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Localized mRNA translation mediated by Staufen is a novel mechanism regulating cytoskeletal reorganization in response to podocyte injury.

ABSTRACT: Podocyte injury that compromises the glomerular filtration barrier is an initiating feature of chronic kidney disease. Podocytes extend major cytoplasmic projections that ultimately subdivide into interdigitating foot processes to form a scaffold that supports the glomerular filtration barrier. We investigated whether podocytes, like other cell types that elaborate complex cytoplasmic projections, utilize RNA transport and local translation in order to synthesize proteins at sites distal from the cell body. Here we show that mice deficient in the RNA binding proteins Staufen1 and 2 are significantly more sensitive to podocyte injury. Furthermore, Staufen2 associates with the podocyte cytoskeleton and is present in foot processes. After injury, Staufen2 and translating ribosomes increase markedly in areas of effacement adjacent to the glomerular basement membrane. Lastly, we found that Staufen2-bound RNAs are enriched in those encoding proteins mediating cytoskeletal assembly and cell-matrix adhesion. RNA transport and localized translation is identified as a crucial process for maintaining the glomerular filtration barrier.

ORGANISM(S): Mus musculus

PROVIDER: GSE85485 | GEO | 2022/09/01

REPOSITORIES: GEO

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Project description:Glomerular podocytes are highly differentiated cells that are key components of the kidney filtration units. The podocyte cytoskeleton builds the basis for the dynamic podocyte cytoarchitecture and plays a central role for proper podocyte function. Recent studies implicate that immunosuppressive agents including the mTOR-inhibitor everolimus have a protective role directly on the stability of the podocyte cytoskeleton. To elucidate mechanisms underlying mTOR-inhibitor mediated cytoskeletal rearrangements, we carried out microarray gene expression studies to identify target genes and corresponding pathways in response to everolimus. We analyzed the effect of everolimus in a puromycin aminonucleoside experimental in vitro model of podocyte injury. Upon treatment with puromycin aminonucleoside, microarray analysis revealed gene clusters involving cytoskeletal-associated pathways, adhesion, migration and extracellular matrix composition to be affected. Everolimus is capable of protecting podocytes from injury, both on the transcriptome and protein level. Rescued genes included TUBB2B and DCDC2, both involved in microtubule structure formation in neuronal cells but not identified in podocytes so far. Confirming gene expression data, Western-blot analysis in cultured podocytes showed an increase of TUBB2B and DCDC2 protein after everolimus treatment, and immunohistochemistry in healthy control kidneys confirmed a podocyte-specific expression. Microtubule-inhibitor experiments led to a maldistribution of TUBB2B and DCDC2 as well as an aberrant reorganization of the actin cytoskeleton. Tubb2bbrdp/brdp mice showed a delay in glomerular podocyte and capillary development. Taken together, our study suggests that off-target, non-immune mediated effects of the mTOR-inhibitor everolimus on the podocyte cytoskeleton might involve regulation of microtubules, revealing a potential novel role of TUBB2B and DCDC2 in glomerular podocyte development We analyzed the effect of everolimus on gene expression in a puromycin aminonucleoside experimental in vitro model of podocyte injury using microarrays

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Localized mRNA translation mediated by Staufen is a novel mechanism regulating cytoskeletal reorganization in response to podocyte injury.

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