Glioblastoma cell migration is directed by electrical signals.

Electric field (EF) directed cell migration (electrotaxis) is known to occur in glioblastoma multiforme (GBM) and neural stem cells, with key signalling pathways frequently dysregulated in GBM. One such pathway is EGFR/PI3K/Akt, which is down-regulated by peroxisome proliferator activated receptor gamma (PPARγ) agonists. We investigated the effect of electric fields on primary differentiated and glioma stem cell (GSCs) migration, finding opposing preferences for anodal and cathodal migration, respectively. We next sought to determine whether chemically disrupting Akt through PTEN upregulation with the PPARγ agonist, pioglitazone, would modulate electrotaxis of these cells. We found that directed cell migration was significantly inhibited with the addition of pioglitazone in both differentiated GBM and GSCs subtypes. Western blot analysis did not demonstrate any change in PPARγ expression with and without exposure to EF. In summary we demonstrate opposing EF responses in primary GBM differentiated cells and GSCs can be inhibited chemically by pioglitazone, implicating GBM EF modulation as a potential target in preventing tumour recurrence.

Electrical Stimulation Directs Migration, Enhances and Orients Cell Division and Upregulates the Chemokine Receptors CXCR4 and CXCR2 in Endothelial Cells.

Natural direct current electric fields (DC EFs) within tissues undergoing angiogenesis have the potential to influence vessel formation, but how they affect endothelial cells is not clear. We therefore quantified behaviours of human umbilical vein endothelial cells (HUVEC) and human microvasculature endothelial cells (HMEC) stimulated by EFsin vitro. Both cell types migrated faster and toward the cathode; HUVECs responded to fields as low as 50mV/mm, but the HMEC threshold was 100 mV/mm. Mitosis was stimulated at 50 mV/mm for HMEC and at 150 mV/mm for HUVECs, but the cleavage plane was oriented orthogonal to the field vector at 200 mV/mm for both cell types. That different field strengths induced different cell responses suggests distinct underlying cellular mechanisms. A physiological electric field also upregulated expression of CXCR4 and CXCR2 chemokine receptors and upregulated phosphorylation of both chemokines in HUVEC and HMEC cells. Evidence that DC EFs direct endothelial cell migration, proliferation and upregulate chemokines involved in wound healing suggests a key role for electrical control of capillary production during healing. Our data contribute to the molecular mechanisms by which DC EFs direct endothelial cell behaviour and present a novel signalling paradigm in wound healing, tissue regeneration and angiogenesis-related diseases.

Polarized retinal pigment epithelium generates electrical signals that diminish with age and regulate retinal pathology.

The transepithelial potential difference (TEP) across the retinal pigment epithelial (RPE) is dependent on ionic pumps and tight junction "seals" between epithelial cells. RPE cells release neurotrophic growth factors such as pigment epithelial derived factor (PEDF), which is reduced in age-related macular degeneration (AMD). The mechanisms that control the secretion of PEDF from RPE cells are not well understood. Using the CCL2/CX3CR1 double knockout mouse model (DKO), which demonstrates RPE damage and retinal degeneration, we uncovered an interaction between PEDF and the TEP which is likely to play an important role in retinal ageing and in the pathogenesis of AMD. We found that: (a) the expression of ATP1B1 (the Na+ /K+ -ATPase ß1 subunit) was reduced significantly in RPE from aged mice, in patients with CNV (Choroidal Neovascularization) and in DKO mice; (b) the expression of PEDF also was decreased in aged persons and in DKO mice; (c) the TEP across RPE was reduced markedly in RPE cells from DKO mice and (d) an applied electric field (EF) of 50-100 mV/mm, used to mimic the natural TEP, increased the expression and secretion of PEDF in primary RPE cells. In conclusion, the TEP across the RPE depends on the expression of ATP1B1 and this regulates the secretion of PEDF by RPE cells and so may regulate the onset of retinal disease. Increasing the expression of PEDF using an applied EF to replenish a disease or age-reduced TEP may offer a new way of preventing or reversing retinal dysfunction.

Endogenous bioelectric currents promote differentiation of the mammalian lens.

The functional roles of bioelectrical signals (ES) created by the flow of specific ions at the mammalian lens equator are poorly understood. We detected that mature, denucleated lens fibers expressed high levels of the α1 and ß1 subunits of Na+ /K+ -ATPase (ATP1A1 and ATP1B1 of the sodium pump) and had a hyperpolarized membrane potential difference (Vmem ). In contrast, differentiating, nucleated lens fiber cells had little ATP1A1 and ATP1B1 and a depolarized Vmem . Mimicking the natural equatorial ES with an applied electrical field (EF) induced a striking reorientation of lens epithelial cells to lie perpendicular to the direction of the EF. An EF also promoted the expression of ß-crystallin, aquaporin-0 (AQP0) and the Beaded Filament Structural Protein 2 (BFSP2) in lens epithelial cells (LECs), all of which are hallmarks of differentiation. In addition, applied EF activated the AKT and CDC2 and inhibition of AKT reduced the activation of CDC2. Our results indicate that the endogenous bioelectrical signal at the lens equator promotes differentiation of LECs into denucleated lens fiber cells via depolarization of Vmem. Development of methods and devices of EF application or amplification in vivo may supply a novel treatment for lens diseases and even promote regeneration of a complete new lens following cataract surgery.

Polarizing intestinal epithelial cells electrically through Ror2.

The apicobasal polarity of enterocytes determines where the brush border membrane (apical membrane) will form, but how this apical membrane faces the lumen is not well understood. The electrical signal across the epithelium could serve as a coordinating cue, orienting and polarizing enterocytes. Here, we show that applying a physiological electric field to intestinal epithelial cells, to mimic the natural electric field created by the transepithelial potential difference, polarized phosphorylation of the actin-binding protein ezrin, increased expression of intestinal alkaline phosphatase (ALPI, a differentiation marker) and remodeled the actin cytoskeleton selectively on the cathode side. In addition, an applied electric field also activated ERK1/2 and LKB1 (also known as STK11), key molecules in apical membrane formation. Disruption of the tyrosine protein kinase transmembrane receptor Ror2 suppressed activation of ERK1/2 and LKB1 significantly, and subsequently inhibited apical membrane formation in enterocytes. Our findings indicate that the endogenous electric field created by the transepithelial potential difference might act as an essential coordinating signal for apical membrane formation at a tissue level, through activation of LKB1 mediated by Ror2-ERK signaling.

Recurrent deletions of ULK4 in schizophrenia: a gene crucial for neuritogenesis and neuronal motility.

Although many pathogenic copy number variations (CNVs) are associated with neuropsychiatric diseases, few of them have been functionally characterised. Here we report multiple schizophrenia cases with CNV abnormalities specific to unc-51-like kinase 4 (ULK4), a serine/threonine kinase gene. Deletions spanning exons 21-34 of ULK4 were present in 4 out of 3391 schizophrenia patients from the International Schizophrenia Consortium, but absent in 3181 controls. Deletions removing exons 33 and 34 of the large splice variant of ULK4 also were enriched in Icelandic schizophrenia and bipolar patients compared with 98,022 controls (P = 0.0007 for schizophrenia plus bipolar disorder). Combining the two cohorts gives a P-value less than 0.0001 for schizophrenia, or for schizophrenia plus bipolar disorder. The expression of ULK4 is neuron-specific and developmentally regulated. ULK4 modulates multiple signalling pathways that include ERK, p38, PKC and JNK, which are involved in stress responses and implicated in schizophrenia. Knockdown of ULK4 disrupts the composition of microtubules and compromises neuritogenesis and cell motility. Targeted Ulk4 deletion causes corpus callosum agenesis in mice. Our findings indicate that ULK4 is a rare susceptibility gene for schizophrenia.

Low expression of chloride channel accessory 1 predicts a poor prognosis in colorectal cancer.

BACKGROUND: Chloride channel accessory 1 (CLCA1) is a CLCA protein that plays a functional role in regulating the differentiation and proliferation of colorectal cancer (CRC) cells. Here we investigated the relationship between the level of CLCA1 and the prognosis of CRC. METHODS: First, the level of CLCA1 was detected quantitatively in normal and cancerous colonic epithelial tissues with immunohistochemistry. Next, the correlations between CLCA1 expression, pathological tumor features, and the overall survival rate of patients was analyzed. Finally, 3 publicly available data sets from the Gene Expression Omnibus were examined: normal CRC versus early CRC (GSE4107), primary CRC versus metastatic lesions (GSE28702), and low chromosomal instability versus high chromosomal instability (GSE30540). RESULTS: The expression of CLCA1 was decreased markedly in tumor specimens. CLCA1 expression was correlated significantly with the histological grade (P < .01) and lymph node metastasis (P < .01). A significantly poorer overall survival rate was found in patients with low levels of CLCA1 expression versus those with high expression levels (P < .05). The results confirmed that the low expression of CLCA1 in CRC was highly associated with tumorigenesis, metastasis, and high chromosomal instability. In addition, the loss of CLCA1 disrupted the differentiation of human colon adenocarcinoma cells (Caco-2) in vitro. CONCLUSIONS: These findings suggest that CLCA1 levels may be a potential predictor of prognosis in primary human CRC. Low expression of CLCA1 predicts disease recurrence and lower survival, and this has implications for the selection of patients most likely to need and benefit from adjuvant chemotherapy.

Interaction between hedgehog signalling and PAX6 dosage mediates maintenance and regeneration of the corneal epithelium.

PURPOSE: To investigate the roles of intracellular signaling elicited by Hedgehog (Hh) ligands in corneal maintenance and wound healing. METHODS: The expression of Hedgehog pathway components in the cornea was assayed by immunohistochemistry, western blot and reverse-transcription polymerase chain reaction (RT-PCR), in wild-type mice and mice that were heterozygous null for the gene encoding the transcription factor, paired box gene 6 (Pax6).  Corneal epithelial wound healing and cell migration assays were performed after pharmacological upregulation and downregulation of the hedgehog pathway.  Reporter mice, mosaic for expression of the gene encoding ß-galactosidase (LacZ), were crossed to Pax6(+/-) mice, mice heterozygous for the gene encoding GLI-Kruppel family member GLI3, and Pax6(+/-)Gli3(+/-) double heterozygotes, to assay patterns of cell migration and corneal epithelial organization in vivo. RESULTS: Corneal epithelial wound healing rates increased in response to application of Sonic hedgehog (Shh), but only in mice with wild-type Pax6 dosage.  Downregulation of Hedgehog signalling inhibited corneal epithelial cell proliferation.  Pax6(+/-) corneal epithelia showed increased proliferation in response to exogenous Shh, but not increased migration. Desert hedgehog (Dhh) was shown to be the major endogenous ligand, with Shh detectable only by RT-PCR and only after epithelial wounding. The activity of phosphatidylinositol-3-OH kinase-γ (PI3Kγ) was not required for the increased migration response in response to Shh.  Nuclear expression of the activator form of the transcription factor Gli3 (which mediates Hh signalling) was reduced in Pax6(+/-) corneal epithelia. Pax6(+/-)Gli3(+/-) double heterozygotes showed highly disrupted patterns of clonal arrangement of cells in the corneal epithelium. CONCLUSIONS: The data show key roles for endogenous Dhh signalling in maintenance and regeneration of the corneal epithelium, demonstrate an interaction between Pax6 and Hh signalling in the corneal epithelium, and show that failure of Hh signalling pathways is a feature of Pax6(+/-) corneal disease that cannot be remedied pharmacologically by addition of the ligands.

Prospective guidance in a free-swimming cell.

A systems theory of movement control in animals is presented in this article and applied to explaining the controlled behaviour of the single-celled Paramecium caudatum in an electric field. The theory-General Tau Theory-is founded on three basic principles: (i) all purposive movement entails prospectively controlling the closure of action-gaps (e.g. a distance gap when reaching, or an angle gap when steering); (ii) the sole informational variable required for controlling gaps is the relative rate of change of the gap (the time derivative of the gap size divided by the size), which can be directly sensed; and (iii) a coordinated movement is achieved by keeping the relative rates of change of gaps in a constant ratio. The theory is supported by studies of controlled movement in mammals, birds and insects. We now show for the first time that it is also supported by single-celled paramecia steering to the cathode in a bi-polar electric field. General Tau Theory is deployed to explain this guided steering by the cell. This article presents the first computational model of prospective perceptual control in a non-neural, single-celled system.

Electrical signals control wound healing through phosphatidylinositol-3-OH kinase-gamma and PTEN.

Wound healing is essential for maintaining the integrity of multicellular organisms. In every species studied, disruption of an epithelial layer instantaneously generates endogenous electric fields, which have been proposed to be important in wound healing. The identity of signalling pathways that guide both cell migration to electric cues and electric-field-induced wound healing have not been elucidated at a genetic level. Here we show that electric fields, of a strength equal to those detected endogenously, direct cell migration during wound healing as a prime directional cue. Manipulation of endogenous wound electric fields affects wound healing in vivo. Electric stimulation triggers activation of Src and inositol-phospholipid signalling, which polarizes in the direction of cell migration. Notably, genetic disruption of phosphatidylinositol-3-OH kinase-gamma (PI(3)Kgamma) decreases electric-field-induced signalling and abolishes directed movements of healing epithelium in response to electric signals. Deletion of the tumour suppressor phosphatase and tensin homolog (PTEN) enhances signalling and electrotactic responses. These data identify genes essential for electrical-signal-induced wound healing and show that PI(3)Kgamma and PTEN control electrotaxis.

Microcurrent Reverses Cigarette Smoke-Induced Angiogenesis Impairment in Human Keratinocytes In Vitro.

Cigarette smoking (CS) leads to several adverse health effects, including diseases, disabilities, and even death. Post-operative and trauma patients who smoke have an increased risk for complications, such as delayed bone or wound healing. In clinical trials, microcurrent (MC) has been shown to be a safe, non-invasive, and effective way to accelerate wound healing. Our study aimed to investigate if MC with the strength of 100 µA may be beneficial in treating CS-related healing impairment, especially in regard to angiogenesis. In this study, we investigated the effect of human keratinocyte cells (HaCaT) on angiogenesis after 72 h of cigarette smoke extract (CSE) exposure in the presence or absence of 100 µA MC. Cell viability and proliferation were evaluated by resazurin conversion, Sulforhodamine B, and Calcein-AM/Hoechst 33342 staining; the pro-angiogenic potential of HaCaT cells was evaluated by tube formation assay and angiogenesis array assay; signaling pathway alterations were investigated using Western blot. Constant exposure for 72 h to a 100 µA MC enhanced the angiogenic ability of HaCaT cells, which was mediated through the PI3K-Akt signaling pathway. In conclusion, the current data indicate that 100 µA MC may support wound healing in smoking patients by enhancing angiogenesis.

The role of electrical signals in murine corneal wound re-epithelialization.

Ion flow from intact tissue into epithelial wound sites results in lateral electric currents that may represent a major driver of wound healing cell migration. Use of applied electric fields (EF) to promote wound healing is the basis of Medicare-approved electric stimulation therapy. This study investigated the roles for EFs in wound re-epithelialization, using the Pax6(+/-) mouse model of the human ocular surface abnormality aniridic keratopathy (in which wound healing and corneal epithelial cell migration are disrupted). Both wild-type (WT) and Pax6(+/-) corneal epithelial cells showed increased migration speeds in response to applied EFs in vitro. However, only Pax6(+/+) cells demonstrated consistent directional galvanotaxis towards the cathode, with activation of pSrc signaling, polarized to the leading edges of cells. In vivo, the epithelial wound site normally represents a cathode, but 43% of Pax6(+/-) corneas exhibited reversed endogenous wound-induced currents (the wound was an anode). These corneas healed at the same rate as WT. Surprisingly, epithelial migration did not correlate with direction or magnitude of endogenous currents for WT or mutant corneas. Furthermore, during healing in vivo, no polarization of pSrc was observed. We found little evidence that Src-dependent mechanisms of cell migration, observed in response to applied EFs in vitro, normally exist in vivo. It is concluded that endogenous EFs do not drive long-term directionality of sustained healing migration in this mouse corneal epithelial model. Ion flow from wounds may nevertheless represent an important component of wound signaling initiation.

Electrical dimensions in cell science.

Cells undergo a variety of physiological processes, including division, migration and differentiation, under the influence of endogenous electrical cues, which are generated physiologically and pathologically in the extracellular and sometimes intracellular spaces. These signals are transduced to regulate cell behaviours profoundly, both in vitro and in vivo. Bioelectricity influences cellular processes as fundamental as control of the cell cycle, cell proliferation, cancer-cell migration, electrical signalling in the adult brain, embryonic neuronal cell migration, axon outgrowth, spinal-cord repair, epithelial wound repair, tissue regeneration and establishment of left-right body asymmetry. In addition to direct effects on cells, electrical gradients interact with coexisting extracellular chemical gradients. Indeed, cells can integrate and respond to electrical and chemical cues in combination. This Commentary details how electrical signals control multiple cell behaviours and argues that study of the interplay between combined electrical and chemical gradients is underdeveloped yet necessary.

Directed migration of human bone marrow mesenchymal stem cells in a physiological direct current electric field.

At sites of bone fracture, naturally-occurring electric fields (EFs) exist during healing and may guide cell migration. In this study, we investigated whether EFs could direct the migration of bone marrow mesenchymal stem cells (BM-MSCs), which are known to be key players in bone formation. Human BM-MSCs were cultured in direct current EFs of 10 to 600 mV/mm. Using time-lapse microscopy, we demonstrated that an EF directed migration of BM-MSCs mainly to the anode. Directional migration occurred at a low threshold and with a physiological EF of ~25 mV/mm. Increasing the EF enhanced the MSC migratory response. The migration speed peaked at 300 mV/mm, at a rate of 42 ±1 µm/h, around double the control (no EF) migration rate. MSCs showed sustained response to prolonged EF application in vitro up to at least 8 h. The electrotaxis of MSCs with either early (P3-P5) or late (P7-P10) passage was also investigated. Migration was passage-dependent with higher passage number showing reduced directed migration, within the range of passages examined. An EF of 200 mV/mm for 2 h did not affect cell senescence, phenotype, or osteogenic potential of MSCs, regardless of passage number within the range tested (P3-P10). Our findings indicate that EFs are a powerful cue in directing migration of human MSCs in vitro. An applied EF may be useful to control or enhance migration of MSCs during bone healing.

Direct Current Electrical Fields Improve Experimental Wound Healing by Activation of Cytokine Secretion and Erk1/2 Pathway Stimulation.

There is growing evidence that cell behaviors can be influenced by the direct current electric fields (EFs). Some behaviors may influence wound healing directly. This study aimed to investigate the effects of EF (200 mV/mm) on immortalized nontumorigenic human epidermal (HaCaT) cells. We established a setup that can transmit an EF and maintain a stable cell culture environment. An EF was applied to HaCaT cells, and scratch-assays were performed as a model of wound healing to observe cell migration. Proliferation was evaluated by mitochondrial activity, total protein, and DNA content. Secretion of healing-associated cytokines was evaluated via cytokine arrays, and Western blot was applied to investigate signaling pathway alterations. Compared with the control group, the migration of cells exposed to EFs significantly increased (p < 0.01). After 7 days, the changes in proliferation also increased significantly (p < 0.05). The cytokine arrays revealed that granulocyte-macrophage colony-stimulating factor (GM-CSF) was the most abundant factor secreted by HaCaT following EF exposure. The signals for phospho-Erk1/2 showed a significant (p < 0.0001) increase following EF exposure. The results demonstrate that exposure of HaCaT cells to EFs has positive effects on migration, proliferation, and cytokine secretion-three important steps in wound healing-and these effects may be partially mediated by activation of the Erk1/2 signaling pathway.

Percutaneous Bioelectric Current Stimulation for Chronic Cluster Headache - A Possible Transformative Approach to Cluster Headache.

BACKGROUND: Cluster headache (CH) is considered to be a catastrophic disease presenting the most severe human pain condition. Available pharmacological treatments are hampered by unwanted side effects, and there is an urgent need for non-pharmacological treatment alternatives. We present a novel therapeutic approach for chronic CH, having evolved from an episodic CH, using a non-invasive percutaneous bioelectric current stimulation (PBCS), which generates static electric fields in the range of the naturally occurring electric potentials. PATIENTS AND METHODS: This study employed a retrospective data analysis of 20 cases of chronic cluster headache (CCH) patients, four of those having had cluster-related surgery (SPG, ONS). All patients were treated with PBCS between 2014 and 2018. Data of these patients were analyzed with respect to frequency of CH attacks and triptan application and followed up for one (20 cases) or two (12 cases) years. RESULTS: Four weeks after the first PBCS treatment, cluster headache attacks were reduced from 2.8 to 1.7 per day and triptan application decreased from 2.5 to 1.5 times/day. Six non-responders, 4 of which had pre-CH surgery, did not show any reaction to PBCS, while 14 responders improved within 4 weeks from 2.2 to 0.7 attacks/day and 2.0 to 0.4 triptan applications/day. A 50% or greater reduction of attack frequency was observed in 10 patients after 4 weeks and in 11 patients after 12 weeks. One year after the first treatment, 13/20 patients experienced a reduction of attack frequency of 50% or more, while remarkably 10 patients were completely free of attack. After 2 years, 8 of 12 patients experienced a reduction of attack frequency of 50% or more and 7 of those were completely symptom-free. No serious adverse effects were observed. CONCLUSION: PBCS is a promising transformative treatment approach for CCH patients. Drug consumption was reduced significantly, and the CCH may revert back to an episodic cluster headache with increasingly long times of remission. Responders can be clearly differentiated from non-responders. The data support the need for randomized controlled trials.

Schizophrenia-related neural and behavioral phenotypes in transgenic mice expressing truncated Disc1.

Disrupted-in-Schizophrenia-1 (DISC1), identified by positional cloning of a balanced translocation (1;11) with the breakpoint in intron 8 of a large Scottish pedigree, is associated with a range of neuropsychiatric disorders including schizophrenia. To model this mutation in mice, we have generated Disc1(tr) transgenic mice expressing 2 copies of truncated Disc1 encoding the first 8 exons using a bacterial artificial chromosome (BAC). With this partial simulation of the human situation, we have discovered a range of phenotypes including a series of novel features not previously reported. Disc1(tr) transgenic mice display enlarged lateral ventricles, reduced cerebral cortex, partial agenesis of the corpus callosum, and thinning of layers II/III with reduced neural proliferation at midneurogenesis. Parvalbumin GABAergic neurons are reduced in the hippocampus and medial prefrontal cortex, and displaced in the dorsolateral frontal cortex. In culture, transgenic neurons grow fewer and shorter neurites. Behaviorally, transgenic mice exhibit increased immobility and reduced vocalization in depression-related tests, and impairment in conditioning of latent inhibition. These abnormalities in Disc1(tr) transgenic mice are consistent with findings in severe schizophrenia.

Electrical signals polarize neuronal organelles, direct neuron migration, and orient cell division.

During early brain development, the axis of division of neuronal precursor cells is regulated tightly and can determine whether neurons remain in the germinal layers or migrate away. Directed neuronal migration depends on the establishment of cell polarity, and cells are polarized dynamically in response to extracellular signals. Endogenous electric fields (EFs) orient cell division and direct migration of a variety of cell types. Here, we show that cell division of cultured hippocampal cells (neuron-like cells and glial-like cells) is oriented strikingly by an applied EF, which also directs neuronal migration. Directed migration involves polarization of the leading neurite, of the microtubule-associated protein MAP-2 and of the Golgi apparatus and the centrosome, all of which reposition asymmetrically to face the cathode. Pharmacological inhibition of Rho-associated coiled-coil forming protein kinases (ROCK) and phosphoinositide 3-kinase decreased, leading neurite orientation and Golgi polarization in the neurons in response to an EF and in parallel decreased the directedness of EF-guided neuronal migration. This work demonstrates that the axis of hippocampal cell division, the establishment of neuronal polarity, the polarization of intracellular structures, and the direction of neuronal migration are all regulated by an extracellular electrical cue.

Expression of the human PAC1 receptor leads to dose-dependent hydrocephalus-related abnormalities in mice.

Hydrocephalus is a common and potentially devastating birth defect affecting the CNS, and its relationship with G protein-coupled receptors (GPCRs) is unknown. We have expressed 2, 4, or 6 copies of a GPCR--the human PAC1 receptor with a 130-kb transgene in the mouse nervous system in a pattern closely resembling that of the endogenous gene. Consistent with PAC1 actions, PKA and PKC activity were elevated in the brains of Tg mice. Remarkably, Tg mice developed dose-dependent hydrocephalus-like characteristics, including enlarged third and lateral ventricles and reduced cerebral cortex, corpus callosum, and subcommissural organ (SCO). Neuronal proliferation and apoptosis were implicated in hydrocephalus, and we observed significantly reduced neuronal proliferation and massively increased neuronal apoptosis in the developing cortex and SCO of Tg embryos, while neurite outgrowth and neuronal migration in vitro remain uncompromised. Ventricular ependymal cilia are crucial for directing cerebrospinal fluid flow, and ependyma of Tg mice exhibited disrupted cilia with increased phospho-CREB immunoreactivity. These data demonstrate that altered neuronal proliferation/apoptosis and disrupted ependymal cilia are the main factors contributing to hydrocephalus in PAC1-overexpressing mice. This is the first report to our knowledge demonstrating that misregulation of GPCRs can be involved in hydrocephalus-related neurodevelopmental disorders.