Proximal tubule apical endocytosis is modulated by fluid shear stress via an mTOR-dependent pathway

Long, Kimberly R.; Shipman, Katherine; Rbaibi, Youssef; Menshikova, Elizabeth V.; Ritov, Vladimir B.; Eshbach, Megan L.; Jiang, Yu; Jackson, Edwin K.; Baty, Catherine J.; Weisz, Ora A.

doi:10.1091/mbc.e17-04-0211

Cited by 49 publications

(92 citation statements)

References 46 publications

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“…Up‐ and downregulated genes were analyzed separately using IPA, and the results are summarized in Table S2. These changes are consistent with the increased lysosomal and mitochondrial biogenesis and adenine nucleotide levels we previously measured in cells exposed to orbital shear stress …”

Section: Resultssupporting

confidence: 92%

“…OK cells were cultured at 0X or 1X OS in serum‐free medium (to deplete fatty acids) and then imaged in base medium spiked with glucose or lactate as described in Methods. Consistent with our previous mass spectrometry measurements, baseline NAD(P)H levels in cells incubated without these fuels were higher in cell cultured at 1X OS compared with cells maintained under static conditions (not shown) . Cells cultured at either 0X OS or 1 X OS were able to generate NAD(P)H when transferred to base medium containing either lactate or glucose, as seen by the increase in autofluorescence over time (Figure ).…”

Section: Resultssupporting

confidence: 90%

“…Moreover, primary cell cultures isolated from kidney cortex tend to rapidly dedifferentiate. We have found that culturing opossum kidney (OK) cells under orbital shear stress results in dramatic upregulation of transport and trafficking proteins, enhanced endocytic capacity, increased apical microvilli and basolateral invaginations and mitochondrial and lysosomal biogenesis . Consistent with the need for increased energy production to maintain these morphological and functional changes, we also observed a significant increase in adenine nucleotide levels in cells cultured under orbital shaking.…”

Section: Introductionsupporting

confidence: 65%

“…On the other hand, PT and other cells are responsive to mechanical signals that also alter transcriptional responses . We previously found that cell culture in sealed laminar flow chambers, where oxygenation is uncoupled from shear stress, enhances endocytic capacity of OK cells, suggesting that flow sensing contributes to PT cell differentiation independent of O 2 availability . However, the relationship between oxygenation, shear stress, and metabolism is complex, as many of the key mediators of metabolic regulation (eg, mammalian target of rapamycin [mTOR] and HIF1α) reciprocally regulate one another and are known to be impacted by changes in O 2 availability and shear stress …”

Section: Resultsmentioning

confidence: 99%

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Shear stress and oxygen availability drive differential changes in opossum kidney proximal tubule cell metabolism and endocytosis

Ren

Gliozzi

Rittenhouse

et al. 2019

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Kidney proximal tubule (PT) cells have high-metabolic demands to drive the extraordinary ion and solute transport, water reabsorption, and endocytic uptake that occur in this nephron segment. Increases in renal blood flow alter glomerular filtration rate and lead to rapid mechanosensitive adaptations in PT transport, impacting metabolic demand. Although the PT reabsorbs essentially all of the filtered glucose, PT cells rely primarily on oxidative metabolism rather than glycolysis to meet their energy demands. We lack an understanding of how PT functions are impacted by changes in O 2 availability via cortical capillaries and mechanosensitive signaling in response to alterations in luminal flow. Previously, we found that opossum kidney (OK) cells recapitulate key features of PT cells in vivo, including enhanced endocytic uptake and ion transport, when exposed to mechanical stimulation by culture on an orbital shaker.We hypothesized that increased oxygenation resulting from orbital shaking also contributes to this more physiologic phenotype. RNA seq of OK cells maintained under static conditions or exposed to orbital shaking for up to 96 hours showed significant time-and culture-dependent changes in gene expression. Transcriptional and metabolomics data were consistent with a decrease in glycolytic flux and with an increased utilization of aerobic metabolic pathways in cells exposed to orbital shaking. Moreover, we found spatial differences in the pattern of mitogenesis vs development of ion transport and endocytic capacities in our culture system that highlight the complexity of O 2 -dependent and mechanosensitive crosstalk to regulate PT cell function.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 90%

Section: Introductionsupporting

confidence: 65%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Shear stress and oxygen availability drive differential changes in opossum kidney proximal tubule cell metabolism and endocytosis

Ren

Gliozzi

Rittenhouse

et al. 2019

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“…In this regard, it is of interest to note that FSS has been shown to trigger Wnt/β-catenin signaling in lymphatic endothelial cells, 33 while Wnt/β-catenin signaling is known to be essential in maintaining UB cells in a precursor state 34 . FSS has also been shown to activate mTOR-dependent pathway in kidney tubules, 35 while mTOR pathway is known to maintain Ret expression in UB tip cells 31 . Further studies are required to clarify these possibilities and identify the signaling pathway(s) that mediates the effect of FSS in UB cells.…”

Section: Resultsmentioning

confidence: 99%

Effect of fluid shear stress on in vitro cultured ureteric bud cells

et al. 2018

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Most kidney cells are continuously exposed to fluid shear stress (FSS) from either blood flow or urine flow. Recent studies suggest that changes in FSS could contribute to the function and injury of these kidney cells. However, it is unclear whether FSS influences kidney development when urinary flow starts in the embryonic kidneys. In this study, we evaluated the influence of FSS on in vitro cultured ureteric bud (UB) cells by using a pumpless microfluidic device, which offers the convenience of conducting parallel cell culture experiments while also eliminating the need for cumbersome electronic driven equipment and intricate techniques. We first validated the function of the device by both mathematical model and experimental measurements. UB cells dissected from E15.5 mouse embryonic kidneys were cultured in the pumpless microfluidic device and subjected to FSS in the range of 0.4–0.6 dyn mm−2 for 48 h (dynamic). Control UB cells were similarly cultured in the device and maintained under a no-flow condition (static). We found from our present study that the exposure to FSS for up to 48 h led to an increase in mRNA expression levels of UB tip cell marker genes (Wnt11, Ret, Etv4) with a decrease in stalk cell marker genes (Wnt7b, Tacstd2). In further support of the enrichment of UB tip cell population in response to FSS, we also found that exposure to FSS led to a remarkable reduction in the binding of lectin Dolichos Biflorus Agglutinin. In conclusion, results of our present study show that exposure to FSS led to an enrichment in UB tip cell populations, which could contribute to the development and function of the embryonic kidney when urine flow starts at around embryonic age E15.5 in mouse. Since UB tip cells are known to be the proliferative progenitor cells that contribute to the branching morphogenesis of the collecting system in the kidney, our finding could imply an important link between the FSS from the initiation of urine flow and the development and function of the kidney.

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Microfluidic Techniques for Next‐Generation Organoid Systems

Gong

Kang

et al. 2022

Adv Materials Inter

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PSCs (iPSCs) and embryonic stem cells (ESCs), or adult stem cells (ASCs). Pioneered in the Yoshiki Sasai lab, where cortical tissues and optic-cuplike structures were firstly induced from ESCs in vitro, [1,2] organoid technology is regarded as a milestone in the stem cell field because it cast light upon the path to stably growing self-aggregating and selfrenewing stem cells into native tissues by mimicking developmental processes. [3] Subsequently, the rapidly developing field of organoid technology is advancing the maturity of technology for developing 3D macrostructures of organs such as the retina, [4] heart, [5] liver, [6] kidney, [7] and intestines. [8] In marked contrast to traditional 2D monocultures of cell lines losing cell-cell and cell-matrix interactions, organoids maintain and define in situ phenotypes fairly well. Despite organoids having shown great progress in tissue morphogenesis and organogenesis, the lack of organ-specific biochemical and physical microenvironments and nonphysiological shape and size have limited the function and real-life applications of organoids. Therefore, innovative strategies are urgently needed to precisely control perfusion conditions, nutrient supply, and mechanical cues in order to establish an optimal microenvironment for organoid cultures.The recently developed organs-on-a-chip (OOC) technology provides an in vivo-like microenvironment, showing great potential to enhance our understanding of organ development, physiology, and pathology. [9] Besides, the application of dynamic flow conditions or mechanical stimuli provided by OOCs can improve the terminal maturation of cells. [10,11] OOCs usually are comprised of specialized cell types and tissue elements (biochemical and biophysical cues of in vivo microenvironment), aiming to capture key functions of a specific organ. [12] Organoids rely on the self-organization of growing stem cell aggregates, whereas OOC is based on a reductionist engineering approach. In addition, organoids are multicellular 3D tissue with an architecture resembling some aspects of original tissues, which are not classified as OOC because of their production through stochastic self-organization from PSCs or ASCs and lack of microenvironment elements. [13] However, organoid and OOC techniques each have their own advantages, and they can be appropriately combined to enable highfidelity human modeling from stem cells. [14] Such synergistic Organoids are 3D multicellular structures derived from pluripotent stem cells (PSCs) or adult stem cells (ASCs), which have attracted increasing interest in the fields of drug screening, cell therapy, and regenerative medicine. Despite considerable success in culturing organoids with native microanatomy, challenges to achieving a physiologically relevant microenvironment remain. Complex dynamic feedback between cells and the extracellular matrix and uncontrollable mechano-physiological cues hamper the further study of organoid systems. Innovative engineering approaches are needed to produce, control, and analy...

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Proximal tubule apical endocytosis is modulated by fluid shear stress via an mTOR-dependent pathway

Cited by 49 publications

References 46 publications

Shear stress and oxygen availability drive differential changes in opossum kidney proximal tubule cell metabolism and endocytosis

Shear stress and oxygen availability drive differential changes in opossum kidney proximal tubule cell metabolism and endocytosis

Effect of fluid shear stress on in vitro cultured ureteric bud cells

Microfluidic Techniques for Next‐Generation Organoid Systems

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