Spiral ganglion cell degeneration-induced deafness as a consequence of reduced GATA factor activity

Hearing loss genes reveal patterns of adaptive evolution at the coding and non-coding levels in mammals

Background

Mammals possess unique hearing capacities that differ significantly from those of the rest of the amniotes. In order to gain insights into the evolution of the mammalian inner ear, we aim to identify the set of genetic changes and the evolutionary forces that underlie this process. We hypothesize that genes that impair hearing when mutated in humans or in mice (hearing loss (HL) genes) must play important roles in the development and physiology of the inner ear and may have been targets of selective forces across the evolution of mammals. Additionally, we investigated if these HL genes underwent a human-specific evolutionary process that could underlie the evolution of phenotypic traits that characterize human hearing.

Results

We compiled a dataset of HL genes including non-syndromic deafness genes identified by genetic screenings in humans and mice. We found that many genes including those required for the normal function of the inner ear such as LOXHD1, TMC1, OTOF, CDH23, and PCDH15 show strong signatures of positive selection. We also found numerous noncoding accelerated regions in HL genes, and among them, we identified active transcriptional enhancers through functional enhancer assays in transgenic zebrafish.

Conclusions

Our results indicate that the key inner ear genes and regulatory regions underwent adaptive evolution in the basal branch of mammals and along the human-specific branch, suggesting that they could have played an important role in the functional remodeling of the cochlea. Altogether, our data suggest that morphological and functional evolution could be attained through molecular changes affecting both coding and noncoding regulatory regions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01170-6.

Combined Mutation of the GATA2 Gene and STAT5B Gene in a Patient with Hypogammaglobulinemia and Autoimmunity

Antibody deficiency is a type of primary immunodeficiency that often manifests as primary hypogammaglobulinemia, with or without repeated infections. Although primary immunodeficiency appears to be contrary to autoimmunity, they usually occur simultaneously, and the specific pathogenesis remains unknown. We herein describe an adult patient with autoimmune manifestations and recurrent infections. The case was characterized by a sustained decrease in serum immunoglobulin A, accompanied by decreased T lymphocytes, B lymphocytes, monocytes, and platelets in the peripheral blood and the presence of antinuclear and anti-SSA antibodies. Whole-exome sequencing for the patient revealed two spontaneous mutations in GATA2 (c.1084C>T) and STAT5B (c.1924A>C). This case report provides evidence that mutations in the GATA2 and STAT5B genes may be pathogenic in primary immunodeficiency and provides genetic evidence for the possible pathogenesis of primary immunodeficiency with autoimmune symptoms. However, further studies are needed to confirm the causal relationship.

A novel germline GATA2 frameshift mutation with a premature stop codon in a family with congenital sensory hearing loss and myelodysplastic syndrome

GATA2 is a zinc-finger transcription factor regulating early hematopoiesis and developmental processes. Heterozygous germline mutations in GATA2 underlie a pleiotropic autosomal dominant disorder, GATA2 deficiency syndrome. The wide spectrum of its clinical features involves familial predisposition to myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) and multiorgan dysfunction, including congenital sensorineural hearing loss (CSHL). We herein report a pedigree with a novel germline frameshift mutation presenting as CSHL and familial MDS. The proband was a 46-year-old man, and his daughter also presented with an identical set of clinical syndromes. Target DNA sequencing identified a novel eight-nucleotide duplicative insertion at exon 5 (NM_032638.4:c.1126_1133dup:p.Lys378Asnfs*12)　of the GATA2 gene. RT-PCR and subcloning analysis showed that the frameshift might result in a truncated mutation with an early stop codon without interfering with the predicted splice site. The predicted mutant protein had 388 amino acids and in silico analysis showed the variant was considered deleterious. This mutation was not detected in unaffected family members. Its deleterious effect is highly likely to have portended the familial MDS and CSHL in this pedigree. Genetic testing among suspected individuals may be warranted for adequate management, including timely transplantation.

Development and Carcinogenesis: Roles of GATA Factors in the Sympathoadrenal and Urogenital Systems

The GATA family of transcription factors consists of six proteins (GATA1-6) that control a variety of physiological and pathological processes. In particular, GATA2 and GATA3 are coexpressed in a number of tissues, including in the urogenital and sympathoadrenal systems, in which both factors participate in the developmental process and tissue maintenance. Furthermore, accumulating studies have demonstrated that GATA2 and GATA3 are involved in distinct types of inherited diseases as well as carcinogenesis in diverse tissues. This review summarizes our current knowledge of how GATA2 and GATA3 participate in the transcriptional regulatory circuitry during the development of the sympathoadrenal and urogenital systems, and how their dysregulation results in the carcinogenesis of neuroblastoma, renal urothelial, and gynecologic cancers.

Rathke's cleft-like cysts arise from Isl1 deletion in murine pituitary progenitors

The transcription factor ISL1 is expressed in pituitary gland stem cells and the thyrotrope and gonadotrope lineages. Pituitary-specific Isl1 deletion causes hypopituitarism with increased stem cell apoptosis, reduced differentiation of thyrotropes and gonadotropes, and reduced body size. Conditional Isl1 deletion causes development of multiple Rathke's cleft-like cysts, with 100% penetrance. Foxa1 and Foxj1 are abnormally expressed in the pituitary gland and associated with a ciliogenic gene-expression program in the cysts. We confirmed expression of FOXA1, FOXJ1, and stem cell markers in human Rathke's cleft cyst tissue, but not craniopharyngiomas, which suggests these transcription factors are useful, pathological markers for diagnosis of Rathke's cleft cysts. These studies support a model whereby expression of ISL1 in pituitary progenitors drives differentiation into thyrotropes and gonadotropes and without it, activation of FOXA1 and FOXJ1 permits development of an oral epithelial cell fate with mucinous cysts. This pituitary-specific Isl1 mouse knockout sheds light on the etiology of Rathke's cleft cysts and the role of ISL1 in normal pituitary development.