[Show abstract][Hide abstract] ABSTRACT: The growing recognition of precision medicine by clinicians, health systems, and the pharmaceutical industry, as well as by patients and policymakers,(1) reflects the emergence of a field that is accelerating rapidly and will leave a major imprint on the practice of medicine. In this article, we summarize the forces accelerating precision medicine, the challenges to its implementation, and the implications for clinical practice. What Is Precision Medicine? The terms precision, personalized, and individualized medicine are often used interchangeably. Many physicians contend that they have always practiced individualized and personalized medicine. We agree and, for this reason, prefer the term precision . . .
Full-text · Article · May 2015 · New England Journal of Medicine
[Show abstract][Hide abstract] ABSTRACT: 17 R esistance to thyroid hormone (RTH) was first de-scribed in 1967 (1), and the first mutations in the THRB gene were identified in 1989 (2,3), only three years after the cloning of the THR genes (4,5). The cardinal features of this syndrome of reduced sensitivity to thyroid hormone are el-evated serum levels of free thyroid hormone with non-suppressed thyrotropin (TSH), often with goiter and no clear symptoms and signs of thyrotoxicosis (6). In fact, signs of decreased and increased thyroid hormone action in different tissues may coexist. During the First International Workshop on Resistance to Thyroid Hormone in Cambridge, United Kingdom, in 1993, a consensus statement was issued to establish a unified no-menclature of THRB gene mutations in RTH (7), as defined above. In the ensuing years more than 3000 cases have been identified, 80% of which harbored mutations in the THRB gene. More recently, two syndromes with reduced cellular access of the biologically active thyroid hormone, triiodo-thyronine (T 3), were identified. These are caused by defects of thyroid hormone cell membrane transport (8,9) and a de-fect reducing the intracellular metabolism generating T 3 from thyroxine (T 4) (10). To accommodate these new findings, it was proposed to broaden the definition of hormone resis-tance. Thus, the Fifth International Workshop on Resistance to Thyroid Hormone, which took place in Lyon, France, in 2005, saw the introduction of the term ''reduced sensitivity to thyroid hormone (RSTH) to encompass all defects that can interfere with the biological activity of a chemically intact thyroid hormone secreted in normal or excessive amounts.'' Following the 10th International Workshop on Resistance to Thyroid Hormone and Action that took place in Quebec City, Canada, in 2012, a number of investigators took on the task to develop a nomenclature for inherited forms of im-paired sensitivity to thyroid hormone (Table 1). The term ''impaired'' was to substitute for ''reduced'' because nascent data indicate that syndromes of increased sensitivity may also exist. We are cognizant that no nomenclature can fit perfectly all aspects of the described syndromes because variability exists. Several aspects were taken into consideration: the already existing nomenclature, new findings, and anticipated putative discoveries. For example, in over 2000 publications ''RTH'' is used to define a phenotype of congenitally in-creased free T 4 with nonsuppressed TSH, irrespective of the presence or absence of a THRB gene mutation (see non-TR-RTH). In view of the identification of THRA gene mu-tations that present a distinct phenotype (11,12), we propose using the term ''RTH a,'' and in new publications to use ''RTH b'' when a THRB gene mutation is present in Citation of this publication should include the three journals in which it has been simultaneously published: Journal of Clinical Endocrinology and Metabolism, Thyroid, and European Thyroid Journal. Departments of
[Show abstract][Hide abstract] ABSTRACT: Genome-wide mutagenesis was performed in mice to identify candidate genes for male infertility, for which the predominant causes remain idiopathic. Mice were mutagenized using N-ethyl-N-nitrosourea (ENU), bred, and screened for phenotypes associated with the male urogenital system. Fifteen heritable lines were isolated and chromosomal loci were assigned using low-density genome-wide SNP arrays. Ten of the 15 lines were pursued further using higher-resolution SNP analysis to narrow the candidate gene regions. Exon sequencing of candidate genes identified mutations in mice with cystic kidneys (Bicc1), cryptorchidism (Rxfp2), restricted germ cell deficiency (Plk4), and severe germ cell deficiency (Prdm9). In two other lines with severe hypogonadism, candidate sequencing failed to identify mutations, suggesting defects in genes with previously undocumented roles in gonadal function. These genomic intervals were sequenced in their entirety and a candidate mutation was identified in SnrpE in one of the two lines. The line harboring the SnrpE variant retains substantial spermatogenesis despite small testis size, an unusual phenotype. In addition to the reproductive defects, heritable phenotypes were observed in mice with ataxia (Myo5a), tremors (Pmp22), growth retardation (unknown gene), and hydrocephalus (unknown gene). These results demonstrate that the ENU screen is an effective tool for identifying potential causes of male infertility.
No preview · Article · Jan 2012 · Mammalian Genome
[Show abstract][Hide abstract] ABSTRACT: The genetic etiologies of male infertility remain largely unknown. To identify genes potentially involved in spermatogenesis and male infertility, we performed genome-wide mutagenesis in mice with N-ethyl-N-nitrosourea and identified a line with dominant hypogonadism and patchy germ cell loss. Genomic mapping and DNA sequence analysis identified a novel heterozygous missense mutation in the kinase domain of Polo-like kinase 4 (Plk4), altering an isoleucine to asparagine at residue 242 (I242N). Genetic complementation studies using a gene trap line with disruption in the Plk4 locus confirmed that the putative Plk4 missense mutation was causative. Plk4 is known to be involved in centriole formation and cell cycle progression. However, a specific role in mammalian spermatogenesis has not been examined. PLK4 was highly expressed in the testes both pre- and postnatally. In the adult, PLK4 expression was first detected in stage VIII pachytene spermatocytes and was present through step 16 elongated spermatids. Because the homozygous Plk4(I242N/I242N) mutation was embryonic lethal, all analyses were performed using the heterozygous Plk4(+/I242N) mice. Testis size was reduced by 17%, and histology revealed discrete regions of germ cell loss, leaving only Sertoli cells in these defective tubules. Testis cord formation (embryonic day 13.5) was normal. Testis histology was also normal at postnatal day (P)1, but germ cell loss was detected at P10 and subsequent ages. We conclude that the I242N heterozygous mutation in PLK4 is causative for patchy germ cell loss beginning at P10, suggesting a role for PLK4 during the initiation of spermatogenesis.
[Show abstract][Hide abstract] ABSTRACT: Steroidogenic factor 1 (SF-1) is essential for the development and function of steroidogenic tissues. Stable incorporation of SF-1 into embryonic stem cells (SF-1-ES cells) has been shown to prime the cells for steroidogenesis. When provided with exogenous cholesterol substrate, and after treatment with retinoic acid and cAMP, SF-1-ES cells produce progesterone but do not produce other steroids such as cortisol, estradiol, or testosterone. In this study, we explored culture conditions that optimize SF-1-mediated differentiation of ES cells into defined steroidogenic lineages. When embryoid body formation was used to facilitate cell lineage differentiation, SF-1-ES cells were found to be restricted in their differentiation, with fewer cells entering neuronal pathways and a larger fraction entering the steroidogenic lineage. Among the differentiation protocols tested, leukemia inhibitory factor (LIF) removal, followed by prolonged cAMP treatment was most efficacious for inducing steroidogenesis in SF-1-ES cells. In this protocol, a subset of SF-1-ES cells survives after LIF withdrawal, undergoes morphologic differentiation, and recovers proliferative capacity. These cells are characterized by induction of steroidogenic enzyme genes, use of de novo cholesterol, and production of multiple steroids including estradiol and testosterone. Microarray studies identified additional pathways associated with SF-1 mediated differentiation. Using biotinylated SF-1 in chromatin immunoprecipitation assays, SF-1 was shown to bind directly to multiple target genes, with induction of binding to some targets after steroidogenic treatment. These studies indicate that SF-1 expression, followed by LIF removal and treatment with cAMP drives ES cells into a steroidogenic pathway characteristic of gonadal steroid-producing cells.
[Show abstract][Hide abstract] ABSTRACT: The most widely read textbook in the history of medicine -- made even more essential to practice and education by an unmatched array of multi-media content DVD contains 53 chapters not found in the book, hundreds of bonus illustrations, and important procedural videos Through six decades, no resource has matched the encylopedic scope, esteemed scholarship, and scientific rigor of Harrison's Principles of Internal Medicine. Both an educational tool and a clinical reference, it remains the most universally respected textbook in all of medical publishing and the pinnacle of current medical knowledge. The eighteenth edition of Harrison's features expanded and more in-depth coverage of key issues in clinical medicine, pathophysiology, and medical education. The acclaimed Harrison's DVD has been updated to include 53 chapters not found in the book, all-new procedural videos commissioned especially for Harrison's, a masterpiece video from internationally renowned neurologist Martin Samuels on the neurological exam, and hundreds of bonus videos. Now presented in two volumes New text design greatly enhances readability New chapters on cutting-edge issues in clinical medicine Expanded fovus on global considerations of health and disease More evidence-based than ever How-to videos cover topics such as central venous line placement, endotracheal intubation, pericardiocentesis, and thoracentis NEW print chapters include: World Demographics of Aging The Biology of Aging Clinical Problems of Aging The Human Microbiome Acinetobacter Infections Antiphospholipid Antibody Syndrom NEW DVD-only chapters include: Primary Care in Low and Middle Income Countries Neoplasia During Pregnancy Fluid and Electrolyte Imbalances and Acid-Base Disturbances: Case Examples Less Common Malignancies of Lymphoid Cells Interstitial Cystitis/Painful Bladder Syndrome The Schilling Test War-Related Neuro-Psychiatric Illness High-Altitude Illness The Clinical Laboratory in Modern Healthcare Authoritative Content Essential to Medical Practice and Education: Condensed Table of Contents: Part 1: General Considerations in Clinical Medicine; Part 2: Cardinal Manifestations and Presentation of Disease; Section 1: Pain; Section 2: Alterations in Body Temperature; Section 3: Nervous System Dysfunction; Section 4: Disorders of the Eyes, Ears, Nose, and Throat; Section 5: Alterations in Circulatory and Respiratory Functions; Section 6: Alterations in Gastrointestinal Function; Section 7: Alterations in Renal and Urinary Tract Function; Section 8: Alterations in Sexaul Function and Reproduction; Section 9: Alterations in the Skin; Section 10: Hematologic Alterations; Part 3: Genes, the Environment, and Disease; Part 4: Regenerative Medicine; Part 5: Aging; Part 6: Nutrition; Part 7: Oncology and Hematology; Section 1: Neoplastic Disorders; Section 2: Hematopoietic Disorders; Section 3: Disorders of Hemostasis; Part 8: Infectious Diseases; Section 1: Basic Considerations in Infectious Diseases; Section 2: Clinical Syndromes: Community-Acquired Infections; Section 3: Clinical Syndromes: Health Care Associated Infections; Section 4: Approach to Therapy for Bacterial Diseases; Section 5: Diseases Caused by Gram-Positive Bacteria; Section 6: Diseases Caused by Gram-Negative Bacteria; Section 7: Miscellaneous Bacterial Infections; Section 8: Mycobacterial Diseases; Section 9: Spirochetal Diseases; Section 10: Diseases Caused by Rickettsia, Mycoplasmas, and Chlamydiae; Section 11: Viral Diseases: General Considerations; Section 12: Infections Due to DNA Viruses; Section 13: Infections Due to DNA and RNA Respiratory Viruses; Section 14: Infections Due to Human Immunodeficiency Virus and Other Retroviruses; Section 15: Infections Due to RNA Viruses; Section 16: Fungal and Algal Infections; Section 17: Protozoal and Helminthic Infections: General Considerations; Section 18: Protozoal Infections; Part 9: Terrorism and Clinical Medicine; Part 10: Disorders of the Cardiovascular System; Section 1: Introduction to Cardiovascular Disorders; Section 2: Diagnosis of Cardiovascular Disorders; Section 3: Disorders of Rhythm; Section 4: Disorders of the Heart; Section 5: Vascular Disease; Part 11: Disorders of the Respiratory System; Section 1: Diagnosis of Respiratory Disorders; Section 2: Diseases of the Respiratory System; Section 3: Neurologic Critical Care; Section 4: Oncologic Emergencies; Part 13: Disorders of the Kidney and Urinary Tract; Part 14: Disorders of the Gastrointestinal System; Section 1: Disorders of the Alimentary Tract; Section 2: Liver and Billiary Tract Disease; Section 3: Disorders of the Pancreas; Part 15: Disorders of the Immune System, Connective Tissue and Joints; Section 1: The Immune System in Health and Diseases; Section 2: Disorders of Immune-Mediated Injury; Section 3: Disorders of the Joints and Adjacent Tissues; Part 16: Endocrinology; Section 2: Disorders of Bone and Mineral Metabolism; Section 3: Disorders of Intermediary Metabolism; Part 17: Neurologic Disorders; Section 1: Diagnosis of Neurologic Disorders; Section 2: Diseases of the Central Nervous System; Section 3: Nerve and Muscle Disorders; Section 4: Chronic Fatigue Syndrome; Section 5: Psychiatric Disorders; Section 6: Allcoholism and Drug Dependency; Part 18: Poisoning, Drug Overdose, and Evenomation; Part 19: High Altitude and Decompression Sickness
[Show abstract][Hide abstract] ABSTRACT: DAX1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1; also known as NROB1, nuclear receptor subfamily 0, group B, member 1) encodes a nuclear receptor that is expressed in embryonic stem (ES) cells, steroidogenic tissues (gonads, adrenals), the ventromedial hypothalamus (VMH), and pituitary gonadotropes. Humans with DAX1 mutations develop an X-linked syndrome referred to as adrenal hypoplasia congenita (AHC). These boys typically present in infancy with adrenal failure but later fail to undergo puberty because of hypogonadotropic hypogonadism (HHG). The adrenal failure reflects a developmental abnormality in the transition of the fetal to adult zone, resulting in glucocorticoid and mineralocorticoid deficiency. The etiology of HHG involves a combined and variable deficiency of hypothalamic GnRH secretion and/or pituitary responsiveness to GnRH resulting in low LH, FSH and testosterone. Treatment with exogenous gonadotropins generally does not induce spermatogenesis. Animal models indicate that DAX1 also plays a critical role in testis development and function. As a nuclear receptor, DAX1 has been shown to function as a transcriptional repressor, particularly of pathways regulated by other nuclear receptors, such as steroidogenic factor 1 (SF1). In addition to reproductive tissues, DAX1 is also expressed at high levels in ES cells and plays a role in the maintenance of pluripotentiality. Here we review the clinical manifestations associated with DAX1 mutations as well as the evolving information about its function based on animal models and in vitro studies.
Preview · Article · Jun 2011 · Molecular and Cellular Endocrinology
[Show abstract][Hide abstract] ABSTRACT: The X-linked Sox3 gene encodes a member of the Sry high-mobility group box proteins, which play a role in many developmental processes including neurogenesis and testis development. This study further examined the role of Sox3 in spermatogenesis. Males without Sox3 expression exhibited a similar number of germ cell nuclear antigen-positive germ cells at 1, 5, and 10 d postpartum (dpp) compared to their wild-type littermates, but there was significant germ cell depletion by 20 dpp. However, spermatogenesis later resumed and postmeiotic germ cells were observed by 56 dpp. The VasaCre transgene was used to generate a germ cell-specific deletion of Sox3. The phenotype of the germ cell-specific Sox3 knockout was similar to the ubiquitous knockout, indicating an intrinsic role for Sox3 in germ cells. The residual germ cells in 20 dpp Sox3(-/Y) males were spermatogonia as indicated by their expression of neurogenin3 but not synaptonemal complex protein 3, which is expressed within cells undergoing meiosis. RNA expression analyses corroborated the histological analyses and revealed a gradual transition from relatively increased expression of spermatogonia genes at 20 dpp to near normal expression of genes characteristic of undifferentiated and meiotic germ cells by 84 dpp. Fluorescent-activated cell sorting of undifferentiated (ret tyrosine kinase receptor positive) and differentiated (kit receptor tyrosine kinase-positive) spermatogonia revealed depletion of differentiated spermatogonia in Sox3(-/Y) tubules. These results indicate that Sox3 functions in an intrinsic manner to promote differentiation of spermatogonia in prepubertal mice but it is not required for ongoing spermatogenesis in adults. The Sox3(-/Y) males provide a unique model for studying the mechanism of germ cell differentiation in prepubertal testes.
[Show abstract][Hide abstract] ABSTRACT: In addition to its role in reproduction, estradiol-17β is critical to the regulation of energy balance and body weight. Estrogen receptor α-null (Erα-/-) mutant mice develop an obese state characterized by decreased energy expenditure, decreased locomotion, increased adiposity, altered glucose homeostasis, and hyperleptinemia. Such features are reminiscent of the propensity of postmenopausal women to develop obesity and type 2 diabetes. The mechanisms by which ERα signaling maintains normal energy balance, however, have remained unclear. Here we used knockin mice that express mutant ERα that can only signal through the noncanonical pathway to assess the role of nonclassical ERα signaling in energy homeostasis. In these mice, we found that nonclassical ERα signaling restored metabolic parameters dysregulated in Erα-/- mutant mice to normal or near-normal values. The rescue of body weight and metabolic function by nonclassical ERα signaling was mediated by normalization of energy expenditure, including voluntary locomotor activity. These findings indicate that nonclassical ERα signaling mediates major effects of estradiol-17β on energy balance, raising the possibility that selective ERα agonists may be developed to reduce the risks of obesity and metabolic disturbances in postmenopausal women.
Full-text · Article · Feb 2011 · The Journal of clinical investigation
[Show abstract][Hide abstract] ABSTRACT: Using genome-wide mutagenesis with N-ethyl-N-nitrosourea (ENU), a mouse mutant with cryptorchidism was identified. Genome mapping and exon sequencing identified a novel missense mutation (D294G) in Relaxin/insulin-like family peptide receptor 2 (Rxfp2). The mutation impaired testicular descent and resulted in decreased testis weight in Rxfp2
mice compared to Rxfp2
+/+ mice. Testicular histology of the Rxfp2
mice revealed spermatogenic defects ranging from germ cell loss to tubules with Sertoli-cell-only features. Genetic complementation analysis using a loss-of-function allele (Rxfp2
−) confirmed causality of the D294G mutation. Specifically, mice with one of each mutant allele (Rxfp2
DG/−) exhibited decreased testis weight and failure of the testes to descend compared to their Rxfp2
+/− littermates. Total and cell-surface expression of mouse RXFP2 protein and intracellular cAMP accumulation were measured. Total expression of the D294G protein was minimally reduced compared to wild-type, but cell-surface expression was markedly decreased. When analyzed for cAMP accumulation, the EC50 was similar for cells transfected with wild-type and mutant RXFP2 receptor. However, the maximum cAMP response that the mutant receptor reached was greatly reduced compared to the wild-type receptor. In silico modeling of leucine rich repeats (LRRs) 7–9 indicated that aspartic acid 294 is located within the β-pleated sheet of LRR8. We thus postulate that mutation of D294 results in protein misfolding and aberrant trafficking. The ENU-induced D294G mutation underscores the role of the INSL3/RXFP2-mediated pathway in testicular descent and expands the repertoire of mutations known to affect receptor trafficking and function.
[Show abstract][Hide abstract] ABSTRACT: The study objective was to determine whether stromal and/or epithelial estrogen receptor-alpha (ERalpha) is required for relaxin to promote proliferation of stromal and epithelial cells in the mouse cervix. Four types of tissue recombinants were prepared with cervical stroma (St) and epithelium (Ep) from wild-type (wt) and ERalpha knockout (ko) mice: wt-St+wt-Ep, wt-St+ko-Ep, ko-St+wt-Ep and ko-St+ko-Ep. Tissue recombinants were grafted under the renal capsule of syngeneic female mice. After 3 wk of transplant growth, hosts were ovariectomized and fitted with silicon implants containing 17beta-estradiol (treatment d 1). Animals were injected sc with relaxin or vehicle PBS at 6-h intervals from 0600 h on d 8 through 0600 h on d 10. To evaluate cell proliferation, 5-bromo-2'-deoxyuridine was injected sc 10 h before tissue recombinants were collected at 1000 h on d 10. Relaxin promoted marked proliferation of both epithelial and stromal cells in tissue recombinants containing wt St (P < 0.001) but far lower proliferation in recombinants prepared with ko St, regardless of whether Ep was derived from wt or ko mice. An additional experiment using mice expressing wt ERalpha, a mutant of ERalpha that selectively lacks classical signaling through estrogen response element binding, or no ERalpha demonstrated that ERalpha must bind to an estrogen response element to enable relaxin's proliferative effects. In conclusion, this study shows that ERalpha-expressing cells in St, using a classical signaling pathway, are necessary for relaxin to promote marked proliferation in both stromal and epithelial cells of the mouse cervix.
[Show abstract][Hide abstract] ABSTRACT: In vitro models have been used to demonstrate that estrogen receptors (ERs) can regulate estrogen-responsive genes either by directly interacting with estrogen-responsive element (ERE) DNA motifs or by interacting with other transcription factors such as AP1. In this study, we evaluated estrogen (E(2))-dependent uterine gene profiles by microarray in the KIKO mouse, an in vivo knock-in mouse model that lacks the DNA-binding function of ERalpha and is consequently restricted to non-ERE-mediated responses. The 2- or 24-h E(2)-mediated uterine gene responses were distinct in wild-type (WT), KIKO, and alphaERKO genotypes, indicating that unique sets of genes are regulated by ERE and non-ERE pathways. After 2 h E(2) treatment, 38% of the WT transcripts were also regulated in the KIKO, demonstrating that the tethered mechanism does operate in this in vivo model. Surprisingly, 1438 E(2)-regulated transcripts were unique in the KIKO mouse and were not seen in either WT or alphaERKO. Pathway analyses revealed that some canonical pathways, such as the Jak/Stat pathway, were affected in a similar manner by E(2) in WT and KIKO. In other cases, however, the WT and KIKO differed. One example is the Wnt/beta-catenin pathway; this pathway was impacted, but different members of the pathway were regulated by E(2) or were regulated in a different manner, consistent with differences in biological responses. In summary, this study provides a comprehensive analysis of uterine genes regulated by E(2) via ERE and non-ERE pathways.
Full-text · Article · Oct 2009 · Molecular Endocrinology