The neuronal ceroid lipofuscinoses (NCL) are a group of disorders defined by shared clinical and pathological features, including seizures and progressive decline in vision, neurocognition, and motor ...functioning, as well as accumulation of autofluorescent lysosomal storage material, or ‘ceroid lipofuscin’. Research has revealed thirteen distinct genetic subtypes. Precisely how the gene mutations lead to the clinical phenotype is still incompletely understood, but recent research progress is starting to shed light on disease mechanisms, in both gene-specific and shared pathways. As the application of new sequencing technologies to genetic disease diagnosis has grown, so too has the spectrum of clinical phenotypes caused by mutations in the NCL genes. Most genes causing NCL have probably been identified, underscoring the need for a shift towards applying genomics approaches to achieve a deeper understanding of the molecular basis of the NCLs and related disorders. Here, we summarize the current understanding of the thirteen identified NCL genes and the proteins they encode, touching upon the spectrum of clinical manifestations linked to each of the genes, and we highlight recent progress leading to a broader understanding of key pathways involved in NCL disease pathogenesis and commonalities with other neurodegenerative diseases.
•The neuronal ceroid lipofuscinoses are a group of inherited neurodegenerative disorders with lysosomal pathology.•There are thirteen distinct genetic subtypes of neuronal ceroid lipofuscinosis, CLN1-14.•With new sequencing technologies, the spectrum of phenotypes associated with NCL gene mutations has widened.•We summarize knowledge on NCL genes and proteins, highlighting areas of intersection among NCLs and related disorders.•Shifting towards genomics approaches will establish a more in-depth understanding of the NCLs and related disorders.
Quantum theory is expected to govern the electromagnetic properties of a quantum metamaterial, an artificially fabricated medium composed of many quantum objects acting as artificial atoms. ...Propagation of electromagnetic waves through such a medium is accompanied by excitations of intrinsic quantum transitions within individual meta-atoms and modes corresponding to the interactions between them. Here we demonstrate an experiment in which an array of double-loop type superconducting flux qubits is embedded into a microwave transmission line. We observe that in a broad frequency range the transmission coefficient through the metamaterial periodically depends on externally applied magnetic field. Field-controlled switching of the ground state of the meta-atoms induces a large suppression of the transmission. Moreover, the excitation of meta-atoms in the array leads to a large resonant enhancement of the transmission. We anticipate possible applications of the observed frequency-tunable transparency in superconducting quantum networks.
Förster resonance energy transfer (FRET) is a versatile method for analyzing protein-protein interactions within living cells. This protocol describes a nondestructive live-cell FRET assay for robust ...quantification of relative binding affinities for protein-protein interactions. Unlike other approaches, our method correlates the measured FRET efficiencies to relative concentration of interacting proteins to determine binding isotherms while including collisional FRET corrections. We detail how to assemble and calibrate the equipment using experimental and theoretical procedures. A step-by-step protocol is given for sample preparation, data acquisition and analysis. The method uses relatively inexpensive and widely available equipment and can be performed with minimal training. Implementation of the imaging setup requires up to 1 week, and sample preparation takes ∼1-3 d. An individual FRET experiment, including control measurements, can be completed within 4-6 h, with data analysis requiring an additional 1-3 h.
Lung emphysema and chronic bronchitis are the two most common causes of chronic obstructive pulmonary disease. Excess macrophage elastase MMP-12, which is predominantly secreted from alveolar ...macrophages, is known to mediate the development of lung injury and emphysema. Here, we discovered the endolysosomal cation channel mucolipin 3 (TRPML3) as a regulator of MMP-12 reuptake from broncho-alveolar fluid, driving in two independently generated Trpml3
mouse models enlarged lung injury, which is further exacerbated after elastase or tobacco smoke treatment. Mechanistically, using a Trpml3
reporter mouse model, transcriptomics, and endolysosomal patch-clamp experiments, we show that in the lung TRPML3 is almost exclusively expressed in alveolar macrophages, where its loss leads to defects in early endosomal trafficking and endocytosis of MMP-12. Our findings suggest that TRPML3 represents a key regulator of MMP-12 clearance by alveolar macrophages and may serve as therapeutic target for emphysema and chronic obstructive pulmonary disease.
We present experimental data on a one-dimensional super-conducting metamaterial that is tunable over a broad frequency band. The basic building block of this magnetic thin-film medium is a ...single-junction (rf-) superconducting quantum interference device (SQUID). Due to the nonlinear inductance of such an element, its resonance frequency is tunable in situ by applying a dc magnetic field. We demonstrate that this results in tunable effective parameters of our metamaterial consisting of 54 rf-SQUIDs. In order to obtain the effective magnetic permeability μr,eff from the measured data, we employ a technique that uses only the complex transmission coefficient S₂₁.
The field of metamaterial research revolves around the idea of creating artificial media that interact with light in a way unknown from naturally occurring materials. This is commonly achieved using ...sub-wavelength lattices of electronic or plasmonic structures, so-called meta-atoms. One of the ultimate goals for these tailored media is the ability to control their properties in situ. Here we show that superconducting quantum interference devices can be used as fast, switchable meta-atoms. We find that their intrinsic nonlinearity leads to simultaneously stable dynamic states, each of which is associated with a different value and sign of the magnetic susceptibility in the microwave domain. Moreover, we demonstrate that it is possible to switch between these states by applying nanosecond-long pulses in addition to the microwave-probe signal. Apart from potential applications for this all-optical metamaterial switch, the results suggest that multistability can also be utilized in other types of nonlinear meta-atoms.
Endolysosomes are dynamic, intracellular compartments, regulating their surface-to-volume ratios to counteract membrane swelling or shrinkage caused by osmotic challenges upon tubulation and ...vesiculation events. While osmosensitivity has been extensively described on the plasma membrane, the mechanisms underlying endolysosomal surface-to-volume ratio changes and identities of involved ion channels remain elusive. Endolysosomes mediate endocytosis, exocytosis, cargo transport, and sorting of material for recycling or degradation. We demonstrate the endolysosomal cation channel TRPML2 to be hypotonicity/mechanosensitive, a feature crucial to its involvement in fast-recycling processes of immune cells. We demonstrate that the phosphoinositide binding pocket is required for TRPML2 hypotonicity-sensitivity, as substitution of L314 completely abrogates hypotonicity-sensitivity. Last, the hypotonicity-insensitive TRPML2 mutant L314R slows down the fast recycling pathway, corroborating the functional importance of hypotonicity-sensitive TRPML2. Our results highlight TRPML2 as an accelerator of endolysosomal trafficking by virtue of its hypotonicity-sensitivity, with implications in immune cell surveillance and viral trafficking.
Mutations in the photoreceptor outer segment (OS) specific peripherin-2 lead to autosomal dominant retinitis pigmentosa (adRP). By contrast, mutations in the peripherin-2 homolog Rom-1 cause digenic ...RP in combination with certain heterozygous mutations in peripherin-2. The mechanisms underlying the differential role of peripherin-2 and Rom-1 in RP pathophysiology remained elusive so far. Here, focusing on two adRP-linked peripherin-2 mutants, P210L and C214S, we analyzed the binding characteristics, protein assembly, and rod OS targeting of wild type (per
), mutant peripherin-2 (per
), or Rom-1 complexes, which can be formed in patients heterozygous for peripherin-2 mutations. Both mutants are misfolded and lead to decreased binding to per
and Rom-1. Furthermore, both mutants are preferentially forming non-covalent per
-per
, per
-per
, and Rom-1-per
dimers. However, only per
-per
, but not per
-per
or Rom-1-per
complexes could be targeted to murine rod OS. Our study provides first evidence that non-covalent per
-per
dimers can be targeted to rod OS. Finally, our study unravels unexpected opposing roles of per
and Rom-1 in rod OS targeting of adRP-linked peripherin-2 mutants and suggests a new treatment strategy for the affected individuals.
In a coupled system of one classical and one quantum mechanical degree of freedom, the quantum degree of freedom can facilitate the escape of the whole system. Such unusual escape characteristics ...have been theoretically predicted as the "Münchhausen effect." We implement such a system by shunting one of the two junctions of a dc SQUID with an additional capacitance. In our experiments, we detect a crossover between quantum and classical escape processes related to the direction of escape. We find that, under varying external magnetic flux, macroscopic quantum tunneling periodically alternates with thermally activated escape, a hallmark of the "Münchhausen effect."
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