-
Brain Research Oct 2023Damage to the axonal white matter tracts within the brain is a key cause of neurological impairment and long-term disability following traumatic brain injury (TBI)....
Damage to the axonal white matter tracts within the brain is a key cause of neurological impairment and long-term disability following traumatic brain injury (TBI). Understanding how axonal injury develops following TBI requires gyrencephalic models that undergo shear strain and tissue deformation similar to the clinical situation and investigation of the effects of post-injury insults like hypoxia. The aim of this study was to determine the effect of post-traumatic hypoxia on axonal injury and inflammation in a sheep model of TBI. Fourteen male Merino sheep were allocated to receive a single TBI via a modified humane captive bolt animal stunner, or sham surgery, followed by either a 15 min period of hypoxia or maintenance of normoxia. Head kinematics were measured in injured animals. Brains were assessed for axonal damage, microglia and astrocyte accumulation and inflammatory cytokine expression at 4 hrs following injury. Early axonal injury was characterised by calpain activation, with significantly increased SNTF immunoreactivity, a proteolytic fragment of alpha-II spectrin, but not with impaired axonal transport, as measured by amyloid precursor protein (APP) immunoreactivity. Early axonal injury was associated with an increase in GFAP levels within the CSF, but not with increases in IBA1 or GFAP+ve cells, nor in levels of TNFα, IL1β or IL6 within the cerebrospinal fluid or white matter. No additive effect of post-injury hypoxia was noted on axonal injury or inflammation. This study provides further support that axonal injury post-TBI is driven by different pathophysiological mechanisms, and detection requires specific markers targeting multiple injury mechanisms. Treatment may also need to be tailored for injury severity and timing post-injury to target the correct injury pathway.
Topics: Male; Animals; Sheep; Brain Injuries; Brain Injuries, Traumatic; Brain; Hypoxia; Inflammation
PubMed: 37400012
DOI: 10.1016/j.brainres.2023.148475 -
MicroPublication Biology 2023The vulva is a polarized epithelial tube that has been studied extensively as a model for cell-cell signaling, cell fate specification, and tubulogenesis. Here we used...
The vulva is a polarized epithelial tube that has been studied extensively as a model for cell-cell signaling, cell fate specification, and tubulogenesis. Here we used endogenous fusions to show that the spectrin cytoskeleton is polarized in this organ, with conventional beta-spectrin ( UNC-70 ) found only at basolateral membranes and beta heavy spectrin ( SMA-1 ) found only at apical membranes. The sole alpha-spectrin ( SPC-1 ) is present at both locations but requires SMA-1 for its apical localization. Thus, beta spectrins are excellent markers for vulva cell membranes and polarity.
PubMed: 37396793
DOI: 10.17912/micropub.biology.000863 -
The Journal of Neuroscience : the... Jul 2023Neural circuit assembly is a multistep process where synaptic partners are often born at distinct developmental stages, and yet they must find each other and form...
Neural circuit assembly is a multistep process where synaptic partners are often born at distinct developmental stages, and yet they must find each other and form precise synaptic connections with one another. This developmental process often relies on late-born neurons extending their processes to the appropriate layer to find and make synaptic connections to their early-born targets. The molecular mechanism responsible for the integration of late-born neurons into an emerging neural circuit remains unclear. Here, we uncovered a new role for the cytoskeletal protein βII-spectrin in properly positioning presynaptic and postsynaptic neurons to the developing synaptic layer. Loss of βII-spectrin disrupts retinal lamination, leads to synaptic connectivity defects, and results in impaired visual function in both male and female mice. Together, these findings highlight a new function of βII-spectrin in assembling neural circuits in the mouse outer retina. Neurons that assemble into a functional circuit are often integrated at different developmental time points. However, the molecular mechanism that guides the precise positioning of neuronal processes to the correct layer for synapse formation is relatively unknown. Here, we show a new role for the cytoskeletal scaffolding protein, βII-spectrin in the developing retina. βII-spectrin is required to position presynaptic and postsynaptic neurons to the nascent synaptic layer in the mouse outer retina. Loss of βII-spectrin disrupts positioning of neuronal processes, alters synaptic connectivity, and impairs visual function.
Topics: Male; Mice; Female; Animals; Spectrin; Cytoskeletal Proteins; Neurons; Cytoskeleton
PubMed: 37369589
DOI: 10.1523/JNEUROSCI.0063-23.2023 -
ELife Jun 2023Spectrins are membrane cytoskeletal proteins generally thought to function as heterotetramers comprising two α-spectrins and two β-spectrins. They influence cell shape...
Spectrins are membrane cytoskeletal proteins generally thought to function as heterotetramers comprising two α-spectrins and two β-spectrins. They influence cell shape and Hippo signaling, but the mechanism by which they influence Hippo signaling has remained unclear. We have investigated the role and regulation of the β-heavy spectrin (β-spectrin, encoded by the gene) in wing imaginal discs. Our results establish that β-spectrin regulates Hippo signaling through the Jub biomechanical pathway due to its influence on cytoskeletal tension. While we find that α-spectrin also regulates Hippo signaling through Jub, unexpectedly, we find that β-spectrin localizes and functions independently of α-spectrin. Instead, β-spectrin co-localizes with and reciprocally regulates and is regulated by myosin. and experiments support a model in which β-spectrin and myosin directly compete for binding to apical F-actin. This competition can explain the influence of β-spectrin on cytoskeletal tension and myosin accumulation. It also provides new insight into how β-spectrin participates in ratcheting mechanisms associated with cell shape change.
Topics: Animals; Actin Cytoskeleton; Cytoskeleton; Drosophila; Drosophila Proteins; Membrane Proteins; Myosin Type II; Spectrin
PubMed: 37367948
DOI: 10.7554/eLife.84918 -
BioRxiv : the Preprint Server For... Jun 2023α-synuclein plays a key role in the pathogenesis of Parkinson's disease and related disorders, but critical interacting partners and molecular mechanisms mediating...
α-synuclein plays a key role in the pathogenesis of Parkinson's disease and related disorders, but critical interacting partners and molecular mechanisms mediating neurotoxicity are incompletely understood. We show that α-synuclein binds directly to ß-spectrin. Using males and females in a model of α-synuclein-related disorders we demonstrate that ß-spectrin is critical for α-synuclein neurotoxicity. Further, the ankyrin binding domain of ß-spectrin is required for α-synuclein binding and neurotoxicity. A key plasma membrane target of ankyrin, Na/K ATPase, is mislocalized when human α-synuclein is expressed in . Accordingly, membrane potential is depolarized in α-synuclein transgenic fly brains. We examine the same pathway in human neurons and find that Parkinson's disease patient-derived neurons with a triplication of the α-synuclein locus show disruption of the spectrin cytoskeleton, mislocalization of ankyrin and Na/K ATPase, and membrane potential depolarization. Our findings define a specific molecular mechanism by which elevated levels of α-synuclein in Parkinson's disease and related α-synucleinopathies leads to neuronal dysfunction and death.
PubMed: 37333277
DOI: 10.1101/2023.06.02.543481 -
Brain and Behavior Sep 2023Cerebral ischemia and diabetes mellitus (DM) are common diseases that often coexist and interact with each other. DM doubles the risk of ischemic stroke, and cerebral...
INTRODUCTION
Cerebral ischemia and diabetes mellitus (DM) are common diseases that often coexist and interact with each other. DM doubles the risk of ischemic stroke, and cerebral ischemia causes stress-induced hyperglycemia. Most experimental stroke studies used healthy animals. Melatonin is neuroprotective against cerebral ischemia-reperfusion injury (CIRI) in non-DM, normoglycemic animals through anti-oxidant effect, anti-inflammation, and anti-apoptosis. Previous studies have also reported a negative correlation between hyperglycemia and urinary melatonin metabolite.
OBJECTIVES
The present study investigated the effects of type 1 DM (T1DM) on CIRI in rats and the role of melatonin against CIRI in T1DM animals.
RESULTS
Our results revealed that T1DM aggravated CIRI, leading to greater weight loss, increased infarct volume, and worse neurological deficit. T1DM aggravated the post-CIRI activation of nuclear factor kappa B (NF-κB) pathway and increase in pro-apoptotic markers. A single intraperitoneal injection of melatonin at 10 mg/kg given 30 min before ischemia onset attenuated CIRI in T1DM rats, resulting in less weight loss, decreased infarct volume, and milder neurological deficit when compared with the vehicle group. Melatonin treatment achieved anti-inflammatory and anti-apoptotic effects with reduced NF-κB pathway activation, reduced mitochondrial cytochrome C release, decreased calpain-mediated spectrin breakdown product (SBDP), and decreased caspase-3-mediated SBDP. The treatment also led to fewer iNOS+ cells, milder CD-68+ macrophage/microglia infiltration, decreased TUNEL+ apoptotic cells, and better neuronal survival.
CONCLUSIONS
T1DM aggravates CIRI. Melatonin treatment is neuroprotective against CIRI in T1DM rats via anti-inflammatory and anti-apoptotic effects.
Topics: Rats; Animals; Melatonin; Rats, Sprague-Dawley; Diabetes Mellitus, Type 1; NF-kappa B; Brain Ischemia; Cerebral Infarction; Reperfusion Injury; Hyperglycemia; Neuroprotective Agents; Infarction, Middle Cerebral Artery
PubMed: 37327371
DOI: 10.1002/brb3.3118 -
Journal of Investigative Medicine High... 2023This case report describes a novel mutation of the gene as a potential pathogenic cause of spherocytosis. A 3-week-old male presented with clinical and laboratory signs...
This case report describes a novel mutation of the gene as a potential pathogenic cause of spherocytosis. A 3-week-old male presented with clinical and laboratory signs consistent with hemolytic spherocytosis, including jaundice, hyperbilirubinemia, anemia, reticulocytosis, negative Coombs test, no ABO or Rh incompatibility, and a peripheral blood smear notable for numerous spherocytes. His laboratory work demonstrated persistent anemia despite daily folate prompting next-generation sequencing which revealed a novel mutation in the gene resulting in a nonfunctioning protein product. Correlation of the genetic finding with clinical presentation may help guide management for this and future patients.
Topics: Infant, Newborn; Humans; Male; Heterozygote; High-Throughput Nucleotide Sequencing; Hyperbilirubinemia; Mutation
PubMed: 37306287
DOI: 10.1177/23247096231180552 -
Frontiers in Molecular Neuroscience 2023Since its discovery in 1999, a substantial body of research has shown that iASPP is highly expressed in various kinds of tumors, interacts with p53, and promotes cancer...
INTRODUCTION
Since its discovery in 1999, a substantial body of research has shown that iASPP is highly expressed in various kinds of tumors, interacts with p53, and promotes cancer cell survival by antagonizing the apoptotic activity of p53. However, its role in neurodevelopment is still unknown.
METHODS
We studied the role of iASPP in neuronal differentiation through different neuronal differentiation cellular models, combined with immunohistochemistry, RNA interference and gene overexpression, and studied the molecular mechanism involved in the regulation of neuronal development by iASPP through coimmunoprecipitation coupled with mass spectrometry (CoIP-MS) and coimmunoprecipitation (CoIP).
RESULTS
In this study, we found that the expression of iASPP gradually decreased during neuronal development. iASPP silencing promotes neuronal differentiation, while its overexpression inhibited neurite differentiation in a variety of neuronal differentiation cellular models. iASPP associated with the cytoskeleton-related protein Sptan1 and dephosphorylated the serine residues in the last spectrin repeat domain of Sptan1 by recruiting PP1. The non-phosphorylated and phosphomimetic mutant form of Sptbn1 inhibited and promoted neuronal cell development respectively.
CONCLUSION
Overall, we demonstrate that iASPP suppressed neurite development by inhibiting phosphorylation of Sptbn1.
PubMed: 37284462
DOI: 10.3389/fnmol.2023.1154770 -
BMC Genomics Jun 2023Hereditary spherocytosis (HS) is a common inherited hemolytic anemia, caused by mutations in five genes that encode erythrocyte membrane skeleton proteins. The red blood...
BACKGROUND
Hereditary spherocytosis (HS) is a common inherited hemolytic anemia, caused by mutations in five genes that encode erythrocyte membrane skeleton proteins. The red blood cell (RBC) lifespan could directly reflect the degree of hemolysis. In the present cohort of 23 patients with HS, we performed next-generation sequencing (NGS) and Levitt's carbon monoxide (CO) breath test to investigate the potential genotype-degree of hemolysis correlation.
RESULTS
In the present cohort, we identified 8 ANK1,9 SPTB,5 SLC4A1 and 1 SPTA1 mutations in 23 patients with HS, and the median RBC lifespan was 14(8-48) days. The median RBC lifespan of patients with ANK1, SPTB and SLC4A1 mutations was 13 (8-23), 13 (8-48) and 14 (12-39) days, respectively, with no statistically significant difference (P = 0.618). The median RBC lifespan of patients with missense, splice and nonsense/insertion/deletion mutations was 16.5 (8-48), 14 (11-40) and 13 (8-20) days, respectively, with no significant difference (P = 0.514). Similarly, we found no significant difference in the RBC lifespan of patients with mutations located in the spectrin-binding domain and the nonspectrin-binding domain [14 (8-18) vs. 12.5 (8-48) days, P = 0.959]. In terms of the composition of mutated genes, 25% of patients with mild hemolysis carried ANK1 or SPTA1 mutations, while 75% of patients with mild hemolysis carried SPTB or SLC4A1 mutations. In contrast, 46.7% of patients with severe hemolysis had ANK1 or SPTA1 mutations and 53.3% of patients with severe hemolysis had SPTB or SLC4A1 mutations. However, there was no statistically significant difference in the distribution of mutated genes between the two groups (P = 0.400).
CONCLUSION
The present study is the first to investigate the potential association between genotype and degree of hemolysis in HS. The present findings indicated that there is no significant correlation between genotype and degree of hemolysis in HS.
Topics: Humans; Hemolysis; Ankyrins; Spectrin; Spherocytosis, Hereditary; Cytoskeletal Proteins; Membrane Proteins; Mutation; Genotype
PubMed: 37280519
DOI: 10.1186/s12864-023-09364-8