Mutation of Gemin5 Causes Defective Hematopoietic Stem/Progenitor Cells Proliferation in Zebrafish Embryonic Hematopoiesis

Function and dysfunction of GEMIN5: understanding a novel neurodevelopmental disorder

The recent identification of a neurodevelopmental disorder with cerebellar atrophy and motor dysfunction (NEDCAM) has resulted in an increased interest in GEMIN5, a multifunction RNA-binding protein. As the largest member of the survival motor neuron complex, GEMIN5 plays a key role in the biogenesis of small nuclear ribonucleoproteins while also exhibiting translational regulatory functions as an independent protein. Although many questions remain regarding both the pathogenesis and pathophysiology of this new disorder, considerable progress has been made in the brief time since its discovery. In this review, we examine GEMIN5 within the context of NEDCAM, focusing on the structure, function, and expression of the protein specifically in regard to the disorder itself. Additionally, we explore the current animal models of NEDCAM, as well as potential molecular pathways for treatment and future directions of study. This review provides a comprehensive overview of recent advances in our understanding of this unique member of the survival motor neuron complex.

Exploring hematopoiesis in zebrafish using forward genetic screening

Zebrafish have emerged as a powerful animal model for investigating the genetic basis of hematopoiesis. Owing to its close genetic and developmental similarities to humans, combined with its rapid reproduction and extensive genomic resources, zebrafish have become a versatile and efficient platform for genetic studies. In particular, the forward genetic screening approach has enabled the unbiased identification of novel genes and pathways related to blood development, from hematopoietic stem cell formation to terminal differentiation. Recent advances in mutant gene mapping have further expanded the scope of forward genetic screening, facilitating the identification of previously unknown genes and pathways relevant to hematopoiesis. In this review, we provide an overview of the zebrafish forward screening approach for hematopoietic gene discovery and highlight the key genes and pathways identified using this method. This review emphasizes the importance of zebrafish as a model system for understanding the genetic basis of hematopoiesis and its associated disorders.

Pathogenic variants in the survival of motor neurons complex gene GEMIN5 cause cerebellar atrophy

Cerebellar ataxia is a genetically heterogeneous disorder. GEMIN5 encoding an RNA-binding protein of the survival of motor neuron complex, is essential for small nuclear ribonucleoprotein biogenesis, and it was recently reported that biallelic loss-of-function variants cause neurodevelopmental delay, hypotonia, and cerebellar ataxia. Here, whole-exome analysis revealed compound heterozygous GEMIN5 variants in two individuals from our cohort of 162 patients with cerebellar atrophy/hypoplasia. Three novel truncating variants and one previously reported missense variant were identified: c.2196dupA, p.(Arg733Thrfs*6) and c.1831G > A, p.(Val611Met) in individual 1, and c.3913delG, p.(Ala1305Leufs*14) and c.4496dupA, p.(Tyr1499*) in individual 2. Western blotting analysis using lymphoblastoid cell lines derived from both affected individuals showed significantly reduced levels of GEMIN5 protein. Zebrafish model for null variants p.(Arg733Thrfs*6) and p.(Ala1305Leufs*14) exhibited complete lethality at 2 weeks and recapitulated a distinct dysplastic phenotype. The phenotypes of affected individuals and the zebrafish mutant models strongly suggest that biallelic loss-of-function variants in GEMIN5 cause cerebellar atrophy/hypoplasia.