Gamma protocadherins in vascular endothelial cells inhibit Klf2/4 to promote atherosclerosis

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of mortality worldwide1. Laminar shear stress (LSS) from blood flow in straight regions of arteries protects against ASCVD by upregulating the Klf2/4 anti-inflammatory program in endothelial cells (ECs)2-8. Conversely, disturbed shear stress (DSS) at curves or branches predisposes these regions to plaque formation9,10. We previously reported a whole genome CRISPR knockout screen11 that identified novel inducers of Klf2/4. Here we report suppressors of Klf2/4 and characterize one candidate, protocadherin gamma A9 (Pcdhga9), a member of the clustered protocadherin gene family12. Pcdhg deletion increases Klf2/4 levels in vitro and in vivo and suppresses inflammatory activation of ECs. Pcdhg suppresses Klf2/4 by inhibiting the Notch pathway via physical interaction of cleaved Notch1 intracellular domain (NICD Val1744) with nuclear Pcdhg C-terminal constant domain (CCD). Pcdhg inhibition by EC knockout (KO) or blocking antibody protects from atherosclerosis. Pcdhg is elevated in the arteries of human atherosclerosis. This study identifies a novel fundamental mechanism of EC resilience and therapeutic target for treating inflammatory vascular disease.

Actinin BioID reveals sarcomere crosstalk with oxidative metabolism through interactions with IGF2BP2

Actinins are strain-sensing actin cross-linkers that are ubiquitously expressed and harbor mutations in human diseases. We utilize CRISPR, pluripotent stem cells, and BioID to study actinin interactomes in human cardiomyocytes. We identify 324 actinin proximity partners, including those that are dependent on sarcomere assembly. We confirm 19 known interactors and identify a network of RNA-binding proteins, including those with RNA localization functions. In vivo and biochemical interaction studies support that IGF2BP2 localizes electron transport chain transcripts to actinin neighborhoods through interactions between its K homology (KH) domain and actinin’s rod domain. We combine alanine scanning mutagenesis and metabolic assays to disrupt and functionally interrogate actinin-IGF2BP2 interactions, which reveal an essential role in metabolic responses to pathological sarcomere activation using a hypertrophic cardiomyopathy model. This study expands our functional knowledge of actinin, uncovers sarcomere interaction partners, and reveals sarcomere crosstalk with IGF2BP2 for metabolic adaptation relevant to human disease.

Ladha et al. combine BioID, human cardiomyocytes, and CRISPR-Cas9 to interrogate the actinin interactome. This reveals 324 actinin proximity partners, including RNA-binding proteins that bind transcripts encoding ETC functional components. Among these RNA-binding proteins, IGF2BP2 directly binds actinin, and actinin-IGF2BP2 interactions regulate ETC transcript localization and metabolic adaptation to sarcomere function.

Sarcomere function activates a p53-dependent DNA damage response that promotes polyploidization and limits in vivo cell engraftment

Human cardiac regeneration is limited by low cardiomyocyte replicative rates and progressive polyploidization by unclear mechanisms. To study this process, we engineer a human cardiomyocyte model to track replication and polyploidization using fluorescently tagged cyclin B1 and cardiac troponin T. Using time-lapse imaging, in vitro cardiomyocyte replication patterns recapitulate the progressive mononuclear polyploidization and replicative arrest observed in vivo. Single-cell transcriptomics and chromatin state analyses reveal that polyploidization is preceded by sarcomere assembly, enhanced oxidative metabolism, a DNA damage response, and p53 activation. CRISPR knockout screening reveals p53 as a driver of cell-cycle arrest and polyploidization. Inhibiting sarcomere function, or scavenging ROS, inhibits cell-cycle arrest and polyploidization. Finally, we show that cardiomyocyte engraftment in infarcted rat hearts is enhanced 4-fold by the increased proliferation of troponin-knockout cardiomyocytes. Thus, the sarcomere inhibits cell division through a DNA damage response that can be targeted to improve cardiomyocyte replacement strategies.

Coronavirus Receptors as Immune Modulators

The Coronaviridae family includes the seven known human coronaviruses (CoV) that cause mild to moderate respiratory infections (HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1) as well as severe illness and death (MERS-CoV, SARS-CoV, SARS-CoV-2). Severe infections induce hyperinflammatory responses that are often intensified by host adaptive immune pathways to profoundly advance disease severity. Proinflammatory responses are triggered by CoV entry mediated by host cell surface receptors. Interestingly, five of the seven strains use three cell surface metallopeptidases (CD13, CD26, and ACE2) as receptors, whereas the others employ O-acetylated-sialic acid (a key feature of metallopeptidases) for entry. Why CoV evolved to use peptidases as their receptors is unknown, but the peptidase activities of the receptors are dispensable, suggesting the virus uses/benefits from other functions of these molecules. Indeed, these receptors participate in the immune modulatory pathways that contribute to the pathological hyperinflammatory response. This review will focus on the role of CoV receptors in modulating immune responses.

Abstract 273: Utilization of Proximity-labeling to Identify Sarcomere Assembly Dependent Interactions

The cardiac sarcomere is a multiprotein complex that generates pulsatile contractile force, enabling the heart to circulate vital nutrients, but its molecular components and dynamic interactions are incompletely understood. Cardiac alpha-actinin-2 (encoded by ACTN2 ; referred to as actinin) functions as the structural backbone of the Z-disc and is prone to mutations that result in human heart failure. We hypothesize that through identifying actinin PPIs at the Z-disc, we can identify new sarcomere functions and gain insights into heart failure pathogenesis. Until now, studying sarcomere PPIs has been challenging due to limitations in purifying intact sarcomere complexes and the inability to detect dynamic molecular interactions. To overcome this, we adapted BioID proximity proteomics to comprehensively study actinin PPIs in human induced pluripotent stem cells (hiPSCs) differentiated into cardiomyocytes (iCMs).We engineered an isogenic hiPSC line carrying an in-frame knock-in of BirA* , which encodes a promiscuous biotin ligase, at the ACTN2 locus. Upon differentiation into iCMs, the Actinin-BirA* fusion construct localizes to the Z-disc and, upon biotin supplementation, biotinylates vicinal proteins. We immunoprecipitated and analyzed Z-disc PPIs via quantitative tandem mass spectrometry. Among the >100 PPIs detected by this method, we identified known interactions including sarcomere and focal adhesion proteins, but also new interactions including proteins involved in translation and metabolism. Furthermore, we wanted to better understand which of these protein interactions are dependent on sarcomere assembly and function, potentially elucidating interactions involved in normal cardiomyocyte biology and disease states. Through disruption of sarcomere assembly in our Actinin-BirA* model, we were also able to identify sarcomere-dependent actinin interactions including specific proteins involved in translation, the unfolded protein response, and glycolysis. Further investigation will allow us to better understand the proteomic network around actinin and provide novel insights into human sarcomere biology.

Validation of a new in vitro Sun Protection Factor method to include a wide range of sunscreen product emulsion types

In 2017, Cosmetics Europe performed a double‐blinded ring test of 24 emulsion‐type sunscreen products, across 3 in vivo test laboratories and 3 in vitro test laboratories, using a new candidate in vitro SPF test method. Based on the results of this work, an article was published showing how data derived from a new lead candidate method conform to new International Standards (ISO) acceptance criteria for alternative SPF test methods (Any alternative method should consider the matrix effect and if required, specify the matrix applicability of the method; Criterion 1a: Systematic differences between methods should be negligible: 95% of all individual results of an alternative method are within the range of ±2× reproducibility standard deviation of the in vivo method, that is overall bias must be below 0.5× reproducibility standard deviation of the in vivo method; Criterion 1b: Measurement uncertainty of an alternative method should be below the measurement uncertainty of the in vivo method. Candidate method predicted values must fall within the full ‘funnel’ (SPF 6‐50+) limits proposed by Cosmetics Europe (derived from the same minimum test design, that is using the ISO24444 Method to measure at least 24 products across at least 3 laboratories using at least 5 test subjects/laboratory, in a blinded fashion).). Of the 24 sunscreen products tested, the majority of emulsions were of the oil‐in‐water (O/W) type, whereas only one was water‐in‐oil (W/O) and there were no products with a mineral‐only sun filter system. In order to confirm the scope of this method, therefore, a new study was conducted that included 73 W/O (12 mineral + organic, 44 mineral only and 17 organic only) and 3 O/W mineral‐only, emulsion‐type sunscreen products (a total of 76 new sunscreen products). When combined with the previous 24 products (tested in 3 different laboratories), this yielded a new data set comprising a total of 100 emulsion‐type sunscreen products, with SPF values ranging from 6 to 50+ (with a total of 148 data points). These products were tested using the double‐plate in vitro SPF test method and compared with the ISO TC217/WG7 acceptance criteria for alternative SPF test methods. Over 95% of paired in vitro: in vivo SPF values lay within the upper and lower limits of the ISO acceptance criteria funnel, with no bias. This new in vitro SPF test method, therefore, meets the minimum requirements for an alternative SPF test method to ISO24444:2010, for emulsion‐type sunscreen products (which make up the majority of marketed sunscreen products).

Abstract P4-07-11: Investigating the activity of ESR1 allosteric compounds in ER+ breast cancer

Breast cancer (BCa) is the most frequently diagnosed cancer in women worldwide. Approximately 80% of breast cancer is estrogen receptor positive (ER+) with 74% demonstrating high expression of estrogen receptor alpha (). Thus, current endocrine therapies such as selective estrogen receptor degraders (i.e.- Fulvestrant) or selective estrogen receptor modulators (i.e-Tamoxifen) are involved modulation of ER signaling. However, most patients develop resistance to these drugs, and disease progression is common resulting in metastatic disease. Therefore, targeting alternative sites on the surface of has been proposed as an effective therapy to directly block its activity. In the present study, we investigated putative AF2 compounds that can bind to AF2 allosteric sites and inhibit complex formation and transcription of targetgenes. In the present study, we characterized a series of allosteric compounds using breast cancer cellular assays. MCF7 parental cells were treated with a series of putative allosteric compounds in a seven day CTG cell proliferation assay, and the compound ERX-11 was found to exhibit anti-proliferative activity. Genomic RNA was isolated after overnight treatment with ERX-11 to investigate compounds treatment on the expression of key ER pathway transcription factors via real time PCR. The degradation effect on nuclear ER and cytoplasmic ER after treatment with ERX-11 were assessed via western blots. We successfully characterized a series of putative allosteric compounds with ERX-11 being the only compound that exhibited anti-proliferative activity in both MCF7 parental and LSZ resistant cells. ERX-11 inhibited the activation of ER transcription gene and degradation of nuclear ER. These findings show promising effects of ERX-11 to block the AF2 sites on the binding domain of ERα with potential therapeutics for ER+ breast cancer.

Citation Format: Uwimana A, Tiong Yip CL, Das R, Cheng Q, Meredith E, Gaither AL. Investigating the activity of ESR1 allosteric compounds in ER+ breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-07-11.

A Contraction Stress Model of Hypertrophic Cardiomyopathy due to Sarcomere Mutations

Thick-filament sarcomere mutations are a common cause of hypertrophic cardiomyopathy (HCM), a disorder of heart muscle thickening associated with sudden cardiac death and heart failure, with unclear mechanisms. We engineered four isogenic induced pluripotent stem cell (iPSC) models of β-myosin heavy chain and myosin-binding protein C3 mutations, and studied iPSC-derived cardiomyocytes in cardiac microtissue assays that resemble cardiac architecture and biomechanics. All HCM mutations resulted in hypercontractility with prolonged relaxation kinetics in proportion to mutation pathogenicity, but not changes in calcium handling. RNA sequencing and expression studies of HCM models identified p53 activation, oxidative stress, and cytotoxicity induced by metabolic stress that can be reversed by p53 genetic ablation. Our findings implicate hypercontractility as a direct consequence of thick-filament mutations, irrespective of mutation localization, and the p53 pathway as a molecular marker of contraction stress and candidate therapeutic target for HCM patients.

Validation of an in vitro sun protection factor (SPF) method in blinded ring-testing

OBJECTIVE

The objective of this work was to investigate the utility of a new in vitro SPF test method in blinded ring-testing, against new ISO acceptance criteria.

METHODS

Twenty four blinded, commercial, emulsion-type, primary sunscreen products, covering the full range of labelled SPF in Europe (SPF6 - 50+), were tested by three test institutes using the current ISO24444:2010 In Vivo SPF Test Method and simultaneously by three separate test laboratories using a new candidate in vitro SPF test method, developed under the leadership of Cosmetics Europe (CE). The resulting relationship between in vitro SPF and in vivo SPF values was then compared with acceptance criteria developed recently by the International Standards (ISO) TC217/WG7 Sun Protection Test Methods Working Group.

RESULTS

Analysis of the mean inter-laboratory in vitro and mean inter-institute in vivo SPF values revealed a strong correlation between in vitro and in vivo values, with a Pearson correlation coefficient of r2  = 0.88 (P < 0.0001), a slope of 1.01 and a non-significant intercept (-1.48; P = 0.62). When these data were compared to the new ISO WG7 acceptance criteria, method bias was found to be extremely low and over 95% of the coupled data lay within the model 'funnel' (defined by upper and lower confidence intervals).

CONCLUSION

In conclusion, the results of blinded ring testing and comparison to new ISO WG7 acceptance criteria indicate that a new in vitro SPF test method meets (and exceeds) these minimum criteria and is an interesting candidate for possible deployment as an industry test methodology.

Sociopsychiatric study of schizophrenia: the follow-up

SYNOPSIS A one-year follow-up of 127 schizophrenic patients admitted to psychiatric hospitals in 1968–69, who had spent at least three months in the community during the year following their admission, revealed that regular taking of medication is the most crucial single factor leading to improvement in the psychiatric status of the patient, regardless of whether he was living in a positive or a negative environment. No difference was found between family of origin and nuclear family, but family setting tended to influence either improvement or deterioration of the patient, whilst patients living in a non-family setting remained predominantly unchanged. The progress of southern European patients was poorer than all the others, independently of their family setting and medication.