Congenital anemia reveals distinct targeting mechanisms for master transcription factor GATA1.

Master regulators, such as the hematopoietic transcription factor (TF) GATA1, play an essential role in orchestrating lineage commitment and differentiation. However, the precise mechanisms by which such TFs regulate transcription through interactions with specific cis-regulatory elements remain incompletely understood. Here, we describe a form of congenital hemolytic anemia caused by missense mutations in an intrinsically disordered region of GATA1, with a poorly understood role in transcriptional regulation. Through integrative functional approaches, we demonstrate that these mutations perturb GATA1 transcriptional activity by partially impairing nuclear localization and selectively altering precise chromatin occupancy by GATA1. These alterations in chromatin occupancy and concordant chromatin accessibility changes alter faithful gene expression, with failure to both effectively silence and activate select genes necessary for effective terminal red cell production. We demonstrate how disease-causing mutations can reveal regulatory mechanisms that enable the faithful genomic targeting of master TFs during cellular differentiation.

A Novel α-Spectrin Pathogenic Variant in Trans to α-Spectrin LELY Causing Neonatal Jaundice With Hemolytic Anemia From Hereditary Pyropoikilocytosis Coexisting With Gilbert Syndrome.

Hereditary pyropoikilocytosis is a subtype of hereditary elliptocytosis because of biallelic mutations of SPTA1, SPTB, and EPB41. The authors present a proband with neonatal jaundice and hemolytic anemia, with poikilocytosis in the blood film. Targeted next-generation sequencing identified Q267del trans to the αLELY allele in SPTA1. In addition, the proband presented coexisting Gilbert syndrome as determined by homozygous mutation of UGT1A1. Investigation of 13 relatives and his sibling revealed that only his sibling showed the same phenotype and genotype as the proband. This is the first report of molecular confirmation of coexisting hereditary pyropoikilocytosis and Gilbert syndrome and a novel mutation in SPTA1.

KLF1 mutation E325K induces cell cycle arrest in erythroid cells differentiated from congenital dyserythropoietic anemia patient-specific induced pluripotent stem cells.

Krüppel-like factor 1 (KLF1), a transcription factor controlling definitive erythropoiesis, is involved in sequential control of terminal cell division and enucleation via fine regulation of key cell cycle regulator gene expression in erythroid lineage cells. Type IV congenital dyserythropoietic anemia (CDA) is caused by a monoallelic mutation at the second zinc finger of KLF1 (c.973G>A, p.E325K). We recently diagnosed a female patient with type IV CDA with the identical missense mutation. To understand the mechanism underlying the dyserythropoiesis caused by the mutation, we generated induced pluripotent stem cells (iPSCs) from the CDA patient (CDA-iPSCs). The erythroid cells that differentiated from CDA-iPSCs (CDA-erythroid cells) displayed multinucleated morphology, absence of CD44, and dysregulation of the KLF1 target gene expression. In addition, uptake of bromodeoxyuridine by CDA-erythroid cells was significantly decreased at the CD235a+/CD71+ stage, and microarray analysis revealed that cell cycle regulator genes were dysregulated, with increased expression of negative regulators such as CDKN2C and CDKN2A. Furthermore, inducible expression of the KLF1 E325K, but not the wild-type KLF1, caused a cell cycle arrest at the G1 phase in CDA-erythroid cells. Microarray analysis of CDA-erythroid cells and real-time polymerase chain reaction analysis of the KLF1 E325K inducible expression system also revealed altered expression of several KLF1 target genes including erythrocyte membrane protein band 4.1 (EPB41), EPB42, glutathione disulfide reductase (GSR), glucose phosphate isomerase (GPI), and ATPase phospholipid transporting 8A1 (ATP8A1). Our data indicate that the E325K mutation in KLF1 is associated with disruption of transcriptional control of cell cycle regulators in association with erythroid membrane or enzyme abnormalities, leading to dyserythropoiesis.

Erythrocyte glutathione is a novel biomarker of Diamond-Blackfan anemia.

Diamond-Blackfan anemia (DBA) is a congenital red cell aplasia with mutations in ribosomal protein (RP) genes. Elevated activity of erythrocyte adenosine deaminase (eADA) has been utilized as a biomarker of DBA. We examined erythrocyte reduced glutathione (GSH) as well as eADA in 22 patients in 18 DBA families, in whom RP gene mutations had been identified. Simultaneous evaluation of both eADA and GSH demonstrated that all examined DBA patients showed elevated values of either eADA or GSH, whereas presence of both eADA and GSH elevation was able to distinguish DBA patients from 34 normal controls and 14 unaffected members of the DBA families. Furthermore, a support vector machines analysis using both eADA and GSH levels yielded a formula to differentiate DBA from both normal controls and non-DBA family members. To confirm the usefulness of the formula, we analyzed additional 7 patients diagnosed by the clinical criteria. Although eADA showed within normal values in 3 patients, all of these patients were diagnosed as 'DBA' by use of the formula. Because extensive analysis of the RP genes failed to detect no causative mutation in approximately 40% of clinically diagnosed DBA patients, GSH may be useful an additional biomarker for diagnosis of DBA.

ATP11C is a major flippase in human erythrocytes and its defect causes congenital hemolytic anemia.

Phosphatidylserine is localized exclusively to the inner leaflet of the membrane lipid bilayer of most cells, including erythrocytes. This asymmetric distribution is critical for the survival of erythrocytes in circulation since externalized phosphatidylserine is a phagocytic signal for splenic macrophages. Flippases are P-IV ATPase family proteins that actively transport phosphatidylserine from the outer to inner leaflet. It has not yet been determined which of the 14 members of this family of proteins is the flippase in human erythrocytes. Herein, we report that ATP11C encodes a major flippase in human erythrocytes, and a genetic mutation identified in a male patient caused congenital hemolytic anemia inherited as an X-linked recessive trait. Phosphatidylserine internalization in erythrocytes with the mutant ATP11C was decreased 10-fold compared to that of the control, functionally establishing that ATP11C is a major flippase in human erythrocytes. Contrary to our expectations phosphatidylserine was retained in the inner leaflet of the majority of mature erythrocytes from both controls and the patient, suggesting that phosphatidylserine cannot be externalized as long as scramblase is inactive. Phosphatidylserine-exposing cells were found only in the densest senescent cells (0.1% of total) in which scramblase was activated by increased Ca(2+) concentration: the percentage of these phosphatidylserine-exposing cells was increased in the patient's senescent cells accounting for his mild anemia. Furthermore, the finding of similar extents of phosphatidylserine exposure by exogenous Ca(2+)-activated scrambling in both control erythrocytes and the patient's erythrocytes implies that suppressed scramblase activity rather than flippase activity contributes to the maintenance of phosphatidylserine in the inner leaflet of human erythrocytes.

[Autopsy case of sarcomatoid malignant pleural mesothelioma].

A 61-year-old man with a sensation of chest compression was admitted to our hospital. He had hemothorax. After drainage with a chest tube, chest CT scan revealed multiple bilateral pulmonary nodules with slight pleural thickening. Open pleural biopsy was performed and the biopsy specimens showed tumor cells with sarcomatoid proliferation, but no definite epithelial pattern. Initial immunohistochemical staining was negative for keratin and carletinin, but positive for desmin, suggesting rhabdomyosarcoma. After supportive care, he died due to progression of the disease. Autopsy revealed extensive invasion suggesting mesothelioma, so the immunohistochemical staining was repeated. Because it revealed patchy staining for keratin and carletinin, this case was diagnosed as sarcomatoid mesothelioma. Differential diagnosis of sarcomatoid mesothelioma or rhabdomyosarcoma is made by immunohistochemical staining, but it is sometimes difficult. For the selection of the best treatment strategy for mesothelioma especially in the early stage, we should be aware of this difficulty.

[A case study of shifting a patient with percutaneous endoscopic gastrostomy (PEG) to home care].

We studied the primary factor preventing a patient with PEG from being transferred to home care focusing on the dietic situation. The study has revealed differences in not the age of the patient, the days of hospitalization or hematological and biochemical test data but in the condition of use of home care services or family makeup. In other words, insufficient use of social resources is considered to prevent shifting to home care or continuation of home care of patients with PEG. It is necessary to understand not only dietic situation but social backgrounds of patients and supply information.

[A case study of shifting a patient with percutaneous endoscopic gastrostomy (PEG) to home care].

We studied the primary factor preventing a patient with PEG from being transferred to home care focusing on the dietetic situation. The study has revealed differences in not the age of the patient, the days of hospitalization or hematological and biochemical test data but in the condition of use of home care services or family makeup. In other words, insufficient use of social resources is considered to prevent shifting to home care or continuation of home care of patients with PEG. It is necessary to understand not only dietetic situation but social backgrounds of patients and supply information.