A Flow Cytometry-Based Approach for the Isolation and Characterization of Neural Stem Cell Primary Cilia

ARL13B controls male reproductive tract physiology through primary and Motile Cilia

ARL13B is a small regulatory GTPase that controls ciliary membrane composition in both motile cilia and non-motile primary cilia. In this study, we investigated the role of ARL13B in the efferent ductules, tubules of the male reproductive tract essential to male fertility in which primary and motile cilia co-exist. We used a genetically engineered mouse model to delete Arl13b in efferent ductule epithelial cells, resulting in compromised primary and motile cilia architecture and functions. This deletion led to disturbances in reabsorptive/secretory processes and triggered an inflammatory response. The observed male reproductive phenotype showed significant variability linked to partial infertility, highlighting the importance of ARL13B in maintaining a proper physiological balance in these small ducts. These results emphasize the dual role of both motile and primary cilia functions in regulating efferent duct homeostasis, offering deeper insights into how cilia related diseases affect the male reproductive system.

GDF15 controls primary cilia morphology and function thereby affecting progenitor proliferation

We recently reported that growth/differentiation factor 15 (GDF15) and its receptor GDNF family receptor alpha-like (GFRAL) are expressed in the periventricular germinal epithelium thereby regulating apical progenitor proliferation. However, the mechanisms are unknown. We now found GFRAL in primary cilia and altered cilia morphology upon GDF15 ablation. Mutant progenitors also displayed increased histone deacetylase 6 (Hdac6) and ciliary adenylate cyclase 3 (Adcy3) transcript levels. Consistently, microtubule acetylation, endogenous sonic hedgehog (SHH) activation and ciliary ADCY3 were all affected in this group. Application of exogenous GDF15 or pharmacological antagonists of either HDAC6 or ADCY3 similarly normalized ciliary morphology, proliferation and SHH signalling. Notably, Gdf15 ablation affected Hdac6 expression and cilia length only in the mutant periventricular niche, in concomitance with ciliary localization of GFRAL. In contrast, in the hippocampus, where GFRAL was not expressed in the cilium, progenitors displayed altered Adcy3 expression and SHH signalling, but Hdac6 expression, cilia morphology and ciliary ADCY3 levels remained unchanged. Thus, ciliary signalling underlies the effect of GDF15 on primary cilia elongation and proliferation in apical progenitors.

Emerging mechanistic understanding of cilia function in cellular signalling

Primary cilia are solitary, immotile sensory organelles present on most cells in the body that participate broadly in human health, physiology and disease. Cilia generate a unique environment for signal transduction with tight control of protein, lipid and second messenger concentrations within a relatively small compartment, enabling reception, transmission and integration of biological information. In this Review, we discuss how cilia function as signalling hubs in cell-cell communication using three signalling pathways as examples: ciliary G-protein-coupled receptors (GPCRs), the Hedgehog (Hh) pathway and polycystin ion channels. We review how defects in these ciliary signalling pathways lead to a heterogeneous group of conditions known as 'ciliopathies', including metabolic syndromes, birth defects and polycystic kidney disease. Emerging understanding of these pathways' transduction mechanisms reveals common themes between these cilia-based signalling pathways that may apply to other pathways as well. These mechanistic insights reveal how cilia orchestrate normal and pathophysiological signalling outputs broadly throughout human biology.

HNSC exosome-derived MIAT improves cognitive disorders in rats with vascular dementia via the miR-34b-5p/CALB1 axis

OBJECTIVE

To explore the molecular mechanism by which hippocampal neural stem cell (HNSC) exosome (exo)-derived MIAT improves cognitive disorders in rats with vascular dementia (VD).

METHODS

Rat hippocampal tissues were collected, and HNSCs and hippocampal neuronal cells (HNCs) were isolated, purified, and identified. Then the exosomes (exo) of the HNSCs were extracted and identified. A VD rat model was constructed. HE staining was used to evaluate the hippocampal pathology in each group. The expressions of the RNAs in the HNSCs were intervened, and the cells were then grouped. ELISA was used to measure the of TNF-α, IL-1, and Aβ1-42 expression levels. The kits were used to determine the oxidative stress factor levels. The targeting relationships among MIAT, miR-34b-5p, and CALB1 were measured using dual-luciferase assays. The MIAT expressions in exo were measured using qRT-PCR. The proliferation and apoptosis of the HNCs were determined using CCK-8 and Annexin V-FITC/PI staining, respectively. The CALB1, TH, and Bcl-2 protein expressions were determined using Western blot. The Morris water maze test was used for the spatial learning and memory testing.

RESULTS

The hippocampal tissues in the model group were clearly damaged, but the pathological characteristics were significantly improved in the exo group. The exo group also showed an increased SOD level, decreased MDA and ROS levels, and down-regulated TNF-α, IL-1, and Aβ1-42 expressions (all P<0.05). MiR-34b-5p had a targeting relationship with both MIAT and CALB1, and MIAT was found to be expressed in exo. The oe-MIAT-exo group and the miR-34b-5p inhibitor group showed significantly up-regulated CALB1, TH, and Bcl-2 protein expressions in the HNCs, increased cell viability, as well as reduced apoptosis, but the si-MIAT-exo group showed the opposite results (all P<0.05). The MiR-34b-5p inhibitor partially reversed the effect on the si-MIAT-exo group. The miR-34b-5p mimic group showed significantly down-regulated CALB1, TH, and Bcl-2 protein expressions in the HNCs, inhibited cell viability, as well as increased apoptosis, but the oe-CALB1 group showed the opposite results (all P<0.05). Oe-CALB1 partially reversed the effect on the miR-34b-5p mimic group. The memory and learning abilities of the rats in the oe-MIAT-exo group and the model + exo group were significantly improved but not as much as they were in the normal rats.

CONCLUSION

MIAT-containing exo from HNSCs can improve cognitive disorders in VD rats via the miR-34b-5p/CALB1 axis.

Regulation of glial cell-derived neurotrophic factor in sevoflurane-induced neuronal apoptosis by long non-coding RNA CDKN2B-AS1 as a ceRNA to adsorb miR-133

OBJECTIVE

To investigate the regulatory mechanism of sevoflurane-induced neuronal apoptosis through analyzing the expression of glial cell-derived neurotrophic factor (GDNF) mediated by miR-133, sponged by long non-coding RNA (lncRNA) CDKN2B-AS1.

METHODS

An in vitro cell injury model was established by using different concentrations of sevoflurane and primary hippocampal neurons. Cell proliferation was detected by Cell Counting Kit-8 (CCK-8); caspase-3 and caspase-9 activities were detected by colorimetry, and apoptotic cells were determined by Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Fluorescence in situ hybridization (FISH) analysis was used to detect localized expression of CDKN2B antisense RNA 1 (CDKN2B-AS1), and dual-luciferase reporter assay was employed to verify the correlation of CDKN2B-AS1 and miR-133, and of miR-133 and GDNF. The expression of CDKN2B-AS1, miR-133, and GDNF mRNA in the cell injury model were measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Western blot was utilized to detect the expression of GDNF protein in the cell injury model.

RESULTS

In the cell injury model, CDKN2B-AS1 was highly expressed in the cytoplasm, and CDKN2B-AS1 and GDNF were downregulated and miR-133 was upregulated as detected by qRT-PCR (all P<0.05). The connections between CDKN2B-AS1 and miR-133, and between miR-133 and GDNF were confirmed. That is, CDKN2B-AS1 regulated the expression of GDNF by adsorbing miR-133 (all P<0.05). In cells treated with sevoflurane, overexpression of CDKN2B-AS1 could inhibit caspase-3 and caspase-9 activities and the degree of apoptosis. miR-133 could partially alleviate the effect of overexpressing CDKN2B-AS1 on cells, and si-GDNF the effect of miR-133 inhibitor (all P<0.05).

CONCLUSION

lncRNA CDKN2B-AS1 can up-regulate the expression of GDNF, inhibit neuronal apoptosis, and ease the toxic effect of sevoflurane on neural cells by acting as a sponge to adsorb miR-133.

HDAC6 Signaling at Primary Cilia Promotes Proliferation and Restricts Differentiation of Glioma Cells

Simple Summary

Glioblastoma is the most common and lethal brain tumor in adults because it becomes resistant to virtually every treatment. Histone deacetylase 6 (HDAC6), which is located primarily in the cytoplasm, has a unique role in promoting the disassembly of cells’ primary cilium, a non-motile “antenna” that must be broken down before cells can progress through the cell cycle. The role of HDAC6 and its function in gliomas have not been investigated with respect to tumor cell cilia. We have found that inhibitors of HDAC6 cause rapid and specific changes inside glioma cilia, reducing tumor cell proliferative capacity and promoting cell differentiation. Importantly, the HDAC6 inhibitors did not affect the proliferation or differentiation of glioma cells that we genetically modified unable to grow cilia. Our findings reveal a conserved and critical role for HDAC6 in glioma growth that is dependent on cilia.

Abstract

Histone deacetylase 6 (HDAC6) is an emerging therapeutic target that is overexpressed in glioblastoma when compared to other HDACs. HDAC6 catalyzes the deacetylation of alpha-tubulin and mediates the disassembly of primary cilia, a process required for cell cycle progression. HDAC6 inhibition disrupts glioma proliferation, but whether this effect is dependent on tumor cell primary cilia is unknown. We found that HDAC6 inhibitors ACY-1215 (1215) and ACY-738 (738) inhibited the proliferation of multiple patient-derived and mouse glioma cells. While both inhibitors triggered rapid increases in acetylated alpha-tubulin (aaTub) in the cytosol and led to increased frequencies of primary cilia, they unexpectedly reduced the levels of aaTub in the cilia. To test whether the antiproliferative effects of HDAC6 inhibitors are dependent on tumor cell cilia, we generated patient-derived glioma lines devoid of cilia through depletion of ciliogenesis genes ARL13B or KIF3A. At low concentrations, 1215 or 738 did not decrease the proliferation of cilia-depleted cells. Moreover, the differentiation of glioma cells that was induced by HDAC6 inhibition did not occur after the inhibition of cilia formation. These data suggest HDAC6 signaling at primary cilia promotes the proliferation of glioma cells by restricting their ability to differentiate. Surprisingly, overexpressing HDAC6 did not reduce cilia length or the frequency of ciliated glioma cells, suggesting other factors are required to control HDAC6-mediated cilia disassembly in glioma cells. Collectively, our findings suggest that HDAC6 promotes the proliferation of glioma cells through primary cilia.

Investigating Primary Cilia during Peripheral Nervous System Formation

The primary cilium plays a pivotal role during the embryonic development of vertebrates. It acts as a somatic signaling hub for specific pathways, such as Sonic Hedgehog signaling. In humans, mutations in genes that cause dysregulation of ciliogenesis or ciliary function lead to severe developmental disorders called ciliopathies. Beyond its role in early morphogenesis, growing evidence points towards an essential function of the primary cilium in neural circuit formation in the central nervous system. However, very little is known about a potential role in the formation of the peripheral nervous system. Here, we investigate the presence of the primary cilium in neural crest cells and their derivatives in the trunk of developing chicken embryos in vivo. We found that neural crest cells, sensory neurons, and boundary cap cells all bear a primary cilium during key stages of early peripheral nervous system formation. Moreover, we describe differences in the ciliation of neuronal cultures of different populations from the peripheral and central nervous systems. Our results offer a framework for further in vivo and in vitro investigations on specific roles that the primary cilium might play during peripheral nervous system formation.

Brain tumors: Cancer stem-like cells interact with tumor microenvironment

Cancer stem-like cells (CSCs) with potential of self-renewal drive tumorigenesis. Brain tumor microenvironment (TME) has been identified as a critical regulator of malignancy progression. Many researchers are searching new ways to characterize tumors with the goal of predicting how they respond to treatment. Here, we describe the striking parallels between normal stem cells and CSCs. We review the microenvironmental aspects of brain tumors, in particular composition and vital roles of immune cells infiltrating glioma and medulloblastoma. By highlighting that CSCs cooperate with TME via various cellular communication approaches, we discuss the recent advances in therapeutic strategies targeting the components of TME. Identification of the complex and interconnected factors can facilitate the development of promising treatments for these deadly malignancies.