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Frontiers in Genetics 2023Pathogenic genetic variants represent a challenge in prenatal counseling, especially when clinical presentation in familial carriers is atypical. We describe a prenatal...
Pathogenic genetic variants represent a challenge in prenatal counseling, especially when clinical presentation in familial carriers is atypical. We describe a prenatal case involving a microarray-detected duplication of which causes X-linked Pelizaeus-Merzbacher disease, a progressive hypomyelinating leukodystrophy. Because of atypical clinical presentation in an older male child, the duplication was examined using a novel technology, optical genome mapping, and was found to be an inverted duplication, which has not been previously described. Simultaneously, segregation analysis identified another healthy adult male carrier of this unique structural rearrangement. The novel structural variant was reclassified, and a healthy boy was delivered. In conclusion, we suggest that examining structural variants with novel methods is warranted especially in cases with atypical clinical presentation and may in these cases lead to improved prenatal and postnatal genetic counseling.
PubMed: 37560384
DOI: 10.3389/fgene.2023.1173426 -
Journal of Photochemistry and... Sep 2023In plants, the major light-harvesting antenna complex (LHCII) is vital for both light harvesting and photoprotection in photosystem II. Previously, we proposed that the...
In plants, the major light-harvesting antenna complex (LHCII) is vital for both light harvesting and photoprotection in photosystem II. Previously, we proposed that the thylakoid membrane itself could switch LHCII into the photoprotective state, qE, via a process known as hydrophobic mismatch. The decrease in the membrane thickness that followed the formation of ΔpH was a key fact that prompted this idea. To test this, we made proteoliposomes from lipids with altered acyl chain length (ACL). Here, we show that ACL regulates the average chlorophyll fluorescence lifetime of LHCII. For liposomes made of lipids with an ACL of 18 carbons, the lifetime was ∼2 ns, like that for the thylakoid membrane. Furthermore, LHCII appears to be quenched in proteoliposomes with an ACL both shorter and longer than 18 carbons. The proteoliposomes made of short ACL lipids display structural heterogeneity revealing two quenched conformations of LHCII, each having characteristic 77 K fluorescence spectra. One conformation spectrally resembles isolated LHCII aggregates, whilst the other resembles LHCII immobilized in polyacrylamide gels. Overall, the decrease in the ACL appears to produce quenched conformations of LHCII, which renders plausible the idea that the trigger of qE is the hydrophobic mismatch.
Topics: Light-Harvesting Protein Complexes; Thylakoids; Photosystem II Protein Complex; Proteolipids; Chlorophyll
PubMed: 37531665
DOI: 10.1016/j.jphotobiol.2023.112758 -
Blood Research Sep 2023Epigenetic studies, particularly research on microRNA (miRNA), have flourished. The abnormal expression of miRNA contributes to the development of hematologic...
BACKGROUND
Epigenetic studies, particularly research on microRNA (miRNA), have flourished. The abnormal expression of miRNA contributes to the development of hematologic malignancies. miR-765 has been reported to inhibit cell proliferation by downregulating proteolipid protein 2 (PLP2), which causes apoptosis. We investigated miR-765 dysregulation in myelodysplastic syndromes (MDS).
METHODS
We compared the expression profiles of miR-765 in 65 patients with MDS and 11 controls. Cell proliferation and apoptosis assays were performed to determine the effects of miR-765 on leukemia cells transfected with the miR-765 mimic. Reverse transcription quantitative PCR (RT-qPCR) and western blotting were performed to examine the targets of miR-765.
RESULTS
We found that miR-765 levels were upregulated 10.2-fold in patients with MDS compared to controls. In refractory cytopenia with multilineage dysplasia, the percentage of patients with elevated miR-765 levels was significantly higher than in other forms of MDS. Experiments with leukemia cells revealed that transfection with a miR-765 mimic inhibited cell proliferation and induced apoptosis. RT-qPCR and western blotting demonstrated that the target of miR-765 was PLP2.
CONCLUSION
These findings imply that upregulation of miR-765 induces apoptosis via downregulation of PLP2 and may have a role in MDS pathogenesis.
PubMed: 37495419
DOI: 10.5045/br.2023.2023097 -
Annals of Clinical and Translational... Sep 2023Hereditary spastic paraplegia (HSP) is a genetically heterogeneous disease caused by over 70 genes, with a significant number of patients still genetically unsolved. In...
OBJECTIVES
Hereditary spastic paraplegia (HSP) is a genetically heterogeneous disease caused by over 70 genes, with a significant number of patients still genetically unsolved. In this study, we recruited a suspected HSP family characterized by spasticity, developmental delay, ataxia and hypomyelination, and intended to reveal its molecular etiology by whole exome sequencing (WES) and long-read sequencing (LRS) analyses.
METHODS
WES was performed on 13 individuals of the family to identify the causative mutations, including analyses of SNVs (single-nucleotide variants) and CNVs (copy number variants). Accurate circular consensus (CCS) long-read sequencing (LRS) was used to verify the findings of CNV analysis from WES.
RESULTS
SNVs analysis identified a missense variant c.195G>T (p.E65D) of MORF4L2 at Xq22.2 co-segregating in this family from WES data. Further CNVs analysis revealed a microdeletion, which was adjacent to the MORF4L2 gene, also co-segregating in this family. LRS verified this microdeletion and confirmed the deletion range (chrX: 103,690,507-103,715,018, hg38) with high resolution at nucleotide level accuracy.
INTERPRETATIONS
In this study, we identified an Xq22.2 microdeletion (about 24.5 kb), which contains distal enhancers of the PLP1 gene, as a likely cause of SPG2 in this family. The lack of distal enhancers may result in transcriptional repression of PLP1 in oligodendrocytes, potentially affecting its role in the maintenance of myelin, and causing SPG2 phenotype. This study has highlighted the importance of noncoding genomic alterations in the genetic etiology of SPG2.
Topics: Humans; Spastic Paraplegia, Hereditary; Myelin Proteolipid Protein; Mutation; Mutation, Missense; Phenotype; Transcription Factors
PubMed: 37475517
DOI: 10.1002/acn3.51848 -
Neurotrauma Reports 2023Myelin loss and oligodendrocyte death are well documented in patients with traumatic brain injury (TBI), as well as in experimental animal models after...
Myelin loss and oligodendrocyte death are well documented in patients with traumatic brain injury (TBI), as well as in experimental animal models after moderate-to-severe TBI. In comparison, mild TBI (mTBI) does not necessarily result in myelin loss or oligodendrocyte death, but causes structural alterations in the myelin. To gain more insight into the impact of mTBI on oligodendrocyte lineage in the adult brain, we subjected mice to mild lateral fluid percussion injury (mFPI) and characterized the early impact (1 and 3 days post-injury) on oligodendrocytes in the corpus callosum using multiple oligodendrocyte lineage markers (platelet-derived growth factor receptor [PDGFR]-α, glutathione -transferase [GST]-π, CC1, breast carcinoma-amplified sequence 1 [BCAS1], myelin basic protein [MBP], myelin-associated glycoprotein [MAG], proteolipid protein [PLP], and FluoroMyelin™). Two regions of the corpus callosum in relation to the impact site were analyzed: areas near (focal) and anterior (distal) to the impact site. mFPI did not result in oligodendrocyte death in either the focal or distal corpus callosum, nor impact on oligodendrocyte precursors (PDGFR-α) and GST-π oligodendrocyte numbers. In the focal but not distal corpus callosum, mFPI caused a decrease in CC1 as well as BCAS1 actively myelinating oligodendrocytes and reduced FluoroMyelin intensity without altering myelin protein expression (MBP, PLP, and MAG). Disruption in node-paranode organization and loss of Nav1.6 nodes were observed in both the focal and distal regions, even in areas without obvious axonal damage. Altogether, our study shows regional differences in mature and myelinating oligodendrocyte in response to mFPI. Further, mFPI elicits a widespread impact on node-paranode organization that affects regions both close to and remotely located from the site of injury.
PubMed: 37435356
DOI: 10.1089/neur.2023.0037 -
Integrative and Comparative Biology Dec 2023Albuminous seeds, dispersed with a minimally developed embryo surrounded by nutrient storage tissue, are pervasive across extinct and extant early diverging angiosperm...
Albuminous seeds, dispersed with a minimally developed embryo surrounded by nutrient storage tissue, are pervasive across extinct and extant early diverging angiosperm lineages. Typically, seed ontogenic studies have focused on the time between fertilization and seed release, but in albuminous seeds, embryogenesis is incomplete at the time of seed dispersal. Here, I studied the morphological and nutritional relationships between the embryo and the endosperm after seed dispersal in Illicium parviflorum (Austrobaileyales). Seeds of I. parviflorum germinate over a period of three months. Different stages during the germination process were anatomically evaluated using a combination of histochemistry and immunocytochemistry. At dispersal, the seeds of Illicium contain a tiny achlorophyllous embryo with minimal histological differentiation, surrounded by copious amounts of lipo-protein globules stored in the endosperm within cell walls rich in un-esterified pectins. Six weeks later, the embryo expanded and differentiated the vascular tissues before the emergence of the radicle through the seed coat, as the stored lipids and proteins coalesced within cells. Six weeks later, the cotyledons contained starch and complex lipids intracellularly, and accumulated low-esterified pectins in their cell walls. The proteolipid-rich albuminous seeds of Illicium exemplify how woody angiosperms of the Austrobaileyales, Amborellales, and many magnoliids release seeds with high-energy storage compounds that are reprocessed by embryos that complete development during germination. Seedlings of these lineages thrive in the understory of tropical environments, which match with the predicted habitats where angiosperms evolved.
Topics: Animals; Seeds; Germination; Illicium; Magnoliopsida; Human Migration; Pectins; Embryonic Development; Lipids
PubMed: 37349968
DOI: 10.1093/icb/icad078 -
MBio Aug 2023Magnetosomes of magnetotactic bacteria (MTB) consist of structurally perfect, nano-sized magnetic crystals enclosed within vesicles of a proteo-lipid membrane. In...
Magnetosomes of magnetotactic bacteria (MTB) consist of structurally perfect, nano-sized magnetic crystals enclosed within vesicles of a proteo-lipid membrane. In species of biosynthesis of their cubo-octahedral-shaped magnetosomes was recently demonstrated to be a complex process, governed by about 30 specific genes that are comprised within compact magnetosome gene clusters (MGCs). Similar, yet distinct gene clusters were also identified in diverse MTB that biomineralize magnetosome crystals with different, genetically encoded morphologies. However, since most representatives of these groups are inaccessible by genetic and biochemical approaches, their analysis will require the functional expression of magnetosome genes in foreign hosts. Here, we studied whether conserved essential magnetosome genes from closely and remotely related MTB can be functionally expressed by rescue of their respective mutants in the tractable model of the . Upon chromosomal integration, single orthologues from other magnetotactic restored magnetosome biosynthesis to different degrees, while orthologues from distantly related and were found to be expressed but failed to re-induce magnetosome biosynthesis, possibly due to poor interaction with their cognate partners within multiprotein magnetosome organelle of the host. Indeed, co-expression of the known interactors MamB and MamM from the alphaproteobacterium increased functional complementation. Furthermore, a compact and portable version of the entire MGCs of was assembled by transformation-associated recombination cloning, and it restored the ability to biomineralize magnetite both in deletion mutants of the native donor and , while co-expression of gene clusters from both and resulted in overproduction of magnetosomes. IMPORTANCE We provide proof of principle that is a suitable surrogate host for the functional expression of foreign magnetosome genes and extended the transformation-associated recombination cloning platform for the assembly of entire large magnetosome gene cluster, which could then be transplanted to different magnetotactic bacteria. The reconstruction, transfer, and analysis of gene sets or entire magnetosome clusters will be also promising for engineering the biomineralization of magnetite crystals with different morphologies that would be valuable for biotechnical applications.
PubMed: 37318230
DOI: 10.1128/mbio.03282-22 -
Frontiers in Cellular Neuroscience 2023Recently, the myelin proteolipid protein gene () was shown to be expressed in the glia of the enteric nervous system (ENS) in mouse. However, beyond this, not much is...
Recently, the myelin proteolipid protein gene () was shown to be expressed in the glia of the enteric nervous system (ENS) in mouse. However, beyond this, not much is known about its expression in the intestine. To address this matter, we investigated expression at the mRNA and protein levels in the intestine of mice at different ages (postnatal days 2, 9, 21, and 88). In this study, we show that expression preferentially occurs during early postnatal development, primarily as the DM20 isoform. Western blot analysis indicated that DM20 migrated according to its formula weight when isolated from the intestine. However, mobilities of both PLP and DM20 were faster than expected when procured from the brain. The 6.2hPLP(+)Z/FL transgene, which uses the first half of the human gene to drive expression of a reporter gene, recapitulated the developmental pattern observed with the native gene in the intestine, indicating that it can be used as a proxy for gene expression. As such, the relative levels of β-galactosidase (β-gal) activity emanating from the 6.2hPLP(+)Z/FL transgene suggest that expression is highest in the duodenum, and decreases successively along the segments, toward the colon. Moreover, removal of the wmN1 enhancer region from the transgene (located within intron 1) resulted in a dramatic reduction in both transgene mRNA levels and β-gal activity in the intestine, throughout development, suggesting that this region contains a regulatory element crucial for expression. This is consistent with earlier studies in both the central and peripheral nervous systems, indicating that it may be a common (if not universal) means by which gene expression is governed.
PubMed: 37293625
DOI: 10.3389/fncel.2023.1175614 -
ELife May 2023The consequences of aneuploidy have traditionally been studied in cell and animal models in which the extrachromosomal DNA is from the same species. Here, we explore a...
The consequences of aneuploidy have traditionally been studied in cell and animal models in which the extrachromosomal DNA is from the same species. Here, we explore a fundamental question concerning the impact of aneuploidy on systemic metabolism using a non-mosaic transchromosomic mouse model (TcMAC21) carrying a near-complete human chromosome 21. Independent of diets and housing temperatures, TcMAC21 mice consume more calories, are hyperactive and hypermetabolic, remain consistently lean and profoundly insulin sensitive, and have a higher body temperature. The hypermetabolism and elevated thermogenesis are likely due to a combination of increased activity level and sarcolipin overexpression in the skeletal muscle, resulting in futile sarco(endo)plasmic reticulum Ca ATPase (SERCA) activity and energy dissipation. Mitochondrial respiration is also markedly increased in skeletal muscle to meet the high ATP demand created by the futile cycle and hyperactivity. This serendipitous discovery provides proof-of-concept that sarcolipin-mediated thermogenesis via uncoupling of the SERCA pump can be harnessed to promote energy expenditure and metabolic health.
Topics: Mice; Humans; Animals; Muscle, Skeletal; Thermogenesis; Energy Metabolism; Proteolipids; Cytoplasm; Chromosomes, Human; Calcium
PubMed: 37249575
DOI: 10.7554/eLife.86023