Metastatic melanoma is an aggressive malignancy with limited long-term treatment success due to therapeutic resistance and immune evasion. The transient receptor potential melastatin 8 (TRPM8) ion channel is overexpressed in melanoma but its role as therapeutic target remains unexplored. We investigated the anti-tumor effects of novel TRPM8 modulators in metastatic melanoma cells using viability assays, apoptosis markers, mitochondrial function analyses, reactive oxygen species (ROS) measurements and gene silencing. Their functional impact was further assessed in 3D melanoma organoids, clonogenic survival assays, and natural killer (NK) cell co-culture systems. TRPM8 is significantly overexpressed in metastatic melanoma, as compared with the normal counterparts. Its pharmacological inhibition with novel modulators selectively induces calcium-independent mitochondrial apoptosis characterized by ROS accumulation, mitochondrial membrane depolarization, cytochrome c release, and caspase-3 activation. This process involves activation of the ATM/p53 pathway and upregulation of pro-apoptotic proteins. Additionally, TRPM8 modulators increase expression of the NK cell-activating ligand ULBP1, enhancing melanoma susceptibility to NK-mediated cytotoxicity. Our study identifies TRPM8 as a promising biomarker in melanoma. Its targeting triggers mitochondrial cell death and simultaneously boosts NK cell recognition via ULBP1/NKG2D engagement. TRPM8 targeting in combination with immunotherapy might be, hence, further explored in clinical setting of advanced melanoma.

Cardiac arrhythmias significantly contribute to morbidity and mortality in cardiovascular diseases. Hereditary ion channel disorders, including Brugada syndrome, long/short QT syndrome and catecholaminergic polymorphic ventricular tachycardia (CPVT), represent critical entities with elevated risk of malignant ventricular arrhythmias. Although beta-blockers, ion channel modulators and implantable cardioverter defibrillators (ICD) are available and the indications for them are increasingly based on genetic analyses, variants of uncertain significance (VUS) substantially impair the risk stratification. Atrial tachyarrhythmias, particular atrial fibrillation, can cause an often-reversible arrhythmia-induced cardiomyopathy (AIC). Pathophysiologically, the Ca2+/calmodulin-dependent protein kinaseII (CaMKII) plays an important role in atrial and ventricular arrhythmias. It can be activated by various pathological triggers, such as high heart rate, neuroendocrine activation and oxidative stress, the latter often resulting from mechano-energetic uncoupling. The development of effective treatment options for arrhythmia-associated cardiovascular diseases requires the use of human model systems in addition to animal experimental approaches, due to the genetic heterogeneity and systemic comorbidities. Patient-specific cardiac stem cell-models enable the classification of VUS and personalised drug testing. The integration of new methodological approaches into existing animal experimental approaches thus paves the way for functionally validated precision medicine and could fundamentally transform the treatment of both disease patterns.

Protease-activated receptor 2 (PAR2) is a G protein-coupled receptor (GPCR) expressed in both the peripheral and central nervous systems. It plays a pivotal role in mediating neuroimmune interactions, particularly in the context of inflammation and pain. Upon activation by proteases, PAR2 modulates nociception through signaling cascades that influence key ion channels, including transient receptor potential (TRP) ion channels vanilloid 1 and 4 (TRPV1 and TRPV4), ankyrin 1 (TRPA1), acid-sensing ion channel 3 (ASIC3), P2X purinoceptor 3 (P2X3), Cav3.2 (T-type Ca2+ channel), and potassium Kv7 (M-current) channels, altering their expression and function. Through this crosstalk, PAR2 contributes to heightened neuronal excitability and pain hypersensitivity in various inflammatory conditions. In this narrative review, we highlight and discuss the mechanistic and functional interplay between PAR2 and nociceptive ion channels, which might be contributing to the pathogenesis of inflammatory pain. Targeting these specific molecular interactions between PAR2 and nociceptive ion channels may offer a promising therapeutic strategy for treating inflammatory pain.

Terahertz (THz) wave is a promising and newly developed technology in biological medicine, especially in neuro-related treatments and devices. The effects of THz waves on ion channels are being revealed. However, the effect of THz waves on Ca2+ and surrounding hydration shells has not been clearly researched yet, restricting the understanding of THz waves' effects on the Ca2+ permeation process in channel structures, such as ion channels. Thus, in this work, we carried out molecular dynamics simulations to fully explore the resonant effects of THz waves on (1) hydrogen bonding among the hydration shells of Ca2+ and (2) desolvation energy of each hydration shell while permeating through an ion channel. Our work indicates that a 14.5THz wave will remold the hydrogen bonding pattern of the second and third hydration shells, weaken the effect of water dipole reorientation effects of the first and second hydration shells, and increase the desolvation energy of the second and third hydration shells. This work expands the method to estimate the ionic desolvation energy under specific conditions and further increases our cognitions on the effects of THz waves on the structure of the Ca2+ hydration shell and its hydrogen bond pattern.

Human respiratory syncytial virus (RSV) is a major pathogen causing acute lower respiratory tract infections in infants, young children, and elderly people worldwide. Viruses often hijack host cell ion channels to optimize their intracellular environment, positioning ion channel blockers as promising antiviral agents. On the outer mitochondrial membrane, voltage-dependent anion channel protein 1 (VDAC1) plays a crucial role in regulating mitochondrial pathway apoptosis and maintaining cellular homeostasis. This study systematically evaluates the antiviral activity of the VDAC1 inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), both in vitro and in vivo. The results demonstrate that VDAC1 is a key factor in RSV infection, and DIDS significantly inhibits viral replication. Functional intervention experiments show that DIDS effectively blocks RSV-induced VDAC1 oligomerization in the mitochondrial membrane, suppressing mitochondrial apoptosis and disrupting chloride ion (Cl-) flux, thereby inhibiting viral replication. Exogenous Cl- supplementation reverses these effects, further highlighting the critical role of VDAC1 in the life cycle of RSV. In conclusion, the antiviral effects and mechanistic insights of DIDS reveal that VDAC1 regulates mitochondrial-mediated apoptosis while also modulating anion homeostasis to promote viral replication. These findings provide a potential target and theoretical foundation for the development of novel antiviral strategies targeting mitochondrial ion channels.IMPORTANCEThe study evaluates the antiviral activity of the VDAC1 inhibitor DIDS against respiratory syncytial virus (RSV), a major cause of lower respiratory tract infections worldwide. VDAC1 is identified as a key factor in RSV infection, with DIDS significantly inhibiting viral replication by blocking RSV-induced VDAC1 oligomerization in the mitochondrial membrane, suppressing mitochondrial apoptosis, and disrupting chloride ion flux. These findings establish that VDAC1-mediated regulation of anion homeostasis and subsequent mitochondrial-mediated apoptosis is a critical mechanism promoting RSV replication, providing a novel target for antiviral strategies.

TMEM175 is an AKT-activated lysosomal potassium- and proton-permeable channel that functions to dissipate voltage and pH gradients generated by the V-type H+-ATPase. Loss-of-function (LOF) variants in TMEM175 have been identified as genetic risk factors for Parkinson's disease (PD), highlighting the potential of small-molecule activators as a novel therapeutic strategy for this disease. We developed a high-throughput screening assay using HEK-293 cells stably overexpressing TMEM175 at the cell surface and screened 960 FDA-approved drugs for TMEM175 potentiators. The screen identified 71 activators, including the cysteinyl leukotriene 1 receptor (CysLT1R) antagonists, pranlukast and montelukast. Because HEK-293 cells lack CysLT1R expression, we suspected these drugs may be direct channel activators. Fluorescence and automated patch clamp assays were used to evaluate the dose-dependency of pranlukast, montelukast, zafirlukast, and the known TMEM175 activator, DCPIB. These experiments revealed rank-order potencies and efficacies of DCPIB ~ zafirlukast > montelukast >> pranlukast. DCPIB, zafirlukast, and pranlukast activated TMEM175 independently of AKT activation, whereas the AKT inhibitor MK2206 partially inhibited montelukast-dependent TMEM175 activation. Computer modeling revealed a conformation-dependent solvent-accessible cavity near T119 and H449 that could participate in drug-induced activation, prompting us to examine these sites with mutagenesis. Not only did T119A and H449A mutations decrease apparent potencies of DCPIB, zafirlukast, and montelukast, but the T119A mutation produced a constitutively open channel phenotype. This study adds zafirlukast to the short list of moderately potent TMEM175 activators and identifies a region of the channel that contributes to activation gating.

N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels that mediate excitatory neurotransmission throughout the brain1. As obligate heterotetramers, their activation requires the binding of both glycine and glutamate2. Although recent structural studies have provided insights into endogenous receptors from select brain regions3, most previous work has relied on recombinant receptors and engineered constructs, which limits our understanding of native NMDARs across the whole brain. Here we identify and resolve ten distinct native NMDAR assemblies from the whole-brain tissue of female C57BL/6 mice using immunoaffinity purification, single-molecule total internal reflection fluorescence microscopy and cryo-electron microscopy. Analyses of the GluN1-GluN2A(S1), GluN1-GluN2A(S2), GluN1-GluN2A(S3), GluN1-GluN2B, GluN1-GluN2A-GluN2B(S1), GluN1-GluN2A-GluN2B(S2), GluN1-GluN2A-GluNX(S1), GluN1-GluN2A-GluNX(S2), GluN1-GluN2B-GluNX and GluN1-GluNX structures reveal that GluN2A is the most prevalent subunit across assemblies. Moreover, the substantial conformational flexibility observed in the GluN2A amino-terminal domain may explain its fast kinetics and dominant role in gating. Dynamic movements of S-ketamine were also captured at the channel vestibule, as was pore dilation in both the GluN1 and GluN2B subunits of a native GluN1-GluN2B receptor. The latter observation represents a previously unknown fully open state of NMDAR. Our large collection of heterogeneous NMDAR structures from whole brain reveals previously unrecognized properties of conformational diversity and channel dilation.

Transient transfection is widely used for protein expression in heterologous systems, yet uncontrolled overexpression frequently introduces artifacts that confound functional analyses. Although stable cell lines can mitigate these issues, generating lines for multiple constructs or variants is often impractical. Common alternatives, such as DNA titration, altered transfection conditions, or promoter swapping, provide only coarse and inconsistent control of protein abundance. Here, we establish a panel of ten human 5´ untranslated regions (5´UTRs) as a modular strategy to tune protein expression during transient transfection. Across three soluble proteins and three membrane proteins, these 5'UTRs produce a reproducible dynamic range of expression, including fine-grained control of eYFP and the large sensory ion channel TRPA1. Notably, one 5'UTR consistently suppresses expression across all proteins tested and alleviates overexpression-associated artifacts, improving functional analysis of a hyperactive channel variant, substantially reducing background in proximity biotinylation assays, and enhancing the specificity of a stress granule marker. In contrast, most 5'UTRs enhance expression of the TRPV1 and TRPM8 sensory receptors, improving protein yield in heterologous systems. Together, this work identifies 5´UTRs as a compact, versatile, and broadly applicable tool to fine-tune protein abundance, enabling more physiologically relevant and assay-optimized expression in transient transfection experiments.

Parkinson's disease (PD), characterized by motor dysfunction and dopaminergic neuron loss in the substantia nigra, is frequently complicated by depression (depression-associated PD, DPD), affecting 40-50% of patients and accelerating disease progression. This study investigated neuroprotective effects in a chronic MPTP-induced mouse model of DPD. We established a chronic PD model induced by MPTP, with motor deficits assessed via rotarod and gait analysis. Depressive phenotypes were confirmed by tail suspension, sucrose preference and forced swim tests. Mice were categorized into DPD and non-depressive groups, followed by 14-day treatment with SVHRSP or vehicle. Post-treatment behavioural evaluations demonstrated that SVHRSP significantly ameliorated depressive symptoms, as evidenced by increased sucrose preference, reduced immobility in the forced swim test and restored cognitive performance in the Y-maze, passive-avoidance and novel-object-recognition tests. Molecular analyses demonstrated that SVHRSP enhanced neuroprotection by normalizing the phosphorylated Akt and CREB levels, reducing neuroinflammatory markers (IBA1, GFAP and cytokines) and modulating synaptic proteins (NR2B and PSD-95). Immunofluorescence further corroborated these findings, confirming reduced NR2B and NR1 expression and preserved neuronal integrity. SVHRSP downregulated Nav1.6 ion channel expression and restored 5-HT2C receptor levels and normalized stress-axis glucocorticoid receptor (GR) expression. Molecular docking simulations revealed strong binding affinities between SVHRSP and CREB/Akt. The results indicate that SVHRSP mitigates motor deficits, depressive symptoms and cognitive impairments in MPTP-induced DPD mice by suppressing CREB-Akt-mediated neuroinflammation and modulating synaptic plasticity. The multitarget mechanism of SVHRSP underscores its potential as a novel therapeutic candidate for DPD.

The human brain performs complex memory and computational tasks with high energy efficiency by regulating ion transport through membrane channels. These signaling mechanisms have been inspiring the development of nanofluidic memristors that emulate synaptic behavior. Here, we describe a membrane ion channel synapse (MICS), constructed from aqueous droplets linked by gramicidin A channels, that achieves neuromorphic functionality. MICS exhibits memristive ion transport with hysteretic current-voltage behavior arising from voltage-dependent channel formation and ion transport dynamics. MICS emulates a range of synaptic behaviors including associative learning. We further demonstrate its application in reservoir computing by performing handwritten digit classification and tic-tac-toe game and explore the system parameters that improve the computational performance. This droplet-based biomimetic synapse offers a potentially scalable and energy-efficient platform for next-generation neuromorphic computingsystems.

Implant-associated infections have become a persistent threat affecting the success rate of clinical implant surgeries. Existing multitype antimicrobial films for implant surfaces still suffer from such problems as film detachment and erroneous killing of normal cells. Targeting the dual-core processes of the electron transport chain (ETC) and the tricarboxylic acid cycle (TCA) within bacterial energy metabolism networks, this work employs an engineered ion implantation method to sequentially inject copper ions and hydrogen ion onto the surface of the nickel-titanium alloy, developing a nondetachable, interface-free modified layer. Hydrogen ion implantation reduces exposed nickel oxide on the substrate to metallic nickel, forming a Cu-Ni microgalvanic system, which can continuously capture electrons from the bacterial membrane ETC, thereby inhibiting bacterial adenosine triphosphate synthesis. Furthermore, copper ions are intracellularly released via bacterial membrane ion channels, triggering a cuprotosis-like process. This process impairs bacterial metabolism, manifested as reduced iron uptake, diminished heme utilization capability, and inhibition of the TCA cycle. In vivo experiments validate its potent antibacterial effect in the infected subcutaneous tissue of a rat model. Moreover, the film can facilitate rapid surface endothelialization. This engineered dual-pathway interference strategy targeting bacterial energy metabolism provides the theoretical guidance for safely reducing the risk of implant infections.

Precise control of the firing of an individual neuron in vivo is a key technology to neuroscience. The laser-induced ion channel opening makes it possible to depolarize neurons and trigger the firing. In this study, we present a noninvasive, opsin-free photostimulation method for activating an individual neuron within the primary visual cortex (V1). This activation is achieved through the transient local scanning of a tightly focused femtosecond laser on the soma of the target neuron that opens the store-operated calcium channels by multiphoton excitation, induces Ca2+ influx, and depolarizes the neurons to trigger action potentials (APs) firing. In the absence of any visual stimuli, the isolated activation of an individual neuron in a cortical ensemble in layer 2/3 of V1 is sufficient to elicit visually guided specific behaviors in awake mice, without co-activating other neurons in the ensemble. Remarkably, the disruption of a single neuron within the ensemble temporarily paralyzes the entire ensemble and suspends behavioral responses to visual stimuli. However, the ensemble rapidly recovers its responsiveness and function. In general, this opsin-free photostimulation method activates targeted individual ensemble neurons in visual cortex of awake mice enabling firing APs and eliciting behaviors.

Autism Spectrum Disorder (ASD) presents with multiple clinical and genetic features. Genomic research during the last ten years has discovered numerous risk genes which include rare high-impact mutations together with common polygenic variants. The various cell types in the brain show different genetic and developmental patterns yet research indicates that multiple genetic disruptions lead to common biological pathways which control synaptic function and chromatin remodeling and ion channel signaling and immune regulation. The study of single-cell and spatial transcriptomics has revealed new information about how these processes occur at specific times and in particular cell types which shows that mid-fetal corticogenesis is a crucial developmental period and that excitatory projection neurons are particularly vulnerable. Scientists conduct maternal immune activation studies to determine how environmental disturbances create identical molecular pathways. This paper focuses on ASD through its genetic heterogeneity and convergent pathways and synaptic dysfunction and precision diagnosis, establishes a framework which connects genetic diversity to common neurobiological effects through the combination of genetic information with transcriptomic data and developmental analysis to create a basis for ASD precision medicine. The model would function as a guiding structure to lead biomarker research and patient classification and intervention development through analysis of personal molecular and developmental patterns.

Autosomal dominant polycystic kidney disease (ADPKD) is the leading monogenic cause of kidney failure and affects millions of people worldwide. Despite the prevalence of ADPKD, limited mechanistic understanding has hindered therapeutic development. Most ADPKD is caused by loss of function variants in Polycystin-1 (PC1). We developed assays that quantify the effect of nontruncating variants on PC1 ciliary localization, membrane trafficking, and Polycystin channel function. We evaluated 29 nontruncating variants in PC1 and found that pathogenic variants disrupt two molecular phenotypes: 1) localization of PC1 at the primary cilium or 2) Polycystin ion channel activity. Ciliary localization of a subset of Polycystin variants was restored when cells were cultured at low temperature. A subset of variants with localization restored by low temperature formed functional channels. This study demonstrated that disruptions in Polycystin ciliary trafficking and channel function are common causes of ADPKD. Defects in ciliary trafficking and channel function can be rescued for a subset of pathogenic variants, establishing a foundation for Polycystin-targeted therapies in ADPKD.

TMEM16A channels conduct Ca2+-activated Cl- currents that underlie essential physiological processes including epithelial secretion, smooth muscle contraction, and sensory transduction. Channel activation requires both intracellular Ca2+ and the signaling phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2), yet the molecular basis of this dual regulation has remained unclear. Using gating molecular-dynamics simulations and structure-guided electrophysiology, we show that PIP2 and Ca2+ cooperatively gate TMEM16A through an allosterically coupled electrostatic network centered on the α4 helix. Specific PIP2 headgroup phosphate interactions are essential for coupling Ca2+ binding to channel opening, while the PIP2 acyl chains engage hydrophobic surfaces of the helix to stabilize the open conformation. Disrupting either component of this lipid-protein interface reduces apparent PIP2 affinity and impairs activation, whereas long-chain PIP2 fully restores wild-type activity. These interactions act in concert with Ca2+-dependent structural rearrangements that widen the conduction pathway and enable Cl- permeation. Our findings establish that both the headgroup phosphates and acyl chains of PIP2 play indispensable and complementary roles in TMEM16A gating. This mechanism defines a cooperative lipid-ion activation process that provides a general framework for understanding phosphoinositide regulation of ion channels and offers opportunities for structure-based design of TMEM16A modulators.

Sudden infant death syndrome (SIDS) remains one of the most common and poorly understood diagnoses of death in infants. In this study, we searched for novel biomarkers to aid in elucidating the pathogenesis of SIDS through a bioinformatics analysis of serum-derived extracellular vesicle (EV) miRNAs using next-generation sequencing. Comparative analyses between infants who died of SIDS and those who died from known causes showed that 15 and 38 miRNAs were significantly up- or down-regulated more than twofold in SIDS, respectively. Myocardial-specific miRNAs, such as miR-1, miR-208, and miR-499, which are known to leak from injured heart, were up-regulated markedly in SIDS EVs. Gene target prediction analyses suggested that the MAP signaling pathway, cardiomyocytes, and cardiac ion channels are involved in the pathogenesis of SIDS. Gene ontology analyses revealed that protein phosphorylation, the actin cytoskeleton and myosin complex, and kinase activity are heavily involved in SIDS. Our results indicate that EV myocardial-specific miRNAs are released into the blood from the heart in SIDS, suggesting the pathogenesis of SIDS is associated with cardiac injury. Studies of EV miRNAs using minimally invasive fluid samples could lead to the discovery of new diagnostic markers for SIDS.

Lethal effects of ivermectin structures on malaria vectors and in silico analysis of interactions with their glutamate-gated chloride ion channels.

In the age of rising antibiotic resistance among various pathogens, the search for alternative antimicrobial strategies has become a pressing scientific challenge. Metal ions are indispensable to life, participating in a vast range of structural and catalytic roles across all forms of biology. The Biological Inorganic Chemistry Group explores the fundamental chemistry of metal ions in biological systems, focusing on their role in host-pathogen interactions. In this article we aim to focus on four aspects, representing the main scientific interests of our group. Metal homeostasis and assimilation chapter explores the coordination chemistry of biologically essential Mn(II) and Fe(II) ions using model peptides and fragments of metal transport proteins. By varying the number and position of His, Asp, and Glu residues, the study revealed how sequence composition governs metal-binding strength and selectivity. Studies on bacterial Fe(II) transporters, such as FeoB, identified potential metal-binding regions and mechanisms of ion transfer, deepening our understanding of metal recognition and transport in biological systems. To better understand iron uptake in pathogens, we explored synthetic siderophore analogs as tools for studying this process. Ferrichrome mimics effectively chelated Fe(III) and were taken up by Pseudomonas putida and Escherichia coli. Fluorescent labeling allowed visualization of these complexes in cells. Ferrioxamine E analogs showed promise as 68Ga-labeled imaging agents. The ability of various siderophores to bind metal ions such as Cu(II), Zn(II), Ni(II), Bi(III), and Zr(IV) has also been studied. One of the chapters focuses on chaperonins and metalloproteinases as bacterial virulence factors. GroEL1, a chaperonin present e.g.in Mycobacterium, binds metal ions like Cu(II) via its unstructured His-rich C-terminal tail, helping bacteria survive under toxic metal conditions. Peptide studies showed that specific His residues position affects metal complex stability, and various metals create distinctly different complex geometries. Bacterial metalloproteinases need Zn(II) for activity. Research on peptide models revealed how Cu(II) and Ni(II) can inhibit these enzymes by displacing Zn(II). Studies on human MMP-14 enabled the identification and detailed characterization of the metal-binding site, as well as the elucidation of the interactions between peptide-based inhibitors, the catalytic metal ion, and the enzyme active site. Detailed knowledge of virulence proteins may enable their use as a potential target for novel drugs. Membrane proteins are vital for transport, signaling, and maintaining membrane integrity. However, their studies are challenging due to poor solubility and detergent sensitivity. Lipoprotein nanodiscs (NDs) has revolutionized research on these proteins, by providing a soluble, stable, and physiologically relevant environment for membrane protein reconstitution. Their defined size, high stability, and compatibility 34 W. WOŹNIAK-LASZCZYŃSKA, K. GŁADYSZ, P. POTOK, M. ZAWADA, B. ORZEŁ, K.SZCZERBA… with structural and functional studies make NDs a powerful tool for investigating membrane transporters, ion channels, and receptors. This article highlights the key aspects of metal interactions with siderophores, transport and chaperone protein fragments, and metalloproteinases, and demonstrates how nanodiscs can advance the study of membrane proteins.

Pentameric glycine receptors (GlyRs) are key modulators of inhibitory neurotransmission, yet visualization of their activity across neuronal compartments has remained a challenge. Current methods that employ intracellularly tagged genetically encoded fluorescent proteins are prone to artefacts, as the tags can disrupt protein interactions that regulate receptor trafficking and positioning within the cell. We developed a novel, genetically encoded GlyRα2 activity reporter by fusing a chloride-sensitive fluorescent protein, mClYFP, to the extracellular N-terminus of GlyRα2. This chimeric receptor allows real-time nanoscopic visualization of the receptor and glycine-induced chloride concentration changes using total internal reflection fluorescence microscopy and ratio image analysis. Simultaneous electrophysiological and fluorescence measurements validated the functionality of both the ion channel and mClYFP components of our GlyRα2 activity reporter. The GlyRα2 ion channel characteristics are preserved, and the extracellular mClYFP tag reports chloride concentration changes in the physiological range. Therefore, mClYFP-GlyRα2 allowed us to detect receptor activity of chloride-permeable ionotropic receptors. In addition, we demonstrate that mClYFP-GlyRα2 can be effectively expressed in physiologically relevant striatal neurons. We present an extracellularly located, receptor-specific sensor that enables surface-accessible tracking of chloride ion dynamics in live cells. Our approach enables spatially resolved, non-invasive monitoring of chloride permeable receptor signaling, offering a powerful tool to investigate pentameric receptor function at the nanoscale.

The ciliopathies are a group of genetic disorders caused by defective function of either the primary cilia (a large number) or the motile cilia (a much smaller number). These have been defined as diseases with mutations in genes encoding individual ciliary or cilia-associated proteins. Recently, it has become apparent that the composition of the ciliary membrane influences its function. For instance, the ciliary membrane contains more cholesterol than other regions of the cell membrane and a variety of unique receptors and ion channels. Additionally, it appears that primary cilia have evolved to lower the threshold for activating signal transduction by establishing the environment essential for signaling pathways on a limited portion of the cell surface. By positioning receptors and downstream signaling components in this thin protrusion at a precise time and location within the plasma membrane, the cell can better orient its physiological response to external stimuli. Cholesterol deficiency can alter cilia formation and function with effects on Sonic hedgehog signaling. In this review, we discuss these new concepts and apply them to the developmental disorder Smith-Lemli-Opitz syndrome and the developmental and neurodegenerative disorder Niemann-Pick C disease, demonstrating that they are also ciliopathies.