In Vitro Cellular & Developmental Biology. Animal最新文献

The presence of nuclear architectural abnormalities is a hallmark of the nuclear envelopathies, which are a group of diseases caused by mutations in genes encoding nuclear envelope proteins. Mutations in the lamin A/C gene cause several diseases, named laminopathies, including muscular dystrophies, progeria syndromes, and lipodystrophy. A mouse model carrying with the Lmna^H222P/H222P mutation (H222P) was shown to develop severe cardiomyopathy but only mild skeletal myopathy, although abnormal nuclei were observed in their striated muscle. In this report, we analyzed the abnormal-shaped nuclei in myoblasts and myotubes isolated from skeletal muscle of H222P mice, and evaluated the expression of nuclear envelope proteins in these abnormal myonuclei. Primary skeletal muscle cells from H222P mice proliferated and efficiently differentiated into myotubes in vitro, similarly to those from wild-type mice. During cell proliferation, few abnormal-shaped nuclei were detected; however, numerous markedly abnormal myonuclei were observed in myotubes from H222P mice on days 5 and 7 of differentiation. Time-lapse observation demonstrated that myonuclei with a normal shape maintained their normal shape, whereas abnormal-shaped myonuclei remained abnormal for at least 48 h during differentiation. Among the abnormal-shaped myonuclei, 65% had a bleb with a string structure, and 35% were severely deformed. The area and nuclear contents of the nuclear blebs were relatively stable, whereas the myocytes with nuclear blebs were actively fused within primary myotubes. Although myonuclei were markedly deformed, the deposition of DNA damage marker (γH2AX) or apoptotic marker staining was rarely observed. Localizations of lamin A/C and emerin were maintained within the blebs, strings, and severely deformed regions of myonuclei; however, lamin B1, nesprin-1, and a nuclear pore complex protein were absent in these abnormal regions. These results demonstrate that nuclear membranes from H222P skeletal muscle cells do not rupture and are resistant to DNA damage, despite these marked morphological changes.

Skeletal muscle tissue increases or decreases its volume by synthesizing or degrading myofibrillar proteins. The ubiquitin-proteasome system plays a pivotal role during muscle atrophy, where muscle ring finger proteins (Murf) function as E3 ubiquitin ligases responsible for identifying and targeting substrates for degradation. Our previous study demonstrated that overexpression of Ozz, an E3 specific to embryonic myosin heavy chain (Myh3), precisely reduced the Myh3 replacement rate in the thick filaments of myotubes (E. Ichimura et al., Physiol Rep. 9:e15003, 2021). These findings strongly suggest that E3 plays a critical role in regulating myosin replacement. Here, we hypothesized that the Murf isoforms, which recognize Myhs as substrates, reduced the myosin replacement rates through the enhanced Myh degradation by Murfs. First, fluorescence recovery after a photobleaching experiment was conducted to assess whether Murf isoforms affected the GFP-Myh3 replacement. In contrast to Murf2 or Murf3 overexpression, Murf1 overexpression selectively facilitated the GFP-Myh3 myosin replacement. Next, to examine the effects of Murf1 overexpression on the replacement of myosin isoforms, Cherry-Murf1 was coexpressed with GFP-Myh1, GFP-Myh4, or GFP-Myh7 in myotubes. Intriguingly, Murf1 overexpression enhanced the myosin replacement of GFP-Myh4 but did not affect those of GFP-Myh1 or GFP-Myh7. Surprisingly, overexpression of Murf1 did not enhance the ubiquitination of proteins. These results indicate that Murf1 selectively regulated myosin replacement in a Myh isoform-dependent fashion, independent of enhanced ubiquitination. This suggests that Murf1 may have a role beyond functioning as a ubiquitin ligase E3 in thick filament myosin replacement.

The generation of genetically engineered pig models that develop pancreas-specific tumors has the potential to advance studies and our understanding of pancreatic cancer in humans. TP53 mutation causes organ-nonspecific cancers, and PDX1-knockout results in the loss of pancreas development. The aim of the present study was to generate a PDX1-knockout pig chimera carrying pancreas complemented by TP53 mutant cells via phytohemagglutinin (PHA)-mediated blastomere aggregation using PDX1 and TP53 mutant blastomeres, as a pig model for developing tumors in the pancreas with high frequency. First, the concentration and exposure time to PHA to achieve efficient blastomere aggregation were optimized. The results showed that using 300 µg/mL PHA for 10 min yielded the highest rates of chimeric blastocyst formation. Genotyping analysis of chimeric blastocysts derived from aggregated embryos using PDX1- and TP53-edited blastomere indicated that approximately 28.6% carried mutations in both target regions, while 14.3-21.4% carried mutations in one target. After the transfer of the chimeric blastocysts into one recipient, the recipient became pregnant with three fetuses. Deep sequencing analysis of the PDX1 and TP53 regions using ear and pancreas samples showed that one fetus carried mutations in both target genes, suggesting that the fetus was a chimera derived from embryo-aggregated PDX1 and TP53 mutant blastomeres. Two out of three fetuses carried only the PDX1 mutation, indicating that the fetuses developed from embryos not carrying TP53-edited blastomeres. The results of the present study could facilitate the further improvement and design of high-frequency developing pancreatic tumor models in pigs.

A variety of CRISPR-Cas9-based gene editing technologies have been developed, including gene insertion and gene replacement, and applied to the study and treatment of diseases. While numerous studies have been conducted to improve the efficiency of gene insertion and to expand the system in various ways, there have been relatively few reports on gene replacement technology; therefore, further improvements are still needed in this context. Here, we developed the REMOVER-PITCh system to establish an efficient long-range gene replacement method and demonstrated its utility at two genomic loci in human cultured cells. REMOVER-PITCh depends on microhomology-assisted gene insertion technology called PITCh with highly multiplexed CRISPR-Cas9. First, we achieved gene replacement of about 20-kb GUSB locus using this system. Second, by applying the previously established knock-in-enhancing platform, the LoAD system, along with REMOVER-PITCh, we achieved the replacement of a longer gene region of about 200 kb at the ARSB locus. Our REMOVER-PITCh system will make it possible to remove and incorporate a variety of sequences from and into the genome, respectively, which will facilitate the generation of various disease and humanized models.

Sinoatrial node (SAN) is the pacemaker of the heart in charge of initiating spontaneous electronical activity and controlling heart rate. Myocytes from SAN can generate spontaneous rhythmic action potentials, which propagate through the myocardium, thereby triggering cardiac myocyte contraction. Acutely, the method for isolating sinoatrial node myocytes (SAMs) is critical in studying the protein expression and function of myocytes in SAN. Currently, the SAMs were isolated by transferring SAN tissue directly into the digestion solution, but it is difficult to judge the degree of digestion, and the system was unstable. Here, we present a modified protocol for the isolation of SAMs in mice, based on the collagenase II and protease perfusion of the heart using a Langendorff apparatus and subsequent dissociation of SAMs. The appearance and droplet flow rate of the heart could be significantly changed during enzymatic digestion via perfusion, which allowed us to easily judge the degree of digestion and avoid incomplete or excessive digestion. The SAMs with stable yield and viability achieved from our optimized approach would facilitate the follow-up experiments.

Bladder outlet obstruction (BOO) is the primary clinical manifestation of benign prostatic hyperplasia, the most common urinary system disease in elderly men, and leads to associated lower urinary tract symptoms. Although BOO is reportedly associated with increased systemic oxidative stress (OS), the underlying mechanism remains unclear. The elucidation of this mechanism is the primary aim of this study. A Sprague-Dawley rat model of BOO was constructed and used for urodynamic monitoring. The bladder tissue of rats was collected and subjected to real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR), histological examination, and immunohistochemical staining. Through bioinformatics prediction, we found that transforming growth factor β2 (TGFβ2) expression was upregulated in rats with BOO compared with normal bladder tissue. In vitro analyses using primary bladder smooth muscle cells (BSMCs) revealed that hydrogen peroxide (H₂O₂) induced TGFβ2 expression. Moreover, H₂O₂ induced epithelial-to-mesenchymal transition (EMT) by reducing E-cadherin, an endothelial marker and CK-18, a cytokeratin maker, and increasing mesenchymal markers, including N-cadherin, vimentin, and α-smooth muscle actin (α-SMA) levels. The downregulation of TGFβ2 expression in BSMCs using siRNA technology alleviated H₂O₂-induced changes in EMT marker expression. The findings of the study indicate that TGFβ2 plays a crucial role in BOO by participating in OS-induced EMT in BSMCs.

Watching living cells through a microscope is much more exciting than seeing pictures of cells in high school and college textbooks. However, bringing cell cultures into the classroom is challenging for biology teachers since culturing cells requires sophisticated and expensive instruments such as a CO₂ incubator and an inverted phase-contrast microscope. Here, we describe easy and affordable methods to culture and observe skeletal muscle cells using the L-15 culture medium, tissue culture flask, standard dry incubator, standard upright microscope, and modified Smartphone microscope. Watching natural living cells in a "Do-It-Yourself (DIY)" way may inspire more students' interest in cell biology.

Muscular dystrophy in the NH-413 chicken is caused by a missense mutation in the WWP1 gene. WWP1 is a HECT-type E3 ubiquitin ligase containing four tandem WW domains that interact with proline-rich peptide motifs of target proteins, and a short region connecting the second and third WW domains is crucial for the E3 ligase to maintain an autoinhibitory state. A mutation of the arginine in the WW2-WW3 linker to glutamine is thought to affect WWP1 function, but there is little information on this mutation to date. In this study, we generated a transgenic (Tg) mouse model expressing the WWP1 transgene with the R436Q mutation, which corresponds to the missense mutation found in the NH-413 chicken. Tg mice showed marked degradation of mutant WWP1 proteins in various tissues, particularly in striated muscle. Immunoprecipitation analysis using a WWP1-specific antibody demonstrated that the mutant WWP1 proteins lacked the C-terminal catalytic cysteine residue that is required for their binding to the E2-substrate complex during their degradation. In vitro analysis using the R436Q mutant of WWP1 lacking this catalytic cysteine residue showed no autodegradation, indicating that the loss-of-function degradation of this protein is caused by self-ubiquitination. Tg mice expressing R436Q WWP1 did not show stunted growth or premature death. Furthermore, histological analysis did not reveal any obvious changes. These observations suggested that the R436Q mutant WWP1 protein, which is released from autoinhibitory mode by its missense mutation, does not have abnormally activated enzyme function to substrates before its self-degradation and loss of enzyme function.

In vitro gill models are becoming increasingly important in aquatic toxicology, yet the fish gill invitrome is underrepresented, encompassing approximately 0.1% of extant species. Here, we describe the establishment and characterisation of two gill-derived, epithelial-like cell lines isolated from fish species of significant importance to New Zealand: Chrysophrys auratus (Australasian snapper) and Oncorhynchus tshawytscha (Chinook salmon). Designated CAgill1PFR (Chrysophrys auratus, gill 1, Plant & Food Research) and OTgill1PFR (Oncorhynchus tshawytscha, gill 1, Plant & Food Research), these cell lines have each been passaged greater than each 70 times over several years and are considered spontaneously immortalised. Both cell lines required serum for growth and exhibited differential responses to basal media formulations. CAgill1PFR was sensitive to low temperatures (4 °C) but replicated at high temperatures (30 °C), whereas OTgill1PFR was sensitive to high temperatures but remained viable at low temperatures, mirroring the natural environment of their host species. Immunostaining revealed expression of epithelial cell markers cytokeratin and E-cadherin, alongside positivity for the mesenchymal cell marker, vimentin. CAgill1PFR was more sensitive to the environmental toxin 3,4 dichloroaniline than OTgill1PFR through measurements of metabolic activity, membrane integrity, and lysosomal function. Furthermore, CAgill1PFR produced less CYP1A activity, indicative of ongoing biotransformation processes, in response to beta-naphthoflavone than OTgill1PFR. These cell lines expand the toolbox of resources and emphasise the need for species-specific aquatic toxicology research.

Polycomb group proteins (PcGs) add repressive post translational histone modifications such as H2AK119ub1, and histone H2A deubiquitinases remove it. Mice lacking histone H2A deubiquitinases such as Usp16 and Bap1 die in embryonic stage, while mice lacking Usp3, Mysm1, Usp12, and Usp21 have been shown to be deficient in hematopoietic lineage differentiation, cell cycle regulation, and DNA repair. Thus, it is likely that histone deubiquitinases may also be required for human endothelial cell differentiation; however, there are no reports about the role of histone H2A deubiquitinase BAP1 in human endothelial cell development. We differentiated human pluripotent stem cells into the endothelial lineage which expressed stable inducible shRNA against BAP1. Our results show that BAP1 is required for human endothelial cell differentiation.