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Molecular Biology of the Cell Aug 2022Bidirectional protein trafficking within cilia is mediated by the intraflagellar transport (IFT) machinery, which contains the IFT-A and IFT-B complexes powered by the...
Bidirectional protein trafficking within cilia is mediated by the intraflagellar transport (IFT) machinery, which contains the IFT-A and IFT-B complexes powered by the kinesin-2 and dynein-2 motors. Mutations in genes encoding subunits of the IFT-A and dynein-2 complexes cause skeletal ciliopathies. Some subunits of the IFT-B complex, including IFT52, IFT80, and IFT172, are also mutated in skeletal ciliopathies. We here show that IFT52 variants found in individuals with short-rib polydactyly syndrome (SRPS) are compromised in terms of formation of the IFT-B holocomplex from two subcomplexes and its interaction with heterotrimeric kinesin-II. -knockout (KO) cells expressing IFT52 variants that mimic the cellular conditions of individuals with SRPS demonstrated mild ciliogenesis defects and a decrease in ciliary IFT-B level. Furthermore, in -KO cells expressing an SRPS variant of IFT52, ciliary tip localization of ICK/CILK1 and KIF17, both of which are likely to be transported to the tip via binding to the IFT-B complex, was significantly impaired. Altogether these results indicate that impaired anterograde trafficking caused by a decrease in the ciliary level of IFT-B or in its binding to kinesin-II underlies the ciliary defects found in skeletal ciliopathies caused by IFT52 variations.
Topics: Adaptor Proteins, Signal Transducing; Cilia; Ciliopathies; Cytoskeletal Proteins; Dyneins; Flagella; Humans; Mutation; Protein Transport
PubMed: 35704471
DOI: 10.1091/mbc.E22-05-0188 -
Disease Models & Mechanisms Jun 2022Heterozygous mutations in SNRPB, an essential core component of the five small ribonucleoprotein particles of the spliceosome, are responsible for cerebrocostomandibular...
Heterozygous mutations in SNRPB, an essential core component of the five small ribonucleoprotein particles of the spliceosome, are responsible for cerebrocostomandibular syndrome (CCMS). We show that Snrpb heterozygous mouse embryos arrest shortly after implantation. Additionally, heterozygous deletion of Snrpb in the developing brain and neural crest cells models craniofacial malformations found in CCMS, and results in death shortly after birth. RNAseq analysis of mutant heads prior to morphological defects revealed increased exon skipping and intron retention in association with increased 5' splice site strength. We found increased exon skipping in negative regulators of the P53 pathway, along with increased levels of nuclear P53 and P53 target genes. However, removing Trp53 in Snrpb heterozygous mutant neural crest cells did not completely rescue craniofacial development. We also found a small but significant increase in exon skipping of several transcripts required for head and midface development, including Smad2 and Rere. Furthermore, mutant embryos exhibited ectopic or missing expression of Fgf8 and Shh, which are required to coordinate face and brain development. Thus, we propose that mis-splicing of transcripts that regulate P53 activity and craniofacial-specific genes contributes to craniofacial malformations. This article has an associated First Person interview with the first author of the paper.
Topics: Animals; Craniofacial Abnormalities; Humans; Intellectual Disability; Mice; Micrognathism; Morphogenesis; Neural Crest; Ribs; Tumor Suppressor Protein p53; snRNP Core Proteins
PubMed: 35593225
DOI: 10.1242/dmm.049544 -
Frontiers in Molecular Neuroscience 2022[This corrects the article DOI: 10.3389/fnmol.2021.757646.].
[This corrects the article DOI: 10.3389/fnmol.2021.757646.].
PubMed: 35571366
DOI: 10.3389/fnmol.2022.871557 -
American Journal of Human Genetics May 2022We report an autosomal recessive, multi-organ tumor predisposition syndrome, caused by bi-allelic loss-of-function germline variants in the base excision repair (BER)...
We report an autosomal recessive, multi-organ tumor predisposition syndrome, caused by bi-allelic loss-of-function germline variants in the base excision repair (BER) gene MBD4. We identified five individuals with bi-allelic MBD4 variants within four families and these individuals had a personal and/or family history of adenomatous colorectal polyposis, acute myeloid leukemia, and uveal melanoma. MBD4 encodes a glycosylase involved in repair of G:T mismatches resulting from deamination of 5'-methylcytosine. The colorectal adenomas from MBD4-deficient individuals showed a mutator phenotype attributable to mutational signature SBS1, consistent with the function of MBD4. MBD4-deficient polyps harbored somatic mutations in similar driver genes to sporadic colorectal tumors, although AMER1 mutations were more common and KRAS mutations less frequent. Our findings expand the role of BER deficiencies in tumor predisposition. Inclusion of MBD4 in genetic testing for polyposis and multi-tumor phenotypes is warranted to improve disease management.
Topics: Adenomatous Polyposis Coli; Colorectal Neoplasms; Endodeoxyribonucleases; Genetic Predisposition to Disease; Germ Cells; Germ-Line Mutation; Humans; Uveal Neoplasms
PubMed: 35460607
DOI: 10.1016/j.ajhg.2022.03.018 -
BMC Medical Genomics Mar 2022Short-rib thoracic dysplasia 3 with or without polydactyly (SRTD3, OMIM: 613091) is an autosomal recessive disorder. SRTD3 presents clinically with a narrow thorax,...
BACKGROUND
Short-rib thoracic dysplasia 3 with or without polydactyly (SRTD3, OMIM: 613091) is an autosomal recessive disorder. SRTD3 presents clinically with a narrow thorax, short ribs, shortened tubular bones, and acetabular roof abnormalities. Clinical signs of SRTD3 vary among individuals. Pathogenic variants of DYNC2H1 (OMIM: 603297) have been reported to cause SRTD3.
METHODS
We performed a detailed clinical prenatal sonographic characterization of a foetus with SRTD3. Trio whole-exome sequencing was used to identify causative variants in the family. The identified variants in the families were validated by Sanger sequencing and mass spectrometry. Multiple computational tools were used to predict the harmfulness of the two variants. A minigene splicing assay was carried out to evaluate the impact of the splice-site variant.
RESULTS
We evaluated prenatal sonographic images of the foetus with SRTD3, including abnormal rib curvature, narrow thorax, bilateral hypoplastic lungs, bilateral polydactyly, syndactyly, and foetal visceral situs inversus with mirror-image dextrocardia. We revealed novel compound variants of DYNC2H1 (NM_001377.3:c.11483T > G (p.Ile3828Arg) and c.2106 + 3A > T). Various statistical methods predicted that the variants would cause harmful effects on genes or gene products. The minigene assay findings suggested that c.2106 + 3A > T caused the skipping over exon 14, producing an exon 14 loss in the protein.
CONCLUSION
This study identified a foetus with SRTD3 with situs inversus totalis with mirror-image dextrocardia in a Chinese family, revealing two novel compound heterozygous dynein cytoplasmic 2 heavy chain 1 (DYNC2H1) variants, expanding the phenotypic spectrum of SRTD3. The minigene study of c.2106 + 3A > T was predicted to cause an inframe exclusion of exon 14, which was predicted to have important molecular functions. Our findings strongly supported the use of WES in prenatal diagnosis and helped to understand the correlation of genotype and phenotypes of DYNC2H1. The specific sonographic findings and the molecular diagnosis helped add experience to further our expertise in prenatal counselling for SRTD3.
Topics: Cytoplasmic Dyneins; Dextrocardia; Female; Fetus; Humans; Polydactyly; Pregnancy; Short Rib-Polydactyly Syndrome; Situs Inversus
PubMed: 35277174
DOI: 10.1186/s12920-022-01205-z -
Frontiers in Molecular Neuroscience 2021TALPID3/KIAA0586 is an evolutionary conserved protein, which plays an essential role in protein trafficking. Its role during gastrointestinal (GI) and enteric nervous...
TALPID3/KIAA0586 is an evolutionary conserved protein, which plays an essential role in protein trafficking. Its role during gastrointestinal (GI) and enteric nervous system (ENS) development has not been studied previously. Here, we analyzed chicken, mouse and human embryonic GI tissues with TALPID3 mutations. The GI tract of TALPID3 chicken embryos was shortened and malformed. Histologically, the gut smooth muscle was mispatterned and enteric neural crest cells were scattered throughout the gut wall. Analysis of the Hedgehog pathway and gut extracellular matrix provided causative reasons for these defects. Interestingly, chicken intra-species grafting experiments and a conditional knockout mouse model showed that ENS formation did not require TALPID3, but was dependent on correct environmental cues. Surprisingly, the lack of TALPID3 in enteric neural crest cells (ENCC) affected smooth muscle and epithelial development in a non-cell-autonomous manner. Analysis of human gut fetal tissues with a mutation showed strikingly similar findings compared to the animal models demonstrating conservation of TALPID3 and its necessary role in human GI tract development and patterning.
PubMed: 35002618
DOI: 10.3389/fnmol.2021.757646 -
The American Journal of Pathology Feb 2022To catalyze severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) research, including development of novel interventive and preventive strategies, the progression...
To catalyze severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) research, including development of novel interventive and preventive strategies, the progression of disease was characterized in a robust coronavirus disease 2019 (COVID-19) animal model. In this model, male and female golden Syrian hamsters were inoculated intranasally with SARS-CoV-2 USA-WA1/2020. Groups of inoculated and mock-inoculated uninfected control animals were euthanized at 2, 4, 7, 14, and 28 days after inoculation to track multiple clinical, pathology, virology, and immunology outcomes. SARS-CoV-2-inoculated animals consistently lost body weight during the first week of infection, had higher lung weights at terminal time points, and developed lung consolidation per histopathology and quantitative image analysis measurements. High levels of infectious virus and viral RNA were reliably present in the respiratory tract at days 2 and 4 after inoculation, corresponding with widespread necrosis and inflammation. At day 7, when the presence of infectious virus was rare, interstitial and alveolar macrophage infiltrates and marked reparative epithelial responses (type II hyperplasia) dominated in the lung. These lesions resolved over time, with only residual epithelial repair evident by day 28 after inoculation. The use of quantitative approaches to measure cellular and morphologic alterations in the lung provides valuable outcome measures for developing therapeutic and preventive interventions for COVID-19 using the hamster COVID-19 model.
Topics: Animals; COVID-19; Cricetinae; Disease Models, Animal; Female; Lung; Male; Mesocricetus; SARS-CoV-2
PubMed: 34767812
DOI: 10.1016/j.ajpath.2021.10.009 -
Journal of Medical Case Reports Nov 2021Over-the-counter medication overdose is a difficult diagnostic challenge for many physicians as common drug screening assays cannot detect these substances. We present a...
BACKGROUND
Over-the-counter medication overdose is a difficult diagnostic challenge for many physicians as common drug screening assays cannot detect these substances. We present a case of acute psychosis, serotonin syndrome, and anticholinergic overdose-like properties in the setting of Coricidin HBP Cough & Cold tablets, known by their street name Triple-C. This is the first case report we are aware of involving a patient presenting with these symptoms and requiring critical-care-level support.
CASE PRESENTATION
A 31-year-old African American female with a past medical history of anxiety, childhood asthma, previous methamphetamine abuse, and coronavirus disease 2019 infection in August 2020 was brought to the emergency department by the local police department with altered mental status. Initial blood work, including extended drug screens, were unremarkable for a definitive diagnosis. This patient required critical-care-level support and high sedation because of her symptoms. Collateral history revealed the patient regularly consumed Triple-C daily for the 6 weeks prior to admission. A trial off sedation was attempted after 24 hours with no complications. The patient admitted to regular Triple-C consumption and auditory hallucinations since adolescence. She was discharged safely after 48 hours back into the community. She was lost to follow-up with psychiatry and internal medicine; however, she was evaluated in the emergency room 1 month later with a similar psychiatric presentation.
CONCLUSION
Overdose of Triple-C should be kept in the differential diagnosis of patients presenting with a triad of psychosis, serotonin syndrome, and anticholinergic overdose, in the setting of unknown substance ingestion.
Topics: Adolescent; Adult; COVID-19; Child; Drug Overdose; Female; Humans; Psychotic Disorders; SARS-CoV-2; Serotonin Syndrome
PubMed: 34732250
DOI: 10.1186/s13256-021-03163-z -
International Journal of Molecular... Sep 2021The Hedgehog (HH) signalling pathway is one of the major pathways controlling cell differentiation and proliferation during human development. This pathway is complex,... (Review)
Review
The Hedgehog (HH) signalling pathway is one of the major pathways controlling cell differentiation and proliferation during human development. This pathway is complex, with HH function influenced by inhibitors, promotors, interactions with other signalling pathways, and non-genetic and cellular factors. Many aspects of this pathway are not yet clarified. The main features of Sonic Hedgehog (SHH) signalling are discussed in relation to its function in human development. The possible role of SHH will be considered using examples of holoprosencephaly and short-rib polydactyly (SRP) syndromes. In these syndromes, there is wide variability in phenotype even with the same genetic mutation, so that other factors must influence the outcome. mutations were the first identified genetic causes of holoprosencephaly, but many other genes and environmental factors can cause malformations in the holoprosencephaly spectrum. Many patients with SRP have genetic defects affecting primary cilia, structures found on most mammalian cells which are thought to be necessary for canonical HH signal transduction. Although SHH signalling is affected in both these genetic conditions, there is little overlap in phenotype. Possible explanations will be canvassed, using data from published human and animal studies. Implications for the understanding of SHH signalling in humans will be discussed.
Topics: Animals; Cilia; Ciliopathies; Hedgehog Proteins; Holoprosencephaly; Humans; Short Rib-Polydactyly Syndrome; Signal Transduction
PubMed: 34576017
DOI: 10.3390/ijms22189854 -
Proceedings of the National Academy of... Sep 2021Skeletal ciliopathies (e.g., Jeune syndrome, short rib polydactyly syndrome, and Sensenbrenner syndrome) are frequently associated with nephronophthisis-like cystic...
Skeletal ciliopathies (e.g., Jeune syndrome, short rib polydactyly syndrome, and Sensenbrenner syndrome) are frequently associated with nephronophthisis-like cystic kidney disease and other organ manifestations. Despite recent progress in genetic mapping of causative loci, a common molecular mechanism of cartilage defects and cystic kidneys has remained elusive. Targeting two ciliary chondrodysplasia loci ( and ) by CRISPR/Cas9 mutagenesis, we established models for skeletal ciliopathies in Froglets exhibited severe limb deformities, polydactyly, and cystic kidneys, closely matching the phenotype of affected patients. A data mining-based in silico screen found to be related to known skeletal ciliopathy genes. CRISPR/Cas9 targeting replicated limb malformations and renal cysts identical to the models of established disease genes. Loss of Ttc30a impaired embryonic renal excretion and ciliogenesis because of altered posttranslational tubulin acetylation, glycylation, and defective axoneme compartmentalization. transcripts are enriched in chondrocytes and osteocytes of single-cell RNA-sequenced embryonic mouse limbs. We identify TTC30A/B as an essential node in the network of ciliary chondrodysplasia and nephronophthisis-like disease proteins and suggest that tubulin modifications and cilia segmentation contribute to skeletal and renal ciliopathy manifestations of ciliopathies in a cell type-specific manner. These findings have implications for potential therapeutic strategies.
Topics: Animals; Bone and Bones; Ciliopathies; Craniosynostoses; Cytoskeletal Proteins; Disease Models, Animal; Ectodermal Dysplasia; Embryo, Nonmammalian; Musculoskeletal Abnormalities; Phenotype; Polycystic Kidney Diseases; Tubulin; Xenopus laevis
PubMed: 34548398
DOI: 10.1073/pnas.2106770118