Biology subjects

Rubinstein, N.

Publications and source records attributed to Rubinstein, N..

4 recordsLinked to original sources

bioRxiv2022

RUNX1 is regulated by androgen receptor to promote cancer stem markers and chemotherapy resistance in triple negative breast cancer.

Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype for which no effective targeted therapies are available. Growing evidence suggests that chemotherapy-resistant cancer cells with stem-like properties (CSC) may repopulate the tumor. Androgen receptor (AR) is expressed in up to 50% of TNBC, and AR inhibition decreases CSC and tumor initiation. Runt-related transcription factor 1 (RUNX1) correlates with poor prognosis in TNBC and is regulated by AR in prostate cancer. Our group has shown that RUNX1 promotes TNBC cell migration and regulates tumor gene expression. We hypothesized that RUNX1 is regulated by AR and that both may work together in TNBC CSC to promote disease recurrence following chemotherapy. Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) experiments in MDA-MB-453 revealed AR binding to RUNX1 regulatory regions. RUNX1 expression is upregulated by dihydrotestosterone (DHT) in MDA-MB-453 and in HCI-009 patient-derived xenograft (PDX) tumors (p<0.05). RUNX1 is increased in a CSC-like experimental model in MDA-MB-453 and SUM-159PT cells (p<0.05). Inhibition of RUNX1 transcriptional activity reduced the expression of CSC markers. Interestingly, RUNX1 inhibition reduced cell viability and enhanced paclitaxel and enzalutamide sensitivity. Targeting RUNX1 may be an attractive strategy to potentiate the anti-tumor effects of AR inhibition, specifically in the slow growing CSC-like populations that resist chemotherapy leading to metastatic disease.

cancer biology↗

bioRxiv2021

Production of a Highly Immunogenic Antigen from SARS-CoV-2 by Covalent Coupling of the Receptor Binding Domain of Spike Protein to a Multimeric Carrier

Since the discovery of SARS-CoV-2, several antigens have been proposed to be part of COVID-19 vaccines. The receptor binding domain (RBD) of Spike protein is one of the promising candidates to develop effective vaccines since it can induce potent neutralizing antibodies. We previously reported the production of RBD in Pichia pastoris and showed it is structurally identical to the protein produced in mammalian HEK-293T cells. In this work we designed an RBD multimer construct with the purpose of increasing RBD immunogenicity. We produced multimeric particles by a transpeptidation reaction between the RBD expressed in P. pastoris and Lumazine Synthase from Brucella abortus (BLS), which is a highly immunogenic and very stable decameric protein of 170 kDa. We vaccinated mice with two doses 30 days apart, and then we measured humoral immune response. When the number of RBD copies coupled to BLS was high (6-7 RBD molecules per BLS decamer, in average), the immune response was significantly better than that elicited by RBD alone or even by RBD-BLS comprising low number of RBD copies (1-2 RBD molecules per BLS decamer). Remarkably, the construct with high number of RBD copies induced high IgG titers with high neutralizing capacity. Furthermore, a superior immune response was observed when Al(OH)3 adjuvant was added to this formulation, exhibiting a higher titer of neutralizing antibodies. Altogether our results suggest that RBD covalent coupled to BLS forming a multimer-particle shows an advantageous architecture to the antigen-presentation to the immune system which enhances immune responses. This new antigen should be considered a potent candidate for a protein-based vaccine.

biochemistry↗

bioRxiv2020

Structural and Functional Comparison of SARS-CoV-2-Spike Receptor Binding Domain Produced in Pichia pastoris and Mammalian Cells

The yeast Pichia pastoris is a cost-effective and easily scalable system for recombinant protein production. In this work we compared the conformation of the receptor binding domain (RBD) from SARS-CoV-2 Spike protein expressed in P. pastoris and in the well established HEK-293T mammalian cell system. RBD obtained from both yeast and mammalian cells was properly folded, as indicated by UV-absorption, circular dichroism and tryptophan fluorescence. They also had similar stability, as indicated by temperature-induced unfolding (observed Tm were 50 {degrees}C and 52 {degrees}C for RBD produced in P. pastoris and HEK-293T cells, respectively). Moreover, the stability of both variants was similarly reduced when the ionic strength was increased, in agreement with a computational analysis predicting that a set of ionic interactions may stabilize RBD structure. Further characterization by HPLC, size-exclusion chromatography and mass spectrometry revealed a higher heterogeneity of RBD expressed in P. pastoris relative to that produced in HEK-293T cells, which disappeared after enzymatic removal of glycans. The production of RBD in P. pastoris was scaled-up in a bioreactor, with yields above 45 mg/L of 90% pure protein, thus potentially allowing large scale immunizations to produce neutralizing antibodies, as well as the large scale production of serological tests for SARS-CoV-2.

biochemistry↗

bioRxiv2019

Molecular and Circuit Architecture of Social Hierarchy

Social hierarchy is a common organizational structure of animal groups, in which an individuals social status generates an adaptive behavioral state that facilitates interactions with other group members. Although generally stable, the social status of an animal can change, underscoring the plasticity of the underlying neural circuits. Here, we uncover the molecular and biophysical properties of a cortico-thalamic circuit that supports the emergence of hierarchy in mice. We established a robust behavioral paradigm to explore the establishment of hierarchy among groups of unfamiliar males, and identified the mediodorsal thalamus (MDT) and the caudal part of anterior cingulate area (cACC) as brain areas that are differentially activated between dominants and subordinates. Glutamatergic MDT neurons project to inhibitory parvalbumin interneurons of the cACC, and activity levels of both cell types control competitive performance. Synaptic inputs and excitability of MDT neurons undergo dramatic changes according to the animal social status, and single nucleus sequencing identified increased transcription of the voltage gated ion channel Trpm3 in dominant mice, leading to enhanced excitatory transmission in the MDT-cACC circuit. Our data suggest a model in which cellular, molecular and biophysical plasticity in a thalamocortical circuit controls the expression of social status.

neuroscience↗