Medial prefrontal dopamine dynamics reflect allocation of selective attention.

The mesocortical dopamine system is comprised of midbrain dopamine neurons that predominantly innervate the medial prefrontal cortex (mPFC) and exert a powerful neuromodulatory influence over this region 1,2 . mPFC dopamine activity is thought to be critical for fundamental neurobiological processes including valence coding and decision-making 3,4 . Despite enduring interest in this pathway, the stimuli and conditions that engage mPFC dopamine release have remained enigmatic due to inherent limitations in conventional methods for dopamine monitoring which have prevented real-time in vivo observation 5 . Here, using a fluorescent dopamine sensor enabling time-resolved recordings of cortical dopamine activity in freely behaving mice, we reveal the coding properties of this system and demonstrate that mPFC dopamine dynamics conform to a selective attention signal. Contrary to the long-standing theory that mPFC dopamine release preferentially encodes aversive and stressful events 6-8 , we observed robust dopamine responses to both appetitive and aversive stimuli which dissipated with increasing familiarity irrespective of stimulus intensity. We found that mPFC dopamine does not evolve as a function of learning but displays striking temporal precedence with second-to-second changes in behavioral engagement, suggesting a role in allocation of attentional resources. Systematic manipulation of attentional demand revealed that quieting of mPFC dopamine signals the allocation of attentional resources towards an expected event which, upon detection triggers a sharp dopamine transient marking the transition from decision-making to action. The proposed role of mPFC dopamine as a selective attention signal is the first model based on direct observation of time-resolved dopamine dynamics and reconciles decades of competing theories.

IBEX: A versatile multiplex optical imaging approach for deep phenotyping and spatial analysis of cells in complex tissues.

The diverse composition of mammalian tissues poses challenges for understanding the cell-cell interactions required for organ homeostasis and how spatial relationships are perturbed during disease. Existing methods such as single-cell genomics, lacking a spatial context, and traditional immunofluorescence, capturing only two to six molecular features, cannot resolve these issues. Imaging technologies have been developed to address these problems, but each possesses limitations that constrain widespread use. Here we report a method that overcomes major impediments to highly multiplex tissue imaging. "Iterative bleaching extends multiplexity" (IBEX) uses an iterative staining and chemical bleaching method to enable high-resolution imaging of >65 parameters in the same tissue section without physical degradation. IBEX can be employed with various types of conventional microscopes and permits use of both commercially available and user-generated antibodies in an "open" system to allow easy adjustment of staining panels based on ongoing marker discovery efforts. We show how IBEX can also be used with amplified staining methods for imaging strongly fixed tissues with limited epitope retention and with oligonucleotide-based staining, allowing potential cross-referencing between flow cytometry, cellular indexing of transcriptomes and epitopes by sequencing, and IBEX analysis of the same tissue. To facilitate data processing, we provide an open-source platform for automated registration of iterative images. IBEX thus represents a technology that can be rapidly integrated into most current laboratory workflows to achieve high-content imaging to reveal the complex cellular landscape of diverse organs and tissues.

gC1qR/HABP1/p32 Is a Potential New Therapeutic Target Against Mesothelioma.

Mesothelioma is an aggressive cancer of the serous membranes with poor prognosis despite combination therapy consisting of surgery, radiotherapy, and platinum-based chemotherapy. Targeted therapies, including immunotherapies, have reported limited success, suggesting the need for additional therapeutic targets. This study investigates a potential new therapeutic target, gC1qR/HABP1/p32 (gC1qR), which is overexpressed in all morphologic subtypes of mesothelioma. gC1qR is a complement receptor that is associated with several cellular functions, including cell proliferation and angiogenesis. In vitro and in vivo experiments were conducted to test the hypothesis that targeting gC1qR with a specific gC1qR monoclonal antibody 60.11 reduces mesothelioma tumor growth, using the biphasic mesothelioma cell line MSTO-211H (MSTO). In vitro studies demonstrate cell surface and extracellular gC1qR expression by MSTO cells, and a modest 25.3 ± 1.8% (n = 4) reduction in cell proliferation by the gC1qR blocking 60.11 antibody. This inhibition was specific for targeting the C1q binding domain of gC1qR at aa 76-93, as a separate monoclonal antibody 74.5.2, directed against amino acids 204-218, had no discernable effect. In vivo studies, using a murine orthotopic xenotransplant model, demonstrated an even greater reduction in MSTO tumor growth (50% inhibition) in mice treated with the 60.11 antibody compared to controls. Immunohistochemical studies of resected tumors revealed increased cellular apoptosis by caspase 3 and TUNEL staining, in 60.11 treated tumors compared to controls, as well as impaired angiogenesis by decreased CD31 staining. Taken together, these data identify gC1qR as a potential new therapeutic target against mesothelioma with both antiproliferative and antiangiogenic properties.

Is the A-Chain the Engine That Drives the Diversity of C1q Functions? Revisiting Its Unique Structure.

The immunopathological functions associated with human C1q are still growing in terms of novelty, diversity, and pathologic relevance. It is, therefore, not surprising that C1q is being recognized as an important molecular bridge between innate and adaptive immunity. The secret of this functional diversity, in turn, resides in the elegant but complex structure of the C1q molecule, which is assembled from three distinct gene products: A, B, and C, each of which has evolved from a separate and unique ancestral gene template. The C1q molecule is made up of 6A, 6B, and 6C polypeptide chains, which are held together through strong covalent and non-covalent bonds to form the 18-chain, bouquet-of-flower-like protein that we know today. The assembled C1q protein displays at least two distinct structural and functional regions: the collagen-like region (cC1q) and the globular head region (gC1q), each being capable of driving a diverse range of ligand- or receptor-mediated biological functions. What is most intriguing, however, is the observation that most of the functions appear to be predominantly driven by the A-chain of the molecule, which begs the question: what are the evolutionary modifications or rearrangements that singularly shaped the primordial A-chain gene to become a pluripotent and versatile component of the intact C1q molecule? Here, we revisit and discuss some of the known unique structural and functional features of the A-chain, which may have contributed to its versatility.