Deletion of LBR N-terminal domains recapitulates Pelger-Huet anomaly phenotypes in mouse without disrupting X chromosome inactivation.
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ABSTRACT:
SUBMITTER: Young AN
PROVIDER: S-EPMC8041748 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Pelger-Huet anomaly is usually autosomal dominant, although it is likely that new mutations are common. This condition is characterized by granulocytes that are either bilobed or completely unsegmented. Here is a report of a 46 year old Indian lady who presented with fever to the hospital and on evaluation, her peripheral blood smear showed extreme hypolobation of granulocytes. Along with normal appearing neutrophils there were many neutrophils with bilobed and single monolobated nuclei which accounted for 82 % of the neutrophils. After identifying these neutrophilic abnormalities which were suggestive of Pelgeroid changes, the other family members were also screened and were found to be having similar morphologic abnormalities in granulocytes. As these changes were evident in granulocytic leucocytes of the patient as well as her mother, both her sisters and her son, with exception of her brother, the diagnosis of familial Pelger-Huet Anomaly was considered in this case.
| S-EPMC4925487 | biostudies-literature
Project description:The principal human blood granulocyte (neutrophil) possesses a lobulated and deformable nucleus, important to facilitate rapid egress from blood vessels as these cells migrate to sites of bacterial or fungal infection. This unusual nuclear shape is a product of elevated levels of an integral membrane protein of the nuclear envelope lamin B receptor (LBR) and of decreased amounts of lamin A/C. In humans, a genetic deficiency of LBR produces Pelger-Huët anomaly, resulting in blood neutrophils that exhibit hypolobulated nuclei with redistributed heterochromatin. Structural changes in nuclear architecture occur during granulopoiesis within bone marrow. The exact mechanisms of this nuclear shape change and of heterochromatin redistribution remain largely unknown. As a tool to facilitate analysis of these mechanisms, a stable LBR knockdown subline of HL-60 cells was established. During in vitro granulopoiesis induced with retinoic acid, the LBR knockdown cells retain an ovoid shaped nucleus with reduced levels of lamin A/C; while, the parent cells develop highly lobulated nuclei. In contrast, macrophage forms induced in LBR knockdown cells by in vitro treatment with phorbol ester were indistinguishable from the parent cells, judged by both nuclear shape and attached cell morphology. The capability of differentiation of LBR knockdown HL-60 cells should facilitate a detailed analysis of the molecular relationship between LBR levels, granulocyte nuclear shape and heterochromatin distribution.
| S-EPMC3027054 | biostudies-literature
Project description:BackgroundHereditary short stature syndromes are clinically and genetically heterogeneous disorders and the cause have not been fully identified. Yakuts are a population isolated in Asia; they live in the far east of the Russian Federation and have a high prevalence of hereditary short stature syndrome including 3-M syndrome. A novel short stature syndrome in Yakuts is reported here, which is characterised by autosomal recessive inheritance, severe postnatal growth retardation, facial dysmorphism with senile face, small hands and feet, normal intelligence, Pelger-Huët anomaly of leucocytes, and optic atrophy with loss of visual acuity and colour vision. This new syndrome is designated as short stature with optic atrophy and Pelger-Huët anomaly (SOPH) syndrome.AimsTo identify a causative gene for SOPH syndrome.MethodsGenomewide homozygosity mapping was conducted in 33 patients in 30 families.ResultsThe disease locus was mapped to the 1.1 Mb region on chromosome 2p24.3, including the neuroblastoma amplified sequence (NBAS) gene. Subsequently, 33 of 34 patients were identified with SOPH syndrome and had a 5741G/A nucleotide substitution (resulting in the amino acid substitution R1914H) in the NBAS gene in the homozygous state. None of the 203 normal Yakuts individuals had this substitution in the homozygous state. Immunohistochemical analysis revealed that the NBAS protein is well expressed in retinal ganglion cells, epidermal skin cells, and leucocyte cytoplasm in controls as well as a patient with SOPH syndrome.ConclusionThese findings suggest that function of NBAS may associate with the pathogenesis of short stature syndrome as well as optic atrophy and Pelger-Huët anomaly.
| S-EPMC2921285 | biostudies-literature
Project description:The most common cytogenetic abnormality found in complex karyotype high risk MDS/AML is del5q. Disease is often identified through visual inspection and recognition of abnormalities such as pseudo-Pelger-Huet anomaly (PPHA), which presents as deviations of normal neutrophil nuclear morphology. The link between PPHA and leukemia is unknown, but mutations in the lamin B1 receptor (LBR) have been identified as the cause of benign presence in otherwise normal individuals. Lamin B1 (LMNB1) is the ligand for LBR and is important for maintaining nuclear lamina integrity and influencing 3D gene structural changes that impact transcription; the LMNB1 gene locus is also contained with chromosome 5q, so we hypothesized that appearance of PPHA is potentially caused by del5q in MDS/AML containing the LMNB1. To help characterize the potential role of LMNB1 in normal hematopoietic stem and progenitor cells (HSPCs), we infected CD34+ cord blood HSPCs with lentiviruses expressing shRNAs targeting LMNB1 (LB1) and luciferase (C11) as a control and assessed changes in transcription due to LMNB1 disruption via RNSeq and 3D genome structural changes through HiC. Neutrophils were also differentiated from LMNB1 shRNA and control treated CD34+ cord blood HSPCs and transcriptional/structural changes identified via RNAseq and HiC. Additionally, to understand long-term in vivo effects of LMNB1 loss on self-renewal and lineage bias, we engrafted control and LMNB1 shRNA infected CD34+ HSPCs into NSG mice and harvest hCD34+ cells 12 weeks later for scRNAseq.
2022-03-11 | GSE174533 | GEO
Project description:PurposeThe potential for malicious use of radiation, or radiation accidents could potentially lead to acute, high radiation doses to the public. Following acute accidental exposure to high doses of radiation, medical intervention is pivotal to the survivability of the patient, and the sooner the appropriate measures are taken the better the odds for survival. Early estimates of acute accidental radiation doses can be determined via biomarkers such as dicentric chromosome analysis or scenario reconstruction using computer software. However, both take valuable time and can be expensive. Increased frequencies of abnormal neutrophils in peripheral blood, referred to as pseudo Pelger-Huët anomalies (PPHAs), have been shown to be potential biomarkers of radiation exposure in several scenarios, including the 1958 Y-12 criticality accident and the radium dial painters. PPHAs are potentially a faster and cheaper quantitative biomarker for radiation exposure, and here they were evaluated in acutely exposed rhesus macaques.Methods and materialsPeripheral blood smears from acutely exposed rhesus macaques were evaluated for the percentage of neutrophils that displayed the PPHA morphology using light microscopy. Irradiated animals received 0 to 8.5 Gy total body radiation using one of two strategies: (1) linear accelerator-produced 6 MV photons delivered at 80 cGy/minute; or (2) Cobalt 60-produced gamma irradiation delivered at 60 cGy/min. Zero dose animals were used to determine a baseline percentage of PPHAs, and blood smears taken periodically throughout the lifetime of exposed animals post-irradiation were used to determine the persistence and biokinetics of PPHAs.ResultsThe baseline prevalence of the PPHA in rhesus macaques was determined to be 0.58 ± 0.46%. The dose-response curve with doses ranging from 0 Gy to 8.5 Gy (LD90/30) displayed a strong positive correlation between PPHA percentage and acute radiation dose (R2 of 0.88 p = 3.62 × 10-22). Statistically significant differences were found when animals were separated into dose cohorts of 0, 4, 6.4-6.5, and 8-8.5 Gy. The biokinetics model utilized only 4 Gy exposures and blood smears taken periodically over 3.1 years post-irradiation. PPHA morphology increases quickly following irradiation and appears stable over 3.1 years post-irradiation.ConclusionPPHA morphology was confirmed to be present in rhesus macaques, a dose-response relationship was constructed, and it is stable over 3 years post-irradiation. This study demonstrates that PPHA analysis can be a fast and cheap method of biodosimetry. Future studies will work to determine the accuracy of dose determination and lower limits of detection.
| S-EPMC9446855 | biostudies-literature
Project description:The lamin B receptor (LBR) is an inner nuclear membrane protein with a structural function interacting with chromatin and lamins, and an enzymatic function as a sterol reductase. Heterozygous LBR mutations cause nuclear hyposegmentation in neutrophils (Pelger anomaly), while homozygous mutations cause prenatal death with skeletal defects and abnormal sterol metabolism (Greenberg dysplasia). It has remained unclear whether the lethality in Greenberg dysplasia is due to cholesterol defects or altered nuclear morphology.To answer this question we characterized two LBR missense mutations and showed that they cause Greenberg dysplasia. Both mutations affect residues that are evolutionary conserved among sterol reductases. In contrast to wildtype LBR, both mutations failed to rescue C14 sterol reductase deficient yeast, indicating an enzymatic defect. We found no Pelger anomaly in the carrier parent excluding marked effects on nuclear structure. We studied Lbr in mouse embryos and demonstrate expression in skin and the developing skeletal system consistent with sites of histological changes in Greenberg dysplasia. Unexpectedly we found in disease-relevant cell types not only nuclear but also cytoplasmatic LBR localization. The cytoplasmatic LBR staining co-localized with ER-markers and is thus consistent with the sites of endogeneous sterol synthesis. We conclude that LBR missense mutations can abolish sterol reductase activity, causing lethal Greenberg dysplasia but not Pelger anomaly. The findings separate the metabolic from the structural function and indicate that the sterol reductase activity is essential for human intrauterine development.
| S-EPMC3027044 | biostudies-literature
Project description:Lamin B1 deletion in myeloid neoplasms alters hematopoietic cell fate and causes Pelger-Huët nuclear anomaly
| PRJNA730500 | ENA
Project description:Dystroglycan is a transmembrane glycoprotein that links the extracellular basement membrane to cytoplasmic dystrophin. Disruption of the extensive carbohydrate structure normally present on ?-dystroglycan causes an array of congenital and limb girdle muscular dystrophies known as dystroglycanopathies. The essential role of dystroglycan in development has hampered elucidation of the mechanisms underlying dystroglycanopathies. Here, we developed a dystroglycanopathy mouse model using inducible or muscle-specific promoters to conditionally disrupt fukutin (Fktn), a gene required for dystroglycan processing. In conditional Fktn-KO mice, we observed a near absence of functionally glycosylated dystroglycan within 18 days of gene deletion. Twenty-week-old KO mice showed clear dystrophic histopathology and a defect in glycosylation near the dystroglycan O-mannose phosphate, whether onset of Fktn excision driven by muscle-specific promoters occurred at E8 or E17. However, the earlier gene deletion resulted in more severe phenotypes, with a faster onset of damage and weakness, reduced weight and viability, and regenerating fibers of smaller size. The dependence of phenotype severity on the developmental timing of muscle Fktn deletion supports a role for dystroglycan in muscle development or differentiation. Moreover, given that this conditional Fktn-KO mouse allows the generation of tissue- and timing-specific defects in dystroglycan glycosylation, avoids embryonic lethality, and produces a phenotype resembling patient pathology, it is a promising new model for the study of secondary dystroglycanopathy.
| S-EPMC3428090 | biostudies-other
Project description:BackgroundEbstein anomaly (EA) is a heterogeneous congenital heart defect (CHD), frequently accompanied by diverse cardiac and extracardiac comorbidities, resulting in a wide range of clinical outcomes.HypothesisPhenotypic characterization of EA patients has the potential to identify variables that influence prognosis and subgroups with distinct contributing factors.MethodsA comprehensive cross-sectional phenotypic characterization of 147 EA patients from one of the main referral institutions for CHD in Colombia was carried out. The most prevalent comorbidities and distinct subgroups within the patient cohort were identified through cluster analysis.ResultsThe most prevalent cardiac comorbidities identified were atrial septal defect (61%), Wolff-Parkinson-White syndrome (WPW; 27%), and right ventricular outflow tract obstruction (25%). Cluster analysis showed that patients can be classified into 2 distinct subgroups with defined phenotypes that determine disease severity and survival. Patients in cluster 1 represented a particularly homogeneous subgroup with a milder spectrum of disease, including only patients with WPW and/or supraventricular tachycardia (SVT). Cluster 2 included patients with more diverse cardiovascular comorbidities.ConclusionsThis study represents one of the largest phenotypic characterizations of EA patients reported. The data show that EA is a heterogeneous disease, very frequently associated with cardiovascular and noncardiovascular comorbidities. Patients with WPW and SVT represent a homogeneous subgroup that presents with a less severe spectrum of disease and better survival when adequately managed. This should be considered when searching for genetic causes of EA and in the clinical setting.
| S-EPMC6489938 | biostudies-literature
Project description:Idiopathic primary hyperaldosteronism (IHA) and low-renin essential hypertension (LREH) are common forms of hypertension, characterized by an elevated aldosterone-renin ratio and hypersensitivity to angiotensin II. They are suggested to be 2 states within a disease spectrum that progresses from LREH to IHA as the control of aldosterone production by the renin-angiotensin system is weakened. The mechanism(s) that drives this progression remains unknown. Deletion of Twik-related acid-sensitive K(+) channels (TASK) subunits, TASK-1 and TASK-3, in mice (T1T3KO) produces a model of human IHA. Here, we determine the effect of deleting only TASK-3 (T3KO) on the control of aldosterone production and blood pressure. We find that T3KO mice recapitulate key characteristics of human LREH, salt-sensitive hypertension, mild overproduction of aldosterone, decreased plasma-renin concentration with elevated aldosterone:renin ratio, hypersensitivity to endogenous and exogenous angiotensin II, and failure to suppress aldosterone production with dietary sodium loading. The relative differences in levels of aldosterone output and aldosterone:renin ratio and in autonomy of aldosterone production between T1T3KO and T3KO mice are reminiscent of differences in human hypertensive patients with LREH and IHA. Our studies establish a model of LREH and suggest that loss of TASK channel activity may be one mechanism that advances the syndrome of low renin hypertension.
| S-EPMC3357084 | biostudies-literature