Step-function luminopsins for bimodal prolonged neuromodulation

Although molecular tools for controlling neuronal activity by light have vastly expanded, there are still unmet needs which require development and refinement. For example, light delivery into the brain is still a major practical challenge that hinders potential translation of optogenetics in human patients. In addition, it would be advantageous to manipulate neuronal activity acutely and precisely as well as chronically and non-invasively, using the same genetic construct in animal models. We have previously addressed these challenges by employing bioluminescence and have created a new line of opto-chemogenetic probes termed luminopsins by fusing light-sensing opsins with light-emitting luciferases. In this report, we incorporated Chlamydomonas channelrhodopsin 2 with step-function mutations as the opsin moiety in the new luminopsin fusion protein termed step-function luminopsin (SFLMO). Bioluminescence-induced photocurrent lasted longer than the bioluminescence signal due to very slow deactivation of the mutated channel. In addition, bioluminescence was able to activate most of the channels on the cell surface due to the extremely high light sensitivity of the channel. This efficient channel activation was partly mediated by radiationless bioluminescence resonance energy transfer due to the proximity of luciferase and opsin. To test the utility of SFLMOs in vivo, we transduced the substantia nigra unilaterally via a viral vector in male rats. Injection of the luciferase substrate as well as conventional photostimulation via fiber optics elicited circling behaviors. Thus, SFLMOs expand the current approaches for manipulation of neuronal activity in the brain and add more versatility and practicality to optogenetics in freely behaving animals.     

Improved trafficking and expression of luminopsins for more efficient optical and pharmacological control of neuronal activity

Luminopsins (LMOs) are chimeric proteins consisting of a luciferase fused to an opsin that provide control of neuronal activity, allowing for less cumbersome and less invasive optogenetic manipulation. It was previously shown that both an external light source and the luciferase substrate, coelenterazine (CTZ), could modulate activity of LMO-expressing neurons, although the magnitudes of the photoresponses remained subpar. In this study, we created an enhanced iteration of the excitatory luminopsin LMO3, termed eLMO3, that has improved membrane targeting due to the insertion of a Golgi trafficking signal sequence. In cortical neurons in culture, the expression of eLMO3 resulted in significant reductions in the formation of intracellular aggregates, as well as in a significant increase in total photocurrents. Furthermore, we corroborated the findings with injections of adeno-associated viral vectors into the deep layers of the somatosensory cortex (the barrel cortex) of male mice. We observed greatly reduced numbers of intracellular puncta in eLMO3-expressing cortical neurons compared to those expressing the original LMO3. Finally, we quantified CTZ-driven behavior, namely whisker-touching behavior, in male mice with LMO3 expression in the barrel cortex. After CTZ administration, mice with eLMO3 displayed significantly longer whisker responses than mice with LMO3. In summary, we have engineered the superior LMO by resolving membrane trafficking defects, and we demonstrated improved membrane targeting, greater photocurrents, and greater functional responses to stimulate with CTZ.     

YES1 activation induces acquired resistance to neratinib in HER2‐amplified breast and lung cancers

Molecular‐targeted therapies directed against human epidermal growth factor receptor 2 (HER2) are evolving for various cancers. Neratinib is an irreversible pan‐HER tyrosine kinase inhibitor and has been approved by the FDA as an effective drug for HER2‐positive breast cancer. However, acquired resistance of various cancers to molecular‐targeted drugs is an issue of clinical concern, and emergence of resistance to neratinib is also considered inevitable. In this study, we established various types of neratinib‐resistant cell lines from HER2‐amplified breast and lung cancer cell lines using several drug exposure conditions. We analyzed the mechanisms of emergence of the resistance in these cell lines and explored effective strategies to overcome the resistance. Our results revealed that amplification of YES1, which is a member of the SRC family, was amplified in two neratinib‐resistant breast cancer cell lines and one lung cancer cell line. Knockdown of YES1 by siRNA and pharmacological inhibition of YES1 by dasatinib restored the sensitivity of the YES1‐amplified cell lines to neratinib in vitro. Combined treatment with dasatinib and neratinib inhibited tumor growth in vivo. This combination also induced downregulation of signaling molecules such as HER2, AKT and MAPK. Our current results indicate that YES1 plays an important role in the emergence of resistance to HER2‐targeted drugs, and that dasatinib enables such acquired resistance to neratinib to be overcome.     

Co-targeting bromodomain and extra-terminal proteins and MCL1 induces synergistic cell death in melanoma

The treatment of melanoma has been markedly improved by the introduction of targeted therapies and checkpoint blockade immunotherapy. Unfortunately, resistance to these therapies remains a limitation. Novel anticancer therapeutics targeting the MCL1 anti-apoptotic protein have shown impressive responses in haematological cancers but are yet to be evaluated in melanoma. To assess the sensitivity of melanoma to new MCL1 inhibitors, we measured the response of 51 melanoma cell lines to the novel MCL1 inhibitor, S63845. Additionally, we assessed combination of this drug with inhibitors of the bromodomain and extra-terminal (BET) protein family of epigenetic readers, which we postulated would assist MCL1 inhibition by downregulating anti-apoptotic targets regulated by NF-kB such as BCLXL, BCL2A1 and XIAP, and by upregulating pro-apoptotic proteins including BIM and NOXA. Only 14% of melanoma cell lines showed sensitivity to S63845, however, combination of S63845 and I-BET151 induced highly synergistic apoptotic cell death in all melanoma lines tested and in an in vivo xenograft model. Cell death was dependent on caspases and BAX/BAK. Although the combination of drugs increased the BH3-only protein, BIM, and downregulated anti-apoptotic proteins such as BCL2A1, the importance of these proteins in inducing cell death varied between cell lines. ABT-199 or ABT-263 inhibitors against BCL2 or BCL2 and BCLXL, respectively, induced further cell death when combined with S63845 and I-BET151. The combination of MCL1 and BET inhibition appears to be a promising therapeutic approach for metastatic melanoma, and presents opportunities to add further BCL2 family inhibitors to overcome treatment resistance.     

Prediction‐Based Learning and Processing of Event Knowledge

Knowledge of common events is central to many aspects of cognition. Intuitively, it seems as though events are linear chains of the activities of which they are comprised. In line with this intuition, a number of theories of the temporal structure of event knowledge have posited mental representations (data structures) consisting of linear chains of activities. Competing theories focus on the hierarchical nature of event knowledge, with representations comprising ordered scenes, and chains of activities within those scenes. We present evidence that the temporal structure of events typically is not well‐defined, but it is much richer and more variable both within and across events than has usually been assumed. We also present evidence that prediction‐based neural network models can learn these rich and variable event structures and produce behaviors that reflect human performance. We conclude that knowledge of the temporal structure of events in the human mind emerges as a consequence of prediction‐based learning.     

Contribution of equilibrative nucleoside transporters 1 and 2 to gemcitabine uptake in pancreatic cancer cells

Hepatic arterial infusion (HAI) chemotherapy is expected to be a more effective and safer method to treat the hepatic metastasis of pancreatic cancer than intravenous (iv) administration because of higher tumor exposure and lower systemic exposure. To clarify the uptake mechanism of nucleoside anticancer drugs, including gemcitabine (GEM), in pancreatic cancer, we investigated the uptakes of radiolabeled uridine (a general substrate of nucleoside transporters) and GEM in pancreatic cancer cell lines MIA‐PaCa2 and As‐PC1. Uridine uptake was inhibited by non‐labeled GEM and also by S‐(4‐nitrobenzyl)‐6‐thioinosine (NBMPR; an inhibitor of equilibrative nucleoside transporters, ENTs) in a concentration‐dependent manner, suggesting that ENTs contribute to uridine uptake in pancreatic cancer cells. As for GEM, saturable uptake was mediated by high‐ and low‐affinity components with K_m values of micromolar and millimolar orders, respectively. Uptake was inhibited in a concentration‐dependent manner by NBMPR and was sodium ion‐independent. Moreover, the concentration dependence of uptake in the presence of 0.1 μM NBMPR showed a single low‐affinity site. These results indicated that the high‐ and low‐affinity sites correspond to hENT1 and hENT2, respectively. The results indicated that at clinically relevant hepatic concentrations of GEM in GEM‐HAI therapy, the metastatic tumor exposure of GEM is predominantly determined by hENT2 under unsaturated conditions, suggesting that hENT2 expression in metastatic tumor would be a candidate biomarker for indicating anticancer therapy with GEM‐HAI.