Biology subjects

Liu, L. L.

Publications and source records attributed to Liu, L. L..

6 recordsLinked to original sources

bioRxiv2025

Adeno-associated viruses (AAVs) induce dose-dependent neonatal ventriculomegaly following intracerebroventricular administration

Cell-type-specific expression of synthetic/endogenous proteins or genetic sequences has significantly advanced our understanding of the central nervous system (CNS). Adeno-associated virus (AAV)-delivery to cerebrospinal fluid (CSF) mediates transfection of target cells to enable sustained delivery of secretory proteins into the CSF, offering promising avenues for both CNS therapy and mechanistic studies. However, despite the advantages afforded by AAV tropism-based cellular selectivity and transgene delivery, both preclinical studies and clinical trials report short- and long-term adverse effects, particularly immune activation. Especially relevant for CSF biology, CNS immune insults raise the risk of CSF dysregulation, including hydrocephalus. These risks may be exacerbated in pediatric populations, where ongoing CNS development, including immature meninges, choroid plexus (ChP), and skull structures, may further impair any ability to compensate for CSF dysregulation. To systematically address these risks and provide guidelines for minimizing CNS immune insults by AAVs, we test the dose-dependent effects of intracerebroventricular (ICV) injections of 3 AAV serotypes (AAV2/5, AAV2/4, and AAV.PHP.eB) to neonatal (P0.5) CD1 mouse pups. Histological analysis verified AAV2/5 tropism limited to ChP epithelial cells (CPECs), whereas AAV.PHP.eB transfected both CPECs and ependymal regions. By contrast, AAV2/4 shows limited transfection in the brain. Further, we find that ICV injections of all 3 AAV serotypes at the high dose (4x109 genome copy GC/pup) induced ventriculomegaly by P7.5, while the low dose (1x109 GC/pup) was well tolerated. Additionally, high-dose AAV2/5 tropism became more permissive, transfecting the ChP and also ependymal cells and some neurons. Longitudinal MRI of P0.5 pups with high-dose AAV2/5 ICV injections highlighted quick progression of ventriculomegaly. CSF ELISA analysis detected elevated pro-inflammatory cytokine CCL2 in AAV2/5 and AAV2/4 high-dose groups, indicating CNS inflammation. Moreover, decreased CSF TTR concentrations in high-dose groups suggest ChP dysfunction. We further revealed that earlier in utero high-dose ICV AAV2/5 injections at E13.5 induced even more severe ventriculomegaly and that adult animals were also susceptible to ventriculomegaly after high-dose AAV ICV delivery. Taken together, our data emphasize critical safety considerations of CSF-based AAV delivery, particularly during brain development. Further, these results call for an optimized dosage for perinatal ICV AAV applications. HighlightsO_LICSF-administration of AAVs results in unique cellular tropism in neonatal brains. C_LIO_LIIntracerebroventricular AAV delivery induces dose-dependent neonatal ventriculomegaly. C_LIO_LINeonatal ventriculomegaly by AAV overdose develops quickly and progressively. C_LIO_LIAAV overdose ventriculomegaly correlates with ChP/CSF dyshomeostasis and inflammation. C_LIO_LIAdult and embryonic brains are also susceptible to dose-dependent AAV-induced ventriculomegaly. C_LI

neuroscience↗

bioRxiv2025

Lead (Pb) exposure results in cell type specific changes in the mouse retina and optic nerve.

Chronic exposure to lead (Pb) is known to cause deficits in neuronal function across the nervous system, including the visual nervous system. Visual deficits have been observed in both humans and rodent models following Pb exposure. However, how Pb exposure causes visual deficits is poorly understood. In this study, we evaluated the effects of Pb toxicity on the retina and optic nerve of the mouse visual nervous system. We used C57BL/6 adult mice of both sexes and divided them into one of three different exposure groups. Adult mice received daily oral gavage of 108mg/kg Na-acetate (control), 54mg/kg Pb-acetate (low dose), or 108mg/kg Pb-acetate (high dose) for 4 weeks. At the end of Pb exposure, whole blood, retina, and optic nerve samples were collected for Pb quantification by atomic absorption spectroscopy and tissue immunohistochemical analyses. Cell type specific markers were used to quantify changes in cell density of retinal ganglion cells (RGCs), oligodendrocytes (OLs), oligodendrocyte precursor cells (OPCs), and myelin structure. Following Pb exposure, we observed a small, but significant reduction in the cell density of RGCs in the retina. However, we found no significant changes in branch thickness or coverage of retinal vasculature following Pb exposure. In the optic nerve after Pb exposure, we found a significant reduction in the cell density of OLs and OPCs. Finally, using immunolabeling for Caspr and Nav1.6, we observed significant structural changes in nodes of Ranvier, suggesting a disruption in myelin structure. Our findings suggested that Pb toxicity may impair survival and maturation process of oligodendrocytes, changes in myelin structures, and potential demyelination of the optic nerve. These results provide the foundation for future investigations into the molecular mechanisms of Pb-dependent changes in myelination and visual nervous system function.

pharmacology and toxicology↗

bioRxiv2023

Choroid Plexus Modulates Subventricular Zone Adult Neurogenesis and Olfaction Through Secretion of Small Extracellular Vesicles

The choroid plexus (CP) in brain ventricles secrete cerebrospinal fluid (CSF) that bathes the adjacent subventricular zone (SVZ); the latter is the largest neurogenic region in adult brain harboring neural stem/progenitor cells (NSPCs) and supplies newborn neurons to the olfactory bulb (OB) for normal olfaction. We discovered the presence of a CP-SVZ regulatory (CSR) axis in which the CP, by secreting small extracellular vesicles (sEVs), regulated adult neurogenesis in the SVZ and maintained olfaction. The proposed CSR axis was supported by 1) differential neurogenesis outcomes in the OB when animals treated with intracerebroventricular (ICV) infusion of sEVs collected from the CP of normal or manganese (Mn)-poisoned mice, 2) progressively diminished SVZ adult neurogenesis in mice following CP-targeted knockdown of SMPD3 to suppress CP sEV secretion, and 3) compromised olfactory performance in these CP-SMPD3-knockdown mice. Collectively, our findings demonstrate the biological and physiological presence of this sEV-dependent CSR axis in adult brains. HighlightsO_LICP-secreted sEVs regulate adult neurogenesis in the SVZ. C_LIO_LICP-secreted sEVs modulate newborn neurons in the OB. C_LIO_LISuppression of sEV secretion from the CP deteriorates olfactory performance. C_LI

neuroscience↗

bioRxiv2022

Genome-wide analyses of PAM-relaxed Cas9 genome editors reveal substantial off-target effects by ABE8e in rice

PAM-relaxed Cas9 nucleases, cytosine base editors and adenine base editors are promising tools for precise genome editing in plants. However, their genome-wide off-target effects are largely undetermined. Here, we conduct whole-genome sequencing (WGS) analyses of transgenic plants edited by xCas9, Cas9-NGv1, Cas9-NG, SpRY, nCas9-NG-PmCDA1, nSpRY-PmCDA1 and nSpRY-ABE8e in rice. Our results reveal different guide RNA (gRNA)-dependent off-target effects with different editors. De novo generated new gRNAs by SpRY editors lead to additional but not substantial off-target mutations. Strikingly, ABE8e results in ~500 genome-wide A-to-G off-target mutations at TA motif sites per transgenic plant. The preference of the TA motif by ABE8e is also observed at the target sites. Finally, we investigate the timeline and mechanism of somaclonal variation due to tissue culture, which chiefly contributes to the background mutations. This study provides a comprehensive understanding on the scales and mechanisms of off-target and background mutations during PAM-relaxed genome editing in plants.

genetics↗

bioRxiv2021

Comprehensive molecular features of polycystic ovary syndrome revealed by transcriptome analysis of oocytes and cumulus cells

PCOS is typically characterized by polycystic ovarian morphology, hyperandrogenism, ovulatory dysfunction and infertility. Furthermore, PCOS patients undergoing ovarian stimulation have more oocytes, however, poor quality of oocytes lead to lower fertilization and implantation rates, decreased pregnancy and increased miscarriage rates. Our study suggests that global gene expression and cell to cell interactions of oocytes and CCs are significantly altered in women with PCOS. Noticeably, genes related to microtubules such as TUBB8 and TUBA1C are abnormally highly expressed in PCOS oocytes, reducing oocyte quality. The pattern of transposable element expression distinguishes PCOS from Control oocytes, implying the role of transposable elements in the occurrence of PCOS.

cell biology↗

bioRxiv2018

TRPML1-mediated Modulation of Dense-core Granules Tunes Functional Potential in NK Cells

Inhibitory signaling during natural killer (NK) cell education translates into increased responsiveness to activation; however the intracellular mechanism for functional tuning by inhibitory receptors remains unclear. We found that educated NK cells expressing self-MHC specific inhibitory killer cell immunoglobulin-like receptors (KIR) show accumulation of granzyme B, localized in dense-core secretory lysosomes, converged close to the centrosome. This discrete morphological phenotype persists in self-KIR+ NK cells independently of transcriptional programs that regulate effector function, metabolism and lysosomal biogenesis. The granzymeB dense, large secretory lysosomes in self-KIR+ NK cells were efficiently released upon target cell recognition, contributing to their enhanced cytotoxic capacity. Secretory lysosomes are part of the acidic lysosomal compartment, which has been shown to channel calcium and mediate intracellular signalling in several cell types. Interference of signaling from acidic Ca2+ stores in primary NK cells reduced both target-specific Ca2+-flux, degranulation and cytokine production. Furthermore, inhibition of PI(3,5)P2 synthesis or genetic silencing of the PI(3,5)P2-regulated lysosomal Ca2+-channel TRPML1 led to increased levels of granzyme B and enhanced functional potential. These results indicate an intrinsic role for lysosomal homeostasis in NK cell education.

immunology↗