Carboxyl-terminal sequences in APOA5 are important for suppressing ANGPTL3/8 activity.

Apolipoprotein AV (APOA5) lowers plasma triglyceride (TG) levels by binding to the angiopoietin-like protein 3/8 complex (ANGPTL3/8) and suppressing its capacity to inhibit lipoprotein lipase (LPL) catalytic activity and its ability to detach LPL from binding sites within capillaries. However, the sequences in APOA5 that are required for suppressing ANGPTL3/8 activity have never been defined. A clue to the identity of those sequences was the presence of severe hypertriglyceridemia in two patients harboring an APOA5 mutation that truncates APOA5 by 35 residues ("APOA5Δ35"). We found that wild-type (WT) human APOA5, but not APOA5Δ35, suppressed ANGPTL3/8's ability to inhibit LPL catalytic activity. To pursue that finding, we prepared a mutant mouse APOA5 protein lacking 40 C-terminal amino acids ("APOA5Δ40"). Mouse WT-APOA5, but not APOA5Δ40, suppressed ANGPTL3/8's capacity to inhibit LPL catalytic activity and sharply reduced plasma TG levels in mice. WT-APOA5, but not APOA5Δ40, increased intracapillary LPL levels and reduced plasma TG levels in Apoa5-/- mice (where TG levels are high and intravascular LPL levels are low). Also, WT-APOA5, but not APOA5Δ40, blocked the ability of ANGPTL3/8 to detach LPL from cultured cells. Finally, an antibody against a synthetic peptide corresponding to the last 26 amino acids of mouse APOA5 reduced intracapillary LPL levels and increased plasma TG levels in WT mice. We conclude that C-terminal sequences in APOA5 are crucial for suppressing ANGPTL3/8 activity in vitro and for regulating intracapillary LPL levels and plasma TG levels in vivo.

Angiopoietin-like protein 4/8 complex-mediated plasmin generation leads to cleavage of the complex and restoration of LPL activity.

Triglyceride (TG) metabolism is highly regulated by angiopoietin-like protein (ANGPTL) family members [Y. Q. Chen et al., J. Lipid Res. 61, 1203-1220 (2020)]. During feeding, ANGPTL8 forms complexes with the fibrinogen-like domain-containing protein ANGPTL4 in adipose tissue to decrease ANGPTL3/8- and ANGPTL4-mediated lipoprotein lipase (LPL)-inhibitory activity and promote TG hydrolysis and fatty acid (FA) uptake. The ANGPTL4/8 complex, however, tightly binds LPL and partially inhibits it in vitro. To try to reconcile the in vivo and in vitro data on ANGPTL4/8, we aimed to find novel binding partners of ANGPTL4/8. To that end, we performed pulldown experiments and found that ANGPTL4/8 bound both tissue plasminogen activator (tPA) and plasminogen, the precursor of the fibrinolytic enzyme plasmin. Remarkably, ANGPTL4/8 enhanced tPA activation of plasminogen to generate plasmin in a manner like that observed with fibrin, while minimal plasmin generation was observed with ANGPTL4 alone. The addition of tPA and plasminogen to LPL-bound ANGPTL4/8 caused rapid, complete ANGPTL4/8 cleavage and increased LPL activity. Restoration of LPL activity in the presence of ANGPTL4/8 was also achieved with plasmin but was blocked when catalytically inactive plasminogen (S760A) was added to tPA or when plasminogen activator inhibitor-1 was added to tPA + plasminogen, indicating that conversion of plasminogen to plasmin was essential. Together, these results suggest that LPL-bound ANGPTL4/8 mimics fibrin to recruit tPA and plasminogen to generate plasmin, which then cleaves ANGPTL4/8, enabling LPL activity to be increased. Our observations thus reveal a unique link between the ANGPTL4/8 complex and plasmin generation.

Decoding the role of angiopoietin-like protein 4/8 complex-mediated plasmin generation in the regulation of LPL activity.

After feeding, adipose tissue lipoprotein lipase (LPL) activity should be maximized, therefore the potent LPL-inhibitory activity of angiopoietin-like protein 4 (ANGPTL4) must be blocked by ANGPTL8 through formation of ANGPTL4/8 complexes. ANGPTL4/8 tightly binds and protects LPL but also partially inhibits its activity. Recently, we demonstrated ANGPTL4/8 also binds tissue plasminogen activator (tPA) and plasminogen to generate plasmin that cleaves ANGPTL4/8 to restore LPL activity. Although fully active LPL in the fat postprandially is desirable, ANGPTL4/8 removal could subject LPL to profound inhibition by ANGPTL3/8 (the most potent circulating LPL inhibitor), inhibition by other LPL inhibitors like ANGPTL4, ANGPTL3, and ApoC3 or interfere with ApoC2-mediated LPL activation. To understand better these potential paradoxes, we examined LPL inhibition by ANGPTL3/8, ANGPTL4, ANGPTL3, and ApoC3 and LPL stimulation by ApoC2 in the presence of ANGPTL4/8 + tPA + plasminogen. Remarkably, ANGPTL3/8-mediated LPL inhibition was almost completely blocked, with the mechanism being cleavage of fibrinogen-like domain-containing ANGPTL3 present in the ANGPTL3/8 complex. The LPL-inhibitory effects of ANGPTL4, ANGPTL3, and ApoC3 were also largely reduced in the presence of ANGPTL4/8 + tPA + plasminogen. In contrast, the ability of ApoC2 to stimulate LPL activity was unaffected by ANGPTL4/8-mediated plasmin generation. Together, these results explain how plasmin generated by increased postprandial ANGPTL4/8 levels in adipose tissue enables maximal LPL activity by preventing ANGPTL3/8, ANGPTL4, ANGPTL3, and ApoC3 from inhibiting LPL, while permitting ApoC2-mediated LPL activation to occur.

Impact of HIV treat-all and complementary policies on ART linkage in 13 PEPFAR-supported African countries.

BACKGROUND: In 2015, the World Health Organization recommended that all people living with HIV begin antiretroviral treatment (ART) regardless of immune status, a policy known as 'Treat-All to end AIDS', commonly referred to as Treat-All. Almost all low- and middle-income countries adopted this policy by 2019. This study describes how linkage to treatment of newly diagnosed persons changed between 2015 and 2018 and how complementary policies may have similarly increased linkage for 13 African countries. These countries adopted and implemented Treat-All policies between 2015 and 2018 and were supported by the U.S. Government's President's Emergency Plan for AIDS Relief (PEPFAR). The focuses of this research were to understand 1) linkage rates to ART initiation before and after the adoption of Treat-All in each country; 2) how Treat-All implementation differed across these countries; and 3) whether complementary policies (including same-day treatment initiation, task-shifting, reduced ART visits, and reduced ART pickups) implemented around the same time may have increased ART linkage. METHODS: HIV testing and treatment data were collected by PEPFAR country programs in 13 African countries from 2015 to 2018. These countries were chosen based on the completeness of policy data and availability of program data during the study period. Program data were used to calculate proxy linkage rates. These rates were compared relative to the Treat All adoption period and the adoption of complementary policies. RESULTS: The 13 countries experienced an average increase in ART linkage of 29.3% over the entire study period. In examining individual countries, all but two showed increases in linkage to treatment immediately after Treat All adoption. Across all countries, those that had adopted four or more complementary policies showed an average increased linkage of 39.8% compared to 13.9% in countries with fewer than four complementary policies. CONCLUSIONS: Eleven of 13 country programs examined in this study demonstrated an increase in ART linkage after Treat-All policy adoption. Increases in linkage were associated with complementary policies. When exploring new public health policies, policymakers may consider which complementary policies might also help achieve the desired outcome of the public health policy.

An anti-ANGPTL3/8 antibody decreases circulating triglycerides by binding to a LPL-inhibitory leucine zipper-like motif.

Triglycerides (TG) are required for fatty acid transport and storage and are essential for human health. Angiopoietin-like-protein 8 (ANGPTL8) has previously been shown to form a complex with ANGPTL3 that increases circulating TG by potently inhibiting LPL. We also recently showed that the TG-lowering apolipoprotein A5 (ApoA5) decreases TG levels by suppressing ANGPTL3/8-mediated LPL inhibition. To understand how LPL binds ANGPTL3/8 and ApoA5 blocks this interaction, we used hydrogen-deuterium exchange mass-spectrometry and molecular modeling to map binding sites of LPL and ApoA5 on ANGPTL3/8. Remarkably, we found that LPL and ApoA5 both bound a unique ANGPTL3/8 epitope consisting of N-terminal regions of ANGPTL3 and ANGPTL8 that are unmasked upon formation of the ANGPTL3/8 complex. We further used ANGPTL3/8 as an immunogen to develop an antibody targeting this same epitope. After refocusing on antibodies that bound ANGPTL3/8, as opposed to ANGPTL3 or ANGPTL8 alone, we utilized bio-layer interferometry to select an antibody exhibiting high-affinity binding to the desired epitope. We revealed an ANGPTL3/8 leucine zipper-like motif within the anti-ANGPTL3/8 epitope, the LPL-inhibitory region, and the ApoA5-interacting region, suggesting the mechanism by which ApoA5 lowers TG is via competition with LPL for the same ANGPTL3/8-binding site. Supporting this hypothesis, we demonstrate that the anti-ANGPTL3/8 antibody potently blocked ANGPTL3/8-mediated LPL inhibition in vitro and dramatically lowered TG levels in vivo. Together, these data show that an anti-ANGPTL3/8 antibody targeting the same leucine zipper-containing epitope recognized by LPL and ApoA5 markedly decreases TG by suppressing ANGPTL3/8-mediated LPL inhibition.

BET 2: CT versus MRI for occult hip fractures.

A short-cut review was carried out to establish whether CT or MRI is better at detecting an occult hip fracture. Six studies were directly relevant to the question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. The clinical bottom line is that CT is a valid first-line investigation for a suspected plain X-ray occult hip fracture. If clinical suspicion remains after a negative CT scan, then MRI should be used.

A review of infectious disease epidemiology in emergency medical service clinicians.

BACKGROUND: The emergency medical service (EMS) workforce is at high risk of occupationally-acquired infections. This review synthesized existing literature on the prevalence, incidence, and severity of infections in the EMS workforce. METHODS: We searched PubMed, Embase, CINAHL, and SCOPUS from January 1, 2006 to March 15, 2022 for studies in the US that involved EMS clinician or firefighter populations and reported 1 or more health outcomes related to occupationally-acquired infections. RESULTS: Of the 25 studies that met the inclusion criteria, most focused on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, with prevalence rates ranging from 1.1% to 36.2% (median 6.7%). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in 4 studies ranged from 1.9% to 6.4%, and the prevalence of Hepatitis C in 1 study was 1.3%. Few studies reported incidence rates. The prevalence or incidence of these infections generally did not differ by age or gender, but 4 studies reported differences by race or ethnicity. In the 4 studies that compared infection rates between EMS clinicians and firefighters, EMS clinicians had a higher chance of hospitalization or death from SAR-CoV-2 (odds ratio 4.23), a higher prevalence of Hepatitis C in another study (odds ratio 1.74), and no significant difference in MRSA colonization in a separate study. CONCLUSIONS: More research is needed to better characterize the incidence and severity of occupationally-acquired infections in the EMS workforce.

Current Evidence for Infection Prevention and Control Interventions in Emergency Medical Services: A Scoping Review.

OBJECTIVES: The aim of this review was to summarize current evidence from the United States on the effectiveness of practices and interventions for preventing, recognizing, and controlling occupationally acquired infectious diseases in Emergency Medical Service (EMS) clinicians. REPORT AND METHODS: PubMed, Embase, CINAHL, and SCOPUS were searched from January 1, 2006 through March 15, 2022 for studies in the United States that involved EMS clinicians and firefighters, reported on one or more workplace practices or interventions that prevented or controlled infectious diseases, and included outcome measures. Eleven (11) observational studies reported on infection prevention and control (IPC) practices providing evidence that hand hygiene, standard precautions, mandatory vaccine policies, and on-site vaccine clinics are effective. Less frequent handwashing (survey-weight adjusted odds ratio [OR] 4.20; 95% confidence interval [CI], 1.02 to 17.27) and less frequent hand hygiene after glove use (survey-weight adjusted OR 10.51; 95% CI, 2.54 to 43.45) were positively correlated with nasal colonization of Methicillin-resistant Staphylococcus aureus (MRSA). Lack of personal protective equipment (PPE) or PPE breach were correlated with higher severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seropositivity (unadjusted risk ratio [RR] 4.2; 95% CI, 1.03 to 17.22). Workers were more likely to be vaccinated against influenza if their employer offered the vaccine (unadjusted OR 3.3; 95% CI, 1.3 to 8.3). Active, targeted education modules for H1N1 influenza were effective at increasing vaccination rates and the success of on-site vaccine clinics. CONCLUSIONS: Evidence from the United States exists on the effectiveness of IPC practices in EMS clinicians, including hand hygiene, standard precautions, mandatory vaccine policies, and vaccine clinics. More research is needed on the effectiveness of PPE and vaccine acceptance.

Viral load scale-up in south Sudan: Strategic implementation of tools to monitor HIV treatment success among people living with HIV.

INTRODUCTION: As access to antiretroviral therapy (ART) for people with HIV (PWH) in the Republic of South Sudan (RSS) increases, viral load (VL) suppression is critical to protect global HIV response investments. We describe VL scale-up between 2017-2020 in the RSS President's Emergency Plan for AIDS Relief (PEPFAR)-supported program. METHODS: President's Emergency Plan for AIDS Relief (PEPFAR) South Sudan developed a VL scale-up plan and tools spanning the VL cascade: pre-test, test and post-test and included assessment of clinical facility and laboratory readiness; clinical and laboratory forms and standard operating procedures for test ordering, specimen collection, processing, results return and utilization; procedures to map clients, monitor turn-around-times (TAT), and an electronic system to monitor VL performance. RESULTS: Between 2017 to 2020, VL monitoring was established in 58 facilities, with 59,600 VL samples processed, and improvements in TAT (150-28 days) and rejection rates (1.9%-0.8%). VL documentation improved for dates of ART initiation, VL test request and dispatch, and HIV regimen. Total average time from high VL to repeat VL decreased from 15.9 months to 6.4 months in 2017 and 2019, respectively. CONCLUSIONS: A concerted approach to VL scale-up has been fundamental as South Sudan strives towards UNAIDS 95-95-95 targets for PWH on ART.

Characteristics of SARS-CoV-2 Seropositivity among Emergency Department Healthcare Workers at a Tertiary Care Center in Baltimore.

Early in the COVID-19 pandemic (March−July 2020 in Baltimore), emergency department (ED) healthcare workers (HCWs) were considered to be at greater risk of contracting SARS-CoV-2. Limited data existed, however, on the prevalence of SARS-CoV-2 infection and its impact in this workforce population. We enrolled 191 ED HCWs from a tertiary academic center, administered baseline and weekly surveys, and tested them twice (July and December 2020) for serum antibodies against SARS-CoV-2 spike protein. Approximately 6% (11 of 191, 5.8%) of ED HCWs had spike antibodies in July, a prevalence that doubled by December (21 of 174, 12.1%). A positive PCR test was self-reported by 15 of 21 (71%) seropositive and 6 of 153 (4%) seronegative HCWs (p < 0.001). Of the total 27 HCWs who had antibodies and/or were PCR positive, none required hospitalization, 18 (67%) had a self-perceived COVID-19 illness, and 12 of the 18 reported symptoms. The median number of missed workdays was 8.5 (ranging from 2 to 21). While most seropositive ED HCWs who reported symptoms took work absences, none required hospitalization, indicating that COVID-19's impact on staffing prior to vaccination was not as great as feared.

Crystal structure of active CDK4-cyclin D and mechanistic basis for abemaciclib efficacy.

Despite the biological and therapeutic relevance of CDK4/6 for the treatment of HR+, HER2- advanced breast cancer, the detailed mode of action of CDK4/6 inhibitors is not completely understood. Of particular interest, phosphorylation of CDK4 at T172 (pT172) is critical for generating the active conformation, yet no such crystal structure has been reported to date. We describe here the x-ray structure of active CDK4-cyclin D3 bound to the CDK4/6 inhibitor abemaciclib and discuss the key aspects of the catalytically-competent complex. Furthermore, the effect of CDK4/6 inhibitors on CDK4 T172 phosphorylation has not been explored, despite its role as a potential biomarker of CDK4/6 inhibitor response. We show mechanistically that CDK4/6i stabilize primed (pT172) CDK4-cyclin D complex and selectively displace p21 in responsive tumor cells. Stabilization of active CDK4-cyclin D1 complex can lead to pathway reactivation following alternate dosing regimen. Consequently, sustained binding of abemaciclib to CDK4 leads to potent cell cycle inhibition in breast cancer cell lines and prevents rebound activation of downstream signaling. Overall, our study provides key insights demonstrating that prolonged treatment with CDK4/6 inhibitors and composition of the CDK4/6-cyclin D complex are both critical determinants of abemaciclib efficacy, with implications for this class of anticancer therapy.

COVID-19 mitigation measures to maintain access to essential health services: new opportunities with long-term benefits.

The coronavirus disease 2019 (COVID-19) pandemic has substantially impacted health systems globally. To highlight potential opportunities to improve health service delivery in low- and middle-income countries, we describe lessons learned from published literature and experiences responding to the pandemic. The benefits of healthcare service measures implemented during the pandemic with potential for lasting benefits for strengthening health systems are highlighted: 1) innovative pharmaceutical dispensing methods; 2) appointment-based systems in health facilities; 3) telehealth to provide patient care; 4) task shifting to redistribute healthcare workloads; and 5) home-based pulse oximetry to monitor oxygen levels. These measures can reduce unnecessary contact with healthcare staff while maintaining critical health service delivery and may be of value to continue after the pandemic subsides.

Providing Quality of Care in Fragile and Vulnerable Settings: Lessons from South Sudan.

BACKGROUND: In 2020, the World Health Organization (WHO) released a report concerning planning and actions to provide quality of care in fragile, conflict-affected, and vulnerable areas. South Sudan, the world's newest country, has encountered both natural and man-made disasters in recent years that have posed marked challenges to delivery of care. The Southern Sudan Healthcare Organization (SSHCO) operates as a non-governmental organization (NGO) in this setting, delivering and improving healthcare through war, flooding, and infectious outbreaks. OBJECTIVE: The goal of this paper is to highlight the challenges faced in providing care in South Sudan from an NGO perspective and apply the recent WHO guidelines on quality of care to optimize practical implementation. METHOD: Each of the WHO's eight elements for quality of care in South Sudan were examined in relation to the experience of SSHCO from 2013-2021. Analysis included: 1. summary of the WHO element; 2. examples of successful implementation; 3. barriers to implementation; and 4. recommendations to improve implementation. FINDINGS: The team found that communication and coordination were the most important aspects of improving quality of care in South Sudan. These should be prioritized and include intergovernmental partners, the local and national Ministry of Health (MOH), NGOs, and community stakeholders. Communication and coordination should foster community engagement, improved data collecting and reporting, and sharing of publicly accessible information. Better clinical staff training and governance are also required to ensure the most effective use of limited resources. CONCLUSION: South Sudan faces many barriers to quality of care with communication and coordination identified among the foremost issues. Practical application of the WHO elements of quality of care can assist NGOs in effectively identifying areas for improvement to deliver better quality essential health services.

A structure-based engineering approach to abrogate pre-existing antibody binding to biotherapeutics.

Development of biotherapeutics is hampered by the inherent risk of immunogenicity, which requires extensive clinical assessment and possible re-engineering efforts for mitigation. The focus in the pre-clinical phase is to determine the likelihood of developing treatment-emergent anti-drug antibodies (TE-ADA) and presence of pre-existing ADA in drug-naïve individuals as risk-profiling strategies. Pre-existing ADAs are routinely identified during clinical immunogenicity assessment, but their origin and impact on drug safety and efficacy have not been fully elucidated. One specific class of pre-existing ADAs has been described, which targets neoepitopes of antibody fragments, including Fabs, VH, or VHH domains in isolation from their IgG context. With the increasing number of antibody fragments and other small binding scaffolds entering the clinic, a widely applicable method to mitigate pre-existing reactivity against these molecules is desirable. Here is described a structure-based engineering approach to abrogate pre-existing ADA reactivity to the C-terminal neoepitope of VH(H)s. On the basis of 3D structures, small modifications applicable to any VH(H) are devised that would not impact developability or antigen binding. In-silico B cell epitope mapping algorithms were used to rank the modified VHH variants by antigenicity; however, the limited discriminating capacity of the computational methods prompted an experimental evaluation of the engineered molecules. The results identified numerous modifications capable of reducing pre-existing ADA binding. The most efficient consisted of the addition of two proline residues at the VHH C-terminus, which led to no detectable pre-existing ADA reactivity while maintaining favorable developability characteristics. The method described, and the modifications identified thereby, may provide a broadly applicable solution to mitigate immunogenicity risk of antibody-fragments in the clinic and increase safety and efficacy of this promising new class of biotherapeutics.

Primary vaginal adenocarcinoma of intestinal type or occult metastatic colon cancer: a diagnostic dilemma from a vaginal skin tag.

The presentation of a new vaginal lesion could represent a variety of diagnoses from benign warts to more sinister primary malignancies. Rarely, a new lesion could represent a metastatic deposit from a malignancy elsewhere in the body. Colonic carcinomas are the third most common malignancy, frequently metastasising to the liver and lung. There have been a small number of cases in the literature reporting vaginal metastases from colonic carcinoma and this is usually indicative of advanced disseminated disease. We present an interesting case of a 65-year-old female with a strong family history of bowel cancer who originally presented with a vaginal skin tag that was biopsied and found to be a moderately differentiated adenocarcinoma. The immunohistochemistry profile was cytokeratin (CK) 20 positive/CK 7 negative, highly suggestive of a bowel cancer primary. However, subsequent extensive radiological and endoscopic investigations failed to identify a colonic primary tumor. The vaginal lesion was successfully excised, and no systemic treatments were warranted. To date, no primary cancer has been identified; the patient remains asymptomatic with no clinical signs of disease recurrence 5 years following her initial diagnosis. This case represents a diagnostic dilemma between two very rare diagnoses of either a vaginal metastasis from an occult colonic primary tumor or a primary vaginal adenocarcinoma of endometrioid morphology demonstrating intestinal immunophenotype. Organizing colonic screening is recommended in view of the high risk of colonic adenocarcinoma.

Gene conversion is a frequent mechanism of inactivation of the wild-type allele in cancers from MLH1/MSH2 deletion carriers.

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominantly inherited cancer predisposition syndrome caused by germ line mutations in DNA mismatch repair genes, predominantly MLH1 and MSH2, with large genomic rearrangements accounting for 5% to 20% of all mutations. Although crucial to the understanding of cancer initiation, little is known about the second, somatic hit in HNPCC tumorigenesis, commonly referred to as loss of heterozygosity. Here, we applied a recently developed method, multiplex ligation-dependent probe amplification, to study MLH1/MSH2 copy number changes in 16 unrelated Swiss HNPCC patients, whose cancers displayed microsatellite instability and loss of MLH1 or MSH2 expression, but in whom no germ line mutation could be detected by conventional screening. The aims of the study were (a) to determine the proportion of large genomic rearrangements among Swiss MLH1/MSH2 mutation carriers and (b) to investigate the frequency and nature of loss of heterozygosity as a second, somatic event, in tumors from MLH1/MSH2 germ line deletion carriers. Large genomic deletions were found to account for 4.3% and 10.7% of MLH1 and MSH2 mutations, respectively. Multiplex ligation-dependent probe amplification analysis of 18 cancer specimens from two independent sets of Swiss and Finnish MLH1/MSH2 deletion carriers revealed that somatic mutations identical to the ones in the germ line occur frequently in colorectal cancers (6 of 11; 55%) and are also present in extracolonic HNPCC-associated tumors. Chromosome-specific marker analysis implies that loss of the wild-type allele predominantly occurs through locus-restricted recombinational events, i.e., gene conversion, rather than mitotic recombination or deletion of the respective gene locus. (Cancer Res 2006; (66)2: 659-64).

Citrullination/Methylation Crosstalk on Histone H3 Regulates ER-Target Gene Transcription.

Posttranslational modifications of histone tails are a key contributor to epigenetic regulation. Histone H3 Arg26 and Lys27 are both modified by multiple enzymes, and their modifications have profound effects on gene expression. Citrullination of H3R26 by PAD2 and methylation of H3K27 by PRC2 have opposing downstream impacts on gene regulation; H3R26 citrullination activates gene expression, and H3K27 methylation represses gene expression. Both of these modifications are drivers of a variety of cancers, and their writer enzymes, PAD2 and EZH2, are the targets of drug therapies. After biochemical and cell-based analysis of these modifications, a negative crosstalk interaction is observed. Methylation of H3K27 slows citrullination of H3R26 30-fold, whereas citrullination of H3R26 slows methylation 30,000-fold. Examination of the mechanism of this crosstalk interaction uncovered a change in structure of the histone tail upon citrullination which prevents methylation by the PRC2 complex. This mechanism of crosstalk is reiterated in cell lines using knockdowns and inhibitors of both enzymes. Based our data, we propose a model in which, after H3 Cit26 formation, H3K27 demethylases are recruited to the chromatin to activate transcription. In total, our studies support the existence of crosstalk between citrullination of H3R26 and methylation of H3K27.

Crystal structure of human ABAD/HSD10 with a bound inhibitor: implications for design of Alzheimer's disease therapeutics.

The enzyme 17beta-hydroxysteroid dehydrogenase type 10 (HSD10), also known as amyloid beta-peptide-binding alcohol dehydrogenase (ABAD), has been implicated in the development of Alzheimer's disease. This protein, a member of the short-chain dehydrogenase/reductase family of enzymes, has been shown to bind beta-amyloid and to participate in beta-amyloid neurotoxicity. We have determined the crystal structure of human ABAD/HSD10 complexed with NAD(+) and an inhibitory small molecule. The inhibitor occupies the substrate-binding site and forms a covalent adduct with the NAD(+) cofactor. The crystal structure provides a basis for the design of potent, highly specific ABAD/HSD10 inhibitors with potential application in the treatment of Alzheimer's disease.

Genetic predisposition as a basis for chemoprevention, surgical and other interventions in colorectal cancer.

Strategies of cancer prevention are generally developed with the population at large in mind. However, special attention is warranted for those persons with rare genetic traits associated with a greatly elevated risk of developing colorectal cancer (CRC) and some other malignancies: Orphan diseases demand Orphan preventive measures! Recent advances in modern genetics have enhanced our understanding of several genes and the specific germ-line mutations responsible for colorectal carcinogenesis. A number of features provide evidence for a genetic predisposition to CRC. These include typical clinical and histological features of a particular syndrome, a familial aggregation of CRC and associated malignancies, young age at onset of CRC, occurrence of multiple neoplasias and/or unusual localisation of the tumour (e.g., right side of the colon). In hereditary colorectal cancer, genetic testing can easily be demonstrated as cost-effective.