Biology subjects

Kalejaiye, T. D.

Publications and source records attributed to Kalejaiye, T. D..

4 recordsLinked to original sources

bioRxiv2026

Inefficient autophagosome formation limits the temporal dynamics of OPTN-mediated mitophagy in neurons

Mitophagy is an essential quality control mechanism that maintains neuronal health by selectively removing damaged mitochondria via autophagosomes. In neurons, mitophagy is mainly driven by Optineurin (OPTN), a selective autophagy receptor that is recruited to damaged mitochondria. Consistent with its role in maintaining mitochondrial integrity, OPTN-mediated mitophagy is upregulated in response to mild oxidative stress. However, many mechanistic studies of mitophagy have relied on non-neuronal systems and acute mitochondrial damage paradigms. Thus, it remains unclear how well these findings translate to physiological stress conditions in neurons. Here, we investigated the temporal dynamics of neuronal mitophagy under mild oxidative stress using live-cell imaging in primary rat hippocampal neurons. Surprisingly, we found that in neurons, autophagosomes failed to readily engulf OPTN-positive (OPTN+) mitochondria, revealing a novel rate-limiting step in neuronal mitophagy. Interestingly, this inefficient engulfment was specific to OPTN+ mitochondria at mitophagy events. Given the slow progression of mitophagy, we extended our time course to define the timescale of OPTN-regulated mitophagy. Using a pulse-chase assay to monitor long-term mitochondrial turnover, we found that OPTN+ mitochondria colocalized with acidified lysosomes over a timescale significantly longer than reported in non-neuronal cells and acute neuronal models. Since inefficient autophagosome engulfment appeared to limit mitophagy, we stimulated autophagosome formation via nutrient deprivation, which increased lysosomal colocalization with damaged mitochondria and enhanced mitophagy flux. Together, these findings indicate that mitophagy proceeds relatively slowly in neurons, a characteristic that may contribute to neuronal vulnerability in neurodegenerative disease by promoting the accumulation of dysfunctional mitochondria.

cell biology↗

bioRxiv2025

A Novel TRPC6 Mutation Causes Autosomal Dominant FSGS

FSGS is the most common primary glomerular lesion that causes kidney failure in the US. FSGS results from injury or loss of glomerular visceral epithelial cells (i.e. podocytes). Pathogenic variants in TRPC6 can cause FSGS through dysregulated calcium conductance and associated disturbances in podocyte physiology. Here, we describe a 5-generation kindred with FSGS caused by a novel compound C-terminal TRPC6 mutation. Analysis of patient-specific iPSC-derived podocytes and glomerular capillary wall-on-a-chip systems revealed that the compound variants disrupt TRPC6 protein structure, intermolecular interactions, and membrane localization. Combined therapy with Sildenafil and Losartan ameliorated these disturbances compared to conventional immunosuppressive treatment.

genetics↗

bioRxiv2024

Engineered human iPS cell models reveal altered podocytogenesis and glomerular capillary wall in CHD-associated SMAD2 mutations

Early developmental programming involves extensive cell lineage diversification through shared molecular signaling networks. Clinical observations of congenital heart disease (CHD) patients carrying SMAD2 genetic variants revealed correlations with multi-organ impairments at the developmental and functional levels. For example, many CHD patients present with glomerulosclerosis, periglomerular fibrosis, and albuminuria. Still, it remains largely unknown whether SMAD2 variants associated with CHD can directly alter kidney cell fate, tissue patterning, and organ-level function. To address this question, we engineered human iPS cells (iPSCs) and organ-on-a-chip systems to uncover the role of pathogenic SMAD2 variants in kidney podocytogenesis. Our results show that abrogation of SMAD2 causes altered patterning of the mesoderm and intermediate mesoderm (IM) cell lineages, which give rise to nearly all kidney cell types. Upon further differentiation of IM cells, the mutant podocytes failed to develop arborizations and interdigitations. A reconstituted glomerulus-on-a-chip platform exhibited significant proteinuria as clinically observed in glomerulopathies. This study implicates CHD-associated SMAD2 mutations in kidney tissue malformation and provides opportunities for therapeutic discovery in the future.

bioengineering↗

bioRxiv2021

BSG/CD147 and ACE2 receptors facilitate SARS-CoV-2 infection of human iPS cell-derived kidney podocytes

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the Coronavirus disease 2019 (COVID-19), which was declared a pandemic by the World Health Organization (WHO) in March 2020. The disease has caused more than 5.1 million deaths worldwide. While cells in the respiratory system are frequently the initial target for SARS-CoV-2, clinical studies suggest that COVID-19 can become a multi-organ disease in the most severe cases. Still, the direct affinity of SARS-CoV-2 for cells in other organs such as the kidneys, which are often affected in severe COVID-19, remains poorly understood. MethodIn this study, we employed a human induced pluripotent stem (iPS) cell-derived model to investigate the affinity of SARS-CoV-2 for kidney glomerular podocytes. We studied uptake of the live SARS-CoV-2 virus as well as pseudotyped viral particles by human iPS cell derived podocytes using qPCR, western blot, and immunofluorescence. Global gene expression and qPCR analyses revealed that human iPS cell-derived podocytes express many host factor genes (including ACE2, BSG/CD147, PLS3, ACTR3, DOCK7, TMPRSS2, CTSL CD209, and CD33) associated with SARS-CoV-2 binding and viral processing. ResultInfection of podocytes with live SARS-CoV-2 or spike-pseudotyped lentiviral particles revealed viral uptake by the cells at low Multiplicity of Infection (MOI of 0.01) as confirmed by RNA quantification and immunofluorescence studies. Our results also indicate that direct infection of human iPS cell-derived podocytes by SARS-CoV-2 virus can cause cell death and podocyte foot process retraction, a hallmark of podocytopathies and progressive glomerular diseases including collapsing glomerulopathy observed in patients with severe COVID-19 disease. Additionally, antibody blocking experiments identified BSG/CD147 and ACE2 receptors as key mediators of spike binding activity in human iPS cell-derived podocytes. ConclusionThese results show that SARS-CoV-2 can infect kidney glomerular podocytes in vitro. These results also show that the uptake of SARS-CoV-2 by kidney podocytes occurs via multiple binding interactions and partners, which may underlie the high affinity of SARS-CoV-2 for kidney tissues. This stem cell-derived model is potentially useful for kidney-specific antiviral drug screening and mechanistic studies of COVID-19 organotropism. Significant statementMany patients with COVID19 disease exhibit multiorgan complications, suggesting that SARS-CoV-2 infection can extend beyond the respiratory system. Acute kidney injury is a common COVID-19 complication contributing to increased morbidity and mortality. Still, SARS-Cov-2 affinity for specialized kidney cells remain less clear. By leveraging our protocol for stem cell differentiation, we show that SARS-CoV-2 can directly infect kidney glomerular podocytes by using multiple Spike-binding proteins including ACE2 and BSG/CD147. Our results also indicate that infection by SARS-CoV-2 virus can cause podocyte cell death and foot process effacement, a hallmark of podocytopathies including collapsing glomerulopathy observed in patients with severe COVID-19 disease. This stem cell-derived model is potentially useful for kidney-specific antiviral drug screening and mechanistic studies of COVID-19 organotropism.

bioengineering↗