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Altered gene expression in kidneys of mice with 2,8-dihydroxyadenine nephrolithiasis
1Departments of Medical and Molecular Genetics and Anatomy, Indiana University School of Medicine, Indianapolis, USA.
Background:
We have developed a knockout mouse model for adenine phosphoribosyltransferase (APRT) deficiency, a condition that often leads to 2,8-dihydroxyadenine (DHA) nephrolithiasis in humans. Aprt knockout male mice develop severe renal damage by three months of age, but this is strain specific. Renal damage in female mice is less pronounced than in males. The gene level changes that promote renal injury in APRT-deficient mice are not known.
Methods:
We used mRNA differential display polymerase chain reaction (DD-PCR) to analyze renal gene expression changes in APRT-deficient male and female mice (strain C3H) compared with age- and sex-matched Aprt heterozygote controls. The differentially amplified bands were reamplified, cloned, sequenced, and queried against the National Center for Biotechnology Information nonredundant databases using the Basic Alignment Search Tool. Relative quantitative reverse transcription-polymerase chain reaction was used to confirm the results of DD-PCR for a selected number of genes in one-, three-, and six-month-old male and female mice.
Results:
Sixty-three differentially amplified bands were identified, including 21 for known genes, and 8 of these were examined further. In three-month-old APRT-deficient male mice, the expression of C10 was increased tenfold, and there was a fourfold to sevenfold increase in the expression of a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS-1), MGP (matrix Gla protein), and lysyl oxidase (LOX). The expression of cholecystokinin-A receptor (CCKAR), imprinted multimembrane-spanning polyspecific transporter-like gene 1 (IMPT-1), and kidney androgen-regulated protein (KAP) was diminished twofold to fourfold, but there was little or no change in the expression of organic anion transporter (OATP). Except for a more than tenfold increase in C10 expression and up to tenfold decrease in KAP expression, APRT-deficient female mice did not show significant changes in gene expression compared with controls.
Conclusions:
These findings suggest that (1) there are sex-related differences in gene expression in DHA lithiasis, possibly caused by increased deposition of DHA crystals in male compared with female kidneys; and (2) the expression of certain genes (for example, C10) may simply be an indication of nonspecific cellular stimulation and may not be related to renal injury.
Insights
Adenine phosphoribosyltransferase (APRT) deficiency causes kidney damage in mice, with males showing more severe renal injury and distinct gene expression changes than females. These findings highlight sex-related differences in 2,8-dihydroxyadenine (DHA) lithiasis pathogenesis.
Area of Science:
- Nephrology
- Genetics
- Biochemistry
Background:
- Adenine phosphoribosyltransferase (APRT) deficiency causes 2,8-dihydroxyadenine (DHA) nephrolithiasis.
- APRT knockout mice exhibit strain-specific renal damage, with males more severely affected than females.
- Underlying gene expression changes in APRT-deficient kidneys remain largely unknown.
Purpose of the Study:
- To investigate sex-specific renal gene expression alterations in APRT-deficient mice.
- To identify potential molecular mechanisms driving renal injury in DHA nephrolithiasis.
Main Methods:
- Utilized mRNA differential display polymerase chain reaction (DD-PCR) to compare gene expression in APRT-deficient and control mice.
- Confirmed differentially expressed genes using relative quantitative reverse transcription-polymerase chain reaction (RT-PCR).
- Analyzed gene expression in male and female mice at one, three, and six months of age.
Main Results:
- Identified 63 differentially expressed gene bands, including 21 known genes.
- In male mice, significant upregulation of C10, ADAMTS-1, MGP, and LOX, and downregulation of CCKAR, IMPT-1, and KAP.
- Female mice showed minimal significant gene expression changes compared to controls, except for C10 and KAP.
Conclusions:
- Sex-related differences in gene expression are evident in DHA lithiasis.
- Increased DHA crystal deposition in male kidneys may contribute to observed sex differences.
- Some gene expression changes, like C10, might reflect general cellular responses rather than direct links to renal injury.