Biology subjects

Golan, N.

Publications and source records attributed to Golan, N..

8 recordsLinked to original sources

bioRxiv2026

Spared corticospinal neurons activate an endogenous plasticity program after partial CNS injury

Functional recovery after incomplete spinal cord injury depends substantially on the capacity of anatomically spared neurons to remodel their connections, yet the molecular programs underlying this endogenous plasticity remain poorly understood. To identify and validate these mechanisms, we combined retrograde labeling, unilateral corticospinal tract injury, spatial transcriptomics, and human stem cell-derived neurons. Injured corticospinal neurons exhibited widespread downregulation with remaining activated pathways dominated by stress, cell death, and degenerative programs. In contrast, spared corticospinal neurons activated a coordinated pro-plasticity program characterized by metabolic, immune, and cytoskeletal remodeling together with selective suppression of growth-inhibitory signaling. Network and drug perturbation analyses identified ARHGEF12 suppression and vorinostat treatment as complementary target- and state-based strategies to enhance neurite regeneration in human neurons. Together, these findings define key components of endogenous plasticity and provide a framework for discovering therapeutic targets for neural repair.

neuroscience↗

bioRxiv2024

An archaeal CBASS system eliminates viruses without killing the host cells

Many cyclic-oligonucleotide-based anti-phage signalling systems (CBASS) defend against viral infections by depleting cellular NAD+ levels, eventually leading to dormancy or death. This abortive infection strategy is beneficial in stopping fast lytic infections, as cells die before spreading the virus to neighbouring cells. However, in chronic viral infections, which often occur in archaea, abortive infection could be detrimental, as the cost of immunity may outweigh that of infection. Here we study an archaeal CBASS system (H-CBASS2) that was expressed in the model species Haloferax volcanii DS2 and Haloferax gibbonsii LR2-5. We show that the system provides protection to H. gibbonsii against a lytic tailed haloarchaeal virus HFTV1 by depleting NAD+, similar to what has been observed for lytic phages in bacteria. H-CBASS2 is also triggered, though with much slower activity, during infection with the chronic, non-lytic virus HFPV-1, and promotes virus clearance after several passages without killing host cells. Moreover, cells that clear the HFPV-1 infection become substantially more resistant to subsequent infections, due to mutations in envelope-associated proteins. Cell death by NAD+ depletion only occurs after a very long infection with HFPV-1 on solid medium. These findings suggest that the magnitude of H-CBASS2 response is somehow tuned to the infection type can benefit the host during non-lytic infections, potentially explaining why such systems are relatively common in archaea.

microbiology↗

bioRxiv2024

Resilience and Charge-Dependent Fibrillation of Functional Amyloids: Interactions of Pseudomonas Biofilm-Associated FapB and FapC

FapC and FapB are biofilm-associated amyloids involved in the virulence of Pseudomonas and other bacteria. We herein demonstrate their exceptional thermal and chemical resilience, suggesting that biofilm structures might withstand standard sterilization, thereby contributing to the persistence of P. aeruginosa infections. Our findings also underscore the impact of environmental factors on Fap proteins, suggesting that orthologs in different Pseudomonas strains adapt to specific environments and roles. Challenging previous assumptions about a simple nucleation role for FapB in promoting FapC aggregation, the study shows a significant influence of FapC on FapB aggregation. The interaction between FapB and FapC is intricate: FapB stabilizes FapC fibrils, while FapC slows down FapB fibrillation but can still serve as a cross-seeding template. This complex interplay is key to understanding their roles in bacterial biofilms. Furthermore, the study highlights distinct differences between Fap and E. colis curli CsgA amyloid, where CsgB assumes a simple unidirectional role in nucleating CsgA fibrillation, emphasizing the importance of a comprehensive understanding of various amyloid systems. This knowledge is vital for developing effective intervention strategies against bacterial infections and leveraging the unique properties of these amyloids in technological applications such as novel bio-nanomaterials or protective coatings.

biochemistry↗

bioRxiv2024

A new archaeal virus that suppresses the transcription of host immunity genes

In some extreme environments, archaeal cells have been shown to have chronic viral infections, and such infections are well-tolerated by the hosts and may potentially protect against more lethal infections by lytic viruses. We have discovered that a natural Haloferax strain (48N), which is closely related to the model organism Haloferax volcanii, is chronically-infected by a lemon-shaped virus, which we could purify from the medium. The chronic infection by this virus, which we named LSV-48N, is never cleared, despite the multiple defense systems of the host that include CRISPR-Cas, and two CBASS systems. Curing 48N of its virus by genetic engineering, led to radical changes in the gene expression profile of 48N and a dramatic improvement in its growth rate. Remarkably, the cured 48N is the fastest-growing haloarchaeon reported to date, with a generation time of approximately 1 hour at 45{degrees}C compared to the typical 2.5 hours of H. volcanii or its infected isogen, and faster than any known haloarchaeon. The virus subverts host defenses by reducing their transcription and interfering with the CRISPR spacer acquisition machinery. Our results suggest that the slow growth of many halophilic archaea could be due to the effects of proviruses within their genomes that consume resources and alter the gene expression of their hosts.

microbiology↗

bioRxiv2021

Structure and conservation of amyloid spines from the Candida albicans Als5 adhesin including similarity to human LARKS

Candida Als family adhesins mediate adhesion to biological and abiotic substrates, as well as fungal cell aggregation and fungal-bacterial co-aggregation. The activity of at least two family members, Als5 and Als1, is dependent on amyloid-like protein aggregation that is initiated by shear force. Each Als adhesin has a [~]300-residue N-terminal Ig-like/invasin region. The following 108-residue, low complexity, threonine-rich (T) domain unfolds under shear to expose a critical amyloid-forming segment 322SNGIVIVATTRTV334 at the interface between the Ig-like/invasin domain 2 and the T domain of Candida albicans Als5. Amyloid prediction programs identified six potential amyloidogenic sequences in the Ig/invasin region and three others in the T domain of C. albicans Als5. Peptides derived from four of these sequences formed fibrils that bound thioflavin T, the amyloid indicator dye, and three of these revealed atomic-resolution structures of cross-{beta} spines. These are the first atomic-level structures for fungal adhesins. One of these segments, from the T domain, revealed kinked {beta}-sheets, similarly to LARKS (Low-complexity, Amyloid-like, Reversible, Kinked segments) found in human functional amyloids. Based on the cross-{beta} structures in Als proteins, we use evolutionary arguments to identify functional amyloidogenic sequences in other fungal adhesins. Thus, cross-{beta} structures are often involved in fungal pathogenesis and potentially in antifungal therapy. ImportanceFungal adhesins form cell-to-cell bonds in biofilms. Many of the cellular interactions are dependent on formation of amyloid-like cross-{beta} protein aggregates. Such structures are called functional amyloids because they perform physiological activities and they are dependent on the same types of protein interactions that form the more familiar amyloid deposits in neurodegenerative diseases. We have identified sequence segments that form cross-{beta} structures in the Als5 adhesin from the human pathogen Candida albicans. Such sequences are widespread among ALS family adhesins, including those from other human pathogens including Candida auris. Moreover, we revealed a structural similarity in a segment originating from Als5 threonine-rich low complexity region to human LARKS, pointing on a common structural motif coding for functional amyloids in different kingdoms of life.

microbiology↗

bioRxiv2021

Single-Cell Transcriptional Profiling of the Adult Corticospinal Tract Reveals Forelimb and Hindlimb Molecular Specialization

The corticospinal tract (CST) is refractory to repair after CNS trauma, resulting in chronic debilitating functional motor deficits after spinal cord injury. While novel pro-axon growth activators have stimulated plasticity and regeneration of corticospinal neurons (CSNs) after injury, robust functional recovery remains elusive. These repair strategies are sub-optimal in part due to underexplored molecular heterogeneity within the developing and adult CST. In this study, we combine retrograde CST tracing with single-cell RNA sequencing to build a comprehensive atlas of CSN subtypes. By comparing CSNs to non-spinally projecting neurons in layer Vb, we identify pan-CSN markers including Wnt7b. By leveraging retrograde tracing, we are able to compare forelimb and hindlimb projecting CSNs, identifying subtype-specific markers, including Cacng7 and Slc16a2 respectively. These markers are expressed in embryonic and neonatal CSNs and can be used to study early postnatal patterning of the CST. Our results provide molecular insight into the differences between anatomically distinct CSN subtypes and provide a resource for future screening and exploitation of these subtypes to repair the damaged CST after injury and disease.

neuroscience↗

bioRxiv2021

Inositol Polyphosphate-5-phosphatase K (Inpp5k) enhances sprouting of corticospinal tract axons after CNS trauma.

Failure of CNS neurons to mount a significant intrinsic growth response after trauma results in chronic functional deficits after spinal cord injury. Approaches to identify novel axon growth activators include transcriptional and repressor screening of embryonic cortical and retinal ganglion neurons in vitro. These high throughput approaches have identified several candidates; however, their inability to comprehensively model the adult CNS has resulted in their exploitation in vivo failing to stimulate significant anatomical and functional gains. To identify novel cell autonomous axon growth activators while maintaining CNS complexity, we screened intact adult corticospinal neurons (CSNs) undergoing functional plasticity after unilateral pyramidotomy. RNA-seq of intact sprouting corticospinal tract (CST) axons showed an enrichment of genes in the 3-phosphoinositide degradation pathways, including six 5-phosphatases. We explored whether Inositol Polyphosphate-5-phosphatase K (Inpp5k) could enhance CST axon growth in clinical models of CNS trauma. Overexpression of Inpp5k in intact adult CSNs enhanced sprouting of intact CST terminals into the denervated cervical cord after pyramidotomy and cortical stroke lesion. Inpp5k overexpression also stimulated sprouting of CST axons in the cervical cord after acute and chronic severe thoracic spinal contusion. We show that Inpp5k stimulates axon growth by elevating the density of active cofilin in the cytosol of labile growth cones, thus stimulating actin polymerization and enhancing microtubule protrusion into distal filopodia. This study identifies Inpp5k as a novel CST growth activator and underscores the veracity of using in vivo transcriptional screening to identify the next generation of cell autonomous factors capable of repairing the damaged CNS. SIGNIFICANCE STATEMENTNeurological recovery is limited after spinal cord injury as CNS neurons are incapable of self-repair post trauma. In vitro screening strategies exploit the intrinsically high growth capacity of embryonic CNS neurons to identify novel axon growth activators. While promising candidates have been shown to stimulate axon growth in vivo, concomitant functional recovery remains incomplete. Using transcriptional profiling of intact adult corticospinal tract neurons undergoing functional plasticity, we identified Inpp5k as a novel axon growth activator capable of stimulating CST axon growth after pyramidotomy, stroke and acute and chronic contusion injuries. These data support using in vivo screening approaches to identify novel axon growth activators.

neuroscience↗

bioRxiv2018

Structural Insights into Curli Amyloid Fibrils suggest Repurposing Anti-amyloid Compounds as Anti-biofilm Agents

Curli amyloid fibrils secreted by Enterobacteriaceae mediate host cell adhesion and contribute to biofilm formation, thereby promoting bacterial resistance to environmental stressors. Here, we present crystal structures of amyloid-forming segments from the major curlin subunit, CsgA, revealing steric zipper fibrils of tightly mated {beta}-sheets, demonstrating a structural link between curli and human pathological amyloids. We propose that these cross-{beta} segments structure the highly robust curli amyloid core. D-enantiomeric peptides, originally developed to interfere with Alzheimers disease-associated Amyloid-{beta}, inhibited CsgA fibrillation and reduced biofilm formation in Salmonella typhimurium. Moreover, CsgA fibrils cross-seeded fibrillation of Amyloid-{beta}, providing further support for the proposed structural resemblance and potential for cross-species amyloid interactions. In this study, we provide structural insights into curli formation, offer a novel strategy for disrupting amyloid-structured biofilms, and hypothesize on the formation of self-propagating prion-like species originating from a microbial source that could influence neurodegenerative diseases.\n\nSignificanceAtomic resolution structural insights into the biofilm-associated curli amyloid fibril secreted by Enterobacteriaceae revealed elements of fibrillar architecture conserved between bacterial and human amyloids. This inspired us to repurpose anti-amyloid drugs designed to target human pathological amyloids as a novel class of anti-biofilm agents. Moreover, the results provide a molecular basis for understanding interspecies cross-seeding of amyloids through the generation of prion-like agents by molecular mimicry. This raises concerns regarding human exposure to exogenous sources of amyloids, such as contaminated food and amyloid-secreting microbes. Overall, we provide a novel framework for investigating interspecies amyloid interactions at the molecular level and offer novel insights into mechanisms which may underlie the evolutionary and etiological relationships between the human and microbial amylomes.

biochemistry↗