Biology subjects

Hernandez, S. A.

Publications and source records attributed to Hernandez, S. A..

4 recordsLinked to original sources

bioRxiv2026

Fine-tuning neuron number: Lzts as a key regulator of neurogenesis and cell proliferation in Ciona

How progenitor mitotic timing is coupled to the number of neurons in a nervous system remains poorly understood, in part because most model systems have large, variable progenitor pools that obscure this relationship. The non-vertebrate chordate Ciona robusta offers a tractable alternative: its larval nervous system arises from an invariant lineage, including four Bipolar Tail Neurons (BTNs) that are reproducibly generated from the caudal neural plate border. Here we investigate the developmental function of the single Ciona ortholog belonging to the leucine zipper tumor suppressor (Lzts) gene family, whose vertebrate members are implicated in cell-cycle regulation and tumor suppression. In Ciona, Lzts is expressed in several embryonic tissues, including differentiating BTNs. Tissue-specific CRISPR/Cas9 knockout of Lzts in the BTN lineage produced supernumerary BTNs, without expanding the embryonic Neurog+ domain, indicating that Lzts acts downstream of BTN specification to limit neuron number. Lzts1 promotes Cdk1 activity via stabilization of Cdc25C, co-expression of Ciona Cdc25C or a non-phosphorylatable Cdk1/2/3 mutant rescued normal BTN number in Lzts crispants, proving the existence of an ancestral Lzts-Cdc25-Cdk1 circuit controlling neural cell cycle. These findings establish Ciona Lzts as a regulator of mitotic tempo determining the BTN number and suggest that this cell-cycle regulatory axis links proliferation to neurogenesis across chordates in vivo.

developmental biology↗

bioRxiv2026

Using CRISPR/Cas9 to investigate the role of candidate human disease gene orthologs in Ciona

The tunicate Ciona robusta offers a tractable non-vertebrate chordate model for probing gene function via tissue-specific, CRISPR/Cas9-mediated mutagenesis in F0. Building on Arcadia Sciences Zoogle platform, which identifies and ranks orthologs of human genes from various non-traditional model organisms, we carried out a pilot project to probe the developmental roles of three notochord- and endoderm-expressed candidate orthologs of human disease genes (Fcho, Pgm3, and Nckap1) alongside a fourth gene (Plastin) implicated in papilla cell elongation. This preprint compiles and updates a series of research project milestones previously posted episodically on Zenodo. Here we summarize the full results and our conclusion about this pilot project. Using CRISPR/Cas9, we found that tissue-specific knockout of Pgm3 and, to a lesser extent, Fcho caused significant defects in larval tail elongation. Separately, CRISPR knockout of Plastin, an actin-bundling gene expressed throughout the sensory-adhesive papillae of the larva, caused a subtle reduction in papilla cell elongation when combined as a duoble knockout with another actin-bundling protein-encoding gene, Villin. These results identify Pgm3 as the most promising candidate for further development as a Ciona-based model of human disease and demonstrate the utility of tissue-specific CRISPR screening for prioritizing candidate disease gene orthologs identified through comparative genomics platforms like Zoogle.

developmental biology↗

bioRxiv2026

Midkine Dependency Defines a Therapeutically Actionable Vulnerability in Medulloblastoma

Medulloblastoma (MB), the most common malignant pediatric brain tumor, remains associated with high recurrence rates and substantial treatment-related morbidity despite aggressive multimodal therapy. Here, we identify midkine (MDK), a secreted growth factor/cytokine, as a previously unrecognized central regulator of MB growth and survival. Tissue microarray analysis revealed elevated MDK protein expression in MB specimens, and single-cell RNA sequencing datasets showed tumor cell-specific MDK expression. Genetic depletion or antibody-mediated neutralization of MDK suppressed proliferation and survival and induced apoptosis across multiple MB cell lines, whereas recombinant MDK supplementation exerted the opposite effect. Mechanistically, phosphokinase profiling and immunoblot analyses showed that MDK signals through multiple receptors, including nucleolin (NCL), LRP1, and syndecan-2 (SDC2), to sustain oncogenic ERK1/2 and Akt-mTOR-S6 signaling. Transcriptomic profiling following MDK silencing or depletion revealed marked suppression of ribosome biogenesis, global protein translation, and MYC-driven programs, coupled with activation of inflammatory and apoptotic responses. Consistently, mechanistic studies utilizing RPS6 staining, ribosomal RNA quantification, puromycin SUnSET, and OPP incorporation assays confirmed that loss of MDK impairs ribosome biogenesis and protein synthesis. Notably, MDK suppression also triggered robust activation of the IFN-cGAS-STING pathway, linking translational stress to innate immune signaling. In orthotopic xenograft models, CRISPR-mediated MDK knockout significantly reduced tumor growth and prolonged survival. Together, these findings establish MDK as a key integrator of oncogenic signaling, translational control, and innate immunity in MB, highlighting MDK as a compelling therapeutic target.

cancer biology↗

bioRxiv2026

Develop a durable, memory-driven, CspZ-targeting Lyme disease vaccine by rationale adjuvant selection

Rational adjuvant selection is a systematic approach based on adjuvant-mediated immunomodulation to identify safe vaccine regimens that enhance protective immunity. Transmitted through ticks and caused by the bacterium Borrelia burgdorferi (Bb), Lyme disease (LD) is the most common vector-borne disease in the Northern hemisphere. There are no effective vaccines, making it suitable for testing the concept of rational adjuvant selection. Here, we formulated our previously developed and effective LD vaccine antigen, CspZ-YAC187S, with different adjuvants suitable for human use; we analyzed the immune response by transcriptomics and tested the vaccine efficacy after Bb infection. We identified Alum-CpG and Alum-Gal to elicit the highest titers of CspZ-YAC187S-dependent protective antibodies and robust levels of protection but through distinct mechanisms of immunomodulation. We demonstrated that immunization with Alum-CpG formulated CspZ-YAC187S provided up to nine months of protective bactericidal antibody titers, as well as recall-memory response to prevent LD after natural infection. Immunity was linked to elevated levels of IgG1 memory cells in the vaccine-triggered immune responses. This work thus identified a durable, memory immunity-driven LD vaccine, ultimately paving the road to understanding the mechanisms of rationale adjuvant selection for vaccine development.

immunology↗