Long-term model predictive control of gene expression at the population and single-cell levels

Gene expression plays a central role in the orchestration of cellular processes. The use of inducible promoters to change the expression level of a gene from its physiological level has significantly contributed to the understanding of the functioning of regulatory networks. However, from a quantitative point of view, their use is limited to short-term, population-scale studies to average out cell-to-cell variability and gene expression noise and limit the nonpredictable effects of internal feedback loops that may antagonize the inducer action. Here, we show that, by implementing an external feedback loop, one can tightly control the expression of a gene over many cell generations with quantitative accuracy. To reach this goal, we developed a platform for real-time, closed-loop control of gene expression in yeast that integrates microscopy for monitoring gene expression at the cell level, microfluidics to manipulate the cells' environment, and original software for automated imaging, quantification, and model predictive control. By using an endogenous osmostress responsive promoter and playing with the osmolarity of the cells environment, we show that long-term control can, indeed, be achieved for both time-constant and time-varying target profiles at the population and even the single-cell levels. Importantly, we provide evidence that real-time control can dynamically limit the effects of gene expression stochasticity. We anticipate that our method will be useful to quantitatively probe the dynamic properties of cellular processes and drive complex, synthetically engineered networks.     

The Complex Intratumoral Heterogeneity of Colon Cancer Highlighted by Laser Microdissection

Aims  

To evaluate the utility of laser microdissection in the comparison of phenotypes and genetic alterations between colon cancer and corresponding liver metastasis in the context of intratumoral heterogeneity.     

Consensus Paper: Current Views on the Role of Cerebellar Interpositus Nucleus in Movement Control and Emotion

In the present paper, we examine the role of the cerebellar interpositus nucleus (IN) in motor and non-motor domains. Recent findings are considered, and we share the following conclusions: IN as part of the olivo-cortico-nuclear microcircuit is involved in providing powerful timing signals important in coordinating limb movements; IN could participate in the timing and performance of ongoing conditioned responses rather than the generation and/or initiation of such responses; IN is involved in the control of reflexive and voluntary movements in a task- and effector system-dependent fashion, including hand movements and associated upper limb adjustments, for quick effective actions; IN develops internal models for dynamic interactions of the motor system with the external environment for anticipatory control of movement; and IN plays a significant role in the modulation of autonomic and emotional functions.     

Limitations of IL-2 and Rapamycin in Immunotherapy of Type 1 Diabetes

Administration of low-dose interleukin-2 (IL-2) alone or combined with rapamycin (RAPA) prevents hyperglycemia in NOD mice. Also, low-dose IL-2 cures recent-onset type 1 diabetes (T1D) in NOD mice, partially by boosting pancreatic regulatory T cells (T_reg cells). These approaches are currently being evaluated in humans. Our objective was to study the effect of higher IL-2 doses (250,000–500,000 IU daily) as well as low-dose IL-2 (25,000 IU daily) and RAPA (1 mg/kg daily) (RAPA/IL-2) combination. We show that, despite further boosting of T_reg cells, high doses of IL-2 rapidly precipitated T1D in prediabetic female and male mice and increased myeloid cells in the pancreas. Also, we observed that RAPA counteracted IL-2 effects on T_reg cells, failed to control IL-2–boosted NK cells, and broke IL-2–induced tolerance in a reversible way. Notably, the RAPA/IL-2 combination failure to cure T1D was associated with an unexpected deleterious effect on glucose homeostasis at multiple levels, including β-cell division, glucose tolerance, and liver glucose metabolism. Our data help to understand the therapeutic limitations of IL-2 alone or RAPA/IL-2 combination and could lead to the design of improved therapies for T1D.In type 1 diabetes (T1D), the immune system destroys the pancreatic β-cells (1). At clinical onset, ∼30% of β-cells are still able to produce insulin (2), thus stopping autoimmune destruction, which at this stage is a promising approach (3). Along the same lines, there is a growing list of phase I/II clinical trials based on immunomodulation that are currently being conducted in T1D patients (4).NOD mice, which develop spontaneous T1D, represent an accepted model for testing new therapies (5), the gold standard being that treatments that cure overt hyperglycemia in these mice may be most appropriate for translation into the clinic, as was the case for anti-CD3 antibodies (Abs) (6), which have been tested in patients with promising results (7). In addition, results from our own group showing that low-dose interleukin-2 (IL-2) can prevent (8) and revert disease in NOD mice (9) have led to the translation of this strategy into clinical trials in T1D patients (clinical trial reg. no. {"type":"clinical-trial","attrs":{"text":"NCT01353833","term_id":"NCT01353833"}}NCT01353833, clinicaltrials.gov).We have shown that in NOD mice, administration of low-dose IL-2 for 5 days induced the remission of new-onset T1D by specifically boosting regulatory T cells (T_reg cells) in the pancreas without activating pathogenic effector T cells (T_eff cells). However, remission was obtained in only 60% of treated mice, and half of them became diabetic again during the following months (9). Consequently, improving IL-2 therapy by optimizing dosing or combining IL-2 with other immunomodulatory drugs, such as rapamycin (RAPA), could be of great importance for the goal of translating this therapy to humans.RAPA has been used in clinical transplantation for many years (10), and it has been safely administered to T1D patients during islet transplantation (11,12). In mice, RAPA monotherapy can prevent T1D development (13); however, it is unable to induce disease reversal (14). Moreover, RAPA and IL-2 were found to be synergistic for the prevention of diabetes in NOD mice (13). Consequently, we decided to test whether RAPA could synergize with short-term IL-2 therapy to reverse T1D and reinforce the development of long-term tolerance.In this work, we have further studied the mechanisms of action of IL-2 and RAPA alone or in combination in the NOD model of T1D.     

Anaemia during pregnancy: impact on birth outcome and infant haemoglobin level during the first 18 months of life

To determine the effect of maternal anaemia on pregnancy outcome and describe its impact on infant haemoglobin level in the first 18 months of life, we conducted a prospective study of 617 pregnant women and their children in Benin. Prevalence of maternal anaemia at delivery was 39.5%, and 61.1% of newborns were anaemic at birth. Maternal anaemia was not associated with low birth weight [OR = 1.2 (0.6-2.2)] or preterm birth [OR = 1.3 (0.7-2.4)], whereas the newborn's anaemia was related to maternal anaemia [OR = 1.8 (1.2-2.5)]. There was no association between an infant's haemoglobin level until 18 months and maternal anaemia. However, malaria attacks during follow-up, male gender and sickle cell trait were all associated with a lower infant haemoglobin level until 18 months, whereas good infant feeding practices and a polygamous family were positively associated with a higher haemoglobin level during the first 18 months of life.