Aromatase deficiency causes altered expression of molecules critical for calcium reabsorption in the kidneys of female mice

Orhan K. Öz, Asghar Hajibeigi, Kevin Howard, Carolyn L. Cummins, Monique Van Abel, Rene J M Bindels, R. Ann Word, Makoto Kuro-o, Charles Y C Pak, Joseph E. Zerwekh

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Abstract

Kidney stones increase after menopause, suggesting a role for estrogen deficiency. ArKO mice have hypercalciuria and lower levels of calcium transport proteins, whereas levels of the Klotho protein are elevated. Thus, estrogen deficiency is sufficient to cause altered renal calcium handling. Introduction: The incidence of renal stones increases in women after menopause, implicating a possible role for estrogen deficiency. We used the aromatase deficient (ArKO) mouse, a model of estrogen deficiency, to test the hypothesis that estrogen deficiency would increase urinary calcium excretion and alter the expression of molecular regulators of renal calcium reabsorption. Materials and Methods: Adult female wildtype (WT), ArKO, and estradiol-treated ArKO mice (n = 5-12/group) were used to measure urinary calcium in the fed and lasting states, relative expression level of some genes involved in calcium reabsorption in the distal convoluted tubule by real-time PCR, and protein expression by Western blotting or immunohistochemistry. Plasma membrane calcium ATPase (PMCA) activity was measured in kidney membrane preparations. ANOVA was used to test for differences between groups followed by posthoc analysis with Dunnett's test. Results: Compared with WT, urinary Ca:Cr ratios were elevated in ArKO mice, renal mRNA levels of transient receptor potential cation channel vallinoid subfamily member 5 (TRPV5), TRPV6, calbindin-D28k, the Na+/Ca+ exchanger (NCX1), and the PMCA1b were significantly decreased, and klotho mRNA and protein levels were elevated. Estradiol treatment of ArKO mice normalized urinary calcium excretion, renal mRNA levels of TRPV5, calbindin-D28k, PMCA1b, and klotho, as well as protein levels of calbindin-D28k, and Klotho. ArKO mice treated wilh estradiol had significantly greater PMCA activity than either untreated ArKO mice or WT mice. Conclusions: Estrogen deficiency caused by aromatase inactivation is sufficient for renal calcium loss. Changes in estradiol levels are associated with coordinated changes in expression of many proteins involved in distal tubule calcium reabsorption. Estradiol seems to act at the genomic level by increasing or decreasing (klotho) protein expression and nongenomically by increasing PMCA activity. PMCA, not NCX1, is likely responsible for extruding calcium in response to in vivo estradiol hormonal challenge. These data provide potential mechanisms for regulation of renal calcium handling in response to changes in serum estrogen levels.

Original languageEnglish (US)
Pages (from-to)1893-1902
Number of pages10
JournalJournal of Bone and Mineral Research
Volume22
Issue number12
DOIs
StatePublished - Dec 2007

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Calcium
Kidney
Plasma Membrane Calcium-Transporting ATPases
Estrogens
Estradiol
Calbindin 1
Menopause
Messenger RNA
Aromatase deficiency
Transient Receptor Potential Channels
Hypercalciuria
Proteins
Kidney Calculi
Aromatase
Real-Time Polymerase Chain Reaction
Analysis of Variance
Carrier Proteins
Western Blotting
Immunohistochemistry
Membranes

Keywords

  • Aromatase
  • Calcium transport proteins
  • Estrogen
  • Kidney
  • Klotho

ASJC Scopus subject areas

  • Surgery

Cite this

Aromatase deficiency causes altered expression of molecules critical for calcium reabsorption in the kidneys of female mice. / Öz, Orhan K.; Hajibeigi, Asghar; Howard, Kevin; Cummins, Carolyn L.; Van Abel, Monique; Bindels, Rene J M; Word, R. Ann; Kuro-o, Makoto; Pak, Charles Y C; Zerwekh, Joseph E.

In: Journal of Bone and Mineral Research, Vol. 22, No. 12, 12.2007, p. 1893-1902.

Research output: Contribution to journalArticle

Öz, Orhan K. ; Hajibeigi, Asghar ; Howard, Kevin ; Cummins, Carolyn L. ; Van Abel, Monique ; Bindels, Rene J M ; Word, R. Ann ; Kuro-o, Makoto ; Pak, Charles Y C ; Zerwekh, Joseph E. / Aromatase deficiency causes altered expression of molecules critical for calcium reabsorption in the kidneys of female mice. In: Journal of Bone and Mineral Research. 2007 ; Vol. 22, No. 12. pp. 1893-1902.
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title = "Aromatase deficiency causes altered expression of molecules critical for calcium reabsorption in the kidneys of female mice",
abstract = "Kidney stones increase after menopause, suggesting a role for estrogen deficiency. ArKO mice have hypercalciuria and lower levels of calcium transport proteins, whereas levels of the Klotho protein are elevated. Thus, estrogen deficiency is sufficient to cause altered renal calcium handling. Introduction: The incidence of renal stones increases in women after menopause, implicating a possible role for estrogen deficiency. We used the aromatase deficient (ArKO) mouse, a model of estrogen deficiency, to test the hypothesis that estrogen deficiency would increase urinary calcium excretion and alter the expression of molecular regulators of renal calcium reabsorption. Materials and Methods: Adult female wildtype (WT), ArKO, and estradiol-treated ArKO mice (n = 5-12/group) were used to measure urinary calcium in the fed and lasting states, relative expression level of some genes involved in calcium reabsorption in the distal convoluted tubule by real-time PCR, and protein expression by Western blotting or immunohistochemistry. Plasma membrane calcium ATPase (PMCA) activity was measured in kidney membrane preparations. ANOVA was used to test for differences between groups followed by posthoc analysis with Dunnett's test. Results: Compared with WT, urinary Ca:Cr ratios were elevated in ArKO mice, renal mRNA levels of transient receptor potential cation channel vallinoid subfamily member 5 (TRPV5), TRPV6, calbindin-D28k, the Na+/Ca+ exchanger (NCX1), and the PMCA1b were significantly decreased, and klotho mRNA and protein levels were elevated. Estradiol treatment of ArKO mice normalized urinary calcium excretion, renal mRNA levels of TRPV5, calbindin-D28k, PMCA1b, and klotho, as well as protein levels of calbindin-D28k, and Klotho. ArKO mice treated wilh estradiol had significantly greater PMCA activity than either untreated ArKO mice or WT mice. Conclusions: Estrogen deficiency caused by aromatase inactivation is sufficient for renal calcium loss. Changes in estradiol levels are associated with coordinated changes in expression of many proteins involved in distal tubule calcium reabsorption. Estradiol seems to act at the genomic level by increasing or decreasing (klotho) protein expression and nongenomically by increasing PMCA activity. PMCA, not NCX1, is likely responsible for extruding calcium in response to in vivo estradiol hormonal challenge. These data provide potential mechanisms for regulation of renal calcium handling in response to changes in serum estrogen levels.",
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author = "{\"O}z, {Orhan K.} and Asghar Hajibeigi and Kevin Howard and Cummins, {Carolyn L.} and {Van Abel}, Monique and Bindels, {Rene J M} and Word, {R. Ann} and Makoto Kuro-o and Pak, {Charles Y C} and Zerwekh, {Joseph E.}",
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T1 - Aromatase deficiency causes altered expression of molecules critical for calcium reabsorption in the kidneys of female mice

AU - Öz, Orhan K.

AU - Hajibeigi, Asghar

AU - Howard, Kevin

AU - Cummins, Carolyn L.

AU - Van Abel, Monique

AU - Bindels, Rene J M

AU - Word, R. Ann

AU - Kuro-o, Makoto

AU - Pak, Charles Y C

AU - Zerwekh, Joseph E.

PY - 2007/12

Y1 - 2007/12

N2 - Kidney stones increase after menopause, suggesting a role for estrogen deficiency. ArKO mice have hypercalciuria and lower levels of calcium transport proteins, whereas levels of the Klotho protein are elevated. Thus, estrogen deficiency is sufficient to cause altered renal calcium handling. Introduction: The incidence of renal stones increases in women after menopause, implicating a possible role for estrogen deficiency. We used the aromatase deficient (ArKO) mouse, a model of estrogen deficiency, to test the hypothesis that estrogen deficiency would increase urinary calcium excretion and alter the expression of molecular regulators of renal calcium reabsorption. Materials and Methods: Adult female wildtype (WT), ArKO, and estradiol-treated ArKO mice (n = 5-12/group) were used to measure urinary calcium in the fed and lasting states, relative expression level of some genes involved in calcium reabsorption in the distal convoluted tubule by real-time PCR, and protein expression by Western blotting or immunohistochemistry. Plasma membrane calcium ATPase (PMCA) activity was measured in kidney membrane preparations. ANOVA was used to test for differences between groups followed by posthoc analysis with Dunnett's test. Results: Compared with WT, urinary Ca:Cr ratios were elevated in ArKO mice, renal mRNA levels of transient receptor potential cation channel vallinoid subfamily member 5 (TRPV5), TRPV6, calbindin-D28k, the Na+/Ca+ exchanger (NCX1), and the PMCA1b were significantly decreased, and klotho mRNA and protein levels were elevated. Estradiol treatment of ArKO mice normalized urinary calcium excretion, renal mRNA levels of TRPV5, calbindin-D28k, PMCA1b, and klotho, as well as protein levels of calbindin-D28k, and Klotho. ArKO mice treated wilh estradiol had significantly greater PMCA activity than either untreated ArKO mice or WT mice. Conclusions: Estrogen deficiency caused by aromatase inactivation is sufficient for renal calcium loss. Changes in estradiol levels are associated with coordinated changes in expression of many proteins involved in distal tubule calcium reabsorption. Estradiol seems to act at the genomic level by increasing or decreasing (klotho) protein expression and nongenomically by increasing PMCA activity. PMCA, not NCX1, is likely responsible for extruding calcium in response to in vivo estradiol hormonal challenge. These data provide potential mechanisms for regulation of renal calcium handling in response to changes in serum estrogen levels.

AB - Kidney stones increase after menopause, suggesting a role for estrogen deficiency. ArKO mice have hypercalciuria and lower levels of calcium transport proteins, whereas levels of the Klotho protein are elevated. Thus, estrogen deficiency is sufficient to cause altered renal calcium handling. Introduction: The incidence of renal stones increases in women after menopause, implicating a possible role for estrogen deficiency. We used the aromatase deficient (ArKO) mouse, a model of estrogen deficiency, to test the hypothesis that estrogen deficiency would increase urinary calcium excretion and alter the expression of molecular regulators of renal calcium reabsorption. Materials and Methods: Adult female wildtype (WT), ArKO, and estradiol-treated ArKO mice (n = 5-12/group) were used to measure urinary calcium in the fed and lasting states, relative expression level of some genes involved in calcium reabsorption in the distal convoluted tubule by real-time PCR, and protein expression by Western blotting or immunohistochemistry. Plasma membrane calcium ATPase (PMCA) activity was measured in kidney membrane preparations. ANOVA was used to test for differences between groups followed by posthoc analysis with Dunnett's test. Results: Compared with WT, urinary Ca:Cr ratios were elevated in ArKO mice, renal mRNA levels of transient receptor potential cation channel vallinoid subfamily member 5 (TRPV5), TRPV6, calbindin-D28k, the Na+/Ca+ exchanger (NCX1), and the PMCA1b were significantly decreased, and klotho mRNA and protein levels were elevated. Estradiol treatment of ArKO mice normalized urinary calcium excretion, renal mRNA levels of TRPV5, calbindin-D28k, PMCA1b, and klotho, as well as protein levels of calbindin-D28k, and Klotho. ArKO mice treated wilh estradiol had significantly greater PMCA activity than either untreated ArKO mice or WT mice. Conclusions: Estrogen deficiency caused by aromatase inactivation is sufficient for renal calcium loss. Changes in estradiol levels are associated with coordinated changes in expression of many proteins involved in distal tubule calcium reabsorption. Estradiol seems to act at the genomic level by increasing or decreasing (klotho) protein expression and nongenomically by increasing PMCA activity. PMCA, not NCX1, is likely responsible for extruding calcium in response to in vivo estradiol hormonal challenge. These data provide potential mechanisms for regulation of renal calcium handling in response to changes in serum estrogen levels.

KW - Aromatase

KW - Calcium transport proteins

KW - Estrogen

KW - Kidney

KW - Klotho

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