Biology subjects

Ishiyama, A.

Publications and source records attributed to Ishiyama, A..

4 recordsLinked to original sources

bioRxiv2022

Single-cell transcriptomic atlas reveals increased regeneration in diseased human inner ears

Mammalian inner ear hair cell loss leads to permanent hearing and balance dysfunction. In contrast to the cochlea, vestibular hair cells of the murine utricle have some regenerative capacity. Whether human utricular hair cells regenerate remains unknown. Here we procured live, mature utricles from organ donors and vestibular schwannoma patients, and present a validated single-cell transcriptomic atlas at unprecedented resolution. We describe previously unknown markers of 25 sensory and non-sensory cell types, with genes of hair cell and supporting cell subtypes displaying striking divergence between mice and humans. We further uncovered transcriptomes unique to hair cell precursors, which we validated to be 14-fold more robust in vestibular schwannoma utricles, representing ongoing regeneration in humans. Lastly, trajectory analysis of the supporting cell-hair cell axis revealed 5 distinct patterns of dynamic gene expression and associated pathways, including mTOR signaling and synaptogenesis. Our dataset constitutes a foundational resource, accessible via a web-based interface, serving to advance knowledge of the normal and diseased human inner ears and tools to stimulate human inner ear regeneration.

cell biology↗

bioRxiv2022

Identification of putative GATA3 regulatory elements and comparison of GATA3 distribution in cochleae of mice, rats, macaques, and humans.

The transcription factor GATA3 plays a critical role in the development of neurons and sensory epithelia of the inner ear. In mouse cochleae, GATA3 is downregulated in certain supporting cells (SCs) and in type I spiral ganglion neurons (SGNs) after development. This reduction of GATA3 in SCs severely limits Atoh1-induced hair cell (HC) regeneration and suggests that a similar downregulation in human cochleae may be limiting for regenerative therapies. However, it is unknown whether GATA3 is similarly or differentially regulated in primates versus rodents. Using CAGE-seq data, we compared over 40 putative GATA3 regulatory elements across species and found both conserved and non-conserved sequences. To assess whether cochlear GATA3 distribution is similar or different between rodents and primates, we immunostained cochleae from mice, rats, macaques, and humans using antibodies raised against highly conserved GATA3 peptide sequences. GATA3 immunostaining in the organs of Corti from all four species revealed a large degree of conservation, where SCs medial and lateral to cochlear HCs exhibited robust nuclear GATA3 immunolabeling, but pillar and Deiters cells had significantly reduced GATA3 immunoreactivity. In all four species, GATA3 was expressed in a subset of SGNs that largely co-expressed peripherin suggesting they were type II SGNs. Only one difference emerged, wherein human cochlear inner hair cells were not GATA3 immunoreactive despite being so in the other species. Overall, the pattern of GATA3 expression in primates appears similar to rodents and reinforces the notion that ATOH1 mediated regenerative therapies may be limited by reduced GATA3 expression in adult SCs.

molecular biology↗

bioRxiv2021

Acute SARS-CoV-2 infection in pregnancy is associated with placental ACE-2 shedding

Human placental tissues have variable rates of SARS-CoV-2 invasion resulting in consistently low rates of fetal transmission suggesting a unique physiologic blockade against SARS-CoV-2. Angiotensin-converting enzyme (ACE)-2, the main receptor for SARS-CoV-2, is expressed as cell surface and soluble forms regulated by a metalloprotease cleavage enzyme, ADAM17. ACE-2 is expressed in the human placenta, but the regulation of placental ACE-2 expression in relation to timing of maternal SARS-CoV-2 infection in pregnancy is not well understood. In this study, we evaluated ACE-2 expression, ADAM17 activity and serum ACE-2 abundance in a cohort of matched villous placental and maternal serum samples from Control pregnancies (SARS-CoV-2 negative, n=8) and pregnancies affected by symptomatic maternal SARS-CoV-2 infections in the 2nd trimester ("2ndTri COVID", n=8) and 3rd trimester ("3rdTri COVID", n=8). In 3rdTri COVID as compared to control and 2ndTri-COVID villous placental tissues ACE-2 mRNA expression was remarkably elevated, however, ACE-2 protein expression was significantly decreased with a parallel increase in ADAM17 activity. Soluble ACE-2 was also significantly increased in the maternal serum from 3rdTri COVID infections as compared to control and 2ndTri-COVID pregnancies. These data suggest that in acute maternal SARS-CoV-2 infections, decreased placental ACE-2 protein may be the result of ACE-2 shedding. Overall, this work highlights the importance of ACE-2 for ongoing studies on SARS-CoV-2 responses at the maternal-fetal interface.

pathology↗

bioRxiv2019

Characterizing Adult cochlear supporting cell transcriptional diversity using single-cell RNA-Seq: Validation in the adult mouse and translational implications for the adult human cochlea

Hearing loss is a problem that impacts a significant proportion of the adult population. Cochlear hair cell loss due to loud noise, chemotherapy and aging is the major underlying cause. A significant proportion of these individuals are dissatisfied with available treatment options which include hearing aids and cochlear implants. An alternative approach to restore hearing would be to regenerate hair cells. Such therapy would require recapitulation of the complex architecture of the organ of Corti, necessitating regeneration of both mature hair cells and supporting cells. Transcriptional profiles of the mature cell types in the cochlea are necessary to can provide a metric for eventual regeneration therapies. To assist in this effort, we sought to provide the first single-cell characterization of the adult cochlear supporting cell transcriptome. We performed single-cell RNA-Seq on FACS-purified adult cochlear supporting cells from the LfngEGFP adult mouse, in which supporting cells express GFP. We demonstrate that adult cochlear supporting cells are transcriptionally distinct from their perinatal counterparts. We establish cell type-specific adult cochlear supporting cell transcriptome profiles, and we validate these expression profiles through a combination of both fluorescent immunohistochemistry and in situ hybridization co-localization and qPCR of adult cochlear supporting cells. Furthermore, we demonstrate the relevance of these profiles to the adult human cochlea through immunofluorescent human temporal bone histopathology. Finally, we demonstrate cell cycle regulator expression in adult supporting cells and perform pathway analyses to identify potential mechanisms for facilitating mitotic regeneration (cell proliferation, differentiation, and eventually regeneration) in the adult mammalian cochlea. Our findings demonstrate the importance of characterizing mature as opposed to perinatal supporting cells.

genomics↗