The evolution of synthetic receptor systems.

Receptors enable cells to detect, process and respond to information about their environments. Over the past two decades, synthetic biologists have repurposed physical parts and concepts from natural receptors to engineer synthetic receptors. These technologies implement customized sense-and-respond programs that link a cell's interaction with extracellular and intracellular cues to user-defined responses. When combined with tools for information processing, these advances enable programming of sophisticated customized functions. In recent years, the library of synthetic receptors and their capabilities has substantially evolved-a term we employ here to mean systematic improvement and expansion. Here, we survey the existing mammalian synthetic biology toolkit of protein-based receptors and signal-processing components, highlighting efforts to evolve and integrate some of the foundational synthetic receptor systems. We then propose a generalized strategy for engineering and improving receptor systems to meet defined functional objectives called a 'metric-enabled approach for synthetic receptor engineering' (MEASRE).

Case report: Characterization of a rare pathogenic variant associated with loss of COL3A1 expression in vascular Ehlers Danlos syndrome.

The vascular subtype of Ehlers Danlos Syndrome (vEDS) is a rare connective tissue disorder characterized by spontaneous arterial, bowel or organ rupture. The diagnosis of vEDS is established in a proband by identification of a heterozygous pathogenic variant in the alpha-1 gene of type III collagen (COL3A1) by molecular analysis. In this report, we present a case of vEDS with life threatening, spontaneous arterial dissections in association with an uncharacterized rare variant of COL3A1, exon19:c.1340G > A. Primary culture of patient skin fibroblasts followed by immunofluorescence revealed a complete absence of COL3A1 protein expression as well as altered morphology. Electron microscopy of the cultured fibroblasts showed abnormal vacuoles in the cytoplasm suggestive of a secretory defect. In this study, we have performed functional characterization of the COL3A1 exon19:c.1340G > A variant for the first time and this may now be classified as likely pathogenic in vEDS. *Both JM and LRL contributed equally in the manuscript and should both be considered as the first author.

Increased Mucin Expression in Oral Mucosal Epithelial Cells in vitro: A Potential New Role of Mycophenolate Mofetil.

OBJECTIVE: Autologous cultured explants of human oral mucosal epithelial cells (OMEC) are a potential therapeutic modality in patients of bilateral ocular surface disease (OSD) with incapacitating dry eye. Mycophenolate mofetil (MMF) has been found to upregulate the mucin production in conjunctival goblet cells in vitro. The aim of this study was to evaluate the effects of MMF on mucin expression in primary cultures of OMEC. METHODS: With informed consent, oral mucosal epithelial tissue samples were obtained from patients undergoing oral surgery for non-malignant conditions. OMEC were cultured on human amniotic membrane (HAM) scaffold for 2 weeks. Mucin expression was quantified using RT-PCR and qPCR before and after treating cultured OMEC with MMF. RESULTS: Morphological studies revealed a confluent sheet of proliferating, stratified oral mucosal epithelial cells. Mucin mRNAs were elucidated by RT-PCR. Compared to untreated controls, MUC1, MUC15 and MUC16 mRNAs and MUC1 protein expression were found to be upregulated in MMF treated primary cultures of OMEC, as assessed by qPCR and immunocytochemistry respectively. CONCLUSION: Our findings demonstrate that MMF can act as a novel enhancer of mucin production in OMEC in vitro. It has the potential to improve dry eye in patients undergoing OMEC transplantation for bilateral OSD.

Identification of High-Risk Aberrant Crypt Foci and Mucin-Depleted Foci in the Human Colon With Study of Colon Cancer Stem Cell Markers.

BACKGROUND: During colonoscopic screening, only macroscopic lesions will be identified, and these are usually the result of multiple genetic abnormalities. Magnification endoscopic detection of aberrant crypt foci (ACF), long before they acquire complex genetic abnormalities, is promising. However, the features of high-risk ACF-like lesions need to be identified. MATERIALS AND METHODS: In the present cross-sectional study, grossly visible normal mucosal flaps were shaved from 152 colectomies, including 96 colorectal cancer (CRC) cases and 56 controls (22 control specimens with disease with malignant potential and 34 without malignant potential). Methylene and Alcian blue stains were performed directly on the unfixed mucosal flaps to identify ACF and mucin-depleted foci (MDF). Detailed topographic analyses, with immunohistochemical staining for ß-catenin and cancer stem cell (CSC) markers (CD44, CD24, and CD166) were performed. RESULTS: ACF, MDF, and ß-catenin-accumulated crypts were detected more in specimens with adjacent CRC. The left colon had ACF with a larger diameter and greater crypt multiplicity, density, and gyriform pit pattern and were considered the high-risk ACF group. MDF, more commonly associated with dysplasia, is also a marker of possible carcinogenesis. The CD44 CSC marker was significantly upregulated in ACF specimens compared with normal controls. Our 3-tier ACF-only pit pattern classification system showed better linearity with mucosal dysplasia than did the 6-tier Kudo classification. CONCLUSION: High-risk ACF, when detected during chromoendoscopic screening, should be followed up. CSCs might play an important role in pathogenesis. Larger studies and genotypic risk stratification for definite identification of high-risk ACF are needed.

Autoregulation and heterogeneity in expression of human Cripto-1.

Cripto-1 (CR-1) is involved in various processes in embryonic development and cancer. Multiple pathways regulate CR-1 expression. Our present work demonstrates a possible positive feedback circuit where CR-1 induces its own expression. Using U-87 MG cells treated with exogenous CR-1, we show that such induction involves ALK4/SMAD2/3 pathway. Stochasticity in gene expression gives rise to heterogeneity in expression in genetically identical cells. Positive feedback increases such heterogeneity and often gives rise to two subpopulations of cells, having higher and lower expression of a gene. Using flow cytometry, we show that U-87 MG cells have a minuscule subpopulation with detectable expression of CR-1. Induction of CR-1 expression, by exogenous CR-1, increases the size of this CR-1 positive subpopulation. However, even at very high dose, most of the cells remain CR-1 negative. We show that population behavior of CR-1 induction has a signature similar to bimodal expression expected in a transcriptional circuit with positive feedback. We further show that treatment of U-87 MG cells with CR-1 leads to higher expression of drug efflux protein MDR-1 in the CR-1 positive subpopulation, indicating correlated induction of these two proteins. Positive feedback driven heterogeneity in expression of CR-1 may play crucial role in phenotypic diversification of cancer cells.