The Disability-Related Education and Training Experiences of Perinatal Care Providers in Ontario.

We describe the disability-related education and training experiences of perinatal care providers in Ontario. Twenty perinatal care providers (e.g., obstetricians, midwives) participated in semi-structured interviews. Using a content analysis approach, we found most acquired disability-related training through their own initiative as opposed to education through professional training programs. Barriers to training included lack of data on disability and pregnancy and limited experiential learning opportunities. Providers recommended that future training focus on experiential learning and social determinants of health, with people with disabilities involved in developing and delivering training. These efforts are vital to optimize pregnancy outcomes for people with disabilities.

Unmet needs, limited access: A qualitative study of postpartum health care experiences of people with disabilities.

AIM: To understand the postpartum care received by birthing people with disabilities and their newborns, from their own perspectives. DESIGN: A qualitative study with semi-structured interviews. METHODS: Between July 2019 and February 2020, in-person and virtual interviews were conducted with 31 people with physical, sensory, and intellectual/developmental disabilities in Ontario, Canada, about the formal inpatient and outpatient services and supports they used in the first few months after they gave birth. Thematic analysis was used identify common themes. RESULTS: We identified three overall themes concerning participants' postpartum care experiences and the different types of formal services received in and out of hospital: (1) lack of adequate care, (2) lack of provider awareness of disability and disability accommodations, and (3) fear of judgement, discrimination, and intrusive surveillance. The identified themes were applicable across disability groups. However, most comments on disability accommodations came from participants with physical or sensory disabilities, while participants with intellectual/developmental disabilities most commonly reported concerns about lack of adequate care and fear of judgement, discrimination, and intrusive surveillance. CONCLUSION: Findings indicate that postpartum care often fails people with disabilities. This could contribute to negative health consequences for them and their newborns. IMPACT: Birthing people with disabilities need multidisciplinary, proactive, and strengths-based postpartum care to mitigate risk for health complications. Further, disability-related training and guidelines for health and social service providers is required. REPORTING METHOD: Consolidated criteria for reporting qualitative research (COREQ). PATIENT OR PUBLIC CONTRIBUTION: Our research team included two peer researchers with physical disabilities who served as co-interviewers and participated in data analysis, contributing their lived experience of disability and interactions with the health care system. All stages of the study were also informed by feedback from the study's Advisory Committee, which comprised women with disabilities (many of whom are parents), disability organization staff, clinicians, and policy representatives.

Barriers to and facilitators of effective communication in perinatal care: a qualitative study of the experiences of birthing people with sensory, intellectual, and/or developmental disabilities.

BACKGROUND: Effective provider-patient communication is a key element of quality health care, including perinatal care. What constitutes "effective communication" in perinatal care may vary according to the population seeking care, such as women with intellectual and developmental disabilities (IDD) and sensory disabilities. Research broadly indicates that communication issues are among the barriers to perinatal care experienced by women with disabilities. However, few studies have explicitly explored their communication experiences in this context. The purpose of this study was to understand the communication experiences of birthing people with IDD and/or sensory disabilities in perinatal care. METHODS: We conducted semi-structured interviews with 17 people with IDD (e.g., autism, cognitive delay) and/or sensory disabilities (e.g., d/Deaf, blind) in Ontario, Canada, who had recently given birth, to explore barriers to and facilitators of effective communication in perinatal care. A combination of deductive and inductive thematic analysis guided data analysis. RESULTS: We found that birthing people with IDD and/or sensory disabilities encountered multiple barriers to effective communication in perinatal care, namely, lack of policies and guidelines, lack of provider experience, lack of provider effort, as well as ableism and provider assumptions. Facilitators included knowledgeable, aware, and supportive providers; access to communication aids and services; tailoring information to patients' disability-related communication needs; empathic communication; and, communication among providers. CONCLUSION: Unmet communication needs may contribute to negative health and social outcomes for birthing people with disabilities and their newborns. Accessibility policy implementation and practice change are needed to meet the communication needs of people with IDD and/or sensory disabilities in perinatal care to ensure positive experiences and outcomes.

ARTS and Siah collaborate in a pathway for XIAP degradation.

ARTS (apoptosis-related protein in the TGF-ß signaling pathway) is a mitochondrial protein that binds XIAP (X-linked inhibitor of apoptosis protein) upon entering the cytosol, thus promoting cell death. Expression of ARTS is lost in some malignancies. Here, we show that ARTS binds to XIAP at BIR1, a domain distinct from the caspase-binding sites. Furthermore, ARTS interacts with the E3 ligase Siah-1 (seven in absentia homolog 1) to induce ubiquitination and degradation of XIAP. Cells lacking either Siah or ARTS contain higher steady-state levels of XIAP. Thus, ARTS serves as an adaptor to bridge Siah-1 to XIAP, targeting it for destruction.

Design, synthesis and evaluation of inhibitor of apoptosis protein (IAP) antagonists that are highly selective for the BIR2 domain of XIAP.

We recently reported the systematic ligand-based rational design and synthesis of monovalent Smac mimetics that bind preferentially to the BIR2 domain of the anti-apoptotic protein XIAP. Expanded structure-activity relationship (SAR) studies around these peptidomimetics led to compounds with significantly improved selectivity (>60-fold) for the BIR2 domain versus the BIR3 domain of XIAP. The potent and highly selective IAP antagonist 8q (ML183) sensitized TRAIL-resistant prostate cancer cells to apoptotic cell death, highlighting the merit of this probe compound as a valuable tool to investigate the biology of XIAP.

Prenatal Care Experiences of Childbearing People With Disabilities in Ontario, Canada.

OBJECTIVE: To explore the care experiences of childbearing people with physical, sensory, and/or intellectual/developmental disabilities during pregnancy. DESIGN: Descriptive qualitative. SETTING: Ontario, Canada, where physician and midwifery care during pregnancy are provided at no direct cost to residents. PARTICIPANTS: Thirty-one people with physical, sensory, and/or intellectual/developmental disabilities (who self-identified as cisgender women [n = 29] and trans or nonbinary persons [n = 2]) who gave birth in the last 5 years. METHODS: We recruited childbearing people with disabilities through disability and parenting organizations, social media, and our team's networks. Using a semistructured guide, we conducted in-person and virtual (e.g., telephone or Zoom) interviews with childbearing people with disabilities in 2019 to 2020. We asked participants about the services they accessed during pregnancy and if services met their needs. We used a reflexive thematic analysis approach to analyze interview data. RESULTS: Across disability groups, we identified four common themes: Unmet Accommodation Needs, Lack of Coordinated Care, Ableism, and Advocacy as a Critical Resource. We found that these experiences manifested in unique ways based on disability type. CONCLUSION: Our findings suggest the need for accessible, coordinated, and respectful prenatal care for people with disabilities, with the requirements of such care depending on the needs of the individual person with a disability. Nurses can play a key role in identifying the needs and supporting people with disabilities during pregnancy. Education and training for nurses, midwives, obstetricians, and other prenatal care providers should focus on disability-related knowledge and respectful prenatal care.

The burn injury transfer feedback form: A 16 year Australian statewide review of burn inter-hospital transfer.

INTRODUCTION: Modern burn care is centralised, and studies show that early, prompt referral to dedicated burn services improve clinical outcomes. We describe the use of a novel clinical instrument, the burn injury Transfer Feedback Form, to support and educate referring clinicians about the early assessment and management of burn injuries. Since 2005, Transfer Feedback Forms have been completed for all burn-injured patients with inter-hospital transfer to a specialised burn unit in the state of New South Wales (NSW), Australia. The aim of this study was to review physiological, procedural, and system or process issues in the care of both adult and paediatric burn-injured patients needing retrieval and transfer in NSW as identified by the Transfer Feedback Form. Secondary objectives were to determine any significant differences in these parameters between metropolitan and regional or remote referring institutions, and if any improvements occurred in these parameters over time. METHODS: This was a retrospective analysis of all patients who were transferred to a burn unit in NSW between July 2005 and July 2021 using their prospectively completed Transfer Feedback Forms. Patients were divided into metropolitan and non-metropolitan referral sources based on geographic location. Clinical issues or deficiencies identified during each patient transfer were then classified into various groups. To determine if transfer-related clinical concerns had changed with time, two distinct periods before and after 2015, when the NSW Trauma App was introduced, were analysed. We compared trends in frequency of transfer-related concerns before and after App introduction by using interrupted time series analysis. RESULTS: A total of 3233 patients had Feedback Forms submitted during the 16-year period. We included 929 children (28.7%) and 2304 adults (71.3%). Transfer-related clinical issues were identified in 904 adults (39.0%) and 484 children (52.0%). In both adult and paediatric patients, the most common transfer-related clinical deficiency was in relation to burn size estimation with 525 patients (43.7%) and 207 patients (30.6%), respectively. Between the time periods analysed, the number of issues arising during inter-hospital transfer fell significantly for both adults (from 46.1% to 26.1%; p < 0.05) and children (from 55.3% to 40.7%; p < 0.05). Segmented regression analysis demonstrated a significant break in the rate of transfer-related clinical issues in 2014 (p < 0.05) and 2015 (p < 0.01) for adults. Accurate body surface area estimations also increased significantly by 53% and 50% for adults and children (p < 0.05 for both), respectively, after 2015. CONCLUSION: Our analysis indicates that the early care of burn-injured patients undergoing inter-hospital transfer is associated with clinical, technical, and logistical challenges. However, introduction of the burn injury Transfer Feedback Form has been associated with improvements in early burn care by referring centres both temporally and geographically. Smartphone-based applications such as the NSW Trauma App have also probably contributed to these findings. Adopting these simple, inexpensive strategies into burn care systems will augment inter-hospital transfer of burn-injured patients, and improve clinical outcomes.

Temporal trends in burn size estimation and the impact of the NSW Trauma App on estimation accuracy.

BACKGROUND: Several studies demonstrated that burn size calculations by referring clinicians are poor. The purpose of this study was to determine if inaccuracies in burn size estimation have improved with time within the same population, and whether widespread roll-out of a smartphone-based TBSA calculator (in the form of the NSW Trauma App) had an impact on accuracy. METHODS: A review of all burn-injured adult patients transferred to Burn Units from August 2015, following the roll out of the NSW Trauma App, to January 2021 was performed. The TBSA determined by the referring centre was compared with the TBSA calculated by the Burn Unit. This was compared to historical data from the same population between January 2009 and August 2013. RESULTS: There were 767 adult burn-injured patients transferred to a Burn Unit between 2015 and 2021. The median overall TBSA was 7%. There were 290 patients (37.9%) who had equivalent TBSA calculations by the referring hospital and the Burn Unit. This was a significant improvement compared to the preceding time period (P < 0.005). Overestimation by the referring hospital occurred in 364 cases (47.5%), which was significantly reduced compared to 2009 - 2013 (P < 0.001). Unlike the earlier time period where changes in estimation accuracy were seen in relation to increasing time after the burn injury, burn size estimation accuracy remained relatively consistent in the contemporary time period with no significant change observed (P = 0.86). CONCLUSIONS: This cumulative, longitudinal study of nearly 1500 adult burn-injured patients over 13 years demonstrates improvements in burn size estimation by referring clinicians over time. It is the largest cohort of patients analysed with respect to burn size estimation and is the first to demonstrate improvements in accuracy of TBSA in association with a smartphone-based app. Adopting this simple strategy into burn retrieval systems will augment early assessment of these injuries and improve outcomes.

Small-molecule antagonists of apoptosis suppressor XIAP exhibit broad antitumor activity.

Apoptosis resistance commonly occurs in cancers, preventing activation of Caspase family cell death proteases. XIAP is an endogenous inhibitor of Caspases overexpressed in many cancers. We developed an enzyme derepression assay, based on overcoming XIAP-mediated suppression of Caspase-3, and screened mixture-based combinatorial chemical libraries for compounds that reversed XIAP-mediated inhibition of Caspase-3, identifying a class of polyphenylureas with XIAP-inhibitory activity. These compounds, but not inactive structural analogs, stimulated increases in Caspase activity, directly induced apoptosis of many types of tumor cell lines in culture, and sensitized cancer cells to chemotherapeutic drugs. Active compounds also suppressed growth of established tumors in xenograft models in mice, while displaying little toxicity to normal tissues. These findings validate IAPs as targets for cancer drug discovery.

XIAP mediates NOD signaling via interaction with RIP2.

NOD1 and NOD2 are members of the NOD-like receptor (NLR) protein family that are involved in sensing the presence of pathogens and are a component of the innate immune system. Upon activation by specific bacterial peptides derived from peptidoglycans, NODs interact via a CARD-CARD interaction with the receptor-interacting protein kinase RIP2, an inducer of NF-kappaB activation. In this report, we show that NOD signaling is dependent on XIAP, a member of the inhibitor of apoptosis protein (IAP) family. Cells deficient in XIAP exhibit a marked reduction in NF-kappaB activation induced by microbial NOD ligands and by over-expression of NOD1 or NOD2. Moreover, we show that XIAP interacts with RIP2 via its BIR2 domain, which could be disrupted by XIAP antagonists SMAC and SMAC-mimicking compounds. Both NOD1 and NOD2 associated with XIAP in a RIP2-dependent manner, providing evidence that XIAP associates with the NOD signalosome. Taken together, our data suggest a role for XIAP in regulating innate immune responses by interacting with NOD1 and NOD2 through interaction with RIP2.

Vaccinia virus protein F1L is a caspase-9 inhibitor.

Apoptosis plays important roles in host defense, including the elimination of virus-infected cells. The executioners of apoptosis are caspase family proteases. We report that vaccinia virus-encoded F1L protein, previously recognized as anti-apoptotic viral Bcl-2 family protein, is a caspase-9 inhibitor. F1L binds to and specifically inhibits caspase-9, the apical protease in the mitochondrial cell death pathway while failing to inhibit other caspases. In cells, F1L inhibits apoptosis and proteolytic processing of caspases induced by overexpression of caspase-9 but not caspase-8. An N-terminal region of F1L preceding the Bcl-2-like fold accounts for caspase-9 inhibition and significantly contributes to the anti-apoptotic activity of F1L. Viral F1L thus provides the first example of caspase inhibition by a Bcl-2 family member; it functions both as a suppressor of proapoptotic Bcl-2 family proteins and as an inhibitor of caspase-9, thereby neutralizing two sequential steps in the mitochondrial cell death pathway.

Design, synthesis and evaluation of monovalent Smac mimetics that bind to the BIR2 domain of the anti-apoptotic protein XIAP.

We report the systematic rational design and synthesis of new monovalent Smac mimetics that bind preferentially to the BIR2 domain of the anti-apoptotic protein XIAP. Characterization of compounds in vitro (including 9i; ML101) led to the determination of key structural requirements for BIR2 binding affinity. Compounds 9h and 9j sensitized TRAIL-resistant breast cancer cells to apoptotic cell death, highlighting the value of these probe compounds as tools to investigate the biology of XIAP.

A Socio-Ecological Approach to Understanding the Perinatal Care Experiences of People with Intellectual and/or Developmental Disabilities in Ontario, Canada.

BACKGROUND: Accessible and quality care during the perinatal period is critical for optimal maternal and neonatal health. Using the socio-ecological model, the purpose of this study was to explore barriers and facilitators that shape the perinatal care experiences of people with intellectual and/or developmental disabilities (IDD). METHODS: Semi-structured interviews were conducted with 10 individuals with IDD in Ontario, Canada, who had given birth within the past 5 years. Interviews focused on care experiences before, during, and after pregnancy. Data were analyzed using a directed content analysis approach, and the socio-ecological model guided analysis. RESULTS: Barriers at the societal (e.g., cultural norms of motherhood), policy/institutional (e.g., child protection policies and practices), interpersonal (e.g., inadequate formal and informal support), and intrapersonal levels (e.g., internalized stigma) contributed to participants having negative perinatal care experiences. Conversely, we identified facilitators on the interpersonal level (e.g., positive interactions with perinatal care providers and familial and social service supports) as positively shaping participants' perinatal care experiences. CONCLUSIONS: Findings reveal that the perinatal care experiences of people with IDD are shaped by several interrelated factors that largely stem from societal-level barriers, such as dominant (stigmatizing) discourses of disability. To improve the perinatal care experiences of people with IDD, there is a need for interventions at multiple levels. These include the development of policies to support perinatal care for diverse populations and training care providers to enact policies at the institutional and interpersonal levels.

Design and synthesis of a simplified inhibitor for XIAP-BIR3 domain.

Based on tetrapeptide AVPI, we were able to design and synthesize a new simplified scaffold to inhibit the BIR3 domain of the XIAP protein at low micromolar range. The uncomplicated synthesis and the binding activity of the molecule disclosed here represent an attractive alternative to develop new compounds targeting the protein-protein interaction of XIAP/caspase9.

Targeting the apoptotic machinery in pancreatic cancers using small-molecule antagonists of the X-linked inhibitor of apoptosis protein.

Resistance to apoptosis is a hallmark of many solid tumors, including pancreatic cancers, and may be the underlying basis for the suboptimal response to chemoradiation therapies. Overexpression of a family of inhibitor of apoptosis proteins (IAP) is commonly observed in pancreatic malignancies. We determined the therapeutic efficacy of recently described small-molecule antagonists of the X-linked IAP (XIAP) in preclinical models of pancreatic cancer. Primary pancreatic cancers were assessed for XIAP expression by immunohistochemistry, using a pancreatic cancer tissue microarray. XIAP small-molecule antagonists ("XAntag"; compounds 1396-11 and 1396-12) and the related compound 1396-28 were tested in vitro in a panel of human pancreatic cancer cell lines (Panc1, Capan1, and BxPC3) and in vivo in s.c. xenograft models for their ability to induce apoptosis and impede neoplastic growth. In addition, pancreatic cancer cell lines were treated with XAntags in conjunction with either tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or with radiation to determine potential synergy for such dual targeting of the apoptotic machinery. XIAP was overexpressed in 14 of 18 (77%) of primary pancreatic cancers. The XAntags1396-11 and 1396-12, but not the inactive isomer 1396-28, induced profound apoptosis in multiple pancreatic cancer cell lines tested in vitro, with a IC(50) in the range of 2 to 5 mumol/L. Mechanistic specificity of the XAntags for the baculoviral IAP repeat-2 domain of XIAP was shown by preferential activation of downstream "effector" caspases (caspase-3 and caspase-7) versus the upstream "initiator" caspase-9. S.c. BxPC3 xenograft growth in athymic mice was significantly inhibited by monotherapy with XAntags; treated xenografts showed marked apoptosis and increased cleavage of caspase-3. Notably, striking synergy was demonstrable when XAntags were combined with either TRAIL or radiation therapy, as measured by growth inhibition in vitro and reduced colony formation in soft agar of pancreatic cancer cell lines, at dosages where these therapeutic modalities had minimal to modest effects when used alone. Finally, XAntags in combination with the standard-of-care agent for advanced pancreatic cancer, gemcitabine, resulted in significantly greater inhibition of in vitro growth than gemcitabine alone. Our results confirm that pharmacologic inhibition of XIAP is a potent therapeutic modality in pancreatic cancers. These antagonists are independently capable of inducing pancreatic cancer cell death and also show synergy when combined with proapoptotic ligands (TRAIL), with radiation, and with a conventional antimetabolite, gemcitabine. These preclinical results suggest that targeting of the apoptotic machinery in pancreatic cancers with XAntags is a promising therapeutic option that warrants further evaluation.

cIAP1 Localizes to the nuclear compartment and modulates the cell cycle.

We explored the location and function of the human cIAP1 protein, a member of the inhibitor of apoptosis protein (IAP) family. Unlike family member X-linked IAP (XIAP), which was predominantly cytoplasmic, the cIAP1 protein localized almost exclusively to nuclei in cells, as determined by immunofluorescence microscopy and subcellular fractionation methods. Interestingly, apoptotic stimuli induced nuclear export of cIAP1, which was blocked by a chemical caspase inhibitor. In dividing cells, cIAP1 was released into the cytosol early in mitosis, then reaccumulated in nuclei in late anaphase and in telophase, with the exception of a pool of cIAP1 that associated with the midbody. Survivin, another IAP family member, and cIAP1 were both localized on midbody microtubules at telophase, and also interacted with each other during mitosis. Cells stably overexpressing cIAP1 accumulated in G(2)-M phase and grew slower than control-transfected cells. These cIAP1-overexpressing cells also exhibited cytokinesis defects over 10 times more often than control cells and displayed a mitotic checkpoint abnormality with production of polyploid cells when exposed to microtubule-targeting drugs nocodazole and paclitaxel (Taxol). Our findings demonstrate a role for overexpressed cIAP1 in genetic instability, possibly by interfering with mitotic functions of Survivin. These findings may have important implications for cancers in which cIAP1 overexpression occurs.

Analysis of apoptosis protein expression in early-stage colorectal cancer suggests opportunities for new prognostic biomarkers.

PURPOSE: Although most stage II colon cancers are potentially curable by surgery alone, approximately 20% of patients relapse, suggesting a need for establishing prognostic markers that can identify patients who may benefit from adjuvant chemotherapy. We tested the hypothesis that differences in expression of apoptosis-regulating proteins account for differences in clinical outcome among patients with early-stage colorectal cancer. EXPERIMENTAL DESIGN: Tissue microarray technology was employed to assay the expression of apoptosis-regulating proteins by immunohistochemistry in 106 archival stage II colorectal cancers, making correlations with disease-specific survival. The influence of microsatellite instability (MSI), tumor location (left versus right side), patient age, and gender was also examined. RESULTS: Elevated expression of several apoptosis regulators significantly correlated with either shorter (cIAP2; TUCAN) or longer (Apaf1; Bcl-2) overall survival in univariate and multivariate analyses. These biomarkers retained prognostic significance when adjusting for MSI, tumor location, patient age, and gender. Moreover, certain combinations of apoptosis biomarkers were highly predictive of death risk from cancer. For example, 97% of patients with favorable tumor phenotype of cIAP2(low) plus TUCAN(low) were alive at 5 years compared with 60% of other patients (P = 0.00003). In contrast, only 37% of patients with adverse biomarkers (Apaf1(low) plus TUCAN(high)) survived compared with 83% of others at 5 years after diagnosis (P< 0.0001). CONCLUSIONS: Immunohistochemical assays directed at detection of certain combinations of apoptosis proteins may provide prognostic information for patients with early-stage colorectal cancer, and therefore could help to identify patients who might benefit from adjuvant chemotherapy or who should be spared it.

Characterization of Potent SMAC Mimetics that Sensitize Cancer Cells to TNF Family-Induced Apoptosis.

Members of the Inhibitor of APoptosis (IAP) protein family suppress apoptosis within tumor cells, particularly in the context of immune cell-mediated killing by the tumor necrosis factor (TNF) superfamily cytokines. Most IAPs are opposed endogenously by the second mitochondrial activator of caspases (SMAC), which binds to selected baculovirus IAP repeat (BIR) domains of IAPs to displace interacting proteins. The development of SMAC mimetics as novel anticancer drugs has gained impetus, with several agents now in human clinical trials. To further understand the cellular mechanisms of SMAC mimetics, we focused on IAP family members cIAP1 and cIAP2, which are recruited to TNF receptor complexes where they support cell survival through NF-κB activation while suppressing apoptosis by preventing caspase activation. We established fluorescence polarization (FP) assays for the BIR2 and BIR3 domains of human cIAP1 and cIAP2 using fluorochrome-conjugated SMAC peptides as ligands. A library of SMAC mimetics was profiled using the FP assays to provide a unique structure activity relationship (SAR) analysis compared to previous assessments of binding to XIAP. Potent compounds displayed mean inhibitory binding constants (Ki) of 9 to 27 nM against the BIR3 domains of cIAP1 and cIAP2, respectively. Selected compounds were then characterized using cytotoxicity assays in which a cytokine-resistant human tumor cell line was sensitized to either TNF or lymphotoxin-α (LT-α). Cytotoxicity correlated closely with cIAP1 and cIAP2 BIR3 binding activity with the most potent compounds able to reduce cell viability by 50%. Further testing demonstrated that active compounds also inhibit RIP1 binding to BIR3 of cIAP1 and cIAP2 in vitro and reduce steady-state cIAP1 protein levels in cells. Altogether, these data inform the SAR for our SMAC mimetics with respect to cIAP1 and cIAP2, suggesting that these IAP family members play an important role in tumor cell resistance to cytotoxicity mediated by TNF and LT-α.

Heterotypic interactions among NACHT domains: implications for regulation of innate immune responses.

Proteins of the NACHT [NAIP (neuronal apoptosis inhibitory protein), CIITA (MHC class II transcription activator), HET-E (incompatibility locus protein from Podospora anserina) and TP1 (telomerase-associated protein)] family may serve as critical pathogen-sensing and signal-transducing molecules within the innate immune system. In the present paper, we show that CLAN [CARD (caspase-recruitment domain), LRR (leucine-rich repeat) and NACHT domain-containing protein], a NACHT-containing protein originally demonstrated to bind and activate pro-caspase 1, is also capable of influencing the functions of other members of the NACHT family. Through heterotypic NACHT-domain interactions, CLAN was found to associate with Nod1, Nod2 and NAC [nucleotide-binding domain and CARD-containing protein; NALP1 (NACHT, LRR and PYRIN protein 1)] when co-expressed in HEK-293T (human embryonic kidney) cells. NF-kappaB (nuclear factor kappaB) reporter assays demonstrated that co-expression of either full-length CLAN or the NACHT domain of CLAN significantly inhibited NF-kappaB activation induced by Nod1 or Nod2 overexpression. In addition, co-expression of CLAN or the NACHT domain of CLAN with Nod1 or Nod2 inhibited the ability of these proteins to generate active IL-1beta (interleukin 1beta) through their association with pro-caspase 1. The NACHT domain of CLAN was demonstrated by co-immunoprecipitation experiments to bind all NACHT domains that were tested, including the NACHT domains from CLAN itself, Nod1, Nod2, cryopyrin, NAC, PAN2 [PAAD [pyrin, AIM (absent-in-melanoma), ASC (apoptosis-associated speck-like protein containing a CARD) and death-domain-like]- and NACHT-containing protein] and NAIP (neuronal apoptosis inhibitory protein). Finally, monocyte-expressed CLAN was found to associate with Nod2 following exposure to bacterial peptidoglycan, implying a regulatory role for interaction of these NACHT proteins in the innate immune response. These studies suggest that by mediating hetero-oligomerization, NACHT domains provide a means by which various NACHT-containing proteins may interact, creating protein-interaction networks that potentially modulate immune responses to invading pathogens.

Small-molecule IAP antagonists sensitize cancer cells to TRAIL-induced apoptosis: roles of XIAP and cIAPs.

TNF-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent because it shows apoptosis-inducing activity in transformed, but not in normal, cells. As with most anticancer agents, however, its clinical use is restricted by either inherent or acquired resistance by cancer cells. We demonstrate here that small-molecule SMAC mimetics that antagonize the inhibitor of apoptosis proteins (IAP) potently sensitize previously resistant human cancer cell lines, but not normal cells, to TRAIL-induced apoptosis, and that they do so in a caspase-8-dependent manner. We further show that the compounds have no cytotoxicity as single agents. Also, we demonstrate that several IAP family members likely participate in the modulation of cellular sensitivity to TRAIL. Finally, we note that the compounds that sensitize cancer cells to TRAIL are the most efficacious in binding to X-linked IAP, and in inducing cellular-IAP (cIAP)-1 and cIAP-2 degradation. Our studies thus describe valuable compounds that allow elucidation of the signaling events occurring in TRAIL resistance, and demonstrate that these agents act as potent TRAIL-sensitizing agents in a variety of cancer cell lines.