DNA damage and expression of DNA methylation modulators in urine-derived cells of patients with hypertension and diabetes

Abstract

Diabetes and hypertension have become the primary causes of chronic kidney disease worldwide. However, there are no established markers for early diagnosis or predicting renal prognosis. Here, we investigated the expression profiles of DNA repair and DNA methylation factors in human urinederived cells as a possible diagnostic or renal prognosis-predicting marker. A total of 75 subjects, aged 63.3 ± 1.9 years old, were included in this study. DNA and RNA were extracted from 50 mL of urine samples. We evaluated DnA double-strand breaks (DSBs) by the quantitative long distance-PCR method and performed real-time RT-PCR analysis to analyze the expression of renal cell-specific markers, DNA DSB repair factor KAT5, DNA methyltransferases DNMTs, and demethylation enzymes tets. in patients with hypertension and diabetes, DnA DSBs of the nephrin gene increased with decreased urine KAT5/nephrin expression, consistent with our previous study (Cell Rep 2019). In patients with hypertension, DNA DSBs of the AQP1 gene were increased with elevated urine DNMTs/ AQP1 and TETs/AQP1 expression. Moreover, urine DNMTs/AQP1 expression was significantly correlated with the annual eGFR decline rate after adjustment for age, baseline eGFR, the presence of diabetes and the amount of albuminuria, suggesting a possible role as a renal prognosis predictor. The prevalence of chronic kidney disease (CKD) has increased globally and become recognized as a worldwide health problem 1. Specifically, the number of CKD caused by diabetes or hypertension is constantly growing along with rapid aging of the world population. The DNA damage repair system is indispensable for maintaining genome integrity, and accumulation of DNA damage is linked to aging and age-related diseases. Recently, we have reported a possible association of KAT5 (lysine acetyltransferase 5, Tip60)-mediated DNA damage repair and DNA methylation changes in kidney glomerular podocytes 2. KAT5, a repair factor of DNA double-strand breaks (DSBs), is crucial for podocyte maintenance, and deletion of podocyte KAT5 caused an increase in DNA DSBs together with increased DNA methylation and expression of DNA methyltransferase 1 (DNMT1) and DNMT3B. Reduced KAT5 expression was observed in the glomeruli of diabetic nephropathy in mouse models and humans. However, the association of KAT5 expression with DNA DSB levels and kidney disease progression has not been clarified. A kidney biopsy is an invasive procedure that is not often performed in patients with an early stage of hypertension or diabetes. In addition, many histological findings of hypertensive nephrosclerosis and diabetic kidney disease are common and coexist; therefore, it is hard to determine which pathophysiology plays a dominant role in patients with both hypertension and diabetes. Urine examinations are noninvasive procedures, and because they identify changes in gene expression in urine-derived cells 3-6 , they may be particularly useful for the noninvasive assessment of kidney condition and prediction of renal outcomes in early ...

Loss of genome maintenance accelerates podocyte damage and aging

“…The same holds true for factors involved in other forms of DNA maintenance such as the KEOPS complex (Braun et al, 2017; Hecker et al, 2009) or KAT5, a contributor to DNA methylation and non-homologous endjoining repair (Hishikawa et al, 2019). The Itoh group further linked the proteinuric phenotype to DNA double strand breaks and methylation in the promotor region of slit diaphragm protein nephrin and established an association of DNA double strand breaks in glomeruli of patients suffering from IgA nephropathy (Hayashi et al, 2020; Hishikawa et al, 2020). Our analysis adds considerably to this body of evidence, as we identify multiple factors of DNA maintenance, in particular of NER, to be transcriptionally altered in glomeruli of various renal diseases involving pronounced podocyte damage and loss.…”

“…Likewise, glomerular DNA damage was found to be associated with declining kidney function 12 and cells isolated from the urine of patients suffering from diabetes and hypertension showed increased levels of DNA strand breaks 13 . However, a link between DNA damage and podocyte loss, to date, remains unclear.…”

“…Mutations in the kinase, endopeptidase and other proteins of small size (KEOPS) complex genes caused proteinuria and induced DNA damage response (DDR) in vitro (Braun et al, 2017). Likewise, glomerular DNA damage was found to be associated with declining kidney function (Hayashi et al, 2020) and cells isolated from the urine of patients suffering from diabetes and hypertension showed increased levels of DNA strand breaks (Hishikawa et al, 2020). First evidence of nucleotide excision repair (NER) as an essential pathway in kidney health was recently provided through the identification of Ercc1 mutations causing kidney dysfunction (Apelt et al, 2020).…”

Is Vitamin D Deficiency Related to Increased Cancer Risk in Patients with Type 2 Diabetes Mellitus?

“…Studies performed on podocytes derived from mice models of diabetic kidney disease showed decreased expression of KAT5 , that is responsible for acetylation of ataxia telangiectasia mutant (ATM), a key protein in DNA-DSB repair. The decreased activation of ATM resulting from diminished expression of KAT5 disturbs the control of checkpoints connected with cell cycle arrest, DNA repair or apoptosis [ 140 , 141 ]. It was also demonstrated that insulin via the inactivation of glycogen synthase kinase-3 (GSK-3β) led to impaired DNA repair.…”

Circulating Nucleic Acid-Based Biomarkers of Type 2 Diabetes

“…Instead, the researchers have been more interested in developing biomarkers for one specific comorbidity, kidney disease ( Table 9 ) [ 173 , 174 , 175 ]. Because urine examinations identify changes in gene expression in urine-derived cells [ 176 ], they may be helpful for the noninvasive assessment of kidney condition and prediction in early T2D [ 177 ].…”