Alport syndrome (AS) is the most common inherited glomerular disease among patients with chronic kidney disease. With exome sequencing now widely used in clinical practice, pathogenic variants in Alport-related genes (COL4A3/COL4A4/COL4A5) are increasingly identified in patients with diverse phenotypes, including proteinuria‑predominant disease and kidney failure of unknown etiology. Diagnostic complexity further increases when COL4A3/COL4A4/COL4A5 variants are co‑inherited with pathogenic variants associated with other genetic kidney disorders. We reported a 31‑year‑old male presenting with kidney failure, significant proteinuria, familial hematuria and hyperlipidemia. Whole‑exome sequencing (WES) identified two pathogenic variants: a hemizygous COL4A5 variant (c.2105G > A; p.Gly702Asp) and a heterozygous APOE Kyoto variant (c.127C > T; p.Arg43Cys). Given the potential dual diagnosis of AS and lipoprotein glomerulopathy (LPG), a kidney biopsy was performed. Histologic examination revealed uneven thickness of the glomerular basement membrane consistent with the diagnosis of AS, but no LPG-related lesions were observed, indicating incomplete penetrance of APOE Kyoto variant. Cascade family screening detected APOE Kyoto variant in the patient’s father and elder sister, both of whom lacked proteinuria until follow-up period. This case highlights the complementary role of kidney biopsy alongside WES in AS with complex genetic mechanisms. It also illustrates the incomplete penetrance of APOE Kyoto, common among Chinese carriers.

N-acetylated amino acids systemically accumulate in the circulatory system in patients with chronic kidney disease (CKD), raising questions about their roles in peripheral tissues1,2. Here, targeted metabolomics in patients with CKD identified that circulating N-acetylaspartate (NAA) as the metabolite most closely linked to early cardiac dysfunction. In mice, both CKD and exogenous NAA administration induced pronounced cardiac NAA accumulation, resulting in systolic dysfunction and pathological hypertrophy. Activity-based protein profiling identified cytosolic malate dehydrogenase 1 (MDH1) and sirtuin 2 (SIRT2) as direct targets of NAA. NAA acts as a substrate analogue that occupies the MDH1 substrate-binding pocket, competitively inhibits its enzymatic activity, and disrupts the malate–aspartate shuttle, thereby lowering cytosolic and mitochondrial NAD⁺/NADH ratios, suppressing tricarboxylic acid cycle flux, and compromising cardiomyocyte energy metabolism. Notably, we identified SIRT2 as a previously unrecognized NAA hydrolase that specifically binds and hydrolyzes NAA in an NAD⁺-dependent manner, thereby mitigating NAA-induced metabolic stress. Cardiomyocyte-specific restoration of SIRT2 activity in mice reduced cardiac NAA levels, improved systolic dysfunction, and attenuated hypertrophy. These findings expand sirtuins from protein deacylases to direct regulators of small-molecule metabolites and establish NAA as a kidney–heart metabolic mediator, revealing an amino acid acetylation-dependent layer of energy homeostasis.

Key PointsDeficits in nephron numbers are associated with higher risk of adult-onset kidney disease seen in congenital anomalies of the kidney and urinary tract.Mouse model experiments suggested that absent, small, or homeotic 2-like was vital for kidney development by activating cell cycle genes through histone methylation.Our findings identified absent, small, or homeotic 2-like-regulated genes as a potential target for treating congenital anomalies of the kidney and urinary tract.BackgroundMany congenital anomalies of the kidney and urinary tract involve deficits in the number of nephrons, which are associated with a higher risk of hypertension and CKD later in life. Prior work has implicated histone modifications in regulating kidney lineage-specific gene transcription and nephron endowment. Our earlier study suggested that absent, small, or homeotic 2-like (ASH2L), a core subunit of the H3K4 methyltransferase complex, plays a role in ureteric bud morphogenesis during mammalian kidney development. However, the potential involvement of ASH2L in nephron formation remains an open question.MethodsTo investigate the role of ASH2L in nephron development, we inactivated Ash2l specifically in nephron progenitor cells by crossing Six2-e(Kozak-GFPCre-Wpre-polyA)1 mice with Ash2lfl/fl mice. We used RNA sequencing combined with Cleavage Under Targets and Tagmentation sequencing to screen for gene and epigenomic changes, which were further verified by rescue experiments conducted on ex vivo culture explants.ResultsInactivating ASH2L in nephron progenitor cells disrupted H3K4 trimethylation establishment at promoters of genes controlling nephron progenitor cell stemness, differentiation, and cell cycle, inhibiting their progression through the cell cycle and differentiation into epithelial cell types needed to form nephrons. Inhibition of the TGF-beta/suppressor of mothers against decapentaplegic signaling pathway partially rescued the dysplastic phenotype of the mutants.ConclusionsASH2L-mediated H3K4 methylation was identified as a novel epigenetic regulator of kidney development. Downregulation of ASH2L expression or H3K4 trimethylation may be linked to congenital anomalies of the kidney and urinary tract.

Background:A key goal in managing patients with heterozygous disease-causing COL4A3 and COL4A4 (COL4A3/4) variants, affecting individuals spanning a broad age range, is to slow the development of chronic kidney disease (CKD). Whether age of onset is associated with the risk of CKD has not been investigated. Methods:In 294 patients (118 males) with heterozygous disease-causing COL4A3/4 variants in the Shanghai Registry of Alport Syndrome, we made the comparison of risk of CKD between those showing disease onset before 18 years old (early onset) or from 18 years and older (late onset). CKD were defined as onset of persistent albuminuria (albumin-to-creatinine ratio ≥30 mg/g) or CKD G2 (estimated glomerular filtration rate <90 ml/min/1.73 m2). Results:147 (50.0%) of patients had initial presentation of symptoms of kidney diseases when they were <18 years old [median age at onset, 5.0 years (IQR, 3.0-8.0 years)], and in the remainder when they were older [median age at onset, 30.0 years (IQR, 26.0-38.0 years)]. During a median follow-up of 3.0 years (IQR, 0-10.3 years), earlier disease onset showed significant associations with higher risk of albuminuria [hazard ratio (HR) 7.08, 95% confidence intervals (CI) 4.59-10.93] and CKD G2 (HR 3.49, 95%CI 1.57-7.75). Risk of albuminuria increased by 64%, and risk of CKD G2 increased by 34%, per 5-year step toward younger age at disease onset. Conclusions:Earlier onset of disease may predict higher risk of CKD in patients with heterozygous disease-causing COL4A3/4 variants. This association, if verified in large prospective studies, may help stratify patients by risk of worse prognosis, which can guide their management and preemptive nephroprotective treatment.

Background Many congenital anomalies of the kidney and urinary tract involve deficits in the number of nephrons, which are associated with a higher risk of hypertension and chronic kidney disease later in life. Prior work has implicated histone modifications in regulating kidney lineage-specific gene transcription and nephron endowment. Our earlier study suggested that ASH2L, a core subunit of the H3K4 methyltransferase complex, plays a role in ureteric bud morphogenesis during mammalian kidney development. However, the potential involvement of ASH2L in nephron formation remains an open question. Methods To investigate the role of ASH2L in nephron development, we inactivated Ash2l specifically in nephron progenitor cells by crossing Six2 -e(Kozak-GFPCre-Wpre-polyA)1 mice with Ash2l fl/fl mice. We utilized RNA sequencing combined with Cleavage Under Targets and Tagmentation sequencing to screen for gene and epigenomic changes, which were further verified by rescue experiments conducted on ex vivo culture explants. Results Inactivating ASH2L in nephron progenitor cells disrupted H3K4 trimethylation establishment at promoters of genes controlling nephron progenitor cell stemness, differentiation and cell cycle, inhibiting their progression through the cell cycle and differentiation into epithelial cell types needed to form nephrons. Inhibition of the TGF-β/SMAD signaling pathway partially rescued the dysplastic phenotype of the mutants. Conclusions ASH2L-mediated H3K4 methylation was identified as a novel epigenetic regulator of kidney development. Downregulation of ASH2L expression or H3K4 trimethylation may be linked to congenital anomalies of the kidney and urinary tract.

COQ8B nephropathy, a mitochondrial disorder caused by mutations in the COQ8B gene, is a major pediatric genetic focal segmental glomerulosclerosis (GFSGS) etiology and stands out as one of the few treatable forms with good response to coenzyme Q10 (CoQ10) supplementation. As the diagnosis and clinical experience of COQ8B nephropathy were predominantly in the pediatric population, the long-term efficacy of CoQ10 supplementation and its application in the adult-onset patients remains largely unknown. Here, we report three cases of adult-onset FSGS from unrelated families, all carrying the Chinese common COQ8B mutation (c.737G > A; p.Ser246Asn) with divergent trajectories of renal function following CoQ10 supplementation initiated in different stages of renal dysfunction, providing valuable evidence on the implication of early disease diagnosis and prompt CoQ10 supplementation for the prognosis of adult patients affected with COQ8B nephropathy.

Genetic mutations are closely linked to various renal diseases, revealing important molecular mechanisms that contribute to kidney dysfunction. Here, we reported a 35-year-old Chinese female diagnosed of glomerulotubular nephropathy with multiple extra-renal manifestations including ptosis, corneal dystrophy, macular degeneration, right foot syndactyly. Whole-exome sequencing identified a homozygous frameshift variant in FAT1 (NM_005245: c.7444_7445delGT, p.Val2482AsnfsTer16). Further analysis revealed that this mutation caused translation repression of FAT1. RNA sequencing showed dysregulation of cell adhesion and Rap1 signaling pathways, while immunofluorescence staining demonstrated disrupted β-catenin junctions and cytoskeletal abnormalities in patient-derived primary urinary epithelial cells. Pull-down assays indicated that the reduction in activated Rap1 levels was correlated with the observed cellular defects. These findings provide compelling evidence that this loss-of-function homozygous FAT1 variant is causally associated with nephropathy and congenital anomalies, likely through degradation of transcribed mRNA and impaired protein expression. The results emphasize the critical role of FAT1 in renal development and provide new insights into the molecular mechanisms underlying these conditions.

Objective:Through the investigation of the pathogenicity of COL4A4 heterozygous splicing mutations and the genotype-phenotype correlation in autosomal dominant Alport syndrome (ADAS), to better understand the impact of COL4A4 heterozygous splicing mutations on ADAS. Methods:The study was a case series analysis. Patients from 5 ADAS families with COL4A4 heterozygous splicing mutations detected by whole exome sequencing were recruited by three hospitals. In vivo transcriptional analysis and/or in vitro minigene splicing assay were conducted to determine the splicing patterns and assess the pathogenicity of COL4A4 heterozygous splicing mutations. Results:In the five ADAS pedigrees carrying COL4A4 heterozygous splicing mutations, four novel ADAS splicing patterns were described. In pedigree 1-4, most patients presented with continuous hematuria or/and microalbuminuria. Otherwise,the proband in pedigree 4 presented with macroalbuminuria and the proband in pedigree 1 had progressed to chronic kidney disease stage 2 at the age of 70 years old. In pedigree 5, all patients developed end-stage renal disease between 28 and 41 years old. c.735+3A>G detected in pedigree 1 and pedigree 2 and c.694-1G>C detected in pedigree 3 both led to exon 12 skipping in COL4A4, resulting in 42 nucleotides in-frame deletion (c.694_735del). c.2056+3A>G detected in pedigree 4 led to COL4A4 exon 26 skipping, which caused in-frame deletion of 69 nucleotides (c.1988_2056del). c.2716+5G>T detected in pedigree 5 led to a 360 nucleotides large in-frame deletion, including 100 bp sequence at the 3'end of exon 29,the whole sequence of exon 30 and 89 bp sequence at the 5'end of exon 31 (c.2446_2805del). Conclusions:Renal prognosis differs significantly for patients with small in-frame deletions versus large in-frame deletion splicing abnormalities. Determination of the pathogenicity and the splicing patterns of COL4A4 heterozygous splicing mutations using in vivo and in vitro transcriptional analysis may provide renal prognostic information.

目的 分析非体外循环冠状动脉旁路移植术(off-pump coronary artery bypass grafting,OPCABG)后发生急性肾损伤(acute kidney injury,AKI)的危险因素,建立列线图预测模型.方法 409例行OPCABG术患者,根据术后是否发生AKI分为AKI组和非AKI组.比较2组年龄、既往病史、术前血肌酐、术后中心静脉压等临床资料;采用多因素logistic回归分析OPCABG术后发生AKI的影响因素;根据影响因素建立预测OPCABG术后AKI发生风险的列线图模型,采用Bootstrap法对原始队列进行内部验证,分别绘制校准曲线和ROC曲线评估模型的校准度和区分度,并与Cleveland评分、RAKIS评分进行比较.结果 (1)409例患者术后发生AKI 66例(16.1％).(2)AKI组年龄≥65岁、慢性肾脏病、糖尿病、缺血性脑卒中、术前尿蛋白＞300 mg/L、术前血肌酐＞97 μmol/L、术前应用主动脉内球囊反搏、术后中心静脉压＞14 cm H2O比率(71.2％、13.6％、51.5％、22.7％、13.6％、34.8％、21.2％、47.0％)均高于非 AKI 组(48.1％、1.5％、38.5％、11.4％、5.2％、7.0％、7.9％、25.1％)(P＜0.05),术前 血红蛋 白水平[126.0(112.5,136.5)g/L]、术前估算肾小球滤过率[70.7(49.9,90.6)mL/(min·1.73 m2)]、术后左室射血分数[59.0(53.0,65.0)％]均低于非AKI组[137.0(126.0,147.0)g/L、93.8(77.9,110.9)mL/(min·1.73 m2)、62.0(57.0,67.0)％](P＜0.05),男性、高血压、既往心脏手术、急诊手术、术后中心静脉压＜6 cmH2O比率及体质量指数、移植血管数与非AKI组比较差异均无统计学意义(P＞0.05).(3)年龄(OR=2.150,95％CI:1.128～4.096,P=0.020)、缺血性脑卒中(OR=2.172,95％CI:1.027～4.593,P=0.042)、术前血红蛋白(OR=0.981,95％CI:0.965～0.997,P=0.021)、术前血肌酐(OR=5.626,95％CI:2.708～11.689,P＜0.001)、术前应用主动脉内球囊反搏(OR=2.440,95％CI:1.086～5.478,P=0.031)、术后中心静脉压(OR=2.178,95％CI:1.170～4.052,P=0.014)是OPCABG术后发生AKI的影响因素.(4)根据影响因素建立预测OPCABG术后AKI发生风险的列线图模型,列线图模型校准曲线与理想曲线拟合较好,AUC均大于Cleveland评分和RAKIS评分,列线图模型较Cleveland评分和RAKIS评分有更好的校准度和区分度.结论 年龄、缺血性脑卒中、术前血红蛋白、术前血肌酐、术前应用主动脉内球囊反搏、术后中心静脉压是OPCABG术后发生AKI的影响因素,据此建立的列线图模型预测OPCABG术后AKI发生风险有较高价值.

Significance Statement Causes of congenital anomalies of the kidney and urinary tract (CAKUT) remain unclear. The authors investigated whether and how inactivation of Ash2l —which encodes a subunit of the COMPASS methyltransferase responsible for genome-wide histone H3 lysine K4 (H3K4) methylation—might contribute to CAKUT. In a mouse model, inactivation of Ash2l in the ureteric bud (UB) lineage led to CAKUT-like phenotypes. Removal of ASH2L led to deficient H3K4 trimethylation, which slowed cell proliferation at the UB tip, delaying budding and impairing branching morphogenesis. The absence of ASH2L also downregulated the expression of Ret , Gfra1 , and Wnt11 genes involved in RET/GFRA1 signaling. These findings identify ASH2L-mediated H3K4 methylation as an upstream epigenetic regulator of signaling crucial for UB morphogenesis and indicate that deficiency or dysregulation of these processes may lead to CAKUT. Background Ureteric bud (UB) induction and branching morphogenesis are fundamental to the establishment of the renal architecture and are key determinants of nephron number. Defective UB morphogenesis could give rise to a spectrum of malformations associated with congenital anomalies of the kidney and urinary tract (CAKUT). Signaling involving glial cell line–derived neurotrophic factor and its receptor rearranged during transfection (RET) and coreceptor GFRA1 seems to be particularly important in UB development. Recent epigenome profiling studies have uncovered dynamic changes of histone H3 lysine K4 (H3K4) methylation during metanephros development, and dysregulated H3K4 methylation has been associated with a syndromic human CAKUT. Methods To investigate whether and how inactivation of Ash2l , which encodes a subunit of the COMPASS methyltransferase responsible for genome-wide H3K4 methylation, might contribute to CAKUT, we inactivated Ash2l specifically from the UB lineage in C57BL/6 mice and examined the effects on genome-wide H3K4 methylation and metanephros development. Genes and epigenome changes potentially involved in these effects were screened using RNA-seq combined with Cleavage Under Targets and Tagmentation sequencing. Results UB-specific inactivation of Ash2l caused CAKUT-like phenotypes mainly involving renal dysplasia at birth, which were associated with deficient H3K4 trimethylation. Ash2l inactivation slowed proliferation of cells at the UB tip, delaying budding and impairing UB branching morphogenesis. These effects were associated with downregulation of Ret , Gfra1 , and Wnt11 , which participate in RET/GFRA1 signaling. Conclusions These experiments identify ASH2L-dependent H3K4 methylation in the UB lineage as an upstream epigenetic regulator of RET/GFRA1 signaling in UB morphogenesis, which, if deficient, may lead to CAKUT.

Acute kidney injury (AKI) seriously affects the health of both pregnant women and fetuses. This study aimed to investigate the clinical characteristics and prognosis of pregnancy-related AKI (PR-AKI). This case series study enrolled pregnant women with PR-AKI admitted to the surgical intensive care unit of Xinhua Hospital affiliated to Shanghai Jiaotong University School of Medicine between January 2010 and December 2020. Thirty-one PR-AKI patients were enrolled with a mean age of 29.16 ± 4.97 years. Seventeen pregnant women (54.84%) had complete recovery of renal function, 5 (16.13%) had partial recovery of renal function, 2 (6.45%) patients had no renal function improvement, and 7 (22.58%) died. Among the 31 patients with 35 fetuses, 25 (80.6%) pregnant women had poor fetal outcomes, including 5 cases of stillbirths, 5 neonatal asphyxia, 18 premature births, 10 low birth weight, and 8 deficient birth weight infants. Compared to cases with good fetal outcomes, cases with poor fetal outcomes had significantly shorter gestational weeks (39.26 ± 1.53 vs. 31.62 ± 5.50, P = 0.002), lower platelet count (217.13 ± 122.87 vs. 90.24 ± 84.88, P = 0.005), lower hemoglobin (94.19 ± 13.21 vs. 74.48 ± 20.78, P = 0.036), higher blood urea nitrogen (11.87 ± 4.28 vs. 19.47 ± 10.98, P = 0.013), and higher uric acid (262.41 ± 167.00 vs. 586.87 ± 144.52, P < 0.001). The maternal renal function of women with PR-AKI might improve after treatment, but occurrence rates of adverse fetal outcomes were still high.

Peroxisomal fatty acid α-oxidation is an essential pathway for the degradation of β-carbon methylated fatty acids such as phytanic acid. One enzyme in this pathway is 2-hydroxyacyl CoA lyase (HACL1), which is responsible for the cleavage of 2-hydroxyphytanoyl-CoA into pristanal and formyl-CoA. Hacl1 deficient mice do not present with a severe phenotype, unlike mice deficient in other α-oxidation enzymes such as phytanoyl-CoA hydroxylase deficiency (Refsum disease) in which neuropathy and ataxia are present. Tissues from wild-type and Hacl1−/− mice fed a high phytol diet were obtained for proteomic and lipidomic analysis. There was no phenotype observed in these mice. Liver, brain, and kidney tissues underwent trypsin digestion for untargeted proteomic liquid chromatography-mass spectrometry analysis, while liver tissues also underwent fatty acid hydrolysis, extraction, and derivatisation for fatty acid gas chromatography-mass spectrometry analysis. The liver fatty acid profile demonstrated an accumulation of phytanic and 2-hydroxyphytanic acid in the Hacl1−/− liver and significant decrease in heptadecanoic acid. The liver proteome showed a significant decrease in the abundance of Hacl1 and a significant increase in the abundance of proteins involved in PPAR signalling, peroxisome proliferation, and omega oxidation, particularly Cyp4a10 and Cyp4a14. In addition, the pathway associated with arachidonic acid metabolism was affected; Cyp2c55 was upregulated and Cyp4f14 and Cyp2b9 were downregulated. The kidney proteome revealed fewer significantly upregulated peroxisomal proteins and the brain proteome was not significantly different in Hacl1−/− mice. This study demonstrates the powerful insight brought by proteomic and metabolomic profiling of Hacl1−/− mice in better understanding disease mechanism in fatty acid α-oxidation disorders.

We have assessed the oligomeric structure and antigenic properties of an affinity purified gp160 protein (oligo-gp160) using biosensor technology. Sucrose gradient purification analysis identified the existence of tetrameric, dimeric and monomeric forms of the protein. Reactivity to a broad panel of monoclonal antibodies specific for oligomeric gp160, discontinuous epitopes within monomeric gp120 and several linear epitopes within gp120 (V3) and gp41 was demonstrated. International sera from several countries, where HIV-1 clades A-F are prevalent, including type O from Cameroon, were reactive with oligo-gp160 indicating conserved antigenic epitopes. Enhanced immunologic reactivity per gp160 molecule was obtained with oligo-gp160 as compared to other current HIV-1(IIIB) subunit monomeric envelope gp120/gp160 immunogens suggesting higher HIV-1 envelope protein mimicry. HIV-1 antibodies from sera during acute HIV-1 infection were detectable by oligo-gp160 prior to detection with either a recombinant, monomeric gp120 protein or several commercial HIV-1 screening kits suggesting antibodies sensitive to oligomeric gp160 structure may be present earlier in infection. The oligomeric nature of this gp160 protein preparation and high reactivity with divergent mAbs and HIV-1 sera support the use of this protein as an HIV-1 immunogen.

Objective:To investigate the role of survival motor neuron ( SMN) gene knockout in mice with cisplatin-induced acute kidney injury (AKI). Methods:A mouse model (C57BL/6) of cisplatin-induced AKI was constructed. Twenty male wild type (WT) and SMN+/- mice weighing 22-24 g were randomly divided into four groups: WT mice with saline injection group (WT vehicle, n=5), SMN+/- mice with saline injection group ( SMN+/- vehicle, n=5), WT mice with cisplatin injection group (WT cisplatin, n=5) and SMN+/- mice with cisplatin injection group ( SMN+/- cisplatin, n=5). Mice were injected intraperitoneally with 20 mg/kg cisplatin or 0.9% saline. 72 hours later, the mice were sacrificed, and serum and kidney tissues were collected. The real time PCR and Western blotting were used to measure the expression levels of SMN mRNA and protein. The sarcosine oxidation and urease method were used to measure serum creatinine (Scr) and blood urea nitrogen (BUN) levels. Renal pathologic changes were observed by PAS staining. TUNEL immunofluorescence assay was used to detect the level of apoptosis. Western blotting and immunohistochemistry were used to detect the protein expression levels of apoptosis index poly (ADP-ribose) polymerase (PARP) and endoplasmic reticulum stress index CHOP. Results:Compared with WT mice, SMN mRNA and protein expression levels were lower in SMN+/- mice, and the expression level of SMN mRNA and protein was further decreased after intraperitoneal cisplatin injection (all P<0.05). Compared with WT mice with saline injection group, WT mice with cisplatin injection group had higher levels of Scr, BUN, tubular damage scores, TUNEL positive cell numbers, PARP and CHOP, while the expression levels of above indexes in the SMN+/- mice with cisplatin injection group were higher than those in the WT mice with cisplatin injection group (all P<0.05). Conclusions:SMN gene knockout can aggravate renal pathological damage and apoptosis of renal tubular epithelial cell in cisplatin-induced AKI mice. SMN may be a potential therapeutic target of AKI.

Background: Dent disease is a group of inherited X-linked recessive renal tubular disorders. This group of disorders is characterized by low molecular weight proteinuria (LMWP), nephrocalcinosis, hypercalciuria and renal failure. Case presentation: Here we report one 11-year-old Chinese boy (proband) and one 13-year-old Chinese boy who was proband's cousin, both presented with massive proteinuria. Further laboratory examinations revealed a lack of nephrocalcinosis, nor any other signs of tubular dysfunction, but only LMWP and hypercalciuria. There was no abnormality in growth, renal function or mineral density of the bones. A novel deletion (c.1448delG) in the CLCN5 gene was identified, resulting in a frame shift mutation (p.Gly483fs). The proband's and his cousin's mothers were found to be the carrier of this mutation. Conclusions: In this study, we have found a novel frameshift mutation (c. 1448delG) at exon 11 of the CLCN5 gene which leads to Dent disease 1, expanding the spectrum of CLCN5 mutations.