| 1. |
- Helbig, K. L., et al.
(författare)
-
De Novo Pathogenic Variants in CACNA1E Cause Developmental and Epileptic Encephalopathy with Contractures, Macrocephaly, and Dyskinesias
- 2018
-
Ingår i: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 103:5, s. 666-678
-
Tidskriftsartikel (refereegranskat)abstract
- Developmental and epileptic encephalopathies (DEEs) are severe neurodevelopmental disorders often beginning in infancy or early childhood that are characterized by intractable seizures, abundant epileptiform activity on EEG, and developmental impairment or regression. CACNA1E is highly expressed in the central nervous system and encodes the alpha(1)-subunit of the voltage-gated Ca(V)2.3 channel, which conducts high voltage-activated R-type calcium currents that initiate synaptic transmission. Using next-generation sequencing techniques, we identified de novo CACNA1E variants in 30 individuals with DEE, characterized by refractory infantile-onset seizures, severe hypotonia, and profound developmental impairment, often with congenital contractures, macrocephaly, hyperkinetic movement disorders, and early death. Most of the 14, partially recurring, variants cluster within the cytoplasmic ends of all four S6 segments, which form the presumed Ca(V)2.3 channel activation gate. Functional analysis of several S6 variants revealed consistent gain-of-function effects comprising facilitated voltage-dependent activation and slowed inactivation. Another variant located in the domain II S4-S5 linker results in facilitated activation and increased current density. Five participants achieved seizure freedom on the anti-epileptic drug topiramate, which blocks R-type calcium channels. We establish pathogenic variants in CACNA1E as a cause of DEEs and suggest facilitated R-type calcium currents as a disease mechanism for human epilepsy and developmental disorders.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Ermund, Anna, et al.
(författare)
-
The normal trachea is cleaned by MUC5B mucin bundles from the submucosal glands coated with the MUC5AC mucin
- 2017
-
Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 492:3, s. 331-337
-
Tidskriftsartikel (refereegranskat)abstract
- To understand the mucociliary clearance system, mucins were visualized by light, confocal and electron microscopy, and mucus was stained by Alcian blue and tracked by video microscopy on tracheal explants of newborn piglets. We observed long linear mucus bundles that appeared at the submucosal gland openings and were transported cephalically. The mucus bundles were shown by mass spectrometry and immunostaining to have a core made of MUC5B mucin and were coated with MUC5AC mucin produced by surface goblet cells. The transport speed of the bundles was slower than the airway surface liquid flow. We suggest that the goblet cell MUC5AC mucin anchors the mucus bundles and thus controls their transport. Normal clearance of the respiratory tree of pigs and humans, both rich in submucosal glands, is performed by thick and long mucus bundles. (C) 2017 The Authors. Published by Elsevier Inc.
|
|
| 5. |
- Trillo-Muyo, Sergio, 1983, et al.
(författare)
-
Granule-stored MUC5B mucins are packed by the non-covalent formation of N-terminal head-to-head tetramers
- 2018
-
Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 293:15, s. 5746-5754
-
Tidskriftsartikel (refereegranskat)abstract
- Most MUC5B mucin polymers in the upper airways of humans and pigs are produced by submucosal glands. MUC5B forms N-terminal covalent dimers that are further packed into larger assemblies because of low pH and high Ca2+ in the secretory granule of the mucin-producing cell. We purified the recombinant MUC5B N-terminal covalent dimer and used single-particle electron microscopy to study its structure under intracellular conditions. We found that, at intragranular pH, the dimeric MUC5B organized into head-to-head noncovalent tetramers where the von Willebrand D1-D2 domains hooked into each other. These N-terminal tetramers further formed long linear complexes from which, we suggest, the mucin domains and their C termini project radially outwards. Using conventional and video microscopy, we observed that, upon secretion into the submucosal gland ducts, a flow of bicarbonate-rich fluid passes the mucin-secreting cells. We suggest that this unfolds and pulls out the MUC5B assemblies into long linear threads. These further assemble into thicker mucin bundles in the glandular ducts before emerging at the gland duct opening. We conclude that the combination of intracellular packing of the MUC5B mucin and the submucosal gland morphology creates an efficient machine for producing linear mucin bundles.
|
|
| 6. |
- Tolö, Johan, et al.
(författare)
-
Pathophysiological Consequences of Neuronal alpha-Synuclein Overexpression: Impacts on Ion Homeostasis, Stress Signaling, Mitochondrial Integrity, and Electrical Activity
- 2018
-
Ingår i: Frontiers in Molecular Neuroscience. - : Frontiers Media SA. - 1662-5099. ; 11, s. 1-21
-
Tidskriftsartikel (refereegranskat)abstract
- alpha-Synuclein (alpha-Syn) is intimately linked to the etiology of Parkinson's Disease, as mutations and even subtle increases in gene dosage result in early onset of the disease. However, how this protein causes neuronal dysfunction and neurodegeneration is incompletely understood. We thus examined a comprehensive range of physiological parameters in cultured rat primary neurons overexpressing alpha-Syn at levels causing a slowly progressive neurodegeneration. In contradiction to earlier reports from non-neuronal assay systems we demonstrate that alpha-Syn does not interfere with essential ion handling capacities, mitochondrial capability of ATP production or basic electro-physiological properties like resting membrane potential or the general ability to generate action potentials. alpha-Syn also does not activate canonical stress kinase Signaling converging on SAPK/Jun, p38 MAPK or Erk kinases. Causative for alpha-Syn-induced neurodegeneration are mitochondrial thiol oxidation and activation of caspases downstream of mitochondrial outer membrane permeabilization, leading to apoptosis-like cell death execution with some unusual aspects. We also aimed to elucidate neuroprotective strategies counteracting the pathophysiological processes caused by alpha-Syn. Neurotrophic factors, calpain inhibition and increased lysosomal protease capacity showed no protective effects against alpha-Syn overexpression. In contrast, the major watchdog of outer mitochondrial membrane integrity, Bcl-Xl, was capable of almost completely preventing neuron death, but did not prevent mitochondrial thiol oxidation. Importantly, independent from the quite mono-causal induction of neurotoxicity, alpha-Syn causes diminished excitability of neurons by external stimuli and robust impairments in endogenous neuronal network activity by decreasing the frequency of action potentials generated without external stimulation. This latter finding suggests that alpha-Syn can induce neuronal dysfunction independent from its induction of neurotoxicity and might serve as an explanation for functional deficits that precede neuronal cell loss in synucleopathies like Parkinson's disease or dementia with Lewy bodies.
|
|
| 7. |
|
|
