Release Of Fragments Research Articles

IFI16 inhibits DNA repair that potentiates type-I interferon-induced antitumor effects in triple negative breast cancer.

Tumor DNA-damage response (DDR) has an important role in driving type-I interferon (IFN)-mediated host antitumor immunity, but it is not clear how tumor DNA damage is interconnected with the immune response. Here, we report the role of IFN-γ-inducible protein 16 (IFI16) in DNA repair, which amplifies the stimulator of IFN genes (STING)-type-I IFN signaling, particularly in triple-negative breast cancer (TNBC). IFI16 is rapidly induced and accumulated to the histone-evicted DNA at double-stranded breakage (DSB) sites, where it inhibits recruitment of DDR factors. Subsequently, IFI16 increases the release of DNA fragments to the cytoplasm and induces STING-mediated type-I IFN production. Synergistic cytotoxic and immunomodulatory effects of doxorubicin and type-I IFNs are decreased upon IFI16 depletion invivo. Furthermore, IFI16 expression correlates with improved clinical outcome in patients with TNBC treated with chemotherapy. Together, our findings suggest that type-I IFNs and IFI16 could offer potential therapeutic strategies for TNBC.

Computational Analysis of the Mechanism of Nonenzymatic Peptide Bond Cleavage at the C-Terminal Side of an Asparagine Residue.

The nonenzymatic peptide bond cleavage at the C-terminal side of Asn residues is a protein post-translational modification that occurs under physiological conditions. This reaction proceeds much slower than the deamidation of the Asn side chain and causes denaturation and hypofunction of proteins. The peptide bond cleavage of Asn is detected primarily in crystallins and aquaporin 0 in the eye lens. Therefore, cleavage is thought to be involved in age-related cataracts. In this study, to clarify the mechanism underlying succinimide formation for the peptide bond cleavage of the Asn residue, we performed quantum chemical calculations on the model compound Ace-Asn-Gly-Nme (Ace = acetyl and Nme = methylamino). The density functional theory with the B3LYP/6-31+G(d,p) level of theory was used to obtain optimized geometries. The results suggested that the reaction proceeds through two steps, cyclization and C-terminal fragment release, and the required proton transfers can be mediated by H2PO4– and HCO3– ions. The conformational change of the main chain on the N-terminal side of Asn was needed for the C-terminal fragmentation step, and a separate conformational change at the C-terminal side was required for the cyclization step. Furthermore, the calculated activation barriers of the reactions catalyzed by the H2PO4– ion (130 kJ mol–1) and the HCO3– ion (123 kJ mol–1) were sufficiently low for the reactions to occur under normal physiological conditions.

Neurofilament Proteins as Biomarkers to Monitor Neurological Diseases and the Efficacy of Therapies.

Biomarkers of neurodegeneration and neuronal injury have the potential to improve diagnostic accuracy, disease monitoring, prognosis, and measure treatment efficacy. Neurofilament proteins (NfPs) are well suited as biomarkers in these contexts because they are major neuron-specific components that maintain structural integrity and are sensitive to neurodegeneration and neuronal injury across a wide range of neurologic diseases. Low levels of NfPs are constantly released from neurons into the extracellular space and ultimately reach the cerebrospinal fluid (CSF) and blood under physiological conditions throughout normal brain development, maturation, and aging. NfP levels in CSF and blood rise above normal in response to neuronal injury and neurodegeneration independently of cause. NfPs in CSF measured by lumbar puncture are about 40-fold more concentrated than in blood in healthy individuals. New ultra-sensitive methods now allow minimally invasive measurement of these low levels of NfPs in serum or plasma to track disease onset and progression in neurological disorders or nervous system injury and assess responses to therapeutic interventions. Any of the five Nf subunits – neurofilament light chain (NfL), neurofilament medium chain (NfM), neurofilament heavy chain (NfH), alpha-internexin (INA) and peripherin (PRPH) may be altered in a given neuropathological condition. In familial and sporadic Alzheimer’s disease (AD), plasma NfL levels may rise as early as 22 years before clinical onset in familial AD and 10 years before sporadic AD. The major determinants of elevated levels of NfPs and degradation fragments in CSF and blood are the magnitude of damaged or degenerating axons of fiber tracks, the affected axon caliber sizes and the rate of release of NfP and fragments at different stages of a given neurological disease or condition directly or indirectly affecting central nervous system (CNS) and/or peripheral nervous system (PNS). NfPs are rapidly emerging as transformative blood biomarkers in neurology providing novel insights into a wide range of neurological diseases and advancing clinical trials. Here we summarize the current understanding of intracellular NfP physiology, pathophysiology and extracellular kinetics of NfPs in biofluids and review the value and limitations of NfPs and degradation fragments as biomarkers of neurodegeneration and neuronal injury.

A NOVEL AND RAPID ASSAY FOR EVALUATING DOUBLE-STRAND DNA FRAGMENTATION IN HUMAN SPERMATOZOA

To validate the sperm DNA fragment release assay (LensHooke® R11), a test kit for estimating sperm DNA fragmentation (SDF) with double-strand DNA breaks (SDF-DSBs) in human spermatozoa, and explore its relationship with semen parameters.

Enterococcus peptidoglycan remodeling promotes checkpoint inhibitor cancer immunotherapy.

The antitumor efficacy of cancer immunotherapy can correlate with the presence of certain bacterial species within the gut microbiome. However, many of the molecular mechanisms that influence host response to immunotherapy remain elusive. In this study, we show that members of the bacterial genus Enterococcus improve checkpoint inhibitor immunotherapy in mouse tumor models. Active enterococci express and secrete orthologs of the NlpC/p60 peptidoglycan hydrolase SagA that generate immune-active muropeptides. Expression of SagA in nonprotective E. faecalis was sufficient to promote immunotherapy response, and its activity required the peptidoglycan sensor NOD2. Notably, SagA-engineered probiotics or synthetic muropeptides also augmented anti-PD-L1 antitumor efficacy. Taken together, our data suggest that microbiota species with specialized peptidoglycan remodeling activity and muropeptide-based therapeutics may enhance cancer immunotherapy and could be leveraged as next-generation adjuvants.

SagA promotes immunotherapy response

Microbiome The gut microbiome can influence the treatment outcome for cancer patients receiving PD-L1 immunotherapy, but the mechanisms underlying favorable responses are unclear. Griffin et al. found that a particular type of bacteria called enterococci enhance anti–PD-L1 immunotherapy in mice (see the Perspective by Ansaldo and Belkaid). The researchers show that enterococci secrete an enzyme called SagA that breaks down components of the bacterial cell wall. This process results in the release of muramyl peptide fragments, which in turn act as stimulatory molecules to promote signaling of the innate immune sensor protein NOD2 and improved immunotherapy responses. Science , abc9113, this issue p. [1040][1]; see also abl3656, p. [966][2] [1]: /lookup/doi/10.1126/science.abc9113 [2]: /lookup/doi/10.1126/science.abl3656

Properties of peptides released from salmon and carp via simulated human-like gastrointestinal digestion described applying quantitative parameters.

Apart from the classical (experimental) methods, biologically active peptides can be studied via bioinformatics approach, also known as in silico analysis. This study aimed to verify the following research hypothesis: ACE inhibitors and antioxidant peptides can be released from salmon and carp proteins during simulated in silico human-like gastrointestinal digestion. The potential to release biopeptides was evaluated using the BIOPEP-UWM quantitative criteria including the profile of biological activity, frequency of the occurrence (A)/release (AE) of fragments with an ACE inhibitory or antioxidant activity by selected enzymes, and relative frequency of release of bioactive fragments with a given activity by selected enzymes (W). Salmon collagen and myofibrillar proteins of carp turned out to be the best potential source of the searched peptides–ACE inhibitors and antioxidant peptides. Nonetheless, after digestion, the highest numbers of ACE inhibitors and antioxidant peptides were potentially released from the myofibrillar proteins of salmon and carp. Peptide Ranker Score, Pepsite2, and ADMETlab platform were applied to evaluate peptides’ bioactivity potential, their safety and drug-like properties. Among the 63 sequences obtained after the simulated digestion of salmon and carp proteins, 30 were considered potential biopeptides. The amino acid sequences of ACE-inhibiting and antioxidant peptides were predominated by P, G, F, W, R, and L. The predicted high probability of absorption of most analyzed peptides and their low toxicity should be considered as their advantage.

Oxidative stress following acute kidney injury causes disruption of lung cell cilia and their release into the bronchoaveolar lavage fluid and lung injury, which are exacerbated by Idh2 deletion

Acute kidney injury (AKI) induces distant organ injury, which is a serious concern in patients with AKI. Recent studies have demonstrated that distant organ injury is associated with oxidative stress of organ and damage of cilium, an axoneme-based cellular organelle. However, the role of oxidative stress and cilia damage in AKI-induced lung injury remains to be defined. Here, we investigated whether AKI-induced lung injury is associated with mitochondrial oxidative stress and cilia disruption in lung cells. AKI was induced in isocitrate dehydrogenase 2 (Idh2, a mitochondrial antioxidant enzyme)-deleted (Idh2−/−) and wild-type (Idh2+/+) mice by kidney ischemia-reperfusion (IR). A group of mice were treated with Mito-TEMPO, a mitochondria-specific antioxidant. Kidney IR caused lung injuries, including alveolar septal thickening, alveolar damage, and neutrophil accumulation in the lung, and increased protein concentration and total cell number in bronchoalveolar lavage fluid (BALF). In addition, kidney IR caused fragmentation of lung epithelial cell cilia and the release of fragments into BALF. Kidney IR also increased the production of superoxide, lipid peroxidation, and mitochondrial and nuclei DNA oxidation in lungs and decreased IDH2 expression. Lung oxidative stress and injury relied on the degree of kidney injury. Idh2 deletion exacerbated kidney IR-induced lung injuries. Treatment with Mito-TEMPO attenuated kidney IR-induced lung injuries, with greater attenuation in Idh2−/− than Idh2+/+ mice. Our data demonstrate that AKI induces the disruption of cilia and damages cells via oxidative stress in lung epithelial cells, which leads to the release of disrupted ciliary fragments into BALF.

Pioneer neutrophils release chromatin within in vivo swarms.

Neutrophils are rapidly recruited to inflammatory sites where their coordinated migration forms clusters, a process termed neutrophil swarming. The factors that modulate early stages of neutrophil swarming are not fully understood, requiring the development of new in vivo models. Using transgenic zebrafish larvae to study endogenous neutrophil migration in a tissue damage model, we demonstrate that neutrophil swarming is a conserved process in zebrafish immunity, sharing essential features with mammalian systems. We show that neutrophil swarms initially develop around an individual pioneer neutrophil. We observed the violent release of extracellular cytoplasmic and nuclear fragments by the pioneer and early swarming neutrophils. By combining in vitro and in vivo approaches to study essential components of neutrophil extracellular traps (NETs), we provide in-depth characterisation and high-resolution imaging of the composition and morphology of these release events. Using a photoconversion approach to track neutrophils within developing swarms, we identify that the fate of swarm-initiating pioneer neutrophils involves extracellular chromatin release and that the key NET components gasdermin, neutrophil elastase, and myeloperoxidase are required for the swarming process. Together our findings demonstrate that release of cellular components by pioneer neutrophils is an initial step in neutrophil swarming at sites of tissue injury.

Formation of ZrC-SiC Composites from the Molecular Scale through the Synthesis of Multielement Polymers.

In the field of non-oxide ceramic composites, and by using the polymer-derived ceramic route, understanding the relationship between the thermal behaviour of the preceramic polymers and their structure, leading to the mechanisms involved, is crucial. To investigate the role of Zr on the fabrication of ZrC–SiC composites, linear or hyperbranched polycarbosilanes and polyzirconocarbosilanes were synthesised through either “click-chemistry” or hydrosilylation reactions. Then, the thermal behaviours of these polymeric structures were considered, notably to understand the impact of Zr on the thermal path going to the composites. The inorganic materials were characterised by thermogravimetry-mass spectrometry (TG-MS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). To link the macromolecular structure to the organisation involved during the ceramisation process, eight temperature domains were highlighted on the TG analyses, and a four-step mechanism was proposed for the polymers synthesised by a hydrosilylation reaction, as they displayed better ceramic yields. Globally, the introduction of Zr in the polymer had several effects on the temperature fragmentation mechanisms of the organometallic polymeric structures: (i) instead of stepwise mass losses, continuous fragment release prevailed; (ii) the stability of preceramic polymers was impacted, with relatively good ceramic yields; (iii) it modulated the chemical composition of the generated composites as it led, inter alia, to the consumption of free carbon.

Abstract 675: Radiotherapy inhibits the antitumor immune response through release of immunosuppressive tumor-derived extracellular vesicles in prostate cancer

Abstract Stereotactic ablative radiotherapy (SABR) has shown durable response rates in a subset of prostate cancer patients presenting with low metastatic burden (oligometastasis). By delivering a highly focused dose of radiation, SABR optimizes local control and induces a systemic antitumor immune response which causes tumor regression in non-irradiated metastases at distant sites (called abscopal response). However, cases of abscopal response remain scarce and the disease in majority of patients progresses by developing wide-spread metastasis. Therefore, it is crucial to elucidate the underlying mechanisms of resistance to SABR in non-responder patients and develop more effective combination therapies. By analyzing plasma samples from metastatic castration-resistant prostate cancer (mCRPC) patients, we have observed that radiotherapy induces release of tumor fragments, called extracellular vesicles (EVs). Patients with high levels of tumor-derived EVs were more at risk of developing metastases following radiotherapy. We hypothesize that radiotherapy can inhibit a systemic antitumor immune response by inducing the release of immunosuppressive tumor-derived EVs in prostate cancer. Prostate cancer cell lines (PC3 and DU145) were treated with single dose or fractionated radiotherapy. Levels of EVs were measured with Apogee Micro60-Plus nanoscale flow cytometer and the molecular composition of EVs was analyzed by proteomics and western-blot. Co-culture of prostate cancer cells with CD8+-T cells isolated from healthy donors was used to evaluate the impact of EVs on T-cell activity.For the first time, we identified irradiated PC3 and DU145 prostate cancer cells with both single dose and fractionated radiotherapy exhibiting significant increases in B7H3 protein expression. In accordance with total B7H3 protein level changes, the levels of surface B7H3 protein expression in irradiated PC3 and DU145 cells also significantly increased. Lastly, not only did radiation cause increases in the levels of PC3 and DU145 cell EV release, but also increased B7H3 protein enrichment in those EVs. Given the increases in the B7H3 protein levels in irradiated PC3 and DU145 cell surface and EVs, B7H3 enriched- PC3 and DU145 cell EV treatment to CD8+ T-cells caused significant decreases in the proliferation rates of CD8+ T-cells compared to the proliferation rates of CD8+ T-cells without EV treatment or with non-irradiated PC3 and DU145 cell-derived EV treatment.We anticipate that this proposed study can unveil novel cellular mechanisms underscoring the role of B7H3-enriched prostate cancer cell EVs in halting the radiation-induced anti-tumor immune response. This study warrants investigation into potential therapeutic strategies paired with SABR, making more efficacious anti-metastatic prostate cancer treatments. Citation Format: Yohan Kim, Roxane R. Lavoie, Haidong dong, Sean Park, Fabrice Lucien-Matteoni. Radiotherapy inhibits the antitumor immune response through release of immunosuppressive tumor-derived extracellular vesicles in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 675.

The Replication Stress Response on a Narrow Path Between Genomic Instability and Inflammation.

The genome of eukaryotic cells is particularly at risk during the S phase of the cell cycle, when megabases of chromosomal DNA are unwound to generate two identical copies of the genome. This daunting task is executed by thousands of micro-machines called replisomes, acting at fragile structures called replication forks. The correct execution of this replication program depends on the coordinated action of hundreds of different enzymes, from the licensing of replication origins to the termination of DNA replication. This review focuses on the mechanisms that ensure the completion of DNA replication under challenging conditions of endogenous or exogenous origin. It also covers new findings connecting the processing of stalled forks to the release of small DNA fragments into the cytoplasm, activating the cGAS-STING pathway. DNA damage and fork repair comes therefore at a price, which is the activation of an inflammatory response that has both positive and negative impacts on the fate of stressed cells. These new findings have broad implications for the etiology of interferonopathies and for cancer treatment.

Hetero-Bis-Conjugation of Bioactive Molecules to Half-Sandwich Ruthenium(II) and Iridium(III) Complexes Provides Synergic Effects in Cancer Cell Cytotoxicity.

Four bipyridine-type ligands variably derivatized with two bioactive groups (taken from ethacrynic acid, flurbiprofen, biotin, and benzylpenicillin) were prepared via sequential esterification steps from commercial 2,2'-bipyridine-4,4'-dicarboxylic acid and subsequently coordinated to ruthenium(II) p-cymene and iridium(III) pentamethylcyclopentadienyl scaffolds. The resulting complexes were isolated as nitrate salts in high yields and fully characterized by analytical and spectroscopic methods. NMR and MS studies in aqueous solution and in cell culture medium highlighted a substantial stability of ligand coordination and a slow release of the bioactive fragments in the latter case. The complexes were assessed for their antiproliferative activity on four cancer cell lines, showing cytotoxicity to the low micromolar level (equipotent with cisplatin). Additional biological experiments revealed a multimodal mechanism of action of the investigated compounds, involving DNA metalation and enzyme inhibition. Synergic effects provided by specific combinations of metal and bioactive fragments were identified, pointing toward an optimal ethacrynic acid/flurbiprofen combination for both Ru(II) and Ir(III) complexes.

Syncytiotrophoblast stress in early onset preeclampsia: The issues perpetuating the syndrome

Preeclampsia is a pregnancy-specific syndrome characterized by a sudden increase in blood pressure accompanied by proteinuria and/or maternal multi-system damage associated to poor fetal outcome. In early-onset preeclampsia, utero-placental perfusion is altered, causing constant and progressive damage to the syncytiotrophoblast, generating syncytiotrophoblast stress. The latter leads to the detachment and release of syncytiotrophoblast fragments, anti-angiogenic factors and pro-inflammatory molecules into maternal circulation, resulting in the emergence and persistence of the characteristic symptoms of this syndrome during pregnancy. Therefore, understanding the origin and consequences of syncytiotrophoblast stress in preeclampsia is vital to develop new therapeutic alternatives, focused on reducing the burden of this syndrome. In this review, we describe five central characteristics of syncytial stress that should be targeted or prevented in order to reduce preeclampsia symptoms: histological alterations, syncytiotrophoblast damage, antiangiogenic protein export, placental deportation, and altered syncytiotrophoblast turnover. Therapeutic management of these characteristics may improve maternal and fetal outcomes.

Disassembly of the apical junctional complex during the transmigration of Leptospira interrogans across polarized renal proximal tubule epithelial cells.

Bacterial pathogens have evolved multiple strategies to disassemble epithelial cell apical junctional complexes (AJCs) and infect epithelial cells. Leptospirosis is a widespread zoonotic infection, mainly caused by Leptospira interrogans, and its dissemination across host cell barriers is essential for its pathogenesis. However, the mechanism of bacterial dissemination across epithelial cell barriers remains poorly characterised. In this study, we analysed the interaction of L. interrogans with renal proximal tubule epithelial cells (RPTECs) and found that at 24 hr post‐infection, L. interrogans remain in close contact with the plasma membrane of the RPTEC by extracellularly adhering or crawling. Leptospira interrogans cleaved E‐cadherin and induced its endocytosis with release of the soluble N‐terminal fragment into the extracellular medium. Concomitantly, a gradual decrease in transepithelial electrical resistance (TEER), mislocalisation of AJC proteins (occludin, claudin‐10, ZO‐1, and cingulin) and cytoskeletal rearrangement were observed. Inhibition of clathrin‐mediated E‐cadherin endocytosis prevented the decrease in TEER. We showed that disassembly of AJCs in epithelial cells and transmigration of bacteria through the paracellular route are important for the dissemination of L. interrogans in the host.

Recent, Bioelectricity-Related Articles Selected by Ann M. Rajnicek, Media Editor of Bioelectricity.

Recent, Bioelectricity-Related Articles Selected by Ann M. Rajnicek, Media Editor of Bioelectricity.

Development of a highly sensitive chemiluminescence immunoassay for quantification of aggrecanase-generated ARGS aggrecan fragments in serum

ObjectiveCartilage degradation is a hallmark of osteoarthritis (OA). Aggrecan, a major proteoglycan of articular cartilage extracellular matrix (ECM), is degraded by ADAMTS-5 resulting in the release of ARGS-G2 fragments to synovial fluid and circulation. The aim was to quantify ARGS-G2 in the serum of OA patients using the huARGS immunoassay. MethodsThe immunoassay was produced under GMP conditions and the technical performance was assessed. The biological relevance of the immunoassay was assessed in the conditioned media from a bovine full-depth cartilage explant (BEX) model. The diurnal and inter-day variations of ARGS levels were evaluated in OA patients’ serum. Post-hoc analysis of huARGS was conducted in a sub-cohort of a phase III OA trial testing the safety and efficacy of oral salmon calcitonin. ResultsTechnical performance: huARGS demonstrated good technical performance. Biological relevance: ARGS release was induced by inflamatory facotrs stimulation compared to the vehicle group, reaching a peak at day 3 and gradually decreasing to base level at day 12. The ARGS release was suppressed by the addition of the ADAMTS-4/-5 activation inhibitor. Biological variation: No significant diurnal or inter-day effect was found. Phase III clinical trial: The participants in the lowest group (Q1) of baseline huARGS levels were more likely to progress radiographically than the highest group (Q4): OR 3.38[0.81-14.02]. ConclusionsThe huARGS shows good technical performance and low biological variation. It has the potential to aid drug development in various stages, both as a PD biomarker and identifying progressors who might be likely to respond to an OA drug.

A Link between Replicative Stress, Lamin Proteins, and Inflammation.

Double-stranded breaks (DSB), the most toxic DNA lesions, are either a consequence of cellular metabolism, programmed as in during V(D)J recombination, or induced by anti-tumoral therapies or accidental genotoxic exposure. One origin of DSB sources is replicative stress, a major source of genome instability, especially when the integrity of the replication forks is not properly guaranteed. To complete stalled replication, restarting the fork requires complex molecular mechanisms, such as protection, remodeling, and processing. Recently, a link has been made between DNA damage accumulation and inflammation. Indeed, defects in DNA repair or in replication can lead to the release of DNA fragments in the cytosol. The recognition of this self-DNA by DNA sensors leads to the production of inflammatory factors. This beneficial response activating an innate immune response and destruction of cells bearing DNA damage may be considered as a novel part of DNA damage response. However, upon accumulation of DNA damage, a chronic inflammatory cellular microenvironment may lead to inflammatory pathologies, aging, and progression of tumor cells. Progress in understanding the molecular mechanisms of DNA damage repair, replication stress, and cytosolic DNA production would allow to propose new therapeutical strategies against cancer or inflammatory diseases associated with aging. In this review, we describe the mechanisms involved in DSB repair, the replicative stress management, and its consequences. We also focus on new emerging links between key components of the nuclear envelope, the lamins, and DNA repair, management of replicative stress, and inflammation.

Experimental Models of Liquid Biopsy in Hepatocellular Carcinoma Reveal Clone-Dependent Release of Circulating Tumor DNA.

Liquid biopsy, the molecular analysis of tumor components released into the bloodstream, has emerged as a noninvasive and resourceful means to access genomic information from cancers. Most data derived from translational studies showcase its numerous potential clinical applications. However, data from experimental models are scarce, and little is known about the underlying mechanisms and factors controlling the release of circulating tumor DNA (ctDNA) and cells (CTCs). This study aimed to model liquid biopsy in hepatocellular carcinoma xenografts and to study the dynamics of release of ctDNA and CTCs; this included models of intratumoral heterogeneity (ITH) and metastatic disease. We quantified ctDNA by quantitative polymerase chain reaction (PCR) targeting human long interspersed nuclear element group 1; targeted mutation analysis was performed with digital droplet PCR. CTCs were traced by flow cytometry. Results demonstrated the feasibility of detecting ctDNA, including clone‐specific mutations, as well as CTCs in blood samples of mice. In addition, the concentration of ctDNA and presence of tumor‐specific mutations reflected tumor progression, and detection of CTCs was associated with metastases. Our ITH model suggested differences in the release of DNA fragments impacted by the cell‐clone origin and the treatment. Conclusion: These data present new models to study liquid biopsy and its underlying mechanisms and highlighted a clone‐dependent release of ctDNA into the bloodstream.

Correlated variational treatment of ionization coupled to nuclear motion: Ultrafast pump and ionizing probe of electronic and nuclear dynamics in LiH

Author(s): Bello, RY; Lucchese, RR; Rescigno, TN; McCurdy, CW | Abstract: We demonstrate a theoretical treatment of dissociative single ionization of the LiH molecule using two-color UV-UV pulse sequences that makes use of a highly correlated description of both the ionization continuum and target molecular ion and neutral states to which it is coupled. The present results emphasize how the details of the ionization process at various internuclear distances combine to form a lens through which such experiments image the dynamics of intermediate electronic states populated by the pump pulse. While ionization yields (dissociative and nondissociative) provide information about the amplitudes and phases that build up the molecular wave packet in the neutral states, molecular frame photoelectron angular distributions exhibit the changing character of those states, i.e., from ionic to covalent. In addition, the time-dependent mean kinetic energy of the wave packet on neutral states is clearly mapped onto the kinetic energy release of the atomic fragments produced by the probe ionization pulse.