Cells and Development最新文献

This study mainly analyzed the relationship between nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transforming growth factor-β (TGFβ1)/Smad under high glucose environment and its influence on wound healing. Fibroblast NIH-3T3 was used to analyze the effect of high concentration glucose (20 nmol/mL) on cell viability, migration ability, inflammation level and NF-κB pathway. Pyrrolidinedithiocarbamate (PDTC) was used to inhibit NF-κB for rescue experiments. Diabetic mice were used to construct wound healing models. Recombinant TGF-β1 was used to promote wound healing in diabetic mice. FSL-1 was applied to activate NF-κB to verify the mechanism. High glucose inhibited cell viability and migration ability, promoted the expression of TNF-α, IL-6 and IL-1β, induced the activation of NF-κB pathway in fibroblasts. Inhibition of NF-κB not only blocked the decrease in cell viability and migration ability induced by high glucose, but also relieved the release of inflammatory factors. TGF-β1 activated the TGF-β1/Smad pathway and promoted wound healing in diabetic mice. Activating the NF-κB pathway not only inhibited the activation of the TGF-β1/Smad pathway, but also alleviated the promoting effect of TGF-β1 on wound healing. In a high glucose environment, the activation of NF-κB may inhibit the function of fibroblasts by inhibiting the TGF-β1/Smad pathway, resulting in poor wound healing.

Segmentation of 3D images to identify cells and their molecular outputs can be difficult and tedious. Machine learning algorithms provide a promising alternative to manual analysis as emerging 3D image processing technology can save considerable time. For those unfamiliar with machine learning or 3D image analysis, the rapid advancement of the field can make navigating the newest software options confusing. In this paper, two open-source machine learning algorithms, Cellpose and Stardist, are compared in their application on a 3D light sheet dataset counting fluorescently stained proliferative cell nuclei. The effects of image tiling and background subtraction are shown through image analysis pipelines for both algorithms. Based on our analysis, the relative ease of use of Cellpose and the absence of need to train a model leaves it a strong option for 3D cell segmentation despite relatively longer processing times. When Cellpose's pretrained model yields results that are not of sufficient quality, or the analysis of a large dataset is required, Stardist may be more appropriate. Despite the time it takes to train the model, Stardist can create a model specialized to the users' dataset that can be iteratively improved until predictions are satisfactory with far lower processing time relative to other methods.

The in vitro reconstructions of human salivary glands in service of their eventual medical use represent a challenge for tissue engineering. Here, we present a theoretical approach to the dynamical formation of acinar structures from human salivary cells, focusing on observed stick-slip radial expansion as well as possible growth instabilities. Our findings demonstrate the critical importance of basement membrane remodeling in controlling the growth process.

Troponin I type 1b (Tnni1b) is thought to be a novel isoform that is expressed only in the zebrafish heart. Knocking down of tnni1b can lead to cardiac defects in zebrafish. Although both the zebrafish tnni1b and human troponin I1 (TNNI1) genes are thought to be closely associated with fatal cardiac development, the regulatory molecular mechanisms of these genes are poorly understood. Analyzing the functionally conserved sequence, especially in the noncoding regulatory region involved in gene expression, clarified these mechanisms. In this study, we isolated a 3 kb fragment upstream of Fugu tnni1a that can regulate green fluorescence protein (GFP) expression in a heart-specific manner, similar to the pattern of zebrafish homologue expression. Three evolutionarily conserved regions (ECRs) in the 5′-flanking sequence of Fugu tnni1a were identified by sequence alignment. Deletion analysis led to the identification of ECR2 as a core sequence that affects the heart-specific expression function of the Fugu tnni1a promoter. Interestingly, both the Fugu tnni1a promoter and ECR2 sequence were functionally conserved in zebrafish, although they shared no sequence similarity. Together, the findings of our study provided further evidence for the important role of tnni1a homologous in cardiac development and demonstrated that two functionally conserved sequences in the zebrafish and Fugu genomes may be ECRs, despite their lack of similarity.

Semaphorin 3A (Sema3a) is a chemotropic protein that acts as a neuronal guidance cue and plays a major role in dorsal root ganglion (DRG) sensory neurons projection during embryo development. The present study evaluated the impact of stiffness in the repulsive response of DRG neurons to Sema3a when cultured over substrates of variable stiffness. Stiffness modified DRG neurons morphology and regulated their response to Sema3a, reducing the collapse of growth cones when they were cultured on softer substrates. Sema3a receptors expression was also regulated by stiffness, neuropilin-1 was overexpressed and plexin A4 mRNA was downregulated in stiffer substrates. Cytoskeleton distribution was also modified by stiffness. In softer substrates, βIII-tubulin and actin co-localized up to the leading edge of the growth cones, and as the substrate became stiffer, βIII-tubulin was confined to the transition and peripheral domains of the growth cone. Moreover, a decrease in the α-actinin adaptor protein was also observed in softer substrates. Our results show that substrate stiffness plays an important role in regulating the collapse response to Sema3a and that the modulation of cytoskeleton distribution and Sema3a receptors expression are related to the differential collapse responses of the growth cones.

Segments are repeated anatomical units forming the body of insects. In Drosophila, the specification of the body takes place during the blastoderm through the segmentation cascade. Pair-rule genes such as hairy (h), even-skipped (eve), runt (run), and fushi-tarazu (ftz) are of the intermediate level of the cascade and each pair-rule gene is expressed in seven transversal stripes along the antero-posterior axis of the embryo. Stripes are formed by independent cis-regulatory modules (CRMs) under the regulation of transcription factors of maternal source and of gap proteins of the first level of the cascade. The initial blastoderm of Drosophila is a syncytium and it also coincides with the mid-blastula transition when thousands of zygotic genes are transcribed and their products are able to diffuse in the cytoplasm. Thus, we anticipated a complex regulation of the CRMs of the pair-rule stripes. The CRMs of h 1, eve 1, run 1, ftz 1 are able to be activated by bicoid (bcd) throughout the anterior blastoderm and several lines of evidence indicate that they are repressed by the anterior gap genes slp1 (sloppy-paired 1), tll (tailless) and hkb (huckebein). The modest activity of these repressors led to the premise of a combinatorial mechanism regulating the expression of the CRMs of h 1, eve 1, run 1, ftz 1 in more anterior regions of the embryo. We tested this possibility by progressively removing the repression activities of slp1, tll and hkb. In doing so, we were able to expose a mechanism of additive repression limiting the anterior borders of stripes 1. Stripes 1 respond depending on their distance from the anterior end and repressors operating at different levels.

Growth control establishes organism size, requiring mechanisms to sense and adjust growth during development. Studies of single cells revealed that size homeostasis uses distinct control methods. In multicellular organisms, mechanisms that regulate single cell growth must integrate control across organs and tissues during development to generate adult size and shape. We leveraged the roundworm Caenorhabditis elegans as a scalable and tractable model to collect precise growth measurements of thousands of individuals, measure feeding behavior, and quantify changes in animal size and shape during a densely sampled developmental time course. As animals transitioned from one developmental stage to the next, we observed changes in body aspect ratio while body volume remained constant. Then, we modeled a physical mechanism by which constraints on cuticle stretch could cause changes in C. elegans body shape. The model-predicted shape changes are consistent with those observed in the data. Theoretically, cuticle stretch could be sensed by the animal to initiate larval-stage transitions, providing a means for physical constraints to influence developmental timing and growth rate in C. elegans.