Biology subjects

Engel, J. D.

Publications and source records attributed to Engel, J. D..

7 recordsLinked to original sources

bioRxiv2025

A lipid metabolism defect is an underlying contributor to Diamond Blackfan anemia syndrome

Analysis of neither Diamond Blackfan anemia syndrome (DBAS) cohorts nor animal models has revealed a potential mechanism for the variable anemia phenotype, a key feature of this disease. Here, we utilized an established Rpl5Skax23-Jus/+ murine DBAS model in order to study this dynamic erythropoiesis deficiency. These haploinsufficient mice exhibit variably penetrant craniofacial and cardiac defects mimicking the phenotypes of DBAS patients bearing RPL5 mutations. We additionally discovered that this specific heterozygous splicing mutation is pathogenic and leads to partial intron retention. By examining the transcriptome of fetal liver erythroid progenitors at E12.5, we demonstrate that the downregulation of erythroid differentiation pathways is consistent with the DBAS phenotype. We also identified dysregulated transcription of lipid metabolism genes with significant reduction in the abundance of Scd1 in a subset of E12.5 mutant embryos at risk for erythroid failure. SCD1, a key enzyme that converts saturated to monounsaturated fatty acids, has not been previously linked to erythropoiesis or DBAS. When anemia was induced in adult mice, pretreatment with an SCD1 inhibitor resulted in improved erythropoiesis. This analysis suggests a key role of lipid metabolism in the variable anemia penetrance in DBAS and highlights a previously unappreciated pathway that may serve as a potential target for drug development. Key PointsO_LIThe variable anemia in Rpl5Skax23-Jus/+mice is triggered by intrinsic/extrinsic stress C_LIO_LIRpl5 haploinsufficient murine and human erythroid progenitors exhibit a lipid metabolism signature with downregulation of Scd1/SCD. C_LI

developmental biology↗

bioRxiv2021

A new murine Rpl5 (uL18) mutation provides a unique model of variably penetrant Diamond Blackfan Anemia

Ribosome dysfunction is implicated in multiple abnormal developmental and disease states in humans. Heterozygous germline mutations in genes encoding ribosomal proteins (RPs) are found in the majority of individuals with Diamond Blackfan anemia (DBA) while somatic mutations have been implicated in a variety of cancers and other disorders. Ribosomal protein-deficient animal models show variable phenotypes and penetrance, similar to human DBA patients. The spontaneous anemia remission observed in some DBA patients occurs via unknown mechanism(s) and has not been previously described in animal models. Here we characterized a novel ENU mouse mutant (Skax23m1Jus) with growth and skeletal defects, cardiac malformations and increased mortality. Following genetic mapping and whole exome sequencing, we identified an intronic Rpl5 mutation, which segregated with all affected mice. This mutation was associated with decreased ribosome generation, consistent with Rpl5 haploinsufficiency. Rpl5Skax23-Jus mutant animals had a profound delay in erythroid maturation and increased mortality at embryonic day E12.5, which improved by E14.5. Surviving mutant animals had a macrocytic anemia at birth as well as evidence of ventricular septal defect (VSD). Surviving adult and aged mice exhibited no hematopoietic defect or VSD. We propose that this novel Rpl5Skax23-Jus mutant mouse will be useful to study the factors influencing the variable penetrance and anemia remission that are observed in DBA.

developmental biology↗

bioRxiv2021

GATA3 is essential for separating patterning domains during facial morphogenesis

Neural crest cells (NCCs) within the mandibular and maxillary portions of the first pharyngeal arch are initially competent to respond to signals from either region. However, mechanisms that are only partially understood establish developmental tissue boundaries to ensure spatially correct patterning. In the Hinge and Caps model of facial development, signals from both ventral prominences, referred to as the caps, pattern the adjacent tissues while the intervening region, known as the hinge, maintains separation of the mandibular and maxillary domains. One cap signal is GATA3, a member of the GATA family of zinc-finger transcription factors with a distinct expression pattern in the ventral-most part of the mandibular and maxillary portions of the first arch. Here we show that disruption of Gata3 in mouse embryos leads to hemifacial microsomia, facial bone hypoplasia and syngnathia (bony fusion of the upper and lower jaws). These changes are preceded by gene expression changes in post-migratory NCCs around the maxillomandibular junction (the hinge). GATA3 is thus a crucial component in establishing the network of factors that functionally separate the upper and lower jaws during development. Summary StatementLoss of Gata3 leads to BMP-mediated disruption of Fgf8 expression at the maxillomandibular junction during development, resulting in later fusion of the upper and lower jaws.

developmental biology↗

bioRxiv2021

The epigenetic eraser LSD1 lies at the apex of a reversible erythroid to myeloid cell fate decision

H3K4Me demethylase KDM1a/LSD1 is a therapeutic target for multiple diseases, including the {beta}-globinopathies (sickle cell disease and {beta}-thalassemia) since its inactivation has been shown to lead to robust induction of the fetal globin genes. Here we examined the consequences of conditional inactivation of Lsd1 in adult red blood cells using a new Gata1creERT2 BAC transgene. Loss of Lsd1 activity in mice blocked erythroid differentiation and expanded GMP-like cells, converting hematopoietic differentiation potential from an erythroid to a myeloid fate. The analogous phenotype was also observed in human HSPC, coincident with induction of myeloid transcription factors (e.g. PU.1 and CEBP). Finally, blocking the activity of myeloid transcription factors PU.1 or RUNX1 at the same time as LSD1 reverted myeloid lineage conversion to an erythroid phenotype. The data show that LSD1 promotes erythropoiesis by repressing myeloid cell fate, and that inhibition of myeloid differentiation reverses the lineage switch caused by LSD1 inactivation.

developmental biology↗

bioRxiv2020

Three-dimensional mapping identifies distinct vascular niches for myelopoiesis

In contrast to virtually all other tissues in the body the anatomy of differentiation in the bone marrow remains unknown. This is due to the lack of strategies to examine blood cell production in situ, which are required to better understand differentiation, lineage commitment decisions, and to define how spatial organizing cues inform tissue function. Here we developed imaging approaches to map all myeloid cells in whole bones and generated 3D atlases of granulocyte and monocyte/dendritic cell differentiation during homeostasis. We found that myeloid progenitors leave the hematopoietic stem cell niche during differentiation. Granulocyte and monocyte dendritic cell progenitors (MDP) do not interact, instead they localize to different sinusoids where they give rise to clusters of immature cells. MDP cluster with Ly6Clo monocytes and conventional dendritic cells; these localize to a unique subset of colony stimulating factor 1 (CSF1, the major regulator of monopoiesis1) -expressing sinusoids. Csf1 deletion in the vasculature disrupted the MDP clusters and their interaction with sinusoids, leading to reduced MDP numbers and differentiation ability, with subsequent loss of peripheral Ly6Clo monocytes and dendritic cells. These data indicate that there is a specific spatial organization of definitive hematopoiesis and that local cues produced by distinct blood vessels are responsible for this organization. These maps provide a blueprint for in situ analyses of hematopoiesis in blood disorders.

immunology↗

bioRxiv2018

No evidence for transvection in vivo by a superenhancer:promoter pair integrated into identical open chromatin at the Rosa26 locus

Long-range associations between enhancers and their target gene promoters have been shown to play critical roles in executing genome function. Recent variations of chromosome capture technology have revealed a conprehensive view of intra- and inter-chromosomal contacts between specific genomic sites. The locus control region of the {beta}-globin genes ({beta}-LCR) is a super-enhancer that is capable of activating all of the {beta}-like globin genes within the locus in cis through physical interaction by forming DNA loops. CTCF helps to mediate loop formation between LCR-HS5 and 3HS1 in the human {beta}-globin locus, in this way thought to contribute to the formation of a \"chromatin hub\". The {beta}-globin locus is also in close physical proximity to other erythrocyte-specific genes located long distances away on the same chromosome. In this case, erythrocyte-specific genes gather together at a shared \"transcription factory\" for co-transcription. Theoretically, enhancers could also activate target gene promoters on different chromosomes in trans, a phenomenon originally described as transvection in Drosophilla. Although close physical proximity has been reported for the {beta}-LCR and the {beta}-like globin genes when integrated at the mouse homologous loci in trans, their structural and functional interactions were found to be rare, possibly because a lack of suitable regulatory elements that might facilitate trans interactions. Therefore, we re-evaluated presumptive transvection-like enhancer-promoter communication by introducing CTCF binding sites and erythrocyte-specific transcription units into both LCR-enhancer and {beta}-promoter alleles, each inserted into the mouse ROSA26 locus on separate chromosomes. Following cross-mating of mice to place the two mutant loci at the identical chromosomal position and into active chromation in trans, their transcriptional output was evaluated. The results demonstrate that there was no significant functional association between the LCR and the {beta}-globin gene in trans even in this idealized experimental context.

genomics↗

bioRxiv2018

High throughput single cell sequencing of both T-cell-receptor-beta alleles

Allelic exclusion is a vital mechanism for the generation of monospecificity to foreign antigens in B- and T-lymphocytes. Here we developed a high-throughput barcoded method to simultaneously analyze the VDJ recombination status of both mouse T cell receptor beta alleles in hundreds of single cells using Next Generation Sequencing.

immunology↗