Inositol pyrophosphates inhibit Akt signaling, thereby regulating insulin sensitivity and weight gain.

The inositol pyrophosphate IP7 (5-diphosphoinositolpentakisphosphate), formed by a family of three inositol hexakisphosphate kinases (IP6Ks), modulates diverse cellular activities. We now report that IP7 is a physiologic inhibitor of Akt, a serine/threonine kinase that regulates glucose homeostasis and protein translation, respectively, via the GSK3ß and mTOR pathways. Thus, Akt and mTOR signaling are dramatically augmented and GSK3ß signaling reduced in skeletal muscle, white adipose tissue, and liver of mice with targeted deletion of IP6K1. IP7 affects this pathway by potently inhibiting the PDK1 phosphorylation of Akt, preventing its activation and thereby affecting insulin signaling. IP6K1 knockout mice manifest insulin sensitivity and are resistant to obesity elicited by high-fat diet or aging. Inhibition of IP6K1 may afford a therapeutic approach to obesity and diabetes.

Ectopic sulcular pain: detection and treatment.

Patients who present with acute or chronic posterior dental pain but cannot identify the tooth from which the pain originates may suffer from a common but often unrecognized condition. The present article introduces a new term for this disorder, ectopic sulcular pain (ESP), derived from its unusual presentation, location, and defining symptom. It is tempting to call ESP an infection, but this has not been confirmed. In ESP, oral examination reveals no visual abnormalities, and there are no evident fractures, caries, periodontitis, attachment loss, traumatic occlusion, or periapical abscesses. This confusing symptomatology often leads to incorrect diagnosis and, consequently, treatment that fails to relieve the patient's pain. This article discusses ESP and reports 13 cases in which the condition was identified via intraligamental or topical application of an anesthetic agent to numb the gingiva. In 12 patients, ESP was successfully treated with meticulous oral hygiene, chlorhexidine rinses, and, in some cases, oral antibiotics.

Reprint of: The Content of Troponin, Tropomyosin, Actin, and Myosin in Rabbit Skeletal Muscle Myofibrils.

A stacking sodium dodecyl sulfate polyacrylamide gel electrophoresis system has been used to resolve and quantify all the major myofibrillar protein components (actin, myosin, tropomyosin, and troponin C, T, and I). Quantification was achieved by densitometry of the fast green-stained gels calibrated with the use of purified proteins. The approximate molar ratios of these proteins in rabbit muscle are: actin : myosin: tropomyosin: troponin T: troponin I: troponin C = 7:1:1:1:1:1. On the basis of these results and available structural information one obtains an estimate of 254 myosin molecules per thick filament.

Budget impact analysis of the subcutaneous infliximab (CT-P13 SC) for treating inflammatory bowel disease in the Big-5 European (E5) countries.

BACKGROUND: In 2020, the European Medicines Agency approved infliximab subcutaneous (SC) for the treatment of inflammatory bowel disease. This new mode of infliximab administration will reduce outpatient visits and costs of intravenous (IV) administration. This article describes a budget impact analysis of introducing infliximab SC to the Big-5 European (E5) market (Germany, France, Italy, Spain and UK) for 5 years, from the healthcare payer's perspective. METHODS: A prevalence-based budget impact model was developed to examine the financial impact of infliximab SC. "World with" versus "world without" infliximab SC scenarios were compared, including the potential administration costs of IV administration. RESULTS: Introducing infliximab SC in patients with Crohn's disease (CD) for 5 years resulted in cost savings of €42.0 million in the UK, €59.4 million in Germany, and €46.4 million in France and Italy, but increased budget expenditure in Spain by €3.8 million. For ulcerative colitis (UC), cost savings of €42.7 million in the UK, €44.9 million in Germany, €44.3 million in France, and €53.0 million in Italy occurred, but with no savings in Spain for 5 years. Cost-savings per patient was calculated by diving the net budget saving by number of treatment eligible patients. Maximum and minimum saving per patient per year ranged between €38.25 and €575.74 in CD, both from Germany, and €105.06 (France) and €647.25 (Germany) in UC. CONCLUSION: Healthcare payers in the UK, Germany, France, and Italy, but not in Spain, will make budget savings by using infliximab SC for the treatment of inflammatory bowel disease.

Interaction Between Alcohol Consumption and PNPLA3 Variant in the Prevalence of Hepatic Steatosis in the US Population.

BACKGROUND & AIMS: To our knowledge, the interaction between alcohol consumption and PNPLA3 genotype on hepatic steatosis has not been explored in a representative sample. To examine the interaction between alcohol consumption and PNPLA3 genotype on hepatic steatosis in the US adult population. METHODS: Cross-sectional study of 4,674 adult participants of the Third National Health and Nutrition Examination Survey, Phase 2 (1991-1994) with data on PNPLA3 genotype, self-reported alcohol consumption, ultrasound-defined hepatic steatosis and socio-demographic characteristics. RESULTS: In 1991-1994 in the U.S. population, the weighted allele frequency of the G (risk) allele of the rs738409 at PNPLA3 was 25.4%. We confirmed both a J shaped association between alcohol consumption and hepatic steatosis among those with the CC genotype of PNPLA3, and a higher prevalence of hepatic steatosis among those with PNPLA3 gene G variant. We found evidence of an interaction of PNPLA3 G allele presence on the association between moderate alcohol consumption and hepatic steatosis on both the multiplicative (relative prevalence ratio [RPR]=1.95, 95% confidence interval [CI] 1.04-3.65) and additive scales (relative excess risk due to interaction=0.49, 95% CI 0.13-0.85). Compared to never drinkers, moderate alcohol drinking was associated with a 48% decreased risk of hepatic steatosis only among those without PNPLA3 G allele (PR=0.52, 95% CI 0.26-1.05), with no association among those with at least one copy of the PNPLA3 G allele (PR=1.02, 95% CI 0.68-1.54). CONCLUSIONS: Our results suggest that a highly common and strong genetic susceptibility to liver disease is modifiable by the level of alcohol consumption. Keeping alcohol consumption low may offset genetic predisposition to liver disease.

Increased TLR/MyD88 signaling in patients with obesity: is there a link to COVID-19 disease severity?

COVID-19 is a pandemic disease caused by a coronavirus, designed as SARS CoV-2, whose clinical presentation is widely variable, with most patients having mild or no symptoms, but others developing a malign disease with multi-organ failure and even death. Accumulating data from different populations have shown that obesity is a risk factor for a severe evolution of the disease, however, the mechanisms that explain this association are not clearly understood. An ominous evolution of COVID-19 has been attributed to an exacerbated inflammatory response, designed as "cytokine storm" with augmented production of cytokines/chemokines through the activation of toll-like receptors (TLR) by pathogen-associated molecular patterns, that triggers an inflammatory downstream response, mediated in part by the adaptor molecule, myeloid differentiation factor 88 (MyD88). Previous studies have reported an increased expression of MyD88 and TLRs in people with obesity, mainly in those with metabolic complications. Therefore, we hypothesize, that an underlying increased Myd88/TLR signaling may predispose to patients with obesity to develop an exaggerated and dangerous inflammatory reaction against SARS CoV-2 infection, explaining at least in part, the higher severity of COVID-19. In addition, MyD88/TLR signaling in people with obesity could have a role in the development of several chronic diseases.

Texts don't nudge: An adaptive trial to prevent the spread of COVID-19 in India.

We conduct an adaptive randomized controlled trial to evaluate the impact of a SMS-based information campaign on the adoption of social distancing and handwashing in rural Bihar, India, six months into the COVID-19 pandemic. We test 10 arms that vary in delivery timing and message framing, changing content to highlight gains or losses for either one's own family or community. We identify the optimal treatment separately for each targeted behavior by adaptively allocating shares across arms over 10 experimental rounds using exploration sampling. Based on phone surveys with nearly 4,000 households and using several elicitation methods, we do not find evidence of impact on knowledge or adoption of preventive health behavior, and our confidence intervals cannot rule out positive effects as large as 5.5 percentage points, or 16%. Our results suggest that SMS-based information campaigns may have limited efficacy after the initial phase of a pandemic.

Intracranial pressure in the American Alligator (Alligator mississippiensis): reptilian meninges and orthostatic gradients.

The cranial meninges of reptiles differ from the more widely studied mammalian pattern in that the intraventricular and subarachnoid spaces are, at least partially, isolated. This study was undertaken to investigate the bulk flow of cerebrospinal fluid, and the resulting changes in intracranial pressure, in a common reptilian species. Intracranial pressure was measured using ocular ultrasonography and by surgically implanting pressure cannulae into the cranial subarachnoid space. The system was then challenged by: rotating the animal to create orthostatic gradients, perturbation of the vascular system, administration of epinephrine, and cephalic cutaneous heating. Pressure changes determined from the implanted catheters and through quantification of the optic nerve sheath were highly correlated and showed a significant linear relationship with orthostatic gradients. The catheter pressure responses were phasic, with an initial rapid response followed by a much slower response; each phase accounted for roughly half of the total pressure change. No significant relationship was found between intracranial pressure and either heart rate or blood flow. The focal application of heat and the administration of epinephrine both increased intracranial pressure, the latter influence being particularly pronounced.

How Well Represented Are Women Orthopaedic Surgeons and Residents on Major Orthopaedic Editorial Boards and Publications?

BACKGROUND: Recent studies indicate that women are substantially underrepresented as orthopaedic surgeons and residents compared with other specialties in medicine and medical school. The reasons for this are multifactorial and not completely understood, but previous studies suggest that women may be attracted to fields in which they have female role models. Given that women interested in academia and research may use female editorship and authorship as a proxy for female representation in orthopaedic surgery, we wanted to examine the proportion of women represented in orthopaedic journals and determine if it reflects the distribution of women in orthopaedic surgery as a field. We further wanted to understand if this representation has changed over time in the setting of a slowly shifting gender landscape within orthopaedic surgery. QUESTIONS/PURPOSES: (1) How are women orthopaedic surgeons and residents represented in orthopaedic journals compared with men? (2) Have these proportions changed in the past two decades in light of relatively new efforts to recruit women to the field of orthopaedic surgery? METHODS: The gender composition of editorial boards and first and last authors were obtained from the 1997, 2007, and 2017 volumes of the following journals: The Journal of Bone & Joint Surgery (JBJS), the Journal of the American Academy of Orthopaedic Surgeons (JAAOS), and Clinical Orthopaedics and Related Research® (CORR®). Gender neutral names were searched to obtain a picture to ensure proper tallies. RESULTS: The total combined amount of women first and last authors increased from 88 of 1450 (6%) in 1997 to 152 of 1912 (8%) in 2007 to 723 of 5391 (13%) in 2017. Similarly, three of 113 (3%) editorial board members were women in 1997, three of 105 (3%) were women in 2007 and 10 of 107 (9%) editors were women in 2017. Of note, 0 out of 9 editors-in-chief were women. CONCLUSIONS: Based on the current percentage of women orthopaedic surgeons and residents, women are represented equally or in greater numbers as editors and authors in JAAOS, JBJS, and CORR. This may be in part due to women orthopaedic surgeons entering academic medicine at a greater rate than males. CLINICAL RELEVANCE: Orthopaedic surgeons serving as mentors to prospective female applicants can cite female representation on editorial boards and as authors as an example of gender parity in the field. Additionally, active orthopaedic surgeons who are women interested in these leadership positions should be encouraged that these opportunities exist, regardless of gender.

Targeted inactivation of copper transporter Atp7b in hepatocytes causes liver steatosis and obesity in mice.

Copper-transporting ATPase 2 (ATP7B) is essential for mammalian copper homeostasis. Mutations in ATP7B result in copper accumulation, especially in the liver, and cause Wilson disease (WD). The major role of hepatocytes in WD pathology is firmly established. It is less certain whether the excess Cu in hepatocytes is solely responsible for development of WD. To address this issue, we generated a mouse strain for Cre-mediated deletion of Atp7b and inactivated Atp7b selectively in hepatocytes. Atp7bΔHep mice accumulate copper in the liver, have elevated urinary copper, and lack holoceruloplasmin but show no liver disease for up to 30 wk. Liver inflammation is muted and markedly delayed compared with the age-matched Atp7b-/- null mice, which show a strong type1 inflammatory response. Expression of metallothioneins is higher in Atp7bΔHep livers than in Atp7b-/- mice, suggesting better sequestration of excess copper. Characterization of purified cell populations also revealed that nonparenchymal cells in Atp7bΔHep liver maintain Atp7b expression, have normal copper balance, and remain largely quiescent. The lack of inflammation unmasked metabolic consequences of copper misbalance in hepatocytes. Atp7bΔHep animals weigh more than controls and have higher levels of liver triglycerides and 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase. By 45 wk, all animals develop liver steatosis on a regular diet. Thus copper misbalance in hepatocytes dysregulates lipid metabolism, whereas development of inflammatory response in WD may depend on copper status of nonparenchymal cells. The implications of these findings for the cell-targeting WD therapies are discussed.NEW & NOTEWORTHY Targeted inactivation of copper-transporting ATPase 2 (Atp7b) in hepatocytes causes steatosis in the absence of inflammation.

Activation of liver X receptor/retinoid X receptor pathway ameliorates liver disease in Atp7B(-/-) (Wilson disease) mice.

UNLABELLED: Wilson disease (WD) is a hepatoneurological disorder caused by mutations in the copper-transporter, ATP7B. Copper accumulation in the liver is a hallmark of WD. Current therapy is based on copper chelation, which decreases the manifestations of liver disease, but often worsens neurological symptoms. We demonstrate that in Atp7b(-/-) mice, an animal model of WD, liver function can be significantly improved without copper chelation. Analysis of transcriptional and metabolic changes in samples from WD patients and Atp7b(-/-) mice identified dysregulation of nuclear receptors (NRs), especially the liver X receptor (LXR)/retinoid X receptor heterodimer, as an important event in WD pathogenesis. Treating Atp7b(-/-) mice with the LXR agonist, T0901317, ameliorated disease manifestations despite significant copper overload. Genetic markers of liver fibrosis and inflammatory cytokines were significantly decreased, lipid profiles normalized, and liver function and histology were improved. CONCLUSIONS: The results demonstrate the major role of an altered NR function in the pathogenesis of WD and suggest that modulation of NR activity should be explored as a supplementary approach to improving liver function in WD. (Hepatology 2016;63:1828-1841).

Deregulation of energy metabolism promotes antifibrotic effects in human hepatic stellate cells and prevents liver fibrosis in a mouse model.

Liver fibrosis and cirrhosis result from uncontrolled secretion and accumulation of extracellular matrix (ECM) proteins by hepatic stellate cells (HSCs) that are activated by liver injury and inflammation. Despite the progress in understanding the biology liver fibrogenesis and the identification of potential targets for treating fibrosis, development of an effective therapy remains elusive. Since an uninterrupted supply of intracellular energy is critical for the activated-HSCs to maintain constant synthesis and secretion of ECM, we hypothesized that interfering with energy metabolism could affect ECM secretion. Here we report that a sublethal dose of the energy blocker, 3-bromopyruvate (3-BrPA) facilitates phenotypic alteration of activated LX-2 (a human hepatic stellate cell line), into a less-active form. This treatment-dependent reversal of activated-LX2 cells was evidenced by a reduction in α-smooth muscle actin (α-SMA) and collagen secretion, and an increase in activity of matrix metalloproteases. Mechanistically, 3-BrPA-dependent antifibrotic effects involved down-regulation of the mitochondrial metabolic enzyme, ATP5E, and up-regulation of glycolysis, as evident by elevated levels of lactate dehydrogenase, lactate production and its transporter, MCT4. Finally, the antifibrotic effects of 3-BrPA were validated in vivo in a mouse model of carbon tetrachloride-induced liver fibrosis. Results from histopathology & histochemical staining for collagen and α-SMA substantiated that 3-BrPA promotes antifibrotic effects in vivo. Taken together, our data indicate that sublethal, metronomic treatment with 3-BrPA blocks the progression of liver fibrosis suggesting its potential as a novel therapeutic for treating liver fibrosis.

Tim-3/galectin-9 regulate the homeostasis of hepatic NKT cells in a murine model of nonalcoholic fatty liver disease.

T cell Ig and mucin domain (Tim)-3 is well known to interact with its natural ligand, Galectin-9 (Gal-9), to regulate T cell function. However, little is known about the function of Tim-3/Gal-9 signaling in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) mediated by hepatic NKT cells that also express Tim-3. In the current study, we define the role and the mechanism of Tim-3/Gal-9 signaling in hepatic NKT cell regulation in a mouse model of diet-induced NAFLD. Adult male wild-type or CD1d knockout C57BL/6 mice were fed a high-fat diet to induce steatosis. Some of the mice also received one or a combination of Gal-9, anti-IL-15R/IL-15 mAb, rIL-15, α-galactosylceramide, and multilamellar liposomes containing Cl(2)MDP. The expression of Tim-3 and various markers reflecting cell proliferation, activation, cytokine production, and apoptosis was analyzed. Liver histology, steatosis grade, and hepatic triglyceride content were also evaluated. In the liver, Tim-3(+) NKT cells are in an activated state, and Gal-9 directly induces Tim-3(+) NKT cell apoptosis and contributes to the depletion of NKT cells in diet-induced steatosis. However, Gal-9 also interacts with Tim-3-expressing Kupffer cells to induce secretion of IL-15, thus promoting NKT cell proliferation. Exogenous administration of Gal-9 significantly ameliorates diet-induced steatosis by modulating hepatic NKT cell function. In summary, the Tim-3/Gal-9-signaling pathway plays a critical role in the homeostasis of hepatic NKT cells through activation-induced apoptosis and secondary proliferation and, thus, contributes to the pathogenesis of NAFLD.

Effects of vitamin D3 stimulation of thioredoxin-interacting protein in hepatocellular carcinoma.

AIM: Thioredoxin-interacting protein (TXNIP) promotes oxidative stress by inactivating thioredoxin (TXN). This protein is involved in diverse disease processes, including insulin resistance, atherosclerosis and carcinogenesis. The aim of the present study was to measure the expression and function of TXNIP in in vitro models of liver disease, as well as in primary human hepatocellular carcinoma (HCC) tissue specimens. In addition, we wanted to determine the effects of vitamin D3-induced TXNIP stimulation in HCC-derived cell lines. METHODS: TXNIP expression was measured by quantitative reverse transcription polymerase chain reaction and western blots. TXNIP expression was stimulated by vitamin D exposure and by transfection. Cell proliferation, apoptosis and reactive oxygen species were determined by standard assays. RESULTS: TXNIP expression levels were low in HCC cell lines, and vitamin D3 stimulated TXNIP expression in vitro. In HCC cells transfected with a TXNIP expression vector or treated with exogenous vitamin D3, there was a reduction in cell proliferation and an increase in apoptosis. Cells expressing TXNIP were markedly susceptible to oxidative injury induced by cobalt chloride or bacterial lipopolysaccharide. TXNIP expression was reduced or absent in a majority of primary human HCC specimens relative to matching, non-cancerous liver tissue. CONCLUSION: TXNIP expression is low or absent in human HCC specimens and HCC-derived cell lines. Vitamin D3 stimulates TXNIP expression, resulting in diminished proliferation and enhanced apoptosis. Liver cells expressing TXNIP are primed for oxidative injury. These findings suggest that stimulation of TXNIP expression, by factors such as vitamin D3, may attenuate carcinogenesis in patients with chronic liver disease.

Molecular analysis of human tick-bitten skin yields signatures associated with distinct spatial and temporal trajectories - A proof-of-concept study.

Tick-associated diseases present challenges due to tridirectional interactions among host-specific responses, tick toxins and salivary proteins as well as microbes. We aimed to uncover molecular mechanisms in tick-bitten skin samples (cases) and contralateral skin samples (controls) collected simultaneously from the same participants, using spatial transcriptomics. Cases and controls analysed using NanoString GeoMx Digital Spatial Profiler identified 274 upregulated and 840 downregulated differentially expressed genes (DEGs), revealing perturbations in keratinization and immune system regulation. Samples of skin biopsies taken within 72 h post tick-bite DEGs had changes in protein metabolism and viral infection pathways as compared to samples taken 3 months post tick-bite, which instead displayed significant perturbations in several epigenetic regulatory pathways, highlighting the temporal nature of the host response following tick bites. Within-individual signatures distinguished tick-bitten samples from controls and identified between-individual signatures, offering promise for future biomarker discovery to guide prognosis and therapy.

A mutation in TNNC1-encoded cardiac troponin C, TNNC1-A31S, predisposes to hypertrophic cardiomyopathy and ventricular fibrillation.

Defined as clinically unexplained hypertrophy of the left ventricle, hypertrophic cardiomyopathy (HCM) is traditionally understood as a disease of the cardiac sarcomere. Mutations in TNNC1-encoded cardiac troponin C (cTnC) are a relatively rare cause of HCM. Here, we report clinical and functional characterization of a novel TNNC1 mutation, A31S, identified in a pediatric HCM proband with multiple episodes of ventricular fibrillation and aborted sudden cardiac death. Diagnosed at age 5, the proband is family history-negative for HCM or sudden cardiac death, suggesting a de novo mutation. TnC-extracted cardiac skinned fibers were reconstituted with the cTnC-A31S mutant, which increased Ca(2+) sensitivity with no effect on the maximal contractile force generation. Reconstituted actomyosin ATPase assays with 50% cTnC-A31S:50% cTnC-WT demonstrated Ca(2+) sensitivity that was intermediate between 100% cTnC-A31S and 100% cTnC-WT, whereas the mutant increased the activation of the actomyosin ATPase without affecting the inhibitory qualities of the ATPase. The secondary structure of the cTnC mutant was evaluated by circular dichroism, which did not indicate global changes in structure. Fluorescence studies demonstrated increased Ca(2+) affinity in isolated cTnC, the troponin complex, thin filament, and to a lesser degree, thin filament with myosin subfragment 1. These results suggest that this mutation has a direct effect on the Ca(2+) sensitivity of the myofilament, which may alter Ca(2+) handling and contribute to the arrhythmogenesis observed in the proband. In summary, we report a novel mutation in the TNNC1 gene that is associated with HCM pathogenesis and may predispose to the pathogenesis of a fatal arrhythmogenic subtype of HCM.

Generation and functional characterization of knock-in mice harboring the cardiac troponin I-R21C mutation associated with hypertrophic cardiomyopathy.

The R21C substitution in cardiac troponin I (cTnI) is the only identified mutation within its unique N-terminal extension that is associated with hypertrophic cardiomyopathy (HCM) in man. Particularly, this mutation is located in the consensus sequence for ß-adrenergic-activated protein kinase A (PKA)-mediated phosphorylation. The mechanisms by which this mutation leads to heart disease are still unclear. Therefore, we generated cTnI knock-in mouse models carrying an R21C mutation to evaluate the resultant functional consequences. Measuring the in vivo levels of incorporated mutant and WT cTnI, and their basal phosphorylation levels by top-down mass spectrometry demonstrated: 1) a dominant-negative effect such that, the R21C+/- hearts incorporated 24.9% of the mutant cTnI within the myofilament; and 2) the R21C mutation abolished the in vivo phosphorylation of Ser(23)/Ser(24) in the mutant cTnI. Adult heterozygous (R21C+/-) and homozygous (R21C+/+) mutant mice activated the fetal gene program and developed a remarkable degree of cardiac hypertrophy and fibrosis. Investigation of cardiac skinned fibers isolated from WT and heterozygous mice revealed that the WT cTnI was completely phosphorylated at Ser(23)/Ser(24) unless the mice were pre-treated with propranolol. After propranolol treatment (-PKA), the pCa-tension relationships of all three mice (i.e. WT, R21C+/-, and R21C+/+) were essentially the same. However, after treatment with propranolol and PKA, the R21C cTnI mutation reduced (R21C+/-) or abolished (R21C+/+) the well known decrease in the Ca(2+) sensitivity of tension that accompanies Ser(23)/Ser(24) cTnI phosphorylation. Altogether, the combined effects of the R21C mutation appear to contribute toward the development of HCM and suggest that another physiological role for the phosphorylation of Ser(23)/Ser(24) in cTnI is to prevent cardiac hypertrophy.

The functional properties of human slow skeletal troponin T isoforms in cardiac muscle regulation.

Human slow skeletal troponin T (HSSTnT) shares a high degree of homology with cardiac TnT (CTnT). Although the presence of HSSTnT has not been confirmed in the heart at the protein level, detectable levels of HSSTnT mRNA have been found. Whether HSSTnT isoforms are expressed transiently remains unknown. Because transient re-expression of HSSTnT may be a potential mechanism of regulating function, we explored the effect of HSSTnT on the regulation of cardiac muscle. At least three HSSTnT isoforms have been found to exist in slow skeletal muscle: HSSTnT1 (+exons 5 and 12), HSSTnT2 (+exon 5, -exon 12), and HSSTnT3 (-exons 5 and 12). Another isoform, HSSTnT hypothetical (Hyp) (-exon 5, +exon 12), has only been found at the mRNA level. Compared with HCTnT3 (adult isoform), Tn complexes containing HSSTnT1, -2, and -3 did not alter the actomyosin ATPase activation and inhibition in the presence and absence of Ca(2+), respectively. HSSTnTHyp was not evaluated as it did not form a Tn complex under a variety of conditions. Porcine papillary skinned fibers displaced with HSSTnT1, -2, or -3 and reconstituted with human cardiac troponin I and troponin C (HCTnI·TnC) complex showed a decrease in the Ca(2+) sensitivity of force development and an increase in maximal recovered force (HSSTnT1 and -3) compared with HCTnT3. In contrast, HSSTnTHyp showed an increase in the Ca(2+) sensitivity of force development. This suggests that re- or overexpression of specific SSTnT isoforms might have therapeutic potential in the failing heart because they increase the maximal force of contraction. In addition, circular dichroism and proteolytic digestion experiments revealed structural differences between HSSTnT isoforms and HCTnT3 and that HSSTnT1 is more susceptible to calpain and trypsin proteolysis than the other HSSTnTs. Overall, HSSTnT isoforms despite being homologues of CTnT may display distinct functional properties in muscle regulation.

Yes-associated protein regulates the hepatic response after bile duct ligation.

UNLABELLED: Human chronic cholestatic liver diseases are characterized by cholangiocyte proliferation, hepatocyte injury, and fibrosis. Yes-associated protein (YAP), the effector of the Hippo tumor-suppressor pathway, has been shown to play a critical role in promoting cholangiocyte and hepatocyte proliferation and survival during embryonic liver development and hepatocellular carcinogenesis. Therefore, the aim of this study was to examine whether YAP participates in the regenerative response after cholestatic injury. First, we examined human liver tissue from patients with chronic cholestasis. We found more-active nuclear YAP in the bile ductular reactions of primary sclerosing cholangitis and primary biliary cirrhosis patient liver samples. Next, we used the murine bile duct ligation (BDL) model to induce cholestatic liver injury. We found significant changes in YAP activity after BDL in wild-type mice. The function of YAP in the hepatic response after BDL was further evaluated with liver-specific Yap conditional deletion in mice. Ablating Yap in the mouse liver not only compromised bile duct proliferation, but also enhanced hepatocyte necrosis and suppressed hepatocyte proliferation after BDL. Furthermore, primary hepatocytes and cholangiocytes isolated from Yap-deficient livers showed reduced proliferation in response to epidermal growth factor in vitro. Finally, we demonstrated that YAP likely mediates its biological effects through the modulation of Survivin expression. CONCLUSION: Our data suggest that YAP promotes cholangiocyte and hepatocyte proliferation and prevents parenchymal damage after cholestatic injury in mice and thus may mediate the response to cholestasis-induced human liver disease.

John Gergely (1919-2013): a pillar in the muscle protein field.

Dr. John Gergely passed away on July 26, 2013 after a long and distinguished career. His publications spanned 67 years. He founded the Department of Muscle Research in the Retina Foundation (which later became the Boston Biomedical Research Institute) and served as director for 34 years. Dr. Gergely served on the editorial boards of ten scientific journals. He was elected as a Fellow of both the Biophysical Society and the American Association for the Advancement of Science. Dr. Gergely made major contributions concerning muscle protein structure and function. He was best known for his work on the troponin complex. The insights of John and his associates have provided the foundation for our understanding of calcium regulation in skeletal and cardiac muscle.