Cell stretchers and the LINC complex in mechanotransduction.

How cells respond to mechanical forces from the surrounding environment is critical for cell survival and function. The LINC complex is a central component in the mechanotransduction pathway that transmits mechanical information from the cell surface to the nucleus. Through LINC complex functionality, the nucleus is able to respond to mechanical stress by altering nuclear structure, chromatin organization, and gene expression. The use of specialized devices that apply mechanical strain to cells have been central to investigating how mechanotransduction occurs, how cells respond to mechanical stress, and the role of the LINC complexes in these processes. A large variety of designs have been reported for these devices, with the most common type being cell stretchers. Here we highlight some of the salient features of cell stretchers and suggest some key parameters that should be considered when using these devices. We provide a brief overview of how the LINC complexes contribute to the cellular responses to mechanical strain. And finally, we suggest that stretchers may be a useful tool to study aging.

Design of a 3D printed, motorized, uniaxial cell stretcher for microscopic and biochemical analysis of mechanotransduction.

Cells respond to mechanical cues from their environment through a process of mechanosensing and mechanotransduction. Cell stretching devices are important tools to study the molecular pathways responsible for cellular responses to mechanobiological processes. We describe the development and testing of a uniaxial cell stretcher that has applications for microscopic as well as biochemical analyses. By combining simple fabrication techniques with adjustable control parameters, the stretcher is designed to fit a variety of experimental needs. The stretcher can be used for static and cyclic stretching. As a proof of principle, we visualize stretch induced deformation of cell nuclei via incremental static stretch, and changes in IEX1 expression via cyclic stretching. This stretcher is easily modified to meet experimental needs, inexpensive to build, and should be readily accessible for most laboratories with access to 3D printing.

Tumorigenic and Antiproliferative Properties of the TALE-Transcription Factors MEIS2D and MEIS2A in Neuroblastoma.

Neuroblastoma is one of only a few human cancers that can spontaneously regress even after extensive dissemination, a poorly understood phenomenon that occurs in as many as 10% of patients. In this study, we identify the TALE-homeodomain transcription factor MEIS2 as a key contributor to this phenomenon. We identified MEIS2 as a MYCN-independent factor in neuroblastoma and showed that in this setting the alternatively spliced isoforms MEIS2A and MEIS2D exert antagonistic functions. Specifically, expression of MEIS2A was low in aggressive stage 4 neuroblastoma but high in spontaneously regressing stage 4S neuroblastoma. Moderate elevation of MEIS2A expression reduced proliferation of MYCN-amplified human neuroblastoma cells, induced neuronal differentiation and impaired the ability of these cells to form tumors in mice. In contrast, MEIS2A silencing or MEIS2D upregulation enhanced the aggressiveness of the tumor phenotype. Mechanistically, MEIS2A uncoupled a negative feedback loop that restricts accumulation of cellular retinoic acid, an effective agent in neuroblastoma treatment. Overall, our results illuminate the basis for spontaneous regression in neuroblastoma and identify an MEIS2A-specific signaling network as a potential therapeutic target in this common pediatric malignancy.Significance: This study illuminates the basis for spontaneous regressions that can occur in a common pediatric tumor, with implications for the development of new treatment strategies. Cancer Res; 78(8); 1935-47. ©2018 AACR.

Spectrum of mutations and carrier frequency of familial Mediterranean fever gene in the Algerian population.

OBJECTIVES: FMF is characterized by recurrent self-limiting episodes of fever and painful polyserositis. We aimed to study the spectrum and distribution of MEFV mutations in an Algerian patient cohort using a comprehensive mutation detection method. Using the same methodology, we also studied the carrier rate in an unaffected ethnically matched control cohort. METHODS: We recruited 71 unrelated subjects clinically diagnosed with FMF from various clinics in the central region of Algeria. Two hundred and thirty control subjects were recruited as well. Mutation detection in MEFV was performed by re-sequencing the promoter region, the entire coding sequence and all exon-intron boundaries. RESULTS: We detected eight different mutations located in exons 10 (p.M694I, p.M694V, p.A744S, p.M680I, p.I692Del), 9 (p.I591T), 3 (p.P369S/p.R408Q) and 2 (p.E148Q). Out of the 71 patients, 31 carried at least one mutation. While the 71 patients are expected to have 142 mutant chromosomes, only 50 were identified. p.M694I (17.6%) is the most common mutation, followed by p.M694V (5%), p.E148Q (4.2%), p.A744S (3.5%) and p.M680I (3%). One novel variant was identified in the promoter region in the heterozygous state in three patients and in two controls. The carrier rate of the identifiable mutations is estimated to be 1 : 5. CONCLUSION: This study describes the MEFV mutational spectrum and distribution in the Algerian population. It shows that p.M694I is the most common MEFV mutation in Algerians. It also shows that, similar to other Arabic populations, <50% of mutant chromosomes are identified, even when employing comprehensive strategies.