Biology subjects

Strom, M.

Publications and source records attributed to Strom, M..

3 recordsLinked to original sources

bioRxiv2025

MitoTracker transfers from astrocytes to neurons independently of mitochondria

The neuroprotective transfer of mitochondria from astrocytes to neurons has been primarily investigated by labelling astrocytic mitochondria with the dye MitoTracker. Here we report that MitoTracker transfers to neurons from both astrocytes and astrocyte-conditioned media, independently of mitochondrial transfer. Our observations should prompt an essential re-evaluation of the literature concerning astrocyte-neuron mitochondrial transfer and in other systems in which contact-independent transfer has been observed using mitochondrial dyes.

neuroscience↗

bioRxiv2024

Integration of hunger and hormonal state gates infant-directed aggression

Social behaviour is profoundly shaped by internal physiological states. While significant progress has been made in understanding how individual states such as hunger, stress, or arousal modulate behaviour, animals experience multiple states at any given time. The neural mechanisms that integrate such orthogonal states--and how this integration affects behaviour--remain poorly understood. Here we report how hunger and estrous state converge on neurons in the medial preoptic area (MPOA) to shape infant-directed behaviour. We find that hunger promotes pup-directed aggression in normally non-aggressive virgin female mice. This behavioural switch occurs through inhibition of MPOA neurons, driven by the release of neuropeptide Y (NPY) from Agouti-related peptide-expressing neurons in the arcuate nucleus (ArcAgRP neurons). The propensity for hunger-induced aggression is set by reproductive state, with MPOA neurons detecting changes in progesterone (P4) to estradiol (E2) ratio across the estrous cycle. Hunger and estrous state converge on HCN (hyperpolarization-activated cyclic nucleotide-gated) channels, which sets the baseline activity and excitability of MPOA neurons. Using micro-endoscopic imaging, we confirm these findings in vivo, revealing that MPOA neurons encode a state for pup-directed aggression. This work thus provides a mechanistic understanding of how multiple physiological states are integrated to flexibly control social behaviour.

neuroscience↗

bioRxiv2024

High-throughput screening of human genetic variants by pooled prime editing

Understanding the effects of rare genetic variants remains challenging, both in coding and non-coding regions. While multiplexed assays of variant effect (MAVEs) have enabled scalable functional assessment of variants, established MAVEs are limited by either exogenous expression of variants or constraints of genome editing. Here, we introduce a pooled prime editing (PE) platform in haploid human cells to scalably assay variants in their endogenous context. We first optimized delivery of variants to HAP1 cells, defining optimal pegRNA designs and establishing a co-selection strategy for improved efficiency. We characterize our platform in the context of negative selection by testing over 7,500 pegRNAs targeting SMARCB1 for editing activity and observing depletion of highly active pegRNAs installing loss-of-function variants. We next assess variants in MLH1 via 6-thioguanine selection, assaying 65.3% of all possible SNVs in a 200-bp region spanning exon 10 and distinguishing LoF variants with high accuracy. Lastly, we assay 362 non-coding MLH1 variants across a 60 kb region in a single experiment, identifying pathogenic variants acting via multiple mechanisms with high specificity. Our analyses detail how filtering for highly active pegRNAs can facilitate both positive and negative selection screens. Accordingly, our platform promises to enable highly scalable functional assessment of human variants.

genomics↗