Genetics
Abstract
Testosterone is a key determinant of red blood cell (RBC) biology and susceptibility to hemolysis; however, its contribution to donor-dependent variation in RBC quality and transfusion effectiveness remains unclear. Using data from 2,357 male participants in the NHLBI REDS-III RBC-Omics study, we quantified plasma total testosterone, free testosterone (bioavailable form), and androstenedione and evaluated their associations with donor characteristics, RBC hemolysis, and recipient post-transfusion hemoglobin increments, a clinical measure of RBC transfusion effectiveness. Subphysiological testosterone concentrations were common (~35%) and independently associated with increased storage and osmotic hemolysis. Frequent blood donations were independently associated with lower circulating free testosterone concentrations, even after adjustment for demographic and hematologic factors. Genome-wide association analyses identified loci associated with circulating testosterone, including regions near SHBG, TNFSF12, and the long noncoding RNA BALR6. Several testosterone variants were associated with RBC transfusion effectiveness. Specifically, variants associated with lower testosterone (e.g., TNFSF12) corresponded to higher post-transfusion hemoglobin increments (+9%), whereas BALR6 variants associated with higher testosterone were linked to reduced hemoglobin increments (–40%). In contrast, androstenedione-associated variants were not related to hemolysis or transfusion outcomes. Together, these findings demonstrate that genetic and physiologic variation in testosterone contributes to inter-individual variability in RBC quality and transfusion effectiveness.
Authors
Fang Fang, Nareg Roubinian, Xutao Deng, Cassie Kemmler, Jost Klawitter, Jelena Klawitter, Touraj Shokati, Uwe Christians, Grier P. Page, Tamir Kanias
Abstract
Missense mutations in the UMOD gene are a well-established genetic cause of autosomal dominant tubulointerstitial kidney disease (ADTKD). Here, we report two ADTKD pedigrees carrying de novo UMOD mutations, p.His36Tyr (H36Y) and p.Trp31Cys (W31C). To elucidate the underlying pathogenic mechanisms and explore targeted therapeutic strategies, we generated a UMODH36Y/+ knock-in mouse model using CRISPR/Cas9 technology, which recapitulated the major clinical manifestations observed in patients. Through single-cell RNA sequencing and experimental validation, we demonstrated that uromodulin mutations triggered endoplasmic reticulum (ER) stress and the unfolded protein response, with ferroptosis identified as the predominant mode of cell death in this disease. These findings were further confirmed in plasmid-transfected cell models expressing UMODH36Y and UMODW31C. Moreover, the molecular chaperone HSPA1A was identified as a potential therapeutic target. Geranylgeranylacetone, targeting HSPA1A as a chaperone drug, effectively mitigated endoplasmic reticulum stress, alleviated ferroptosis, and delayed the progression of renal dysfunction. Based on novel uromodulin mutations, our study reveals a pathogenic ER-ferroptosis axis in ADTKD-UMOD, deepens the insight into the pathogenesis of ADTKD-UMOD, and provides a promising strategy for developing chaperone therapy with drug repurposing in genetic kidney diseases.
Authors
Wen Shi, Yan Yang, Xianli Wen, Qianqian Wu, Jinxuan Wei, Xin-Lu Wang, Junyuan Shen, Siqi Peng, Xiaoliang Zhang, Bi-Cheng Liu, Bin Wang
Serine palmitoyltransferase (SPT) inhibition in SPTSSA-related complex hereditary spastic paraplegia
Abstract
Defective feedback inhibition of serine palmitoyltransferase (SPT) caused by pathogenic SPTSSA variants underlies childhood-onset complex hereditary spastic paraplegia, yet the developmental timing and therapeutic reversibility of sphingolipid dysregulation remain unclear. We generated a knock-in mouse carrying the disease-associated SptssaT51I variant and show that heterozygous animals exhibit preserved intrinsic SPT activity but impaired ORMDL-mediated regulation, leading to sustained elevation of bioactive sphingolipid intermediates that peak during postnatal myelination. Although gross myelin formation was initially maintained, excess sphingolipid flux rendered oligodendrocytes and neurons selectively vulnerable. Dietary L-serine, which augments SPT substrate availability, amplified sphingolipid accumulation in mutant but not wild-type mice, unmasking progressive spasticity, axonal injury, myelin ultrastructural defects, and, when administered during early postnatal development, severe pulmonary pathology likely responsible for lethality. Pharmacologic SPT inhibition with myriocin normalized sphingolipid synthesis, prevented serine-induced lethality, and reversed neurological and metabolic abnormalities. Translating these findings, treatment of a child with SPTSSA-T51I–associated complex hereditary spastic paraplegia using the FDA approved SPT inhibitor D-Cycloserine resulted in sustained improvement in spasticity, reduced baclofen requirement, and decreased plasma levels of neurofilament light chain (NFL). These data define dysregulated sphingolipid biosynthesis as a developmentally and metabolically sensitive driver of neurodegeneration and suggest SPT inhibition as a mechanistically grounded therapeutic strategy.
Authors
Yi Gong, Robert Thompson, Ashley M. Glover, Kenneth Gable, Sita D. Gupta, Natalie Golovanov, Julie Tassinari, Nathan Casey, Brian D. Wishart, Elise L. Townsend, April Qian, Martin Selig, Armen Yerevanian, Teresa M. Dunn, Florian Eichler
Abstract
Metastases in renal cell carcinoma (RCC) typically arise from large primary tumors. However, a subset of patients with small renal masses (SRMs; ≤4 cm) can develop metastatic disease. Identifying these tumors is clinically important, as many SRMs are managed with active surveillance, and their study may provide insight into the early acquisition of metastatic competence. It remains unclear whether these tumors acquire distinct metastatic programs or instead show premature activation of the same aggressive programs typically associated with larger tumors. Here, we performed integrated morphological and molecular profiling of a multiinstitutional cohort of metastatic SRMs, including whole-exome sequencing and RNA-Seq, using nonmetastatic primary tumors as controls. Among metastatic, non–clear cell SRMs, we identified NF2-altered tumors, ELOC-mutated RCC, and an mTOR-driven eosinophilic vacuolated tumor. Metastatic clear cell SRMs were enriched by multi-hit aggressive genotypes, including recurrent losses of chromosomes 8p, 9, and 14q, as well as co-occurring driver alterations (≥2 events), including BAP1 and mTOR pathway genes. Transcriptomic analyses revealed enrichment of the non-negative matrix factorization 3 (NMF3) subtype from the IMmotion151 trial-based taxonomy, along with metabolic rewiring and reduced cytotoxic immune effector function. Collectively, these findings identify molecular programs associated with metastatic competence in SRMs, highlight the importance of genomic studies of equivocal non-clear cell SRMs, and provide a biological framework for risk stratification in patients often considered for active surveillance.
Authors
Payal Kapur, Daria Beshnova, Hua Zhong, Ruby Sharma, Pooja Ghatalia, Angela Yoo, Daniel D. Le, Ratna Mukhopadhyay, Alana Christie, Jeffrey Miyata, Shuanzeng Wei, Rana R. McKay, Dinesh Rakheja, Satwik Rajaram, Robert G. Uzzo, A. Ari Hakimi, Zora Modrusan, James Brugarolas
Abstract
Prader-Willi syndrome (PWS) is a complex genetic disorder resulting from the deficiency of several maternally imprinted genes, including SNORD116, in the 15q11-q13 region. Loss of Snord116 in mice recapitulates some of the most salient clinical features of PWS, including growth hormone (GH) deficiency and hypogonadism. This study explored the impact of Snord116 deficiency on early postnatal pituitary development and growth in Snord116-KO mice. Snord116 was found to be expressed in both the anterior and posterior pituitary. Pituitary transcriptomes of Snord116-KO and WT mice at 2 developmental stages, P0 and 4 weeks of age, were interrogated and related to ex vivo analyses of GH secretion in the pituitaries of 5-week-old mice. Significant differences in pituitary transcriptomes were detected between Snord116-KO and WT mice at 4 weeks of age but not at P0. The differentially expressed genes and affected molecular pathways play important roles in regulating embryonic and postnatal pituitary development. Our results suggested that PWS GH deficiency was mainly due to pituitary hypoplasia and decreased GH production but not to reduced GH secretory function per se, implicating Snord116 in the specific molecular/cellular pathways that account for impaired postnatal pituitary development and GH deficiency in PWS.
Authors
Gabriel F. Batzli, Kaiying Guo, Fahrünisa Meryem Betül Erol, Charles A. LeDuc, Lisa C. Burnett, Rudolph L. Leibel, Yiying Zhang
Abstract
BACKGROUND. Loss of the Y chromosome (LOY) is a frequent event in male tumors and has been linked to cancer progression. However, the degree of mosaic LOY (mLOY) within normal tissues from men with or without cancer remains uncharacterized. METHODS. Here we used a FISH-based assay targeting X- and Y-chromosome centromeres to perform a pan-organ analysis of mLOY in 1,000 male tissue samples from 405 individuals representing 11 organs. Automated image processing generated a quantitative FISH-based mLOY score (YchrFISH) that we validated against a transcriptomic surrogate of Y-chromosome dosage from RNA-seq data. RESULTS. mLOY burden varied by tumor type, with highest degree in colorectal carcinoma. Across tissue groups, YchrFISH scores declined progressively from normal tissues of cancer-free men to histologically normal tissues adjacent to cancer and carcinoma (P < 0.0001). Paired analyses confirmed consistently greater mLOY in malignant compared with tumor-adjacent histologically normal tissue in different organs. Spatially resolved RNA-seq maps of bladders removed for cancer demonstrated a transcriptional gradient of Y-chromosome loss from normal urothelium through intraepithelial neoplasia to invasive carcinoma. CONCLUSION. mLOY gradients exist across histologically normal and malignant tissues, consistent with the concept of field cancerization. Our findings support epithelial mLOY as a biomarker of early malignant transformation and, to our knowledge, a previously unrecognized hallmark of male oncogenesis. FUNDING. NIH grants R35CA294022, P01CA163227, and P50CA97186 (the Pacific Northwest Prostate Cancer SPORE) and the Institute for Prostate Cancer Research.
Authors
Arkadiusz Gertych, Huihui Ye, Xingyu Chen, Eric Vail, V. Krishnan Ramanujan, Lauren Brady, Lawrence D. True, Peter S. Nelson, Peter R. Carroll, Dan Theodorescu
Abstract
The FLAD1 gene codes for flavin adenine dinucleotide (FAD) synthase. FAD is a cofactor for many redox enzymes involved in vital processes from respiration to signal transduction. In this work, we described a clinical case of 2 siblings carrying compound heterozygous mutations in the FLAD1 gene resulting in the substitutions A418V and R542* at the protein level. The patients demonstrate adrenal insufficiency, which has not previously been associated with FLAD1 protein defects. To verify that adrenal insufficiency is caused by FLAD1 mutations, we created a personalized mouse model carrying the mutations found in the patients. The mutation in the FLAD1 gene, leading to the A418V substitution, appeared viable in the homozygous state, with minimal difference from the WT. The FLAD1 gene mutation leading to the R542* truncation is lethal when homozygous. The mouse model of the compound heterozygous FLAD1A418V/R542* mutations recapitulated the physiological, biochemical, and endocrine manifestations of FLAD1 mutations in patients. The mouse model created demonstrates the causal effect of FLAD1 mutations on the described pathology and potentially paves the way for understanding the disease’s molecular mechanism and developing better therapies.
Authors
Olga A. Averina, Natalia Yu. Kalinchenko, Vitaly A. Ioutsi, Andrey V. Pirogov, Alexander V. Bogachev, Oleg A. Permyakov, Vitaly S. Buev, Ekaterina A. Guseva, Anastasia V. Priymak, Olga A. Bazhanova, Mariia A. Emelianova, Olga O. Grigoryeva, Galina V. Baydakova, Maxim A. Abakumov, Vasily N. Manskikh, Olga A. Dontsova, Petr V. Sergiev, Anatoly N. Tiulpakov
Abstract
Mutations in mitochondrial DNA (mtDNA) cause various mitochondrial diseases that are currently incurable. Allotopic expression of nuclear-recoded mitochondrial genes represents a promising therapeutic strategy, given its demonstrated capacity to restore mitochondrial function in human cell models harboring mtDNA mutations. However, the in vivo evaluation of allotopic gene therapy has been hindered by optimization challenges and the lack of appropriate animal models. Here, we overcome these limitations by utilizing an optimized AAV2-ND6 construct with codon optimization and mitochondrial targeting sequence in a mouse model bearing the homoplasmic ND6P25L mutation, which recapitulates Leber hereditary optic neuropathy (LHON). High-dose administration of the AAV2-ND6 construct resulted in robust, sustained expression within the retina and optic nerve without apparent systemic toxicity. Strikingly, We compared the therapeutic efficacy in mutant mice at different ages and pre-symptomatic intervention with AAV2-ND6 effectively attenuated disease progression, mitigated retinal cellular deficiencies and optic nerve damage, and restored visual function in ND6P25L mice. Mechanistically, allotopic ND6 expression markedly rescued the mitochondrial dysfunction, corrected dysregulated retinol metabolism and phototransduction pathways, and suppressed apoptotic processes in the mutant retina. Our study validates the safety and therapeutic potential of allotopic expression in vivo and provide critical mechanistic insights into its role in treating LHON and other mitochondrial diseases.
Authors
Cheng Ai, Huiying Li, Jing Wu, Tianwei Zhou, Jing Wang, Shao-Hui Pan, Jun Yu, Douglas C. Wallace, Min-Xin Guan
Abstract
Haploinsufficiency of TBX1, which occurs in 22q11.2 deletion syndrome (22q11.2DS), leads to a heterogeneous spectrum of clinical manifestations, including craniofacial anomalies, immunodeficiency, and congenital heart defects. The variability in syndromic presentation between patients may be partially explained by variants in chromatin regulatory genes that act to further modify TBX1 function. To investigate this relationship, we selected KMT2D as a candidate gene because of its role in the etiology of Kabuki syndrome, which shares overlapping features with 22q11.2DS. We demonstrate that conditional inactivation of Kmt2d in the Tbx1 lineage in Tbx1-heterozygous mice leads to fully penetrant perinatal lethality and increased incidence of craniofacial dysmorphism, thymus and parathyroid gland hypoplasia, and aortic arch anomalies. At early stages, mutant embryos were found to have defects of the caudal pharyngeal apparatus, including abnormal patterning of the third pouch endoderm, hypoplastic fourth arches, and defective fourth arch arteries. Finally, analysis of single-cell RNA sequencing revealed dysregulation, and largely downregulation, of genes involved in basic cellular functions, suggesting that Tbx1 and Kmt2d developmentally converge upon essential biological processes. Overall, these results indicate that reduced dosage of Kmt2d perturbs the developmental landscape of the Tbx1 heterozygote, eliciting phenotypes that are shared between 22q11.2DS and Kabuki syndrome.
Authors
Daniella Miller, Kevyn Jackson, Timothy C. Cox, Bernice E. Morrow
Abstract
Autosomal dominant leukodystrophy (ADLD) is a fatal-adult-onset CNS demyelinating disorder for which no treatment exists. The majority of ADLD cases are caused by duplications of the lamin B1 (LMNB1) gene, resulting in increased LMNB1 expression. While reducing LMNB1 levels represents a logical therapeutic strategy, its efficacy has not been previously demonstrated in any in vivo model. Mouse models with oligodendrocyte-specific human LMNB1 (hLMNB1) overexpression recapitulate salient features of ADLD. Using a modified version of this model, where hLMNB1 can be inducibly downregulated, we demonstrated that hLMNB1 reduction can prevent or substantially ameliorate disease progression. Therapeutic effects were maximized when hLMNB1 reduction was induced before expected symptom onset, resulting in improvements in behavioral, biochemical, histopathological, and survival measures relative to untreated animals. Reducing hLMNB1 levels after symptom onset led to improved survival, but mixed results for other disease phenotypes. In addition, we identified potential biomarkers that track disease progression. Furthermore, we demonstrated that near-complete knockdown of murine LMNB1 expression in adulthood did not result in any overt CNS phenotype. Together, these results provide a proof of concept supporting LMNB1 reduction as a therapeutic strategy and offer a rationale for treatments aimed at lowering levels of this protein in ADLD.
Authors
Nathan Herdman, Kaveh Moradi, Bruce Nmezi, Anushe Munir, Krizchelle A. Magtoto, Fang Liu, Mara Sullivan, Xuemei Zeng, Thomas K. Karikari, Quasar S. Padiath
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