Cilia Length Research Articles

Effects of Sesquiterpene Lactones on Primary Cilia Formation (Ciliogenesis).

Sesquiterpene lactones (SLs), plant-derived metabolites with broad spectra of biological effects, including anti-tumor and anti-inflammatory, hold promise for drug development. Primary cilia, organelles extending from cell surfaces, are crucial for sensing and transducing extracellular signals essential for cell differentiation and proliferation. Their life cycle is linked to the cell cycle, as cilia assemble in non-dividing cells of G0/G1 phases and disassemble before entering mitosis. Abnormalities in both primary cilia (non-motile cilia) and motile cilia structure or function are associated with developmental disorders (ciliopathies), heart disease, and cancer. However, the impact of SLs on primary cilia remains unknown. This study evaluated the effects of selected SLs (grosheimin, costunolide, and three cyclocostunolides) on primary cilia biogenesis and stability in human retinal pigment epithelial (RPE) cells. Confocal fluorescence microscopy was employed to analyze the effects on primary cilia formation (ciliogenesis), primary cilia length, and stability. The effects on cell proliferation were evaluated by flow cytometry. All SLs disrupted primary cilia formation in the early stages of ciliogenesis, irrespective of starvation conditions or cytochalasin-D treatment, with no effect on cilia length or cell cycle progression. Interestingly, grosheimin stabilized and promoted primary cilia formation under cilia homeostasis and elongation treatment conditions. Thus, SLs have potential as novel drugs for ciliopathies and tumor treatment.

Integrative species delimitation of the Selaginella sanguinolenta (Selaginellaceae) group with description of a new species, S. baodongii

AbstractSelaginella sanguinolenta group is widely distributed from the Himalayas to Siberia and the Russian Far East, including four to nine taxa. Despite progress in recent phylogenetic studies of the S. sanguinolenta group, the problem of species delimitation in this group remains. We revise the taxonomy of the S. sanguinolenta group based on an integrative approach considering morphological, molecular, and geographical evidence. The sampling for molecular analysis based on rbcL, psbA, and 26S nrDNA sequence data involved 71 individuals, covering the geographical range of this group. A total of 21 morphological traits from 103 specimens were explored using principal component analysis and linear discriminant analysis (LDA). The LDA results indicate that the combination of ventral leaf cilium length and ventral/dorsal leaf carinate characteristics enable a success rate of more than 90% in distinguishing between S. aitchisonii (western Himalayas to northern China), S. jacquemontii (western Himalayas to southwest China), and S. sanguinolenta (Russian Far East regions to northeast China). The phylogenetic analysis results of nuclear and plastid DNA markers further disclose the clear molecular differentiation. Selaginella nummularifolia, S. rossii, and S. sajanensis are well‐defined species based on morphological and molecular evidence with narrow distribution ranges respectively. Based on molecular and morphological evidence, in combination with distribution information, we finally recognize seven species in the S. sanguinolenta group, including a new species, S. baodongii sp. nov. from the bordering regions of Russia and China in northeast Asia.

Fluid shear stress triggers cholesterol biosynthesis and uptake in inner medullary collecting duct cells, independently of nephrocystin-1 and nephrocystin-4.

Renal epithelial cells are subjected to fluid shear stress of urine flow. Several cellular structures act as mechanosensors-the primary cilium, microvilli and cell adhesion complexes-that directly relay signals to the cytoskeleton to regulate various processes including cell differentiation and renal cell functions. Nephronophthisis (NPH) is an autosomal recessive tubulointerstitial nephropathy leading to end-stage kidney failure before adulthood. NPHP1 and NPHP4 are the major genes which code for proteins that form a complex at the transition zone of the primary cilium, a crucial region required for the maintenance of the ciliary composition integrity. These two proteins also interact with signaling components and proteins associated with the actin cytoskeleton at cell junctions. Due to their specific subcellular localization, we wondered whether NPHP1 and NPHP4 could ensure mechanosensory functions. Using a microfluidic set up, we showed that murine inner medullary collecting ductal cells invalidated for Nphp1 or Nphp4 are more responsive to immediate shear exposure with a fast calcium influx, and upon a prolonged shear condition, an inability to properly regulate cilium length and actin cytoskeleton remodeling. Following a transcriptomic study highlighting shear stress-induced gene expression changes, we showed that prolonged shear triggers both cholesterol biosynthesis pathway and uptake, processes that do not seem to involve neither NPHP1 nor NPHP4. To conclude, our study allowed us to determine a moderate role of NPHP1 and NPHP4 in flow sensation, and to highlight a new signaling pathway induced by shear stress, the cholesterol biosynthesis and uptake pathways, which would allow cells to cope with mechanical stress by strengthening their plasma membrane through the supply of cholesterol.

Leukemia inhibitory factor shortens primary cilia by upregulating C-C motif chemokine 2 in human neural stem/progenitor cells.

Primary cilia on neural stem/progenitor cells (NSPCs) play an important role in determining cell fate, although the regulatory mechanisms involved in the ciliogenesis remain largely unknown. In this study, we analyzed the effect of the leukemia inhibitory factor (LIF) for the primary cilia in immortalized human NSPCs. LIF withdrawal elongated the primary cilia length, whereas the addition of LIF shortened it. Microarray gene expression analysis revealed that differentially expressed genes (DEGs) associated with LIF treatment were related with the multiple cytokine signaling pathways. Among the DEGs, C-C motif chemokine 2 (CCL2) had the highest ranking and its increase in the protein concentration in the NSPCs-conditioned medium after the LIF treatment was confirmed by ELISA. Interestingly, we found that CCL2 was a negative regulator of cilium length, and LIF-induced shortening of primary cilia was antagonized by CCL2-specific antibody, suggesting that LIF could influence cilia length via upregulating CCL2. The shortening effect of LIF and CCL2 on primary cilia was also observed in SH-SY5Y cells. The results of the study suggested that the LIF-CCL2 axis may well be a regulator of NSPCs and its primary cilia length, which could affect multiple cellular processes, including NSPC proliferation and differentiation.

Enhancement of convective flow in ternary hybrid nanofluid induced by metachronal propulsion

This paper aims to inspect the mixed convective ciliary transport of ternary hybrid nanofluid through a curved channel having ciliated walls. Titanium oxide, Alumina oxide, and Silicon dioxide nanoparticles are taken for the current problem with blood as a base fluid. Due to the complexity of the flow regime, curvilinear coordinates are utilized to modulate resultant equations for two-dimensional flow under the consideration of heat source/sink effects. The attributes of ciliary structures are revealed by the dominance of viscous impacts over inertial impacts utilizing the long-wavelength approximation. The impacts of several interesting parameters on the flow fields are scrutinized via graphs. It can be examined that liquid velocity is enhanced by enhancing the cilia length parameter. The considered nanomaterials have remarkable applications in maintaining the heat transfer rate in blood flow through arteries.

Identification and Analysis of Primary Cilia in the Corneal Endothelial Cells of Patients with Bullous Keratopathy

Purpose To identify primary cilia in human corneal endothelial cells (CECs) obtained from patients with bullous keratopathy (BK). Methods This study involved CEC specimens obtained from 10 eyes of 10 consecutive patients (three males and seven females; mean age: 74.5 years, range: 68–90 years) with BK who underwent Descemet’s stripping automated endothelial keratoplasty at Baptist Eye Institute, Kyoto, Japan between August 2019 and September 2020. Three corneal buttons obtained from 3 patients who underwent penetrating keratoplasty for keratoconus were used as 'non-BK' controls. All specimens were evaluated with immunofluorescence staining using an antibody against acetylated α-tubulin. Results Ciliary expression was observed in six of the 10 CEC specimens; i.e. in two specimens obtained from BK patients after glaucoma surgery (trabeculectomy), in two specimens obtained from patients with Fuchs endothelial corneal dystrophy, and in two specimens obtained from a patient with BK after laser iridotomy for primary angle closure. There was acetylated α-tubulin staining but no hair-like structures in two specimens, and ciliary expression was unknown in two specimens due to the absence of cells. The length of the primary cilia varied between all specimens. In contrast, no primary cilia were observed in the corneal buttons obtained from the three keratoconus patients. Conclusion The findings in this study clearly demonstrate the expression of primary cilia in the CECs of patients afflicted with BK.

The Scaffold Protein KATNIP Enhances CILK1 Control of Primary Cilia.

The primary cilium functions as a cellular sensory organelle and signaling antenna that detects and transduces extracellular signals. Mutations in the human gene CILK1 (ciliogenesis associated kinase 1) cause abnormal cilia elongation and faulty Hedgehog signaling, associated with developmental disorders and epilepsy. CILK1 is a protein kinase that requires dual phosphorylation of its TDY motif for activation and its extended C-terminal intrinsically disordered region (IDR) mediates targeting to the basal body and substrate recognition. Proteomics previously identified katanin-interacting protein (KATNIP), also known as KIAA0556, as a CILK1 interacting partner. In this study we discovered that CILK1 colocalizes with KATNIP at the basal body and the CILK1 IDR is sufficient to mediate binding to KATNIP. Deletion analysis of KATNIP shows one of three domains of unknown function (DUF) is required for association with CILK1. KATNIP binding with CILK1 drastically elevated CILK1 protein levels and TDY phosphorylation in cells. This resulted in a profound increase in phosphorylation of known CILK1 substrates and suppression of cilia length. Thus, KATNIP functions as a regulatory subunit of CILK1 that potentiates its actions. This advances our understanding of the molecular basis of control of primary cilia.

Abstract P430: Primary Neuronal Cilium As A Novel Mediator Of Angiotensin II And Hypertension

Cilia are membrane-bound, microtubular projections emanating from the cell surface and present on virtually all cell types including neurons. Cilia abnormalities (ciliopathies) have been linked to a broad range of diseases including hypertension. Moreover, we previously reported that DOCA-salt hypertension is associated with alterations in cilia in select nuclei involved in cardiovascular regulation and fluid homeostasis such as the supraoptic nucleus, but the underlying mechanisms are not known. Given the well-established role of the brain renin-angiotensin system in DOCA-salt hypertension, we hypothesized that Angiotensin II (Ang II) contribute to neuronal cilia abnormalities in hypertension. We began by examining the effect of Ang II on cilia in two different neuronal cell lines, mouse hypothalamic N47 and Cath.a. Ang II treatment (100 nM for 4 hrs) caused a significant increase in cilia length of N47 cells that were transiently transfected with a Flag-tagged AT1a receptor (AT1aR) compared to non-transfected cells (3.83±0.15 μm vs 2.25±0.06 μm, P<0.05). No change in cilia length was observed in AT1aR positive (2.71±0.09 μm) or negative cells (2.55±0.07 μm) treated with vehicle. Moreover, Ang II had no effect on cilia in N47 cells transfected with a Flag-tagged AT2R. Ang II also significantly increased cilia length in Cath.a cells which express the endogenous AT1aR. Truncation of AT1aR at position 318 resulted in loss of Ang II induced cilia elongation in N47 cells, indicating that the C-terminus of the receptor is important for Ang II regulation of cilia. Next, we evaluated the effect of Ang II infusion with minipumps (480ng/kg/min) on neuronal cilia in C57BL/6 mice. Mice infused with Ang II for 5 days which have elevated blood pressure displayed abnormally elongated cilia in the supraoptic nucleus (8.28±0.12 μm vs 6.37± 0.11 μm, P<0.05). Interestingly, Ang II-induced cilia elongation preceded the development of hypertension as it was observed in mice infused with Ang II for 2 days when no change in blood pressure was detected. These findings point to Ang II as an important regulator of neuronal cilia via AT1aR. This represents a novel mechanism for cardiovascular regulation by the renin-angiotensin system.

HDAC6 inhibition regulates substrate stiffness-mediated inflammation signaling in chondrocytes.

Osteoarthritis (OA) is a chronic disease and is difficult to cure. Chondrocytes are highly mechanosensitive. Therefore, mechanical therapies have received attention as a therapeutic direction for OA. The stiffness, as a critical cue of the extracellular matrix (ECM), affects cell growth, development, and death. In this study, we use polydimethylsiloxane (PDMS) to create substrates with varying stiffness for chondrocyte growth, interleukin-1β (IL-1β) treatment to mimic the inflammatory environment, and Tubastatin A (Tub A) to inhibit histone deacetylase 6 (HDAC6). Our results show that stiff substrates can be anti-inflammatory and provide a better matrix environment than soft substrates. Inhibition of HDAC6 improves the inflammatory environment caused by IL-1β and coordinates with inflammation to spread the chondrocyte area and primary cilia elongation. Without IL-1β and Tub A treatments, the length of the primary cilia rather than frequency is stiffness-dependent, and their length on stiff substrates are greater than that on soft substrates. In conclusion, we demonstrate that stiff substrates, inflammation, and inhibition of HDAC6 enhance the mechanosensitivity of primary cilia and mediate substrate stiffness to suppress inflammation and protect the matrix.

Electroosmotic flow of cobalt-ferrite nanoparticles in water and ethylene glycol through a ciliary annulus: A biomedical application.

Unique magnetic characteristics of cobalt-ferrite nanoparticles make them suitable for biological imaging and therapeutic applications. Understanding their activity in nanofluids via the ciliary annulus could lead to better contrast agents for magnetic resonance imaging and improved cancer therapy and other medical therapies. This article provides a comprehensive analysis of the theoretical conclusions regarding the transport of a nanofluid by electroosmosis across a ciliary annulus. The nanofluid consists of cobalt-ferrite nanoparticles (CoFe2O4), water (H2O), and ethylene glycol (C2H6O2). As part of the investigation into constructing a physical model, mathematical analysis is performed based on the conservation of mass, momentum, and energy. Dimension-free analysis and mathematical constraints are utilized to learn more about the system. By generating differential equations and including suitable boundary conditions, one can obtain exact solutions, which can then be visually inspected. Recent studies have demonstrated an inverse relationship between flow velocity and cilia length, zeta potential, and Helmholtz-Smoluchowski velocity. The streamlines show that the growth of the trapping boluses is affected by several factors, including the nanoparticles' volume fraction, the cilia's length, the amplitude ratio, the eccentricity, and the zeta potential. These results not only shed light on how nanofluids move, but they also have potential applications in microfluidics, heat transfer, and biomedical engineering.

A Novel Genetic Variant in MBD5 Associated with Severe Epilepsy and Intellectual Disability: Potential Implications on Neural Primary Cilia.

Disruptions in the MBD5 gene have been linked with an array of clinical features such as global developmental delay, intellectual disability, autistic-like symptoms, and seizures, through unclear mechanisms. MBD5 haploinsufficiency has been associated with the disruption of primary cilium-related processes during early cortical development, and this has been reported in many neurodevelopmental disorders. In this study, we describe the clinical history of a 12-year-old child harboring a novel MBD5 rare variant and presenting psychomotor delay and seizures. To investigate the impact of MBD5 haploinsufficiency on neural primary cilia, we established a novel patient-derived cell line and used CRISPR-Cas9 technology to create an isogenic control. The patient-derived neural progenitor cells revealed a decrease in the length of primary cilia and in the total number of ciliated cells. This study paves the way to understanding the impact of MBD5 haploinsufficiency in brain development through its potential impact on neural primary cilia.

Skewed X-inactivation is associated with retinal dystrophy in female carriers of RPGR mutations.

Progressive degeneration of rod and cone photoreceptors frequently is caused by mutations in the X-chromosomal gene Retinitis Pigmentosa GTPase Regulator (RPGR). Males hemizygous for a RPGR mutation often are affected by Retinitis Pigmentosa (RP), whereas female mutation carriers only occasionally present with severe RP phenotypes. The underlying pathomechanism leading to RP in female carriers is not well understood. Here, we analyzed a three-generation family in which two of three female carriers of a nonsense RPGR mutation presented with RP. Among two cell lines derived from the same female family members, differences were detected in RPGR transcript expression, in localization of RPGR along cilia, as well as in primary cilium length. Significantly, these differences correlated with alterations in X-chromosomal inactivation patterns found in the patient-derived cell lines from females. In summary, our data suggest that skewed X-chromosomal inactivation is an important factor that determines the disease manifestation of RP among female carriers of pathogenic sequence alterations in the RPGR gene.

EDL transport of blood-infusing tetra-hybrid nano-additives through a cilia-layered endoscopic arterial path

Electrokinetics has gotten much attention in bioengineering, biomedical sciences, and microfluidics systems. Due to its impactful applications, many researchers are now studying electrokinetic phenomena in hemodynamics. This article is aimed to set up a theoretical framework for the analysis of electric double-layer (EDL) induced dynamics of conducting blood infused with tetra-hybrid nanoparticles via an endoscopic arterial path with a ciliary wall at a slanting position. The thermal analysis is performed by taking the effects of thermal conditions on the artery’s wall in addition to the heat source and Joule heating. How nanoparticles’ structures (spherical, brick, cylindrical, and platelet) affect the streaming and thermal process is examined. Debye-Hückel hypothesis is endorsed to access the Boltzmann distribution of electric potential across an EDL. The arising non-linear model equations are linearized by assuming the lubrication constraints. The compact-form solutions of the succeeding model equations are tracked by employing an analytical strategy. The graphical formats are utilized to assess the hemodynamical behaviour of worthy model factors upon the flow entities. Elevating blood movement through the endoscopic annulus is associated with lower Debye-Hückel length. Blood gets cooled in the ciliated arterial conduit with a larger cilia length. The addition of nanoparticles can regulate excessive heat generation during the blood flow. The platelet shape nanoparticles are more efficient in transferring heat than spheres, bricks and cylinders. The streaming topology is publicized via streamlines. A novel finding in our study is that a longer cilia length can lead to a reduction in blood boluses in the artery with a ciliated wall. This result differs from previous studies. The study has the potential to shape advancements in biomedical engineering, medical devices, and cardiovascular research, such as medications, localized drug delivery, improved endoscopic tools and techniques, tracking therapy progress, etc. It lays the groundwork for innovative applications and paves the way for future research in this exciting field.

CFTR and PC2, partners in the primary cilia in autosomal dominant polycystic kidney disease.

Defects in the primary cilium are associated with autosomal dominant polycystic kidney disease (ADPKD). We used a combination of animal models, Western blotting, and confocal microscopy and discovered that CFTR and polycystin 2 (PC2) are both colocalized to the cilium in normal kidneys, with the levels of both being decreased in cystic epithelia. Cilia were longer in CFTR-null mice and in cystic cells in our ADPKD animal models. We examined septin 2, known to play a role in cilia length, to act as a diffusion barrier and to serve as an enhancer of proliferation. We found that septin 2 protein levels were upregulated and colocalized strongly with CFTR in cystic cells. Application of VX-809, the CFTR corrector, restored CFTR and PC2 toward normal in the cilia, decreased the protein levels of septin 2, and drastically reduced septin 2 colocalization with CFTR. Our data suggest that CFTR is present in the cilia and plays a role there, perhaps through its conductance of Cl-. We also postulate that septin 2 is important for localizing CFTR to the apical membrane in cystic epithelia.NEW & NOTEWORTHY CFTR is present in the primary cilia together with polycystin 2 (PC2). Ablation of CFTR makes cilia longer suggesting that CFTR plays a role there, perhaps through its conductance of Cl.

Maternal protein deficiency alters primary cilia length in renal tubular and impairs kidney development in fetal rat.

Intrauterine malnutrition impairs embryo kidney development and leads to kidney disease and hypertension in adulthood, yet the underlying mechanism remains unclear. With a maternal protein restriction (MPR) rat model, we investigated the critical ciliogenesis factors and β-catenin pathway in FGR fetal kidneys and analyzed the impact of aberrant primary cilia on renal tubular epithelium. The data showed decreased nephron number and renal tubular dysgenesis in FGR fetus. FGR fetus showed deregulated expression of ciliogenesis factors including upregulation of IFT88 and downregulation of DYNLT1, accompanied with cilia elongation in renal tubular epithelial cells. Wnt7b, the key ligand for Wnt/β-catenin signaling, was downregulated and nuclear translocation of β-catenin was decreased. The proapoptotic protein was upregulated. In vitro study with HK-2 cells showed that overexpression of IFT88 lengthened the cilia, inhibited β-catenin signaling. Besides, IFT88 overexpression suppressed cell proliferation, activated autophagy, and induced cell apoptosis. Inhibition of autophagy partly restored the cilia length and cell viability. Likewise, knockdown of DYNLT1 led to cilia elongation, suppressed cell proliferation, and promoted apoptosis in HK-2 cell. However, the cilia elongation induced by DYNLT1 knockdown was not autophagy-dependent, but associated with reactive oxygen species (ROS) accumulation. We elucidated that intrauterine protein malnutrition led to deregulation of ciliogenesis factors and cilia elongation in renal tubular epithelial, inhibited β-catenin signaling, and induced cell apoptosis and ultimately, compromised kidney development.

An entropy model for Carreau nanofluid ciliary flow with electroosmosis and thermal radiations: A numerical study.

In order to localize heat production and drug activation, it is possible for drug delivery to make use of nanofluids containing thermal radiation. By limiting the amount of medication that is administered to healthy tissues, this approach increases drug distribution. We explore the effect that thermal radiation has on the flow of a ternary-hybrid nanofluid composed of titanium oxide (TiO2), silica (SiO2), and aluminum oxide (AI2O3). The base liquid that we use for our Carreau constitutive model is blood. Entropy and electroosmosis are both taken into account when the conduit is connected to the battery terminals outside. Following the step of translating the observation model into a wave frame, the physical restrictions of the lubrication theory are used in order to provide a more complete explanation for the wave occurrences. In this work, shooting is used to simulate boundary value issues that are solved with Mathematica NDSolve. The production of the least amount of entropy and a rise in thermodynamic efficiency are achieved by the motion of cilia and elastic electroosmotic pumping. It is also observed that heat transfer is proportional to the length of cilia. Nusselt number is increased by large cilia but skin friction got a reduction.

#3679 ANOCTAMIN 1 INHIBITION SUPPRESSES CYSTOGENESIS BY ENHANCING CILIOGENESIS AND THE CILIARY DOSAGE OF POLYCYSTINS

Abstract Background and Aims Autosomal dominant polycystic kidney disease (ADPKD) is a ciliopathy which is characterized by abnormal tubular epithelial proliferation and fluid secretion. Anoctamin 1 (ANO1) is a calcium-dependent chloride channel, which has recently been shown to be involved in ADPKD progression. However, how ANO1 contributes to ADPKD is largely unexplored. Method 1. Based on mRNA gene chips, the expression of ANO1 abnormally increased in human ADPKD kidneys. 2. Immunohistochemical staining showed ANO1 location. 3. Real-time PCR and Western blot showed mRNAs and protein of ANO1 in ADPKD patients and animal model-PKD1RC/RC mice. 4. Confocal immunofluorescence showed ANO1 and PC2 location in the cilia. 5. 3D gel culture to verify the function of ANO1 in cysts formation. 6. ANO1 inhibitors and siRNA to discover STAT3 and ERK pathway in ADPKD cell by WB. Results We found that ANO1 is consistently upregulated inhuman and mouse PKD kidneys. Intriguingly, ANO1 located in a vesicle-like patten at the ciliary base but not on the ciliary surface. ANO1 deficiency promotes both ciliogenesis and the ciliary dosage of polycystin-2 in human Pkd1-/- cells, and reduced cyst formation in 3D culture models. Moreover, inhibition of ANO1 abolished the activation of STAT3 and ERK pathways in PKD cells. Conclusion Our data indicate ANO1 may aggravate ADPKD by regulating the cilia length and PC2 expression. Moreover, ANO1 could support cyst growth by activating STAT3 and ERK pathways. Thus ANO1 is a negative regulator for both cilia formation and cilia trafficking of polycystins and provide mechanistic insights regarding the therapeutic potential of ANO1 pathway in ADPKD treatment.

Eupatilin Improves Cilia Defects in Human CEP290 Ciliopathy Models.

The photoreceptor outer segment is a highly specialized primary cilium that is essential for phototransduction and vision. Biallelic pathogenic variants in the cilia-associated gene CEP290 cause non-syndromic Leber congenital amaurosis 10 (LCA10) and syndromic diseases, where the retina is also affected. While RNA antisense oligonucleotides and gene editing are potential treatment options for the common deep intronic variant c.2991+1655A>G in CEP290, there is a need for variant-independent approaches that could be applied to a broader spectrum of ciliopathies. Here, we generated several distinct human models of CEP290-related retinal disease and investigated the effects of the flavonoid eupatilin as a potential treatment. Eupatilin improved cilium formation and length in CEP290 LCA10 patient-derived fibroblasts, in gene-edited CEP290 knockout (CEP290 KO) RPE1 cells, and in both CEP290 LCA10 and CEP290 KO iPSCs-derived retinal organoids. Furthermore, eupatilin reduced rhodopsin retention in the outer nuclear layer of CEP290 LCA10 retinal organoids. Eupatilin altered gene transcription in retinal organoids by modulating the expression of rhodopsin and by targeting cilia and synaptic plasticity pathways. This work sheds light on the mechanism of action of eupatilin and supports its potential as a variant-independent approach for CEP290-associated ciliopathies.

Increase in primary cilia number and length upon VDAC1 depletion contributes to attenuated proliferation of cancer cells

Primary cilia (PCs) that are present in most human cells and perform sensory function or signal transduction are lost in many solid tumors. Previously, we identified VDAC1, best known to regulate mitochondrial bioenergetics, to negatively regulate ciliogenesis. Here, we show that downregulation of VDAC1 in pancreatic cancer-derived Panc1 and glioblastoma-derived U-87MG cells significantly increased ciliation. Those PCs were significantly longer than the control cells. Such increased ciliation possibly inhibited cell cycle, which contributed to reduced proliferation of these cells. VDAC1-depletion also led to longer PCs in quiescent RPE1 cells. Therefore, serum-induced PC disassembly was slower in VDAC1-depleted RPE1 cells. Overall, this study reiterates the importance of VDAC1 in modulating tumorigenesis, due to its novel role in regulating PC disassembly and cilia length.

Regulation of Primary Cilium Length by O-GlcNAc during Neuronal Development in a Human Neuron Model.

The primary cilium plays critical roles in the homeostasis and development of neurons. Recent studies demonstrate that cilium length is regulated by the metabolic state of cells, as dictated by processes such as glucose flux and O-GlcNAcylation (OGN). The study of cilium length regulation during neuron development, however, has been an area left largely unexplored. This project aims to elucidate the roles of O-GlcNAc in neuronal development through its regulation of the primary cilium. Here, we present findings suggesting that OGN levels negatively regulate cilium length on differentiated cortical neurons derived from human-induced pluripotent stem cells. In neurons, cilium length increased significantly during maturation (after day 35), while OGN levels began to drop. Long-term perturbation of OGN via drugs, which inhibit or promote its cycling, during neuron development also have varying effects. Diminishing OGN levels increases cilium length until day 25, when neural stem cells expand and undergo early neurogenesis, before causing cell cycle exit defects and multinucleation. Elevating OGN levels induces greater primary cilia assembly but ultimately results in the development of premature neurons, which have higher insulin sensitivity. These results indicate that OGN levels and primary cilium length are jointly critical in proper neuron development and function. Understanding the interplays between these two nutrient sensors, O-GlcNAc and the primary cilium, during neuron development is important in paving connections between dysfunctional nutrient-sensing and early neurological disorders.