to an increase in dendritic spine density in primary hippocampal neurons. Cell exposure studies reveal that the increase in spine density can persist for days in the presence of these compounds, but returns to normal spine density levels within 24 h when the compounds are removed, demonstrating the capability to reversibly control spinogenic activity. Time-lapse imaging of dissociated hippocampal neuronal cultures shows that these compounds promote a net increase in spine density through the formation of new spines. Biochemical studies support that promotion of spine formation by these compounds is accompanied by Ras activation. These spinogenic molecules were also capable of inhibiting a suspected mechanism for dendritic spine loss induced by Alzheimer-related aggregated amyloid-␤ peptides in primary neurons. Evaluation of this new group of spinogenic agents reveals that they also exhibit relatively low toxicity at concentrations displaying activity. Collectively, these results suggest that small molecules that promote spine formation could be potentially useful for ameliorating cognitive deficiencies associated with spine loss in neurodegenerative diseases such as Alzheimer disease, and may also find use as general cognitive enhancers.

Benzothiazole amphiphiles promote RasGRF1‐associated dendritic spine formation in human stem cell‐derived neurons

“…3A). The observed~20% increase in expression of RasGRF1 levels in the presence of BAM agents was similar to the increase in RasGRF1 levels observed in rodent models exposed to these compounds [14]. For this experiment, we attempted to quantify the number of PSD95-positive puncta along MAP2-labeled neurites in treated vs. control cells.…”

“…2A). These results are in contrast to the significant increase in Ras-GRF1 expression levels found in primary rat hippocampal neurons dosed with the same concentrations of BAMs 1-3 [14]. These opposing results could be due to lower abundance of neuronal and synaptic proteins found in undifferentiated neuroblastoma cells compared to mature mammalian neurons [29].…”

“…We next sought to examine whether BAMs 1-3 could elicit the same phenotypic increase in PSD95 puncta in human neurons as was previously observed in rat primary hippocampal neuronal culture [14]. For this experiment, we dosed 3-month-old neurons derived from iPSCs with 0 or 5 lM BAMs 1-3 for 24 h. Neurons were then fixed, and immunochemistry was performed to examine the relative density of PSD95-positive puncta located along MAP2-labeled segments of dendrites (Fig.…”

“…To date, relatively few compounds have been shown to increase dendritic spine density [14][15][16][17][18][19][20][21][22]. For instance, we have previously reported that benzothiazole amphiphiles (BAMs) can increase dendritic spine density in primary rat hippocampal neuronal culture [15] as well as in vivo in wild-type mice and in a 3xTg mouse model for AD [23][24][25].…”

Mechanisms of radiotherapy-associated cognitive disability in patients with brain tumours

“…164,165 Benzothiazole amphiphiles promote the formation of dendritic spines in primary hippocampal neurons and may help overcome the effects of radiation. 166 In addition recent data suggests that stem and progenitor cells are likely key targets in radiation brain injury and cognitive decline, stem cell niches may be compromised by inflammation, vascular damage, and extracellular matrix destruction. Stem cell niches are distributed throughout the brain, so one approach may be to ‘re-engineer’ CNS stem cell niches soon after irradiation.…”