Recurrent FAN1 p.W707X Pathogenic Variant Originating Before ad 1800 Underlies High Frequency of Karyomegalic Interstitial Nephritis in South Pacific Islands.
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ABSTRACT:
SUBMITTER: Gueguen L
PROVIDER: S-EPMC8344115 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundKaryomegalic interstitial nephritis (KIN) is a rare disease entity first described by Burry in 1974. The term KIN was introduced by Mihatsch et al. in 1979. KIN is characterized by chronic tubulointerstitial nephritis associated with enlarged tubular epithelial cell nuclei, which leads to a progressive decline of renal function. The prevalence of this disease is less than 1% of all biopsies, and its pathogenesis is unclear. KIN results from mutations in FAN1 (FANCD2/FANCI-Associated Nuclease 1), a gene involved in the DNA damage response pathway, particularly in the kidney. In this study, we report two Tunisian consanguineous families with KIN caused by mutations in the FAN1 gene.MethodsDirect sequencing of the coding regions and flanking intronic sequences of the FAN1 gene was performed in three affected members. Three prediction programs (Polyphen-2 software, SIFT, and MutationTaster) were used to predict the functional effect of the detected variations.ResultsTwo causative frameshift variants in the FAN1 gene were identified in each family: The previously described frameshift mutation c.2616delA (p.Asp873ThrfsTer17) and a novel mutation c.2603delT (p.Leu868ArgfsTer22) classified as "pathogenic" according to the American College of Medical Genetics and Genomics (ACMG) guidelines.ConclusionTo our best knowledge, this is the first Tunisian study involving familial cases of KIN with mutations in the FAN1 gene. We hypothesize that these findings can expand the mutational spectrum of KIN and provide valuable information on the genetic cause of KIN.
| S-EPMC8201669 | biostudies-literature
Project description:BackgroundKaryomegalic interstitial nephritis (KIN) is a rare hereditary cause of chronic kidney disease. It typically causes progressive renal impairment with haemoproteinuria requiring renal replacement therapy before 50 years of age. It has been associated with mutations in the Fanconi anaemia-associated nuclease 1 (FAN1) gene and has an autosomal recessive pattern of inheritance. Leukocyte chemotactic factor 2 amyloidosis (ALECT2) is the third most common cause of amyloid nephropathy presenting with chronic kidney disease and variable proteinuria. We report a novel mutation in the FAN1 gene causing KIN and to our knowledge, the first case of concurrent KIN and ALECT.Case presentationWe describe the case of 44 year old Pakistani woman, presenting with stage four non-proteinuric chronic kidney disease, and a brother on dialysis. Renal biopsy demonstrated KIN and concurrent ALECT2. Genetic sequencing identified a novel FAN1 mutation as the cause of her KIN and she is being managed conservatively for chronic kidney disease. Her brother also had KIN with no evidence of amyloidosis and is being worked up for kidney transplantation.ConclusionThis case highlights two rare causes of chronic kidney disease considered underdiagnosed in the wider population due to their lack of proteinuria, and may contribute to the cohort of patients reaching end stage renal disease without a renal biopsy. We report a novel mutation of the FAN1 gene causing KIN, and report the first case of concurrent KIN and ALECT2. This case highlights the importance of renal biopsy in chronic kidney disease of unclear aetiology which has resulted in a diagnosis with implications for kidney transplantation and family planning.
| S-EPMC7049196 | biostudies-literature
Project description:Chronic kidney disease (CKD) represents a major health burden. Its central feature of renal fibrosis is not well understood. By exome sequencing, we identified mutations in FAN1 as a cause of karyomegalic interstitial nephritis (KIN), a disorder that serves as a model for renal fibrosis. Renal histology in KIN is indistinguishable from that of nephronophthisis, except for the presence of karyomegaly. The FAN1 protein has nuclease activity and acts in DNA interstrand cross-link (ICL) repair within the Fanconi anemia DNA damage response (DDR) pathway. We show that cells from individuals with FAN1 mutations have sensitivity to the ICL-inducing agent mitomycin C but do not exhibit chromosome breakage or cell cycle arrest after diepoxybutane treatment, unlike cells from individuals with Fanconi anemia. We complemented ICL sensitivity with wild-type FAN1 but not with cDNA having mutations found in individuals with KIN. Depletion of fan1 in zebrafish caused increased DDR, apoptosis and kidney cysts. Our findings implicate susceptibility to environmental genotoxins and inadequate DNA repair as novel mechanisms contributing to renal fibrosis and CKD.
| S-EPMC3412140 | biostudies-literature
Project description:The Fan1 endonuclease is required for repair of DNA interstrand cross-links (ICLs). Mutations in human Fan1 cause karyomegalic interstitial nephritis (KIN), but it is unclear whether defective ICL repair is responsible or whether Fan1 nuclease activity is relevant. We show that Fan1 nuclease-defective (Fan1(nd/nd)) mice develop a mild form of KIN. The karyomegalic nuclei from Fan1(nd/nd) kidneys are polyploid, and fibroblasts from Fan1(nd/nd) mice become polyploid upon ICL induction, suggesting that defective ICL repair causes karyomegaly. Thus, Fan1 nuclease activity promotes ICL repair in a manner that controls ploidy, a role that we show is not shared by the Fanconi anemia pathway or the Slx4-Slx1 nuclease also involved in ICL repair.
| S-EPMC4803050 | biostudies-literature
Project description:Karyomegalic interstitial nephritis (KIN) is a chronic interstitial nephropathy characterized by tubulointerstitial nephritis and formation of enlarged nuclei in the kidneys and other tissues. We recently reported that recessive mutations in the gene encoding FANCD2/FANCI-associated nuclease 1 (FAN1) cause KIN in humans. FAN1 is a major component of the Fanconi anemia-related pathway of DNA damage response (DDR) signaling. To study the pathogenesis of KIN, we generated a Fan1 knockout mouse model, with abrogation of Fan1 expression confirmed by quantitative RT-PCR. Challenging Fan1-/- and wild-type mice with 20 mg/kg cisplatin caused AKI in both genotypes. In contrast, chronic injection of cisplatin at 2 mg/kg induced KIN that led to renal failure within 5 weeks in Fan1-/- mice but not in wild-type mice. Cell culture studies showed decreased survival and reduced colony formation of Fan1-/- mouse embryonic fibroblasts and bone marrow mesenchymal stem cells compared with wild-type counterparts in response to treatment with genotoxic agents, suggesting that FAN1 mutations cause chemosensitivity and bone marrow failure. Our data show that Fan1 is involved in the physiologic response of kidney tubular cells to DNA damage, which contributes to the pathogenesis of CKD. Moreover, Fan1-/- mice provide a new model with which to study the pathomechanisms of CKD.
| S-EPMC5118483 | biostudies-literature
Project description:The balance of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) determines the integrity of the extracellular matrix. TIMP3 is the most highly expressed tissue inhibitor of metalloproteinase (TIMP) in the kidney, but its function in renal disease is incompletely understood. In this study, TIMP3-/- mice demonstrated an age-dependent chronic tubulointerstitial fibrosis. After unilateral ureteral obstruction (UUO), young TIMP3-/- mice exhibited increased renal injury (tubular atrophy, cortical and medullary thinning, and vascular damage) compared with wild-type mice. In addition, TIMP3-/- mice had greater interstitial fibrosis; increased synthesis and deposition of type I collagen; increased activation of fibroblasts; enhanced apoptosis; and greater activation of MMP2, but not MMP9, after UUO. TIMP3 deficiency also led to accelerated processing of TNFalpha, demonstrated by significantly higher TACE activity and greater soluble TNFalpha levels by 3 d after UUO. The additional deletion of TNFalpha markedly reduced inflammation, apoptosis, and induction of a number of MMPs. Moreover, inhibition of MMPs in TIMP3-/-/TNFalpha-/- mice further abrogated postobstructive injury and prevented tubulointerestitial fibrosis. In humans, TIMP3 expression increased in the renal arteries and proximal tubules of subjects with diabetic nephropathy or chronic allograft nephropathy. Taken together, these results provide evidence that TIMP3 is an important mediator of kidney injury, and regulating its activity may have therapeutic benefit for patients with kidney disease.
| S-EPMC2689897 | biostudies-other
Project description:This study examines the effect of interstitial inflammation and interstitial fibrosis and tubular atrophy on renal survival in lupus nephritis.Baseline characteristics, initial (n = 301) and repeat biopsies (n = 94) and clinical outcomes for patients with biopsy-proven lupus nephritis from 1998 to 2014 were retrospectively collected from the medical record. Clinical and morphologic variables were evaluated using a Cox proportional hazards model and multiple imputation to address missing data. Renal survival was defined as the time from initial biopsy to end-stage renal disease [estimated glomerular filtration rate (eGFR) <15?mL/min/1.73 m2], dialysis or transplant.A total of 218 patients had follow-up and Class IV had worse renal survival, especially in patients with active and chronic glomerular lesions {relative to non-IV; Class IV-A: hazard ratio [HR] 0.92 [95% confidence interval (CI) 0.41-2.04], Class IV-AC: HR 5.02 [95% CI 2.70-9.36]}. Interstitial inflammation grade [relative to interstitial inflammation <5%; interstitial inflammation 5-25%: HR 2.36 (95% CI 1.13-4.91), interstitial inflammation 25-50%: HR 3.84 (95% CI 1.53-9.62), interstitial inflammation >50%: HR 7.67 (95% CI 3.75-15.67)] and increased interstitial fibrosis and tubular atrophy (IFTA) category [relative to IFTA <5%; IFTA 5-25%: HR 3.93 (95% CI 1.58-9.75), IFTA 25-50%: HR 4.01 (95% CI 1.37-11.70), IFTA >50%: HR 13.99 (95% CI 4.91-39.83)] predicted worse renal survival among all patients and those with Class IV on initial and repeat biopsy (n = 94) in a dose-dependent manner. Interstitial inflammation grade and IFTA category were significant predictors of renal survival in a multivariable model adjusted for age, gender, race, ethnicity and serum creatinine.Interstitial inflammation and IFTA independently affect renal survival and grading these lesions stratifies risk within the International Society of Nephrology and Renal Pathology Society classification of lupus nephritis.
| S-EPMC5888814 | biostudies-other
Project description:WNT signaling mediates various physiological and pathological processes. We previously showed that WNT10A is a novel angio/stromagenic factor involved in such processes as tumor growth, wound healing and tissue fibrosis. In this study, we investigated the role of WNT10A in promoting the fibrosis that is central to the pathology of acute interstitial nephritis (AIN). We initially asked whether there is an association between kidney function (estimated glomerular filtration rate; eGFR) and WNT10A expression using kidney biopsies from 20 patients with AIN. Interestingly, patients with WNT10A expression had significantly lower eGFR than WNT10A-negative patients. However, changes in kidney function were not related to the level of expression of other WNT family members. Furthermore, there was positive correlation between WNT10A and ?-SMA expression. We next investigated the involvement of WNT10A in kidney fibrosis processes using COS1 cells, a kidney fibroblast cell line. WNT10A overexpression increased the level of expression of fibronectin and peroxiredoxin 5. Furthermore, WNT10A overexpression renders cells resistant to apoptosis induced by hydrogen peroxide and high glucose. Collectively, WNT10A may induce kidney fibrosis and associate with kidney dysfunction in AIN.
| S-EPMC4108433 | biostudies-literature
Project description:Tertiary lymphoid structure signatures are associated with immune checkpoint inhibitor related acute interstitial nephritis
| EGAD00010002406 | EGA
Project description:Carp interstitial nephritis and gill necrosis virus (CNGV) is an unclassified large DNA virus that morphologically resembles members of the Herpesviridae but contains a large (ca. approximately 280-kbp) linear double-stranded DNA. This virus has also been named koi herpesvirus, koi herpes-like virus, and cyprinid herpesvirus 3. CNGV is the cause of a lethal disease that afflicts common carp and koi. By using immunohistochemistry, molecular analysis, and electron microscopy we previously demonstrated that this virus is present mainly in the intestine and kidney of infected fish. Based on these observations, we postulated that viruses and/or viral components may appear in droppings of infected carp. Here we report that (i) by using PCR we demonstrated that fish droppings contain viral DNA, (ii) fish droppings contain viral antigens which are useful for CNGV diagnosis, and (iii) fish droppings contain active virus which can infect cultured common carp brain cells and induce the disease in naïve fish following inoculation. Thus, our findings show that CNGV can be identified by using droppings without taking biopsies or killing fish and that infectious CNGV is present in the stools of sick fish. The possibility that fish droppings preserve viable CNGV during the nonpermissive seasons is discussed.
| S-EPMC1287658 | biostudies-literature