Genetics
Abstract
Emerging evidence suggests that cryptic translation within long noncoding RNAs (lncRNAs) may produce novel proteins with important developmental/physiological functions. However, the role of this cryptic translation in complex diseases (e.g., cancer) remains elusive. Here, we applied an integrative strategy combining ribosome profiling and CRISPR/Cas9 screening with large-scale analysis of molecular/clinical data for breast cancer (BC) and identified estrogen receptor α–positive (ER+) BC dependency on the cryptic ORFs encoded by lncRNA genes that were upregulated in luminal tumors. We confirmed the in vivo tumor-promoting function of an unannotated protein, GATA3-interacting cryptic protein (GT3-INCP) encoded by LINC00992, the expression of which was associated with poor prognosis in luminal tumors. GTE-INCP was upregulated by estrogen/ER and regulated estrogen-dependent cell growth. Mechanistically, GT3-INCP interacted with GATA3, a master transcription factor key to mammary gland development/BC cell proliferation, and coregulated a gene expression program that involved many BC susceptibility/risk genes and impacted estrogen response/cell proliferation. GT3-INCP/GATA3 bound to common cis regulatory elements and upregulated the expression of the tumor-promoting and estrogen-regulated BC susceptibility/risk genes MYB and PDZK1. Our study indicates that cryptic lncRNA-encoded proteins can be an important integrated component of the master transcriptional regulatory network driving aberrant transcription in cancer, and suggests that the “hidden” lncRNA-encoded proteome might be a new space for therapeutic target discovery.
Authors
Caishang Zheng, Yanjun Wei, Peng Zhang, Longyong Xu, Zhenzhen Zhang, Kangyu Lin, Jiakai Hou, Xiangdong Lv, Yao Ding, Yulun Chiu, Antrix Jain, Nelufa Islam, Anna Malovannaya, Yun Wu, Feng Ding, Han Xu, Ming Sun, Xi Chen, Yiwen Chen
Abstract
Genetic defects of GNAS, the imprinted gene encoding the stimulatory G protein α-subunit, are responsible for multiple diseases. Abnormal GNAS imprinting causes pseudohypoparathyroidism type 1B (PHP1B), a prototype of mammalian end-organ hormone resistance. Hypomethylation at the maternally methylated GNAS A/B region is the only shared defect in PHP1B patients. In autosomal dominant (AD) PHP1B kindreds, A/B hypomethylation is associated with maternal microdeletions at either the GNAS NESP55 differentially methylated region or the STX16 gene located ~170 kb upstream. Functional evidence is meager regarding the causality of these microdeletions. Moreover, the mechanisms linking A/B methylation and these putative imprinting control regions (ICRs), NESP-ICR and STX16-ICR, remain unknown. Here, we generated a human embryonic stem cell model of AD-PHP1B by introducing ICR deletions using CRISPR/Cas9. Using this model, we showed that NESP-ICR is required for methylation and transcriptional silencing of A/B on the maternal allele. We also found that SXT16-ICR is a long-range enhancer of NESP55 transcription, which originates from maternal NESP-ICR. Furthermore, we demonstrated that STX16-ICR is an embryonic stage-specific enhancer enabled by the direct binding of pluripotency factors. Our findings uncover an essential GNAS imprinting control mechanism and advance the molecular understanding of the PHP1B pathogenesis.
Authors
Yorihiro Iwasaki, Cagri Aksu, Monica Reyes, Birol Ay, Qing He, Murat Bastepe
Abstract
Although certain human genetic variants are conspicuously loss-of-function, decoding the impact of many variants is challenging. Previously, we described a leukemia predisposition syndrome (GATA2-deficiency) patient with a germline GATA2 variant that inserts nine amino acids between the two zinc fingers (9aa-Ins). Here, we conducted mechanistic analyses using genomic technologies and a genetic rescue system with Gata2 enhancer-mutant hematopoietic progenitor cells to compare how GATA2 and 9aa-Ins function genome-wide. Despite nuclear localization, 9aa-Ins was severely defective in occupying and remodeling chromatin and regulating transcription. Variation of the inter-zinc finger spacer length revealed that insertions were more deleterious to activation than repression. GATA2-deficiency generated a lineage-diverting gene expression program and a hematopoiesis-disrupting signaling network in progenitors with reduced Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) and elevated Interleukin-6 (IL-6) signaling. As insufficient GM-CSF signaling causes pulmonary alveolar proteinosis and excessive IL-6 signaling promotes bone marrow failure, GATA2-deficiency patient phenotypes, these results inform mechanisms underlying GATA2-linked pathologies.
Authors
Mabel Minji Jung, Siqi Shen, Giovanni A. Botten, Thomas Olender, Koichi R. Katsumura, Kirby D. Johnson, Alexandra A. Soukup, Peng Liu, Qingzhou Zhang, Zena D. Jensvold, Peter W. Lewis, Robert A. Beagrie, Jason K.K. Low, Lihua Yang, Joel P. Mackay, Lucy A. Godley, Marjorie Brand, Jian Xu, Sunduz Keles, Emery H. Bresnick
Abstract
Although protein hydroxylation is a relatively poorly characterized post-translational modification, it has received significant recent attention following seminal work uncovering its role in oxygen sensing and hypoxia biology. Although the fundamental importance of protein hydroxylases in biology is becoming clear, the biochemical targets and cellular functions often remain enigmatic. JMJD5 is a ‘JmjC-only’ protein hydroxylase that is essential for murine embryonic development and viability. However, no germline variants in JmjC-only hydroxylases, including JMJD5, have yet been described that are associated with any human pathology. Here we demonstrate that biallelic germline JMJD5 pathogenic variants are deleterious to JMJD5 mRNA splicing, protein stability, and hydroxylase activity, resulting in a human developmental disorder characterised by severe failure to thrive, intellectual disability, and facial dysmorphism. We show that the underlying cellular phenotype is associated with increased DNA replication stress and that this is critically dependent on the protein hydroxylase activity of JMJD5. This work contributes to our growing understanding of the role and importance of protein hydroxylases in human development and disease.
Authors
Sally C. Fletcher, Charlotte L. Hall, Tristan J. Kennedy, Sander Pajusalu, Monica H. Wojcik, Uncaar Boora, Chan Li, Kaisa Teele Oja, Eline Hendrix, Christian A.E. Westrip, Regina Andrijes, Sonia K. Piasecka, Mansi Singh, Mohammed E. El-Asrag, Anetta Ptasinska, Vallo Tillmann, Martin R. Higgs, Deanna Alexis Carere, Andrew D. Beggs, John Pappas, Rachel Rabin, Stephen J. Smerdon, Grant S. Stewart, Katrin Õunap, Mathew L. Coleman
Abstract
Sulfate plays a pivotal role in numerous physiological processes in the human body, including bone and cartilage health. A role of the anion transporter SLC26A1 (Sat1) for sulfate reabsorption in the kidney is supported by the observation of hyposulfatemia and hypersulfaturia in Slc26a1-knockout mice. The impact of SLC26A1 on sulfate homeostasis in humans remains to be defined. By combining clinical genetics, functional expression assays, and population exome analysis, we identify SLC26A1 as a sulfate transporter in humans and experimentally validate several loss-of-function alleles. Whole-exome sequencing from a patient presenting with painful perichondritis, hyposulfatemia, and renal sulfate wasting revealed a homozygous mutation in SLC26A1, which has not been previously described to the best of our knowledge. Whole-exome data analysis of more than 5,000 individuals confirmed that rare, putatively damaging SCL26A1 variants were significantly associated with lower plasma sulfate at the population level. Functional expression assays confirmed a substantial reduction in sulfate transport for the SLC26A1 mutation of our patient, which we consider to be novel, as well as for the additional variants detected in the population study. In conclusion, combined evidence from 3 complementary approaches supports SLC26A1 activity as a major determinant of sulfate homeostasis in humans. In view of recent evidence linking sulfate homeostasis with back pain and intervertebral disc disorder, our study identifies SLC26A1 as a potential target for modulation of musculoskeletal health.
Authors
Anja Pfau, Karen I. López-Cayuqueo, Nora Scherer, Matthias Wuttke, Annekatrin Wernstedt, Daniela González Fassrainer, Desiree E.C. Smith, Jiddeke M. van de Kamp, Katharina Ziegeler, Kai-Uwe Eckardt, Friedrich C. Luft, Peter S. Aronson, Anna Köttgen, Thomas J. Jentsch, Felix Knauf
Abstract
Preimplantation embryo arrest (PREMBA) is a common cause of female infertility and recurrent failure of assisted reproductive technology. However, the genetic basis of PREMBA is largely unrevealed. Here, using whole-exome sequencing data from 606 women experiencing PREMBA compared with 2,813 controls, we performed a population and gene–based burden test and identified a candidate gene, karyopherin subunit α7 (KPNA7). In vitro studies showed that identified sequence variants reduced KPNA7 protein levels, impaired KPNA7 capacity for binding to its substrate ribosomal L1 domain-containing protein 1 (RSL1D1), and affected KPNA7 nuclear transport activity. Comparison between humans and mice suggested that mouse KPNA2, rather than mouse KPNA7, acts as an essential karyopherin in embryonic development. Kpna2–/– female mice showed embryo arrest due to zygotic genome activation defects, recapitulating the phenotype of human PREMBA. In addition, female mice with an oocyte-specific knockout of Rsl1d1 recapitulated the phenotype of Kpna2–/– mice, demonstrating the vital role of substrate RSL1D1. Finally, complementary RNA (cRNA) microinjection of human KPNA7, but not mouse Kpna7, was able to rescue the embryo arrest phenotype in Kpna2–/– mice, suggesting mouse KPNA2 might be a homologue of human KPNA7. Our findings uncovered a mechanistic understanding for the pathogenesis of PREMBA, which acts by impairing nuclear protein transport, and provide a diagnostic marker for PREMBA patients.
Authors
Wenjing Wang, Yoichi Miyamoto, Biaobang Chen, Juanzi Shi, Feiyang Diao, Wei Zheng, Qun Li, Lan Yu, Lin Li, Yao Xu, Ling Wu, Xiaoyan Mao, Jing Fu, Bin Li, Zheng Yan, Rong Shi, Xia Xue, Jian Mu, Zhihua Zhang, Tianyu Wu, Lin Zhao, Weijie Wang, Zhou Zhou, Jie Dong, Qiaoli Li, Li Jin, Lin He, Xiaoxi Sun, Ge Lin, Yanping Kuang, Lei Wang, Qing Sang
Abstract
Mutations of G protein coupled receptors (GPCRs) cause various human diseases, but the mechanistic details are limited. Here we establish p.E303K in the gene encoding the endothelin receptor type A (ETAR/EDNRA) as a recurrent mutation causing Mandibulofacial dysostosis with alopecia (MFDA), with craniofacial changes similar to those caused by p.Y129F. Mouse models carrying either of these missense mutations exhibit a partial maxillary-to-mandibular transformation, which is rescued by deleting the ligand endothelin 3 (ET3/EDN3). Pharmacological experiments confirmed the causative ETAR mutations as gain-of-function, dependent on ET3. To elucidate how an amino acid substitution far from the ligand binding site can increase ligand affinity, we used molecular dynamics (MD) simulations. E303 is located at the intracellular end of transmembrane domain 6, and its replacement by a lysine increases flexibility of this portion of the helix, thus favoring G-protein binding and leading to G-protein-mediated enhancement of agonist affinity. The Y129F mutation located under the ligand binding pocket reduces the sodium-water network, thereby affecting the extracellular portion of helices in favor of ET3 binding. These findings provide insight into the pathogenesis of MFDA and into allosteric mechanisms regulating GPCR function, that may provide the basis for drug design targeting GPCRs.
Authors
Yukiko Kurihara, Toru Ekimoto, Christopher T. Gordon, Yasunobu Uchijima, Ryo Sugiyama, Taro Kitazawa, Akiyasu Iwase, Risa Kotani, Rieko Asai, Véronique Pingault, Mitsunori Ikeguchi, Jeanne Amiel, Hiroki Kurihara
Abstract
Multiple genetic loci have been reported for progeroid syndromes. However, the molecular defects in some extremely rare forms of progeria have yet to be elucidated. Here we report a 21-year-old man of Chinese origin who had a novel autosomal recessive form of progeria, characterized by severe dwarfism, mandibular hypoplasia, hyperopia and partial lipodystrophy. Analyses of exome sequencing data of the entire family revealed only one rare homozygous missense variant, (c.86C>T; p.Pro29Leu), in TOMM7 in the proband, while the parents and two unaffected siblings were heterozygous for the variant. TOMM7, a nuclear gene, encodes a translocase in the outer mitochondrial membrane. The TOMM complex constitutes the outer membrane pore for import of several preproteins into mitochondria. Proteomics analyses of mitochondria from cultured fibroblasts of the proband, as compared to control fibroblasts, revealed increases in several proteins involved in oxidative phosphorylation, but reduced abundance of proteins involved in the phospholipid metabolism. We also observed elevated basal and maximal oxygen consumption rates in the fibroblasts from the proband as compared to control fibroblasts. We conclude that altered mitochondrial protein import due to loss of function bi-allelic variant in TOMM7 can cause severe growth retardation and progeroid features.
Authors
Abhimanyu Garg, Wee-Teik Keng, Zhenkang Chen, Adwait Amod Sathe, Chao Xing, Pavithira Devi Kailasam, Yanqiu Shao, Nicholas P. Lesner, Claire B. Llamas, Anil K. Agarwal, Prashant Mishra
Abstract
22q11.2 deletion syndrome (22q11.2DS) is the most common human chromosomal microdeletion, causing developmentally linked congenital malformations; thymus hypoplasia, hypoparathyroidism and/or cardiac defects. Thymus hypoplasia leads to T cell lymphopenia, which most often results in mild SCID. Despite decades of research, the molecular underpinnings leading to thymus hypoplasia in 22q11.2DS remain unknown. Comparing embryonic thymuses from mouse models of 22q11.2DS (Tbx1neo2/neo2) revealed similar proportions of mesenchymal-, epithelial- and hematopoietic- cell types as controls. Yet, the small thymuses were growth restricted in fetal organ cultures. Replacement of Tbx1neo2/neo2 thymus mesenchymal cells with normal ones restored tissue growth. Comparative single cell RNA sequencing of embryonic thymuses uncovered 17 distinct cell subsets, with transcriptome differences predominant in the 5 mesenchymal subsets from the Tbx1neo2/neo2 line. Transcripts impacted include extracellular matrix (ECM) proteins, consistent with increased collagen deposition seen in the small thymuses. Attenuating collagen cross-links with minoxidil restored thymus tissue expansion for hypoplastic lobes. In colony forming assays, the Tbx1neo2/neo2-derived mesenchymal cells had reduced expansion potential, contrasting the normal growth of thymus epithelial cells. These findings suggest that mesenchymal cells are causal to the small embryonic thymuses in 22q11.2DS mouse models, correctable by substituting with normal mesenchyme.
Authors
Pratibha Bhalla, Qiumei Du, Ashwani Kumar, Chao Xing, Angela Moses, Igor Dozmorov, Christian A. Wysocki, Ondine B. Cleaver, Timothy J. Pirolli, Mary Louise Markert, M. Teresa de la Morena, Antonio Baldini, Nicolai S.C. van Oers
Abstract
Initiation and maintenance of transcriptional states are critical for controlling normal tissue homeostasis and differentiation. Cyclin Dependent Kinases CDK8/CDK19 (Mediator kinase) are regulatory components of Mediator, a highly conserved complex that orchestrates enhancer-mediated transcriptional output. While Mediator kinase has been implicated in the transcription of genes necessary for development and growth, its function in mammals has not been well defined. Using a suite of genetically defined models and pharmacological inhibitors, we show that Cdk8/19 function in a redundant manner to regulate intestinal lineage-specification in human and mouse. Mechanistically, we find that the Mediator kinase module binds and phosphorylates key components of the chromatin remodelling complex SWI/SNF in intestinal epithelial cells. Concomitantly, SWI/SNF and MED12-Mediator co-localise at distinct lineage-specifying enhancers in a CDK8/19 dependent manner. As such, these studies reveal a novel transcriptional mechanism of intestinal cell specification, coordinated by the interaction between the chromatin remodelling complex SWI/SNF and Mediator kinase.
Authors
Marius V. Dannappel, Danxi Zhu, Xin Sun, Hui Kheng Chua, Marle Poppelaars, Monica Suehiro, Subash Khadka, Terry C.C. Lim Kam Sian, Dhanya Sooraj, Melissa Loi, Hugh Gao, Daniel Croagh, Roger J. Daly, Pouya Faridi, Thomas Boyer, Ron Firestein
Copyright © 2023 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)