Biology subjects

Rurak, G. M.

Publications and source records attributed to Rurak, G. M..

4 recordsLinked to original sources

bioRxiv2026

In Vivo Massively Parallel Reporter Assay Reveals Sequence Determinants of mRNA Localization in Astrocytes

RNA localization and local translation are essential mechanisms to fine-tune spatiotemporal gene expression in the nervous system. However, efficiently assessing the thousands of possible sequence determinants of RNA localization is a challenge, particularly for cell types that only reach morphological maturity in vivo. Here, we developed an in vivo Massively Parallel Reporter Assay (MPRA), termed Synaptoneurosomal (SN)-MPRA to enable identification of sequence determinants of mRNA localization and local translation, and applied this to astrocytes. We evaluated multiple models of RNA localization for two locally translated astrocyte mRNAs, Glt1 and Sparc, including increased transcript abundance, "zipcode" elements, and RNA secondary structure. Our results establish a high-throughput in vivo framework for identifying cis-regulatory sequences driving RNA localization and local translation, and suggest astrocytes use diverse mechanisms to regulate subcellular gene expression. More broadly, SN-MPRA offers a versatile platform to study RNA localization in vivo, where biological context and intercellular interactions are preserved.

neuroscience↗

bioRxiv2025

Single-Cell Resolution of Individual Variation in Hypothalamic Neurons Allows Targeted Manipulation Affecting Social Motivation

Despite decades of research, connecting molecular and cellular phenotypes to complex behavioral traits remains an elusive goal1. Social motivation exhibits individual trait variation2, which we hypothesize is mediated by molecular and cellular variability across hypothalamic neurons. To test this, we generated single-nucleus RNA-sequencing profiles3,4 of >120,000 neurons from tuberal hypothalamus and adjacent thalamus in 36 mice, balanced across sex and autism-associated mutation5, with all mice assessed for social motivation2. First, we show that molecular activation patterns predict behavior across individuals: specifically, activation of paraventricular Agtr1a+ (angiotensin receptor 1a) neurons predicted reduced social behavior. Subsequent inhibition of AGTR1A with telmisartan--an FDA-approved antihypertensive6--improved social orienting. Second, we show natural variation in neuronal proportions--likely arising from stochastic developmental events7--is sufficient to shape adult behavior even among genetically-identical individuals: we identified multiple neuronal populations whose relative abundance predicted social reward-seeking behavior. Chemogenetic inhibition of one such population, Nxph4+ neurons of the postero-lateral hypothalamus8, suppressed multiple aspects of social motivation. This work establishes proof-of-principle for an approach where single-cell genomics precisely maps neural substrates governing behavior. This approach revealed that stochastic variations in neuronal architecture deterministically influence social motivation, and enabled identification of therapeutically-actionable targets with immediate translational potential for disorders with social deficits.

genetics↗

bioRxiv2023

Astroglial Hmgb1 regulates postnatal astrocyte morphogenesis and cerebrovascular maturation.

Astrocytes are intimately linked with brain vessels, a relationship that is critical for neuronal health and function. However, astroglial factors driving these physical and functional associations during postnatal brain development have yet to be identified. We characterized structural and transcriptional changes in mouse cortical astrocytes and microvessels during the first two postnatal weeks and found that high-mobility group box 1 (Hmgb1), normally upregulated with injury and involved in adult cerebrovascular repair, was highly expressed in astrocytes at birth and then decreased rapidly. Astrocyte-selective ablation of Hmgb1 at birth affected astrocyte morphology and endfoot placement, altered distribution of endfoot proteins connexin43 and aquaporin-4, induced transcriptional changes in astrocytes related to cytoskeleton remodeling, and profoundly disrupted endothelial ultrastructure. While lack of astroglial Hmgb1 did not affect the blood-brain barrier or angiogenesis postnatally, it impaired neurovascular coupling and behavior in adult mice. These findings identify astroglial Hmgb1 as a key player in postnatal gliovascular maturation.

developmental biology↗

bioRxiv2019

Translatomic database of cortical astroglia across male and female mouse development reveals two distinct developmental phenotypes

Astroglial cells are emerging as key players in the development and homeostatic maintenance of neurons and neuronal networks. Astroglial cell functions are critical to neuronal migration and maturation, myelination, and synapse dynamics, however little is known about astroglial phenotypic changes over development. Furthermore, astroglial cells express steroid hormone receptors and show rapid responses to hormonal manipulations, however, despite important sex differences in telencephalic regions such as the cortex and hippocampus few studies have examined sex differences in astroglial cells in development and outside of the hypothalamus and amygdala. To phenotype cortical astroglial cells across postnatal development while considering potential sex differences, we used translating ribosome affinity purification together with RNA sequencing (TRAPseq) and immunohistochemistry to phenotype the entire astroglial translatome in males and females at key developmental time points: P1, P4, P7, P14, P35 and in adulthood. Overall, we found two distinct astroglial phenotypes between early (P1-P7) and late development (P14-Adult). We also noted that although astroglia show few basal sex differences in adulthood, they show significant sex differences in developmental gene expression patterns, with peak sex differences observed at P7. At least part of the sex differences observed at P7 appear to be due to males reaching a more mature astroglial phenotype earlier than females. Together, these data clearly delineate and phenotype astroglia across development and identify sex differences in astroglial developmental programs. Importantly, these developmental sex differences could have an impact on the construction and maintenance of neuronal networks and potential developmental windows of vulnerability to neurologic and psychiatric disease.

neuroscience↗