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Evidence for a causal link between adaptor protein PDZK1 downregulation and Na⁺/H⁺ exchanger NHE3 dysfunction in human and murine colitis.

Yeruva S, Chodisetti G, Luo M, Chen M, Cinar A, Ludolph L, Lünnemann M, Goldstein J, Singh AK, Riederer B, Bachmann O, Bleich A, Gereke M, Bruder D, Hagen S, He P, Yun C, Seidler U - Pflugers Arch. (2014)

Bottom Line: A dysfunction of the Na(+)/H(+) exchanger isoform 3 (NHE3) significantly contributes to the reduced salt absorptive capacity of the inflamed intestine.PDZK1 mRNA and protein expression was strongly decreased in inflamed human and murine intestinal tissue as compared to inactive disease or control tissue, whereas that of NHE3 or NHERF1 was not.We conclude that a decrease in PDZK1 expression, whether induced by inflammation, shRNA-mediated knockdown, or heterozygous breeding, is associated with a decreased NHE3 transport rate in human and murine enterocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625, Hannover, Germany.

ABSTRACT
A dysfunction of the Na(+)/H(+) exchanger isoform 3 (NHE3) significantly contributes to the reduced salt absorptive capacity of the inflamed intestine. We previously reported a strong decrease in the NHERF family member PDZK1 (NHERF3), which binds to NHE3 and regulates its function in a mouse model of colitis. The present study investigates whether a causal relationship exists between the decreased PDZK1 expression and the NHE3 dysfunction in human and murine intestinal inflammation. Biopsies from the colon of patients with ulcerative colitis, murine inflamed ileal and colonic mucosa, NHE3-transfected Caco-2BBe colonic cells with short hairpin RNA (shRNA) knockdown of PDZK1, and Pdzk1-gene-deleted mice were studied. PDZK1 mRNA and protein expression was strongly decreased in inflamed human and murine intestinal tissue as compared to inactive disease or control tissue, whereas that of NHE3 or NHERF1 was not. Inflamed human and murine intestinal tissues displayed correct brush border localization of NHE3 but reduced acid-activated NHE3 transport activity. A similar NHE3 transport defect was observed when PDZK1 protein content was decreased by shRNA knockdown in Caco-2BBe cells or when enterocyte PDZK1 protein content was decreased to similar levels as found in inflamed mucosa by heterozygote breeding of Pdzk1-gene-deleted and WT mice. We conclude that a decrease in PDZK1 expression, whether induced by inflammation, shRNA-mediated knockdown, or heterozygous breeding, is associated with a decreased NHE3 transport rate in human and murine enterocytes. We therefore hypothesize that inflammation-induced loss of PDZK1 expression may contribute to the NHE3 dysfunction observed in the inflamed intestine.

No MeSH data available.


Related in: MedlinePlus

PDZK1 protein expression in the distal ileum of TnfΔARE+/+ and +/− mice. PDZK1 protein expression was analyzed by Western analysis in the total tissue lysates (n = 2 pairs of mice) and scraped mucosa (n = 5 pairs of mice) of distal ileum from TnfΔARE mice. PDZK1 protein abundance was found to be strongly decreased in both scraped mucosa and total tissue lysates from the distal ileum of TnfΔARE+/− mice as compared to WT littermates
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Fig3: PDZK1 protein expression in the distal ileum of TnfΔARE+/+ and +/− mice. PDZK1 protein expression was analyzed by Western analysis in the total tissue lysates (n = 2 pairs of mice) and scraped mucosa (n = 5 pairs of mice) of distal ileum from TnfΔARE mice. PDZK1 protein abundance was found to be strongly decreased in both scraped mucosa and total tissue lysates from the distal ileum of TnfΔARE+/− mice as compared to WT littermates

Mentions: Protein expression of PDZK1 was measured in total tissue lysates or in scraped mucosa of the distal ileum in TnfΔARE+/+ and TnfΔARE+/− mice, the strong reduction in PDZK1 protein content was confirmed both in total tissue lysates and in the scraped mucosa (Fig. 3).Fig. 3


Evidence for a causal link between adaptor protein PDZK1 downregulation and Na⁺/H⁺ exchanger NHE3 dysfunction in human and murine colitis.

Yeruva S, Chodisetti G, Luo M, Chen M, Cinar A, Ludolph L, Lünnemann M, Goldstein J, Singh AK, Riederer B, Bachmann O, Bleich A, Gereke M, Bruder D, Hagen S, He P, Yun C, Seidler U - Pflugers Arch. (2014)

PDZK1 protein expression in the distal ileum of TnfΔARE+/+ and +/− mice. PDZK1 protein expression was analyzed by Western analysis in the total tissue lysates (n = 2 pairs of mice) and scraped mucosa (n = 5 pairs of mice) of distal ileum from TnfΔARE mice. PDZK1 protein abundance was found to be strongly decreased in both scraped mucosa and total tissue lysates from the distal ileum of TnfΔARE+/− mice as compared to WT littermates
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4383727&req=5

Fig3: PDZK1 protein expression in the distal ileum of TnfΔARE+/+ and +/− mice. PDZK1 protein expression was analyzed by Western analysis in the total tissue lysates (n = 2 pairs of mice) and scraped mucosa (n = 5 pairs of mice) of distal ileum from TnfΔARE mice. PDZK1 protein abundance was found to be strongly decreased in both scraped mucosa and total tissue lysates from the distal ileum of TnfΔARE+/− mice as compared to WT littermates
Mentions: Protein expression of PDZK1 was measured in total tissue lysates or in scraped mucosa of the distal ileum in TnfΔARE+/+ and TnfΔARE+/− mice, the strong reduction in PDZK1 protein content was confirmed both in total tissue lysates and in the scraped mucosa (Fig. 3).Fig. 3

Bottom Line: A dysfunction of the Na(+)/H(+) exchanger isoform 3 (NHE3) significantly contributes to the reduced salt absorptive capacity of the inflamed intestine.PDZK1 mRNA and protein expression was strongly decreased in inflamed human and murine intestinal tissue as compared to inactive disease or control tissue, whereas that of NHE3 or NHERF1 was not.We conclude that a decrease in PDZK1 expression, whether induced by inflammation, shRNA-mediated knockdown, or heterozygous breeding, is associated with a decreased NHE3 transport rate in human and murine enterocytes.

View Article: PubMed Central - PubMed

Affiliation: Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Carl-Neuberg-Straße 1, 30625, Hannover, Germany.

ABSTRACT
A dysfunction of the Na(+)/H(+) exchanger isoform 3 (NHE3) significantly contributes to the reduced salt absorptive capacity of the inflamed intestine. We previously reported a strong decrease in the NHERF family member PDZK1 (NHERF3), which binds to NHE3 and regulates its function in a mouse model of colitis. The present study investigates whether a causal relationship exists between the decreased PDZK1 expression and the NHE3 dysfunction in human and murine intestinal inflammation. Biopsies from the colon of patients with ulcerative colitis, murine inflamed ileal and colonic mucosa, NHE3-transfected Caco-2BBe colonic cells with short hairpin RNA (shRNA) knockdown of PDZK1, and Pdzk1-gene-deleted mice were studied. PDZK1 mRNA and protein expression was strongly decreased in inflamed human and murine intestinal tissue as compared to inactive disease or control tissue, whereas that of NHE3 or NHERF1 was not. Inflamed human and murine intestinal tissues displayed correct brush border localization of NHE3 but reduced acid-activated NHE3 transport activity. A similar NHE3 transport defect was observed when PDZK1 protein content was decreased by shRNA knockdown in Caco-2BBe cells or when enterocyte PDZK1 protein content was decreased to similar levels as found in inflamed mucosa by heterozygote breeding of Pdzk1-gene-deleted and WT mice. We conclude that a decrease in PDZK1 expression, whether induced by inflammation, shRNA-mediated knockdown, or heterozygous breeding, is associated with a decreased NHE3 transport rate in human and murine enterocytes. We therefore hypothesize that inflammation-induced loss of PDZK1 expression may contribute to the NHE3 dysfunction observed in the inflamed intestine.

No MeSH data available.


Related in: MedlinePlus