A population of mitochondrion-rich cells in the pars recta of mouse kidney

Abstract

Following perfusion of adult mouse kidney with a solution of nitroblue tetrazolium (NBT), certain epithelial cells in the pars recta (S3) segments of proximal tubules react to form cytoplasmic deposits of blue diformazan particles. Such cells are characterized by dark cytoplasm, small and often elliptical nuclei, elaborate, process-bearing profiles, and abundant mitochondria. The atypical epithelial cells display the additional characteristic of immunoreactivity for a wide spectrum of antigens, including mesenchymal proteins such as vimentin. Though present in kidneys of untreated or sham-operated animals, they are particularly evident under experimental conditions such as unilateral ureteral obstruction (UUO), appearing in both contralateral and obstructed kidneys over the course of a week's duration, but disappearing from the obstructed kidney as it undergoes the profound atrophy attributable to deterioration of the population of its proximal tubules. The cells do not appear in neonatal kidneys, even those undergoing UUO, but begin to be recognizable soon after weaning (28 days). It is possible that diformazan-positive cells in the mouse S3 tubular segment constitute a resident population of cells that can replenish or augment the tubule. Although somewhat similar cells, with dark cytoplasm and vimentin expression, have been described in human, rat, and transgenic mouse kidney (Smeets et al., 2013; Berger et al., 2014), those cells—known as “scattered tubule cells” or “proximal tubule rare cells” differ from the S3-specific cells in that they are present throughout the entire proximal tubule, often lack a brush border, and have only few mitochondria.

Comprehensive Cell Type Specific Transcriptomics of the Human Kidney

“…The 1 st sub-cluster were not dying cells as the median number of genes and transcripts were higher than cluster 1, so we hypothesize that they belong to this poorly characterized cell type ( Supplementary Fig. 2f-g) 18 . The 2 nd sub-cluster marked parietal epithelial cells (PECs) (CL_1000452) lining the Bowman's capsule, which are known to specifically express VCAM1 19 .…”

“…2a-d). PT cells in general and a subset of mouse S3 PT cells have been described to be especially abundant in mitochondria 18 . The 1 st sub-cluster were not dying cells as the median number of genes and transcripts were higher than cluster 1, so we hypothesize that they belong to this poorly characterized cell type ( Supplementary Fig.…”

Mitochondrial dysfunction and endoplasmic reticulum stress in the promotion of fibrosis in obstructive nephropathy induced by unilateral ureteral obstruction

“…After surgery, the contralateral UUO‐NOKs experience compensatory growth with little structural change 43 . Meanwhile, UUO‐OKs exhibit rapid loss of proximal tubular mass at 7dUUO followed by severe atrophy at 14dUUO 43 . Additionally, in UUO‐OKs, renal blood flow and oxygen tension decrease in both cortical (since 4hUUO) and medullary (since 8hUUO) sections, 18 which has been hypothesized to have significant effects on substrates' availability and energy metabolism, mainly in UUO‐OKs.…”

Species diversity regarding the presence of proximal tubular progenitor cells of the kidney

“…Recently it was reported that cells morphologically similar to human PTPCs were found in the S3 segment, pars recta, in male mice. 15 The cells were characterized by positive staining for vimentin, but in contrast to human PTPCs the cells had abundant mitochondria. These mitochondrion high cells transiently increased in numbers following UUO, but were subsequently lost, due to atrophy after a few days.…”