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354 results on '"Leipziger J"'

5. Circadian gene expression in mouse renal proximal tubule.

Author

Bingham, M.A., Neijman, K., Yang, C.R., Aponte, A., Mak, A., Kikuchi, H., Jung, H.J., Poll, B.G., Raghuram, V., Park, E., Chou, C.L., Chen, Lihe, Leipziger, J., Knepper, M.A., Dona, M.A., Bingham, M.A., Neijman, K., Yang, C.R., Aponte, A., Mak, A., Kikuchi, H., Jung, H.J., Poll, B.G., Raghuram, V., Park, E., Chou, C.L., Chen, Lihe, Leipziger, J., Knepper, M.A., and Dona, M.A.

Abstract

Item does not contain fulltext, Circadian variability in kidney function is well recognized but is often ignored as a potential confounding variable in physiological experiments. Here, we have created a data resource consisting of expression levels for mRNA transcripts in microdissected proximal tubule segments from mice as a function of the time of day. Small-sample RNA sequencing was applied to microdissected S1 proximal convoluted tubules and S2 proximal straight tubules. After stringent filtering, the data were analyzed using JTK-Cycle to detect periodicity. The data set is provided as a user-friendly webpage at https://esbl.nhlbi.nih.gov/Databases/Circadian-Prox2/. In proximal convoluted tubules, 234 transcripts varied in a circadian manner (4.0% of the total). In proximal straight tubules, 334 transcripts varied in a circadian manner (5.3%). Transcripts previously known to be associated with corticosteroid action and with increased flow were found to be overrepresented among circadian transcripts peaking during the "dark" portion of the day [zeitgeber time (ZT)14-22], corresponding to peak levels of corticosterone and glomerular filtration rate in mice. To ask whether there is a time-of-day dependence of protein abundances in the kidney, we carried out LC-MS/MS-based proteomics in whole mouse kidneys at ZT12 and ZT0. The full data set (n = 6,546 proteins) is available at https://esbl.nhlbi.nih.gov/Databases/Circadian-Proteome/. Overall, 293 proteins were differentially expressed between ZT12 and ZT0 (197 proteins greater at ZT12 and 96 proteins greater at ZT0). Among the regulated proteins, only nine proteins were found to be periodic in the RNA-sequencing analysis, suggesting a high level of posttranscriptional regulation of protein abundances.NEW & NOTEWORTHY Circadian variation in gene expression can be an important determinant in the regulation of kidney function. The authors used RNA-sequencing transcriptomics and LC-MS/MS-based proteomics to identify gene products expressed in a period

Published
2023

20. Transepithelial pressure pulses induce nucleotide release in polarized MDCK cells

Author

Praetorius, H.A., Frokiaer, J., and Leipziger, J.

Subjects
Epithelial cells, Calcium metabolism, Biological sciences
Abstract

The release of nucleotides is involved in mechanosensation in various epithelial cells. Intriguingly, kidney epithelial cells are absolutely dependent on the primary cilium to sense changes in apical laminar flow. During fluid passage, the renal epithelial cells are subjected to various mechanical stimuli in addition to changes in the laminar flow rate. In the distal part of the collecting duct, the epithelial cells are exposed to pressure changes and possibly distension during papillary contractions. The aim of the present study was to determine whether nucleotide release contributes to mechanosensation in kidney epithelial cells, thereby establishing whether pressure changes are sufficient to produce nucleotide-mediated responses. Madin-Darby canine kidney (MDCK) cells grown on permeable supports were mounted in a closed double perfusion chamber on an inverted microscope. The intracellular [Ca.sup.2+] concentration ([[[Ca.sup.2+]].sub.i]) was monitored with the [Ca.sup.2+]-sensitive fluorescence probe fluo 4. Transepithelial pressure pulses of 30-80 mmHg produced a transient increase in [[[Ca.sup.2+]].sub.i] of MDCK cells. This response is independent of the primary cilium, since it is readily observed in immature cells that do not yet express primary cilia. The amplitudes of the pressure-induced [Ca.sup.2+] transients varied with the applied chamber pressure in a quantity-dependent manner. The ATPase apyrase and the P2Y antagonist suramin significantly reduced the pressure-induced [Ca.sup.2+] transients. Applying apyrase or suramin to both sides of the preparation simultaneously nearly abolished the pressure-induced [Ca.sup.2+] response. In conclusion, these observations suggest that rapid pressure changes induce both apical and basolateral nucleotide release that contribute to mechanosensation in kidney epithelial cells. ATP; P2Y; calcium; mechanosensation

Published
2005

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