Young S. Oh

Biogenesis and Topology of the Transient Receptor Potential Ca2+ Channel TRPC1

The TRPC ion channels are candidates for the store-operated Ca2+ entry pathway activated in response to depletion of intracellular Ca2+ stores. Hydropathy analyses indicate that these proteins contain eight hydrophobic regions (HRs) that could potentially form α-helical membrane-spanning segments. Based on limited sequence similarities to other ion channels, it has been proposed that only six of the eight HRs actually span the membrane and that the last two membrane-spanning segments (HRs 6 and 8) border the ion-conducting pore of which HR 7 forms a part. Here we study the biogenesis and transmembrane topology of human TRPC1 to test this model. We have employed a truncation mutant approach combined with insertions of glycosylation sites into full-length TRPC1. In our truncation mutants, portions of the TRPC1 sequence containing one or more HRs were fused between the enhanced green fluorescent protein and a C-terminal glycosylation tag. These chimeras were transiently expressed in the human embryonic cell line HEK-293T. Glycosylation of the tag was used to monitor its location relative to the lumen of the endoplasmic reticulum and thereby HR orientation. Our data indicate that HRs 1, 4, and 6 cross the membrane from cytosol to the ER lumen, that HRs 2, 5, and 8 have the opposite orientation, and that HR 3 is left out of the membrane on the cytosolic side. Our results also show that the sequence downstream of HR 8 plays an important role in anchoring its C-terminal end on the cytosolic side of the membrane. This effect appears to prevent HR 7 from spanning the bilayer and to result in its forming a pore-like structure of the type previously envisioned for the TRPC channels. We speculate that a similar mechanism may be responsible for the formation of other ion channel pores.

Investing in High Blood Pressure Research: A National Institutes of Health Perspective

Hypertension (HTN), traditionally defined as systolic blood pressure ≥140 mm Hg and diastolic blood pressure ≥90 mm Hg, or currently taking medication to lower high blood pressure,1–3 is a common and chronic disease that currently affects 77 million Americans. The National Health and Nutrition Examination Survey conducted in 2009 to 2010 found an overall HTN prevalence of 28.6% in American adults aged ≥18 years.3 Prevalence increased greatly with age, ranging from 6.8% among individuals aged 18 to 39 years to 30.4% in those aged 40 to 59 years, and to 66.7% in individuals aged ≥60 years. HTN is a major risk factor for the most deadly cardiovascular diseases, preceding the development of heart failure in 91% of cases; it is present in 69% of individuals who suffer their first heart attack and in 77% of those having their first stroke.2 HTN and diabetes mellitus combined are the strongest predictors of chronic renal disease. Even prehypertension, defined as untreated systolic blood pressure of 120 to 139 mm Hg or untreated diastolic blood pressure of 80 to 89 mm Hg, is associated with elevated relative and absolute risks for cardiovascular disease outcomes, which differ by race and increase with age.5 The status of HTN severity and treatment (ie, treated or not) are both components of personal risk-estimating algorithms, such as the Framingham General Cardiovascular Risk Score,6 based on data from the National Heart, Lung, and Blood Institute (NHLBI)-sponsored, longitudinal, observational Framingham study.7 Conversely, treatment of HTN was shown to lead to reduction of cardiovascular disease complications, with benefit levels largely relating to the extent of high blood pressure lowering. Treatment of HTN often requires the use of various and sometimes concomitant medications, frequently accompanied by significant side-effects. Trials that previously targeted high systolic blood …

National Heart, Lung, and Blood Institute Working Group Report on Salt in Human Health and Sickness Building on the Current Scientific Evidence

Humans have had a long and complex relationship with salt. Although highly valued in many societies, dietary salt has long been associated with high blood pressure1–3 and, more recently, with other diseases.4–6 Some individuals with hypertension often display salt-sensitive blood pressure changes, which is a condition more prevalent among blacks, older people, and individuals with renal insufficiency or diabetes mellitus.7–9 In general, for those with salt-sensitive hypertension, excess sodium intake is associated with higher blood pressure, whereas a low-salt diet decreases blood pressure.3 In spite of this well-known association, the basic molecular and cellular mechanisms underlying the effects of salt on blood pressure regulation are still not well understood. Furthermore, individuals with high blood pressure are at increased risk for multiple diseases (ie, coronary artery disease, heart failure, stroke, and renal disease) although at present whether or not a high dietary salt intake can directly lead to these diseases (ie, in the absence of hypertension) is not known. Our understanding of the effect of salt on health has grown even more complex recently. Researchers have reported a new connection between salt and autoimmunity: a high-salt diet was shown to accelerate autoimmune activity in a mouse model of multiple sclerosis.10,11 In addition, a close connection between hypertension and the immune system has been revealed.12–16 However, the causal relationships between salt, immunity, and hypertension (eg, how salt could mediate interactions between the immune system and the vasculature, brain, or kidney to increase blood pressure) are not well understood. The National Heart, Lung, and Blood Institute convened a Working Group (WG) in 2014 to discuss this new emerging scientific area in hypertension research. The WG brought together experts from diverse backgrounds including hypertension, epidemiology, preeclampsia, cardiovascular disease, …

Anatomy of Success: The Top 100 Cited Scientific Reports Focused On Hypertension Research

• Online Data Supplement Hypertension affects ≈78 million adults (1 in 3 adults) in the United States and is a major risk factor for cardiovascular disease, stroke, and chronic kidney disease.1 Thus, hypertension represents a formidable challenge to US healthcare. In 2010, hypertension was projected to cost US

Report of the National Heart, Lung, and Blood Institute Working Group on the Role of Microbiota in Blood Pressure Regulation: Current Status and Future Directions

93.5 billion in healthcare services, medications, and missed days of work.2 In 2012, the National Institutes of Health (NIH), the largest funding source for biomedical research in the world, spent

Shifting Demographics among Research Project Grant Awardees at the National Heart, Lung, and Blood Institute (NHLBI)

215 million to support hypertension research.3,4 In this study, we undertook an effort to identify the most frequently cited 100 articles that describe advances focused on hypertension research. The number of citations an article receives after its publication is a measure of its recognition and suggests the effect of its information within the scientific community. Therefore, a bibliometric analysis (ie, citation and content analysis) of the scientific literature may be used to identify influential articles, research topics, authors, and so on in a specific scientific field. To date, although several journals provide statistics of their own publications, we were unable to find an across-the-board bibliometric analysis of hypertension research. Here, we report the results of a bibliometric analysis that aimed to examine key characteristics of the top 100 cited articles that focused on hypertension published during the past century (T100), including citation ranking, year of publication, publishing journal, type of study, country of origin, funding source, and authorship. We used the Science Citation Index (SCI)–expanded (1900–2013) database provided by the Institute for Scientific Information Web of Science (http://thomsonreuters.com/web-of-science/) to determine the 100 most frequently cited articles in hypertension research. The search topic terms included were hypertension, hypertensive, or blood pressure. The articles identified by these search terms were accessed and reviewed online through the NIH library, and …

A special report on the NHLBI initiative to study cellular and molecular mechanisms of arterial stiffness and its association with hypertension

A recent American Heart Association report shows that 34% of US adults ≥20 years of age have hypertension representing ≈86 million adults.1 A substantial increase in the prevalence of hypertension has occurred globally.2 The projected number of individuals with systolic blood pressure of ≥140 mm Hg has doubled from 442 million in 1990 to 874 million in 2015. Hypertension is one of the most prevalent risk factors for cardiovascular disease (CVD).1 Results of the recently concluded SPRINT (Systolic Blood Pressure Intervention Trial) funded by the National Heart, Lung, and Blood Institute showed that among older adults with hypertension but without diabetes mellitus, lowering systolic blood pressure to a target goal of 120 mm Hg, compared with the standard goal of 140 mm Hg, resulted in significantly lower rates of fatal and nonfatal cardiovascular events and death from any cause.3 Some groups such as blacks who display both disproportionately earlier onset and higher prevalence of hypertension have increased risk of blood pressure (BP)–related cardiovascular and renal disease complications compared with non-Hispanic whites. Despite intensive attempts to influence lifestyle changes, nutritional counseling, and intensive antihypertensive drug treatment strategies, ≈14% of all hypertension patients seem to be resistant to antihypertensive interventions.1 Resistant hypertension is defined as BP above goal (>140/90 mm Hg) on ≥3 BP-lowering medications or needing ≥4 medications prescribed at optimal dose to control BP to goal. Thus, both increased prevalence and inability to achieve BP goals in a large patient population with hypertension are creating a tremendous healthcare burden. In addition, no novel antihypertensive drugs have been added to our formulary since 1995, when the first angiotensin receptor antagonist was approved in the United States. The recent attempts to use percutaneous renal artery sympathetic denervation, as a novel means to control hypertension, have been largely unsuccessful to date.4 …

“The Good Old R01”: Challenging Downward Funding Success Trends at the National Heart, Lung, and Blood Institute

The present study was initiated because of concerns expressed by NHLBI-funded mid-career investigators regarding perceived difficulties in the renewal of their grant awards. This led us to ask: “Are mid-career investigators experiencing disproportionate difficulties in the advancement of their professional careers?” Our portfolio analysis indicates that there has been a significant and evolving shift in the demographics of research project grant (RPG) awardees at NHLBI. In 1998, mid-career (ages 41–55) investigators constituted approximately 60% of all investigators with the remaining 40% being equally divided between early-stage (ages 24–40) investigators and established (ages 56 to 70 and older) investigators. However, since 1998, the proportion of established RPG awardees has been increasing in a slowly progressive and strikingly linear fashion. At the same time the proportion of early-stage awardees fell precipitously until 2006 and then stabilized. During the same period, the proportion of mid-career awardees, which had been relatively stable through 2006, began to fall significantly. In examining potential causes of these demographic shifts we have identified certain inherent properties within the RPG award system that appear to promote an increasingly more established awardee population and a persistent decrease in the proportion of mid-career investigators. A collateral result of these demographic shifts, when combined with level or declining funding, is a significant reduction in the number of RPG awards received by NHLBI mid-career investigators and a corresponding decrease in the number of independent research laboratories.

Evidence that the COOH terminus of human presenilin 1 is located in extracytoplasmic space

Large arteries (especially the aorta) lose elasticity and thicken with aging and as a consequence of other conditions, thus leading to central arterial stiffening and associated adverse effects on blood flow and pressure. Arterial stiffness can be defined and measured in different ways, at a local level or systemically. Increases in either the intrinsic (material) stiffness or net structural (combined geometric and material) arterial stiffness, or both, can increase the velocity at which the pressure pulse travels along the arterial tree and central pulse pressure, which can negatively impact downstream resistance vessels and organs (ie, heart, brain, and kidney). Clarifying temporal and causal relationships between arterial stiffening and hypertension was identified by NHLBI as an important gap of knowledge, with a potential for clinical translation. NIH (National Institutes of Health)-funded studies, more than half of them supported by the NHLBI (Online Figure), have investigated various aspects of arterial stiffening in humans and in experimental models. To enable a more focused research effort on this topic, NHLBI launched a Request for Applications (RFA) HL-10 -027, entitled Cellular and Molecular Mechanisms of Arterial Stiffening and Its Relationship to Development of Hypertension (R01). This initiative supported 11 R01 awards during 2010 to 2015 (Online Table II; cumulative ≈

Effect of γ-secretase inhibitors on muscarinic receptor-mediated calcium signaling in human salivary epithelial cells

20 million dollars in total costs), which represented a significant component of the overall NHLBI investment in this field. Here, we report a summary of important scientific findings that resulted from this NHLBI-initiated research effort, constituting the basis of > 200 original research and review articles (Online Table II), some highlighted here, many conference presentations, and several patents . In humans, increased arterial stiffness, or loss of elastic compliance of large arteries, has been linked to an increased risk of myocardial infarction, heart failure, stroke, and kidney disease, among other conditions. Pulse wave velocity (PWV), …