EHBP1L1, an apicobasal polarity regulator, is critical for nuclear polarization during enucleation of erythroblasts

Integrated analysis of the complete sequence of a macaque genome

The crab-eating macaques (Macaca fascicularis) and rhesus macaques (Macaca mulatta) are pivotal in biomedical and evolutionary research1-3. However, their genomic complexity and interspecies genetic differences remain unclear4. Here, we present a complete genome assembly of a crab-eating macaque, revealing 46% fewer segmental duplications and 3.83 times longer centromeres than those of humans5,6. We also characterize 93 large-scale genomic differences between macaques and humans at a single-base-pair resolution, highlighting their impact on gene regulation in primate evolution. Using ten long-read macaque genomes, hundreds of short-read macaque genomes and full-length transcriptome data, we identified roughly 2 Mbp of fixed-genetic variants, roughly 240 Mbp of complex loci, 16.76 Mbp genetic differentiation regions and 110 alternative splice events, potentially associated with various phenotypic differences between the two macaque species. In summary, the integrated genetic analysis enhances understanding of lineage-specific phenotypes, adaptation and primate evolution, thereby improving their biomedical applications in human disease research.

The HELP-UnaG Fusion Protein as a Bilirubin Biosensor: From Theory to Mature Technological Development

HUG is the HELP-UnaG recombinant fusion protein featuring the typical functions of both HELP and UnaG. In HUG, the HELP domain is a thermoresponsive human elastin-like polypeptide. It forms a shield enwrapping the UnaG domain that emits bilirubin-dependent fluorescence. Here, we recapitulate the technological development of this bifunctional synthetic protein from the theoretical background of its distinct protein moieties to the detailed characterization of its macromolecular and functional properties. These pieces of knowledge are the foundations for HUG production and application in the fluorometric analysis of bilirubin and its congeners, biliverdin and bilirubin glucuronide. These bile pigments are metabolites that arise from the catabolism of heme, the prosthetic group of cytochromes, hemoglobin and several other intracellular enzymes engaged in electron transfer, oxygen transport and protection against oxygen free radicals. The HUG assay is a powerful, user-friendly and affordable analytical tool that alone supports research at each level of complexity or taxonomy of living entities, from enzymology, cell biology and pathophysiology to veterinary and clinical sciences.

European EHBP1L1 Genotyping Survey of Dyserythropoietic Anemia and Myopathy Syndrome in English Springer Spaniels

Dyserythropoietic anemia and myopathy syndrome (DAMS) with neonatal losses was recently characterized as an autosomal recessive disorder caused by an EHBP1L1 frameshift variant in English Springer Spaniels (ESSPs). The frequency and dissemination of the mutation remained unknown. The EHBP1L1 protein is essential for muscle function, and the Rab8/10-EHBP1L1-Bin1-dynamin axis participates in nuclear polarization during the enucleation of erythroblasts. Lack of EHBP1L1 function decreases enucleation, leading to increased numbers of nucleated erythrocytes, which are characteristic of DAMS. A genotyping survey for the EHBP1L1 variant was conducted based upon submitted samples of ESSPs from Europe. DNA was extracted, and a real-time PCR assay, with allele-specific TaqMan probes for EHBP1L1 wild-type and frameshift deletion, was applied. Between September 2022 and August 2024, 803 samples were received from 18 European countries. The EHBP1L1 mutant allele frequency was 9.7%, including 4 homozygous dogs and 148 heterozygotes. The mutant EHBP1L1 allele was found in 13 countries. A total of 6 homozygous and 73 heterozygous ESSPs reported on an open database could be tracked to an original common ancestor. Although the survey is biased, it indicates that the mutant EHBP1L1 variant is disseminated in the breed and across Europe. The genotyping of ESSPs is recommended to diagnose DAMS and guide breeders.

Erythroblast enucleation at a glance

Erythroid enucleation, the penultimate step in mammalian erythroid terminal differentiation, is a unique cellular process by which red blood cells (erythrocytes) remove their nucleus and accompanying nuclear material. This complex, multi-stage event begins with chromatin compaction and cell cycle arrest and ends with generation of two daughter cells: a pyrenocyte, which contains the expelled nucleus, and an anucleate reticulocyte, which matures into an erythrocyte. Although enucleation has been compared to asymmetric cell division (ACD), many mechanistic hallmarks of ACD appear to be absent. Instead, enucleation appears to rely on mechanisms borrowed from cell migration, endosomal trafficking and apoptosis, as well as unique cellular interactions within the microenvironment. In this Cell Science at a Glance article and the accompanying poster, we summarise current insights into the morphological features and genetic drivers regulating the key intracellular events that culminate in erythroid enucleation and engulfment of pyrenocytes by macrophages within the bone marrow microenvironment.

Enhancing terminal erythroid differentiation in human embryonic stem cells through TRIB3 overexpression

Tribbles pseudokinase 3 (TRIB3) expression significantly increases during terminal erythropoiesis in vivo. However, we found that TRIB3 expression remained relatively low during human embryonic stem cell (hESC) erythropoiesis, particularly in the late stage, where it is typically active. TRIB3 was expressed in megakaryocyte-erythrocyte progenitor cells and its low expression was necessary for megakaryocyte differentiation. Thus, we proposed that the high expression during late stage of erythropoiesis could be the clue for promotion of maturation of hESC-derived erythroid cells. To our knowledge, the role of TRIB3 in the late stage of erythropoiesis remains ambiguous. To address this, we generated inducible TRIB3 overexpression hESCs, named TRIB3tet-on OE H9, based on a Tet-On system. Then, we analyzed hemoglobin expression, condensed chromosomes, organelle clearance, and enucleation with or without doxycycline treatment. TRIB3tet-on OE H9 cells generated erythrocytes with a high proportion of orthochromatic erythroblast in flow cytometry, enhanced hemoglobin and related protein expression in Western blot, decreased nuclear area size, promoted enucleation rate, decreased lysosome and mitochondria number, more colocalization of LC3 with LAMP1 (lysosome marker) and TOM20 (mitochondria marker) and up-regulated mitophagy-related protein expression after treatment with 2 μg/mL doxycycline. Our results showed that TRIB3 overexpression during terminal erythropoiesis may promote the maturation of erythroid cells. Therefore, our study delineates the role of TRIB3 in terminal erythropoiesis, and reveals TRIB3 as a key regulator of UPS and downstream mitophagy by ensuring appropriate mitochondrial clearance during the compaction of chromatin.

Molecular mechanisms of polarized transport to the apical plasma membrane

Cell polarity is essential for cellular function. Directional transport within a cell is called polarized transport, and it plays an important role in cell polarity. In this review, we will introduce the molecular mechanisms of polarized transport, particularly apical transport, and its physiological importance.

Amphiphysin-2 (BIN1) functions and defects in cardiac and skeletal muscle

Amphiphysin-2 is a ubiquitously expressed protein also known as bridging integrator 1 (BIN1), playing a critical role in membrane remodeling, trafficking, and cytoskeleton dynamics in a wide range of tissues. Mutations in the gene encoding BIN1 cause centronuclear myopathies (CNM), and recent evidence has implicated BIN1 in heart failure, underlining its crucial role in both skeletal and cardiac muscle. Furthermore, altered expression of BIN1 is linked to an increased risk of late-onset Alzheimer's disease and several types of cancer, including breast, colon, prostate, and lung cancers. Recently, the first proof-of-concept for potential therapeutic strategies modulating BIN1 were obtained for muscle diseases. In this review article, we discuss the similarities and differences in BIN1's functions in cardiac and skeletal muscle, along with its associated diseases and potential therapies.

Comparative genomics of macaques and integrated insights into genetic variation and population history

The crab-eating macaques ( Macaca fascicularis ) and rhesus macaques ( M. mulatta ) are widely studied nonhuman primates in biomedical and evolutionary research. Despite their significance, the current understanding of the complex genomic structure in macaques and the differences between species requires substantial improvement. Here, we present a complete genome assembly of a crab-eating macaque and 20 haplotype-resolved macaque assemblies to investigate the complex regions and major genomic differences between species. Segmental duplication in macaques is ∼42% lower, while centromeres are ∼3.7 times longer than those in humans. The characterization of ∼2 Mbp fixed genetic variants and ∼240 Mbp complex loci highlights potential associations with metabolic differences between the two macaque species (e.g., CYP2C76 and EHBP1L1 ). Additionally, hundreds of alternative splicing differences show post-transcriptional regulation divergence between these two species (e.g., PNPO ). We also characterize 91 large-scale genomic differences between macaques and humans at a single-base-pair resolution and highlight their impact on gene regulation in primate evolution (e.g., FOLH1 and PIEZO2 ). Finally, population genetics recapitulates macaque speciation and selective sweeps, highlighting potential genetic basis of reproduction and tail phenotype differences (e.g., STAB1 , SEMA3F , and HOXD13 ). In summary, the integrated analysis of genetic variation and population genetics in macaques greatly enhances our comprehension of lineage-specific phenotypes, adaptation, and primate evolution, thereby improving their biomedical applications in human diseases.