Boosting ER-mitochondria calcium transfer to treat Wolfram syndrome.

Wolfram syndrome is a rare genetic disorder characterized by endocrine dysfunction and progressive neurodegeneration. By targeting intracellular calcium dysregulations, a sigma-1 receptor agonist rescued neurological deficits in preclinical models of Wolfram syndrome.

Cytoskeletal dynamics regulates stromal invasion behavior of distinct liver cancer subtypes.

Drug treatment against liver cancer has limited efficacy due to heterogeneous response among liver cancer subtypes. In addition, the functional biophysical phenotypes which arise from this heterogeneity and contribute to aggressive invasive behavior remain poorly understood. This study interrogated how heterogeneity in liver cancer subtypes contributes to differences in invasive phenotypes and drug response. Utilizing histological analysis, quantitative 2D invasion metrics, reconstituted 3D hydrogels, and bioinformatics, our study linked cytoskeletal dynamics to differential invasion profiles and drug resistance in liver cancer subtypes. We investigated cytoskeletal regulation in 2D and 3D culture environments using two liver cancer cell lines, SNU-475 and HepG2, chosen for their distinct cytoskeletal features and invasion profiles. For SNU-475 cells, a model for aggressive liver cancer, many cytoskeletal inhibitors abrogated 2D migration but only some suppressed 3D migration. For HepG2 cells, cytoskeletal inhibition did not significantly affect 3D migration but did affect proliferative capabilities and spheroid core growth. This study highlights cytoskeleton driven phenotypic variation, their consequences and coexistence within the same tumor, as well as efficacy of targeting biophysical phenotypes that may be masked in traditional screens against tumor growth.

Neuronal calcium sensor 1 (NCS1) dependent modulation of neuronal morphology and development.

Calcium (Ca2+ ) signaling is critical for neuronal functioning and requires the concerted interplay of numerous Ca2+ -binding proteins, including neuronal calcium sensor 1 (NCS1). Although an important role of NCS1 in neuronal processes and in neurodevelopmental and neurodegenerative diseases has been established, the underlying mechanisms remain enigmatic. Here, we systematically investigated the functions of NCS1 in the brain. Using Golgi-Cox staining, we observed a reduction in dendritic complexity and spine density in the prefrontal cortex and the dorsal hippocampus of Ncs1-/- mice, which may underlie concomitantly observed deficits in memory acquisition. Subsequent RNA sequencing of Ncs1-/- and Ncs1+/+ mouse brain tissues revealed that NCS1 modulates gene expression related to neuronal morphology and development. Investigation of developmental databases further supported a molecular role of NCS1 during brain development by identifying temporal gene expression patterns. Collectively, this study provides insights into NCS1-dependent signaling and lays the foundation for a better understanding of NCS1-associated diseases.

Pharmacological rescue of cognitive function in a mouse model of chemobrain.

BACKGROUND: After chemotherapy, many cancer survivors suffer from long-lasting cognitive impairment, colloquially known as "chemobrain." However, the trajectories of cognitive changes and the underlying mechanisms remain unclear. We previously established paclitaxel-induced inositol trisphosphate receptor (InsP3R)-dependent calcium oscillations as a mechanism for peripheral neuropathy, which was prevented by lithium pretreatment. Here, we investigated if a similar mechanism also underlay paclitaxel-induced chemobrain. METHOD: Mice were injected with 4 doses of 20 mg/kg paclitaxel every other day to induced cognitive impairment. Memory acquisition was assessed with the displaced object recognition test. The morphology of neurons in the prefrontal cortex and the hippocampus was analyzed using Golgi-Cox staining, followed by Sholl analyses. Changes in protein expression were measured by Western blot. RESULTS: Mice receiving paclitaxel showed impaired short-term spatial memory acquisition both acutely 5 days post injection and chronically 23 days post injection. Dendritic length and complexity were reduced in the hippocampus and the prefrontal cortex after paclitaxel injection. Concurrently, the expression of protein kinase C α (PKCα), an effector in the InsP3R pathway, was increased. Treatment with lithium before or shortly after paclitaxel injection rescued the behavioral, cellular, and molecular deficits observed. Similarly, memory and morphological deficits could be rescued by pretreatment with chelerythrine, a PKC inhibitor. CONCLUSION: We establish the InsP3R calcium pathway and impaired neuronal morphology as mechanisms for paclitaxel-induced cognitive impairment. Our findings suggest lithium and PKC inhibitors as candidate agents for preventing chemotherapy-induced cognitive impairment.

Wolfram Syndrome: a Monogenic Model to Study Diabetes Mellitus and Neurodegeneration.

Wolfram syndrome (WS) is a rare, progressive disorder characterized by childhood-onset diabetes mellitus, optic nerve atrophy, hearing loss, diabetes insipidus, and neurodegeneration. Currently, there is no effective treatment for WS, and patients typically die between 30 and 40 years of age. WS is primarily caused by autosomal recessive mutations in the Wolfram syndrome 1 (WFS1) gene (OMIM 222300), which encodes for wolframin (WFS1). This disorder is therefore a valuable monogenic model for prevalent diseases, particularly diabetes mellitus and neurodegeneration. Whereas reduced survival and secretion are known cellular impairments causing WS, the underlying molecular pathways and the physiological function of WFS1 remain incompletely described. Here, we characterize WFS1 as a regulator of intracellular calcium homeostasis, review our current understanding of the disease mechanism of WS, and discuss candidate treatment approaches. These insights will facilitate identification of new therapeutic strategies not only for WS but also for diabetes mellitus and neurodegeneration.

Calpain inhibitor and ibudilast rescue ß cell functions in a cellular model of Wolfram syndrome.

Wolfram syndrome is a rare multisystem disease characterized by childhood-onset diabetes mellitus and progressive neurodegeneration. Most cases are attributed to pathogenic variants in a single gene, Wolfram syndrome 1 (WFS1). There currently is no disease-modifying treatment for Wolfram syndrome, as the molecular consequences of the loss of WFS1 remain elusive. Because diabetes mellitus is the first diagnosed symptom of Wolfram syndrome, we aimed to further examine the functions of WFS1 in pancreatic ß cells in the context of hyperglycemia. Knockout (KO) of WFS1 in rat insulinoma (INS1) cells impaired calcium homeostasis and protein kinase B/Akt signaling and, subsequently, decreased cell viability and glucose-stimulated insulin secretion. Targeting calcium homeostasis with reexpression of WFS1, overexpression of WFS1's interacting partner neuronal calcium sensor-1 (NCS1), or treatment with calpain inhibitor and ibudilast reversed deficits observed in WFS1-KO cells. Collectively, our findings provide insight into the disease mechanism of Wolfram syndrome and highlight new targets and drug candidates to facilitate the development of a treatment for this disorder and similar diseases.

Neuronal Calcium Sensor 1 is up-regulated in response to stress to promote cell survival and motility in cancer cells.

Changes in intracellular calcium (Ca2+ ) signaling can modulate cellular machinery required for cancer progression. Neuronal calcium sensor 1 (NCS1) is a ubiquitously expressed Ca2+ -binding protein that promotes tumor aggressiveness by enhancing cell survival and metastasis. However, the underlying mechanism by which NCS1 contributes to increased tumor aggressiveness has yet to be identified. In this study, we aimed to determine (a) whether NCS1 expression changes in response to external stimuli, (b) the importance of NCS1 for cell survival and migration, and (c) the cellular mechanism(s) through which NSC1 modulates these outcomes. We found that NCS1 abundance increases under conditions of stress, most prominently after stimulation with the pro-inflammatory cytokine tumor necrosis factor α, in a manner dependent on nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB). We found that NFκB signaling is activated in human breast cancer tissue, which was accompanied by an increase in NCS1 mRNA expression. Further exploration into the relevance of NCS1 in breast cancer progression showed that knockout of NCS1 (NCS1 KO) caused decreased cell survival and motility, increased baseline intracellular Ca2+ levels, and decreased inositol 1,4,5-trisphosphate-mediated Ca2+ responses. Protein kinase B (Akt) activity was decreased in NCS1 KO cells, which could be rescued by buffering intracellular Ca2+ . Conversely, Akt activity was increased in cells overexpressing NCS1 (NCS1 OE). We therefore conclude that NCS1 acts as cellular stress response protein up-regulated by stress-induced NFκB signaling and that NCS1 influences cell survival and motility through effects on Ca2+ signaling and Akt pathway activation.

Polycystin 2 is increased in disease to protect against stress-induced cell death.

Polycystin 2 (PC2 or TRPP1, formerly TRPP2) is a calcium-permeant Transient Receptor Potential (TRP) cation channel expressed primarily on the endoplasmic reticulum (ER) membrane and primary cilia of all cell and tissue types. Despite its ubiquitous expression throughout the body, studies of PC2 have focused primarily on its role in the kidney, as mutations in PC2 lead to the development of autosomal dominant polycystic kidney disease (ADPKD), a debilitating condition for which there is no cure. However, the endogenous role that PC2 plays in the regulation of general cellular homeostasis remains unclear. In this study, we measure how PC2 expression changes in different pathological states, determine that its abundance is increased under conditions of cellular stress in multiple tissues including human disease, and conclude that PC2-deficient cells have increased susceptibility to cell death induced by stress. Our results offer new insight into the normal function of PC2 as a ubiquitous stress-sensitive protein whose expression is up-regulated in response to cell stress to protect against pathological cell death in multiple diseases.