7-Dehydrocholesterol is an endogenous suppressor of ferroptosis.

Ferroptosis is a form of cell death that has received considerable attention not only as a means to eradicate defined tumour entities but also because it provides unforeseen insights into the metabolic adaptation that tumours exploit to counteract phospholipid oxidation1,2. Here, we identify proferroptotic activity of 7-dehydrocholesterol reductase (DHCR7) and an unexpected prosurvival function of its substrate, 7-dehydrocholesterol (7-DHC). Although previous studies suggested that high concentrations of 7-DHC are cytotoxic to developing neurons by favouring lipid peroxidation3, we now show that 7-DHC accumulation confers a robust prosurvival function in cancer cells. Because of its far superior reactivity towards peroxyl radicals, 7-DHC effectively shields (phospho)lipids from autoxidation and subsequent fragmentation. We provide validation in neuroblastoma and Burkitt's lymphoma xenografts where we demonstrate that the accumulation of 7-DHC is capable of inducing a shift towards a ferroptosis-resistant state in these tumours ultimately resulting in a more aggressive phenotype. Conclusively, our findings provide compelling evidence of a yet-unrecognized antiferroptotic activity of 7-DHC as a cell-intrinsic mechanism that could be exploited by cancer cells to escape ferroptosis.

Landscape of brain myeloid cell transcriptome along the spatiotemporal progression of Alzheimer's disease reveals distinct sequential responses to Aß and tau.

Human microglia are critically involved in Alzheimer's disease (AD) progression, as shown by genetic and molecular studies. However, their role in tau pathology progression in human brain has not been well described. Here, we characterized 32 human donors along progression of AD pathology, both in time-from early to late pathology-and in space-from entorhinal cortex (EC), inferior temporal gyrus (ITG), prefrontal cortex (PFC) to visual cortex (V2 and V1)-with biochemistry, immunohistochemistry, and single nuclei-RNA-sequencing, profiling a total of 337,512 brain myeloid cells, including microglia. While the majority of microglia are similar across brain regions, we identified a specific subset unique to EC which may contribute to the early tau pathology present in this region. We calculated conversion of microglia subtypes to diseased states and compared conversion patterns to those from AD animal models. Targeting genes implicated in this conversion, or their upstream/downstream pathways, could halt gene programs initiated by early tau progression. We used expression patterns of early tau progression to identify genes whose expression is reversed along spreading of spatial tau pathology (EC > ITG > PFC > V2 > V1) and identified their potential involvement in microglia subtype conversion to a diseased state. This study provides a data resource that builds on our knowledge of myeloid cell contribution to AD by defining the heterogeneity of microglia and brain macrophages during both temporal and regional pathology aspects of AD progression at an unprecedented resolution.

Therapist Anxious Distress and Avoidance of Implementing Time-Out.

Therapist anxious distress when delivering child mental health treatment has been understudied as a factor that contributes to the underuse of some evidence-based interventions (EBIs), such as time-out for children with disruptive behaviors. This study investigated therapist anxious avoidance of time-out using a three-part, vignette-based survey design. Therapists (n = 198) read a vignette of an in-session time-out and reported on their personal anxious distress and likelihood of discontinuing the implementation of time-out. Therapists also provided open-ended descriptions of challenges to delivering time-out. Therapists reported moderate anxious distress at time points 1 and 2 and lower anxious distress at time 3 when the time-out had resolved. Most therapists endorsed some avoidance of time-out. Binomial logistic regression analyses indicated that increased anxious distress corresponded with an increased probability of avoiding time-out delivery in the future. Qualitative reports expanded on challenges to implementing time-out. Findings suggest the importance of addressing therapist anxious distress when implementing children's mental health treatments.

Dual truncation of tau by caspase-2 accelerates its CHIP-mediated degradation.

Intraneuronal aggregates of the microtubule binding protein Tau are a hallmark of different neurodegenerative diseases including Alzheimer's disease (AD). In these aggregates, Tau is modified by posttranslational modifications such as phosphorylation as well as by proteolytic cleavage. Here we identify a novel Tau cleavage site at aspartate 65 (D65) that is specific for caspase-2. In addition, we show that the previously described cleavage site at D421 is also efficiently processed by caspase-2, and both sites are cleaved in human brain samples. Caspase-2-generated Tau fragments show increased aggregation potential in vitro, but do not accumulate in vivo after AAV-mediated overexpression in mouse hippocampus. Interestingly, we observe that steady-state protein levels of caspase-2 generated Tau fragments are low in our in vivo model despite strong RNA expression, suggesting efficient clearance. Consistent with this hypothesis, we find that caspase-2 cleavage significantly improves the recognition of Tau by the ubiquitin E3 ligase CHIP, leading to increased ubiquitination and faster degradation of Tau fragments. Taken together our data thus suggest that CHIP-induced ubiquitination is of particular importance for the clearance of caspase-2 generated Tau fragments in vitro and in vivo.

Improving the Quality of Children's Mental Health Care with Progress Measures: A Mixed-Methods Study of PCIT Therapist Attitudes.

Progress measures are an evidence-based technique for improving the quality of mental health care, however, clinicians rarely incorporate them into treatment. Research into how measure type impacts clinician preference has been recommended to help improve measure implementation. Parent-Child Interaction Therapy (PCIT) is an assessment-driven treatment that serves as an ideal intervention through which to investigate measure preferences given its routine use of two types of assessments, a behavioral observation (the Dyadic Parent-Child Interaction Coding System) and a parent-report measure (the Eyberg Child Behavior Inventory). This study investigated PCIT therapist attitudes towards progress measures used within PCIT and children's mental health treatment generally. A mixed-method (QUAN + QUAL) study design examined PCIT therapist attitudes towards two types of progress measures and measures used in two contexts (PCIT and general practice). Multi-level modeling of a survey distributed to 324 PCIT therapists identified predictors of therapist attitudes towards measures, while qualitative interviews with 23 therapists expanded and clarified the rationale for differing perceptions. PCIT therapists reported more positive attitudes towards a behavioral observation measure, the DPICS, than a parent-report measure, the ECBI, and towards measures used in PCIT than in general practice. Clinician race/ethnicity was significantly related to measure-specific attitudes. Qualitative interviews highlighted how perceptions of measure reliability, type of data offered, ease of use, utility in guiding sessions and motivating clients, and embeddedness in treatment protocol impact therapist preferences. Efforts to implement progress monitoring should consider preferences for particular types of measures, as well as how therapists are trained to embed measures in treatment.

Elezanumab, a clinical stage human monoclonal antibody that selectively targets repulsive guidance molecule A to promote neuroregeneration and neuroprotection in neuronal injury and demyelination models.

Repulsive guidance molecule A (RGMa) is a potent inhibitor of axonal growth and a regulator of neuronal cell death. It is up-regulated following neuronal injury and accumulates in chronic neurodegenerative diseases. Neutralizing RGMa has the potential to promote neuroregeneration and neuroprotection. Previously we reported that a rat anti-N terminal RGMa (N-RGMa) antibody r5F9 and its humanized version h5F9 (ABT-207) promote neuroprotection and neuroregeneration in preclinical neurodegenerative disease models. However, due to its cross-reactivity to RGMc/hemojuvelin, ABT-207 causes iron accumulation in vivo, which could present a safety liability. Here we report the generation and characterization of a novel RGMa-selective anti-N-RGMa antibody elezanumab, which is currently under Phase 2 clinical evaluation in multiple disease indications. Elezanumab, a human monoclonal antibody generated by in vitro PROfusion mRNA display technology, competes with ABT-207 in binding to N-RGMa but lacks RGMc cross-reactivity with no impact on iron metabolism. It neutralizes repulsive activity of soluble RGMa in vitro and blocks membrane RGMa mediated BMP signaling. In the optic nerve crush and optic neuritis models, elezanumab promotes axonal regeneration and prevents retinal nerve fiber layer degeneration. In the spinal targeted experimental autoimmune encephalomyelitis (EAE) model, elezanumab promotes axonal regeneration and remyelination, decreases inflammatory lesion area and improves functional recovery. Finally, in the mouse cuprizone model, elezanumab reduces demyelination, which is consistent with its inhibitory effect on BMP signaling. Taken together, these preclinical data demonstrate that elezanumab has neuroregenerative and neuroprotective activities without impact on iron metabolism, thus providing a compelling rationale for its clinical development in neurodegenerative diseases.

Exit from dormancy provokes DNA-damage-induced attrition in haematopoietic stem cells.

Haematopoietic stem cells (HSCs) are responsible for the lifelong production of blood cells. The accumulation of DNA damage in HSCs is a hallmark of ageing and is probably a major contributing factor in age-related tissue degeneration and malignant transformation. A number of accelerated ageing syndromes are associated with defective DNA repair and genomic instability, including the most common inherited bone marrow failure syndrome, Fanconi anaemia. However, the physiological source of DNA damage in HSCs from both normal and diseased individuals remains unclear. Here we show in mice that DNA damage is a direct consequence of inducing HSCs to exit their homeostatic quiescent state in response to conditions that model physiological stress, such as infection or chronic blood loss. Repeated activation of HSCs out of their dormant state provoked the attrition of normal HSCs and, in the case of mice with a non-functional Fanconi anaemia DNA repair pathway, led to a complete collapse of the haematopoietic system, which phenocopied the highly penetrant bone marrow failure seen in Fanconi anaemia patients. Our findings establish a novel link between physiological stress and DNA damage in normal HSCs and provide a mechanistic explanation for the universal accumulation of DNA damage in HSCs during ageing and the accelerated failure of the haematopoietic system in Fanconi anaemia patients.

Atf3 links loss of epithelial polarity to defects in cell differentiation and cytoarchitecture.

Interplay between apicobasal cell polarity modules and the cytoskeleton is critical for differentiation and integrity of epithelia. However, this coordination is poorly understood at the level of gene regulation by transcription factors. Here, we establish the Drosophila activating transcription factor 3 (atf3) as a cell polarity response gene acting downstream of the membrane-associated Scribble polarity complex. Loss of the tumor suppressors Scribble or Dlg1 induces atf3 expression via aPKC but independent of Jun-N-terminal kinase (JNK) signaling. Strikingly, removal of Atf3 from Dlg1 deficient cells restores polarized cytoarchitecture, levels and distribution of endosomal trafficking machinery, and differentiation. Conversely, excess Atf3 alters microtubule network, vesicular trafficking and the partition of polarity proteins along the apicobasal axis. Genomic and genetic approaches implicate Atf3 as a regulator of cytoskeleton organization and function, and identify Lamin C as one of its bona fide target genes. By affecting structural features and cell morphology, Atf3 functions in a manner distinct from other transcription factors operating downstream of disrupted cell polarity.

Mechanism suppressing H3K9 trimethylation in pluripotent stem cells and its demise by polyQ-expanded huntingtin mutations.

Pluripotent stem cells are invaluable resources to study development and disease, holding a great promise for regenerative medicine. Here we use human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) from patients with Huntington's disease (HD-iPSCs) to shed light into the normal function of huntingtin (HTT) and its demise in disease. We find that HTT binds ATF7IP, a regulator of the histone H3 methyltransferase SETDB1. HTT inhibits the interaction of the ATF7IP-SETDB1 complex with other heterochromatin regulators and transcriptional repressors, maintaining low levels of H3K9 trimethylation (H3K9me3) in hESCs. Loss of HTT promotes global increased H3K9me3 levels and enrichment of H3K9me3 marks at distinct genes, including transcriptional regulators of neuronal differentiation. Although these genes are normally expressed at low amounts in hESCs, HTT knockdown (KD) reduces their induction during neural differentiation. Notably, mutant expanded polyglutamine repeats in HTT diminish its interaction with ATF7IP-SETDB1 complex and trigger H3K9me3 in HD-iPSCs. Conversely, KD of ATF7IP in HD-iPSCs reduces H3K9me3 alterations and ameliorates gene expression changes in their neural counterparts. Taken together, our results indicate ATF7IP as a potential target to correct aberrant H3K9me3 levels induced by mutant HTT.

The RNA-Protein Interactome of Differentiated Kidney Tubular Epithelial Cells.

BACKGROUND: RNA-binding proteins (RBPs) are fundamental regulators of cellular biology that affect all steps in the generation and processing of RNA molecules. Recent evidence suggests that regulation of RBPs that modulate both RNA stability and translation may have a profound effect on the proteome. However, regulation of RBPs in clinically relevant experimental conditions has not been studied systematically. METHODS: We used RNA interactome capture, a method for the global identification of RBPs to characterize the global RNA-binding proteome (RBPome) associated with polyA-tailed RNA species in murine ciliated epithelial cells of the inner medullary collecting duct. To study regulation of RBPs in a clinically relevant condition, we analyzed hypoxia-associated changes of the RBPome. RESULTS: We identified >1000 RBPs that had been previously found using other systems. In addition, we found a number of novel RBPs not identified by previous screens using mouse or human cells, suggesting that these proteins may be specific RBPs in differentiated kidney epithelial cells. We also found quantitative differences in RBP-binding to mRNA that were associated with hypoxia versus normoxia. CONCLUSIONS: These findings demonstrate the regulation of RBPs through environmental stimuli and provide insight into the biology of hypoxia-response signaling in epithelial cells in the kidney. A repository of the RBPome and proteome in kidney tubular epithelial cells, derived from our findings, is freely accessible online, and may contribute to a better understanding of the role of RNA-protein interactions in kidney tubular epithelial cells, including the response of these cells to hypoxia.

Mutational hierarchies in myelodysplastic syndromes dynamically adapt and evolve upon therapy response and failure.

Clonal evolution is believed to be a main driver for progression of various types of cancer and implicated in facilitating resistance to drugs. However, the hierarchical organization of malignant clones in the hematopoiesis of myelodysplastic syndromes (MDS) and its impact on response to drug therapy remain poorly understood. Using high-throughput sequencing of patient and xenografted cells, we evaluated the intratumoral heterogeneity (n= 54) and reconstructed mutational trajectories (n = 39) in patients suffering from MDS (n = 52) and chronic myelomonocytic leukemia-1 (n = 2). We identified linear and also branching evolution paths and confirmed on a patient-specific level that somatic mutations in epigenetic regulators and RNA splicing genes frequently constitute isolated disease-initiating events. Using high-throughput exome- and/or deep-sequencing, we analyzed 103 chronologically acquired samples from 22 patients covering a cumulative observation time of 75 years MDS disease progression. Our data revealed highly dynamic shaping of complex oligoclonal architectures, specifically upon treatment with lenalidomide and other drugs. Despite initial clinical response to treatment, patients' marrow persistently remained clonal with rapid outgrowth of founder-, sub-, or even fully independent clones, indicating an increased dynamic rate of clonal turnover. The emergence and disappearance of specific clones frequently correlated with changes of clinical parameters, highlighting their distinct and far-reaching functional properties. Intriguingly, increasingly complex mutational trajectories are frequently accompanied by clinical progression during the course of disease. These data substantiate a need for regular broad molecular monitoring to guide clinical treatment decisions in MDS.

Thirty Minutes of Hypobaric Hypoxia Provokes Alterations of Immune Response, Haemostasis, and Metabolism Proteins in Human Serum.

Hypobaric hypoxia (HH) during airline travel induces several (patho-) physiological reactions in the human body. Whereas severe hypoxia is investigated thoroughly, very little is known about effects of moderate or short-term hypoxia, e.g. during airline flights. The aim of the present study was to analyse changes in serum protein expression and activation of signalling cascades in human volunteers staying for 30 min in a simulated altitude equivalent to airline travel. After approval of the local ethics committee, 10 participants were exposed to moderate hypoxia (simulation of 2400 m or 8000 ft for 30 min) in a hypobaric pressure chamber. Before and after hypobaric hypoxia, serum was drawn, centrifuged, and analysed by two-dimensional gel electrophoresis (2-DIGE) and matrix-assisted laser desorption/ionization followed by time-of-flight mass spectrometry (MALDI-TOF). Biological functions of regulated proteins were identified using functional network analysis (GeneMania®, STRING®, and Perseus® software). In participants, oxygen saturation decreased from 98.1 ± 1.3% to 89.2 ± 1.8% during HH. Expression of 14 spots (i.e., 10 proteins: ALB, PGK1, APOE, GAPDH, C1QA, C1QB, CAT, CA1, F2, and CLU) was significantly altered. Bioinformatic analysis revealed an association of the altered proteins with the signalling cascades "regulation of haemostasis" (four proteins), "metabolism" (five proteins), and "leukocyte mediated immune response" (five proteins). Even though hypobaric hypoxia was short and moderate (comparable to an airliner flight), analysis of protein expression in human subjects revealed an association to immune response, protein metabolism, and haemostasis.

Protein profile of basal prostate epithelial progenitor cells--stage-specific embryonal antigen 4 expressing cells have enhanced regenerative potential in vivo.

The long-term propagation of basal prostate progenitor cells ex vivo has been very difficult in the past. The development of novel methods to expand prostate progenitor cells in vitro allows determining their cell surface phenotype in greater detail. Mouse (Lin(-)Sca-1(+) CD49f(+) Trop2(high)-phenotype) and human (Lin(-) CD49f(+) TROP2(high)) basal prostate progenitor cells were expanded in vitro. Human and mouse cells were screened using 242 anti-human or 176 antimouse monoclonal antibodies recognizing the cell surface protein profile. Quantitative expression was evaluated at the single-cell level using flow cytometry. Differentially expressed cell surface proteins were evaluated in conjunction with the known CD49f(+)/TROP2(high) phenotype of basal prostate progenitor cells and characterized by in vivo sandwich-transplantation experiments using nude mice. The phenotype of basal prostate progenitor cells was determined as CD9(+)/CD24(+)/CD29(+)/CD44(+)/CD47(+)/CD49f(+)/CD104(+)/CD147(+)/CD326(+)/Trop2(high) of mouse as well as human origin. Our analysis revealed several proteins, such as CD13, Syndecan-1 and stage-specific embryonal antigens (SSEAs), as being differentially expressed on murine and human CD49f(+) TROP2(+) basal prostate progenitor cells. Transplantation experiments suggest that CD49f(+) TROP2(high) SSEA-4(high) human prostate basal progenitor cells to be more potent to regenerate prostate tubules in vivo as compared with CD49f(+) TROP2(high) or CD49f(+) TROP2(high) SSEA-4(low) cells. Determination of the cell surface protein profile of functionally defined murine and human basal prostate progenitor cells reveals differentially expressed proteins that may change the potency and regenerative function of epithelial progenitor cells within the prostate. SSEA-4 is a candidate cell surface marker that putatively enables a more accurate identification of the basal PESC lineage.

The influence of prostatic anatomy and neurotrophins on basal prostate epithelial progenitor cells.

BACKGROUND: Based on findings of surface marker, protein screens as well as the postulated near-urethral location of the prostate stem cell niche, we were interested whether androgen ablation, distinct anatomic regions within the prostate or neurotrophins have an influence on basal prostate epithelial progenitor cells (PESCs). METHODS: Microdissection of the prostate, enzymatic digestion, and preparation of single cells was performed from murine and human prostates. Adult PESC marker expressions were compared between a group of C57BL/6 mice and a separate group of castrated C57BL/6 mice. Surface markers CD13/CD271 on human prostate epithelial progenitor cells were evaluated by FACS analyses in cells cultured under novel stem cell conditions. The effect of neurotrophins NGF, NT3, and BDNF were evaluated with respect to their influence on proliferation and activation of human basal PESCs in vitro. RESULTS: We demonstrate the highest percentage of CD49f+ and Trop2+ expressing cells in the urethra near prostatic regions of WT mice (Trop2+ proximal: 10% vs. distal to the urethra: 3%, P < 0.001). While a marked increase of Trop2 expressing cells can be measured both in the proximal and distal prostatic regions after castration, the most prominent increase in Trop2+ cells can be measured in the prostatic tissue distant to the urethra. Furthermore, we demonstrate that the proportion of syndecan-1 expressing cells greatly increases in the regions proximal to the urethra after castration (WT: 5% vs. castrated: 40%). We identified heterogeneous CD13 and nerve growth factor receptor (p75(NGFR), CD271) expression on CD49f(+)/TROP2(high) human basal PESCs. Addition of the neurotrophins NT3, BDNF, and NGF to the stem cell media led to a marked temporary increase in the proliferation of human basal PESCs. CONCLUSIONS: Our results in mice support the model, in which the proximal urethral region contains the prostate stem cell niche while a stronger androgen-dependent regulation of adult prostate stem cells can be found in the peripheral prostatic tissue. Neutrophin signaling via nerve growth factor receptor is possibly involved in human prostate stem cell homeostasis.

Immunotherapy alleviates amyloid-associated synaptic pathology in an Alzheimer's disease mouse model.

Cognitive decline in Alzheimer's disease is attributed to loss of functional synapses, most likely caused by synaptotoxic, oligomeric forms of amyloid-ß. Many treatment options aim at reducing amyloid-ß levels in the brain, either by decreasing its production or by increasing its clearance. We quantified the effects of immunotherapy directed against oligomeric amyloid-ß in Tg2576 mice, a mouse model of familial Alzheimer's disease. Treatment of 12-month-old mice with oligomer-specific (A-887755) or conformation-unspecific (6G1) antibodies for 8 weeks did not affect fibrillar plaque density or growth. We also quantified densities of DLG4 (previously known as PSD95) expressing post-synapses and synapsin expressing presynapses immunohistochemically. We found that both pre- and post-synapses were strongly reduced in the vicinity of plaques, whereas distant from plaques, in the cortex and hippocampal CA1 field, only post-synapses were reduced. Immunotherapy alleviated this synapse loss. Synapse loss was completely abolished distant from plaques, whereas it was only attenuated in the vicinity of plaques. These results suggest that fibrillar plaques may act as reservoirs for synaptotoxic, oligomeric amyloid-ß and that sequestering oligomers suffices to counteract synaptic pathology. Therefore, cognitive function may be improved by immunotherapy even when the load of fibrillar amyloid remains unchanged.

Development and characteristics of preclinical experimental models for the research of rare neuroendocrine bladder cancer.

PURPOSE: For rare cancers such as neuroendocrine bladder cancer treatment options are limited due partly to the lack of preclinical models. Techniques to amplify rare primary neuroendocrine bladder cancer cells could provide novel tools for the discovery of drug and diagnostic targets. We developed preclinical experimental models for neuroendocrine bladder cancer. MATERIALS AND METHODS: Fresh tumor tissue from 2 patients with neuroendocrine bladder cancer was used to establish in vitro and in vivo models. We analyzed additional archived tissues in the National Center of Tumor Diseases tissue bank from patients with neuroendocrine bladder cancer. Primary tumor samples were collected during radical cystectomy. PHA-665752 was used to inhibit MET in animal models and cell cultures. The expression of markers and drug targets in neuroendocrine bladder cancer was determined by flow cytometry. The growth of neuroendocrine bladder cancer in vitro was determined by counting live cells. Tumor growth in mice was assessed by measuring tumor volume. Groups were compared using the nonparametric Kruskal-Wallis test. RESULTS: Xenograft models and serum-free cultures of neuroendocrine bladder cancer cells allowed screening for cell surface markers and drug targets. We found expression of the HGF receptor MET in neuroendocrine bladder cancer cultures, xenograft models and primary patient sections. The growth of neuroendocrine bladder cancer spheroids in vitro depended critically on HGF. Treatment of neuroendocrine bladder cancer bearing mice with a MET inhibitor significantly decreased tumor growth compared to that in control treated mice. CONCLUSIONS: Neuroendocrine bladder cancer xenografts and serum-free cultures provided suitable models in which to identify diagnostic markers and therapeutic targets. Using the models, we noted HGF dependent growth of human neuroendocrine bladder cancer and identified MET as a new treatment target for neuroendocrine bladder cancer.

A Mixed-Methods Study of Clinician Adaptations to Parent-Child Interaction Therapy - What about Culture?

Parent-Child Interaction Therapy (PCIT) is an evidence-based practice (EBP) for young children with challenging behaviors. PCIT has been adapted to treat varying presentations and culturally diverse families. Although efforts have been made to disseminate PCIT into community settings, which often serve clinically complex, socio-culturally diverse, and marginalized communities, barriers to disseminating adapted models remain. An alternative strategy to understanding how to increase access to appropriately adapted PCIT is to learn from community clinicians' practice-based adaptations to meet their clients' diverse needs related to clinical presentation, culture, and language. This mixed-method study investigated community clinician adaptations of PCIT. Clinicians (N = 314) were recruited via PCIT listservs to complete a survey collecting background information, and adaptations to PCIT. Most clinicians had a master's degree (72.1%), were licensed (74.2%), and were PCIT-certified (70.7%). Qualitative interviews were conducted with a purposeful sample of 23 community clinicians, who were 39% Spanish-speaking, were 30% Latinx, and 30% reported serving a ≥50% Latinx clientele. Clinicians reported engaging in adaptations aimed at augmenting PCIT more extensively than adaptations involving removing core components. Themes from qualitative interviews converged with quantitative findings, with clinicians most frequently describing augmenting adaptations, and highlighted reasons for adapting PCIT. Clinicians primarily augmented treatment to address clients' clinical presentations. Clinicians rarely adapted treatment specifically for culture, but when mentioned, clinicians discussed tailoring idioms and phrases to match clients' culture for Spanish-speaking clients. Implications for training PCIT clinicians in intervention adaptations will be discussed.

Adapting to Unprecedented Times: Community Clinician Modifications to Parent-Child Interaction Therapy during COVID-19.

Parent-Child Interaction Therapy (PCIT) is an evidence-based practice that effectively prevents and treats child disruptive behaviors and child physical maltreatment and reduces parenting stress. PCIT was adapted for telehealth delivery, internet-delivered PCIT (iPCIT), before the COVID-19 pandemic but was not widely implemented until the rapid transition to telehealth during stay-at-home orders. To understand how clinicians adapted PCIT during COVID-19, we followed up on a previous study investigating community clinician adaptations of PCIT pre-COVID-19 using the Lau et al. (2017) Augmenting and Reducing Framework. Clinicians (N = 179) who responded to the follow-up survey and reported delivering PCIT remotely completed a quantitative measure of adaptations at both time points (Fall 2019; Summer 2020) to assess how adaptations to PCIT changed following lockdown measures. Clinicians (n = 135) also provided qualitative descriptions of adaptations made early in the COVID-19 pandemic. Clinicians in the full sample were 74.3% Non-Hispanic White and 14% Latinx. Most clinicians had a master's degree (66.5%), were licensed (80.4%), and were PCIT-certified (70.4%). Paired samples t-tests showed that clinicians reported similar levels of augmenting t(179) = -0.09, p=.926) and reducing adaptations t(179) = -0.77, p=.442) at both time points. Unlike quantitative findings, qualitative findings indicated that clinicians described engaging in many types of adaptations in response to the pandemic. Clinicians discussed engaging in augmenting adaptations by extending treatment length and integrating other practices into treatment. Clinicians also discussed engaging in reducing adaptations. Implications and future directions will be discussed.

How do Lay Health Worker Engage Caregivers? A Qualitative Study to Enhance Equity in Evidence-Based Parenting Programs.

Engaging caregivers in their children's mental health treatment is critical for delivering high quality, evidence-based care, particularly for young children with externalizing behaviors. Lay health workers (LHWs), including peer providers and promotoras de salud, have been identified as important workforces in addressing structural and stigma-related barriers to engagement in mental health services. Importantly, research has suggested that LHWs may be integral in efforts to address engagement disparities in evidence-based behavioral parent training programs (BPTs) for Latinx caregivers. The purpose of the study was to understand how different LHW workforces engage caregivers within their usual services, in order to inform strategies that improve access to and engagement in BPTs. Qualitative interviews were conducted with two different LHW workforces: volunteer LHWs (i.e., promotoras de salud) (n = 14), who were part of a community-embedded network, and paid LHWs (i.e., parent support partners, home visitors) (n = 9) embedded within children's mental health agencies. Participants were predominately Latinx (79%) and female (96%). Qualitative analyses revealed three primary themes related to engagement strategies used by LHWs to address barriers to care: 1.) Building Trust, 2.) Empowerment, 3.) Increasing Access. Although the majority of themes and sub-themes were consistent across the two LHW workforces, agency-embedded LHWs often discussed having the means to provide resources through their organizations, whereas community-embedded LHWs discussed acting as a bridge to services by providing information and conducting outreach. Findings have implications for partnering with different workforces of LHWs to increase equity in access to BPTs.

Intervention and Implementation Characteristics to Enhance Father Engagement: A Systematic Review of Parenting Interventions.

In recent years, the prevalence rates of children's mental health disorders have increased with current estimates identifying that as many as 15-20% of children meet criteria for a mental health disorder. Unfortunately, the same robust parenting interventions which have long targeted some of the most common and the most treatable child concerns (e.g., externalizing, disruptive behavior, and aggression) have also shown consistently low rates of father engagement. This persistent issue of engagement comes in the wake of an increasingly large body of literature which highlights the unique positive contributions fathers make to children and families when they are engaged in parenting interventions. As the role fathers play in families shifts to become more inclusive of childcare responsibilities and less narrowly defined by financial contributions, it becomes increasingly important to understand how best to engage fathers in interventions that aim to enhance parenting efficacy and family outcomes such as coparenting. The current review examined intervention (e.g., format and setting) and implementation characteristics (e.g., training and agency-level changes) associated with father engagement. Particular attention is paid to studies which described father-specific engagement strategies (e.g., inviting fathers directly, father-only groups, and adapting intervention to incorporate father preferences). A total of 26 articles met inclusion criteria after screening and full-text review. Results indicate that father engagement (i.e., initiating treatment) remains low with 58% of studies either not reporting father engagement or having engagement rates below 50%. More than two-thirds of studies did not include specific father engagement strategies. Those that did focused on changes to treatment format (e.g., including recreational activities), physical treatment setting (e.g., in-home and school), and reducing the number of sessions required for father participation as the most common father-specific engagement strategies. Some studies reported efforts to target racially and ethnically diverse fathers, but review results indicated most participants identified as Non-Hispanic White. Interventions were largely standard behavioral parent training programs (e.g., PCIT and PMT) with few exceptions (e.g., COACHES and cultural adaptations), and very few agencies or programs are systematically making adjustments (e.g., extended clinic hours and changes to treatment format) to engage fathers. Recommendations for future directions of research are discussed including the impact of differential motivation on initial father engagement in treatment, the importance of continuing to support diverse groups of fathers, and the potential for telehealth to address barriers to father engagement.