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Cardiovascular Research May 2023Quiescent, differentiated adult vascular smooth muscle cells (VSMCs) can be induced to proliferate and switch phenotype. Such plasticity underlies blood vessel...
AIMS
Quiescent, differentiated adult vascular smooth muscle cells (VSMCs) can be induced to proliferate and switch phenotype. Such plasticity underlies blood vessel homeostasis and contributes to vascular disease development. Oligoclonal VSMC contribution is a hallmark of end-stage vascular disease. Here, we aim to understand cellular mechanisms underpinning generation of this VSMC oligoclonality.
METHODS AND RESULTS
We investigate the dynamics of VSMC clone formation using confocal microscopy and single-cell transcriptomics in VSMC-lineage-traced animal models. We find that activation of medial VSMC proliferation occurs at low frequency after vascular injury and that only a subset of expanding clones migrate, which together drives formation of oligoclonal neointimal lesions. VSMC contribution in small atherosclerotic lesions is typically from one or two clones, similar to observations in mature lesions. Low frequency (<0.1%) of clonal VSMC proliferation is also observed in vitro. Single-cell RNA-sequencing revealed progressive cell state changes across a contiguous VSMC population at onset of injury-induced proliferation. Proliferating VSMCs mapped selectively to one of two distinct trajectories and were associated with cells showing extensive phenotypic switching. A proliferation-associated transitory state shared pronounced similarities with atypical SCA1+ VSMCs from uninjured mouse arteries and VSMCs in healthy human aorta. We show functionally that clonal expansion of SCA1+ VSMCs from healthy arteries occurs at higher rate and frequency compared with SCA1- cells.
CONCLUSION
Our data suggest that activation of proliferation at low frequency is a general, cell-intrinsic feature of VSMCs. We show that rare VSMCs in healthy arteries display VSMC phenotypic switching akin to that observed in pathological vessel remodelling and that this is a conserved feature of mouse and human healthy arteries. The increased proliferation of modulated VSMCs from healthy arteries suggests that these cells respond more readily to disease-inducing cues and could drive oligoclonal VSMC expansion.
Topics: Adult; Animals; Humans; Muscle, Smooth, Vascular; Cardiovascular Diseases; Cell Proliferation; Atherosclerosis; Phenotype; Spinocerebellar Ataxias; Myocytes, Smooth Muscle; Cells, Cultured
PubMed: 35994249
DOI: 10.1093/cvr/cvac138 -
Frontiers in Immunology 2022Many years ago, our research group has demonstrated extramedullary hematopoiesis in the peripheral zone of murine hepatic schistosomal granulomas. In the present study,...
Many years ago, our research group has demonstrated extramedullary hematopoiesis in the peripheral zone of murine hepatic schistosomal granulomas. In the present study, we revisit this phenomenon using new technical and conceptual approaches. Therefore, newborn mice were percutaneously infected by cercariae and euthanized between 35- and 60-days post infection. Liver samples were submitted to histopathology and immunohistochemical analyses. Cells under mitosis and/or expressing Ki67 demonstrated the proliferation of hematopoietic cells both around the parasite's eggs trapped in the liver and around hepatic vessels. After 50 days post infection, proliferating cells at different levels on differentiation were located preferentially in the peripheral zone of the granulomas, around the vessels and inside the sinusoids. The presence of acidic and sulfated glycoconjugates, reticular fibers and the absence of fibronectin characterized the microenvironment for attraction and maintenance of hematopoiesis. Some neutrophils secreted MMP9 from the earliest points of infection, indicating degradation of the extracellular matrix in regions of histolysis and a possible chemoattraction of hematopoietic stem cells to the liver. Fall-3+ cells and Sca-1+ cells indicated that early hematopoietic progenitors could be mobilized to the liver. Groups of vWF+ megakaryocytes suggest chemoattraction of these cells and/or migration, proliferation, and differentiation of very immature progenitors to this organ. The increase of blood vessels and extramedullary hematopoiesis in this environment, where markers of immature hematopoietic and endothelial cells have been identified, points to the possibility of the presence of progenitors for endothelial and hematopoietic cells in the liver during the infection. There is also the possibility of concomitant migration of more differentiated hematopoietic progenitors, that proliferate and differentiate in the liver, and the occurrence of angiogenesis caused by inflammation or release of ovular antigens that stimulate the activation and proliferation of endothelial cells. Altogether, these data increase knowledge about a murine model that is of interest for investigating the pathology of the schistosomiasis and also the dynamics of hematopoiesis.
Topics: Animals; Endothelial Cells; Granuloma; Hematologic Diseases; Hematopoiesis; Hematopoiesis, Extramedullary; Liver; Mice; Schistosomiasis mansoni
PubMed: 36091027
DOI: 10.3389/fimmu.2022.955034 -
Arteriosclerosis, Thrombosis, and... Aug 2023Collateral arteries act as natural bypasses which reroute blood flow to ischemic regions and facilitate tissue regeneration. In an injured heart, neonatal artery...
BACKGROUND
Collateral arteries act as natural bypasses which reroute blood flow to ischemic regions and facilitate tissue regeneration. In an injured heart, neonatal artery endothelial cells orchestrate a systematic series of cellular events, which includes their outward migration, proliferation, and coalescence into fully functional collateral arteries. This process, called artery reassembly, aids complete cardiac regeneration in neonatal hearts but is absent in adults. The reason for this age-dependent disparity in artery cell response is completely unknown. In this study, we investigated if regenerative potential of coronary arteries is dictated by their ability to dedifferentiate.
METHODS
Single-cell RNA sequencing of coronary endothelial cells was performed to identify differences in molecular profiles of neonatal and adult endothelial cells in mice. Findings from this in silico analyses were confirmed with in vivo experiments using genetic lineage tracing, whole organ immunostaining, confocal imaging, and cardiac functional assays in mice.
RESULTS
Upon coronary occlusion, neonates showed a significant increase in actively cycling artery cells and expressed prominent dedifferentiation markers. Data from in silico pathway analyses and in vivo experiments suggested that upon myocardial infarction, cell cycle reentry of preexisting neonatal artery cells, the subsequent collateral artery formation, and recovery of cardiac function are dependent on arterial VegfR2 (vascular endothelial growth factor receptor-2). This subpopulation of dedifferentiated and proliferating artery cells was absent in nonregenerative postnatal day 7 or adult hearts.
CONCLUSIONS
These data indicate that adult artery endothelial cells fail to drive collateral artery development due to their limited ability to dedifferentiate and proliferate.
Topics: Animals; Mice; Endothelial Cells; Vascular Endothelial Growth Factor A; Collateral Circulation; Coronary Vessels; Cell Proliferation
PubMed: 37345524
DOI: 10.1161/ATVBAHA.123.319319 -
Viruses Jan 2020Human immunodeficiency virus (HIV) is a chronic infection that destroys the immune system in infected individuals. Although antiretroviral therapy is effective at... (Review)
Review
Human immunodeficiency virus (HIV) is a chronic infection that destroys the immune system in infected individuals. Although antiretroviral therapy is effective at preventing infection of new cells, it is not curative. The inability to clear infection is due to the presence of a rare, but long-lasting latent cellular reservoir. These cells harboring silent integrated proviral genomes have the potential to become activated at any moment, making therapy necessary for life. Latently-infected cells can also proliferate and expand the viral reservoir through several methods including homeostatic proliferation and differentiation. The chromosomal location of HIV proviruses within cells influences the survival and proliferative potential of host cells. Proliferating, latently-infected cells can harbor proviruses that are both replication-competent and defective. Replication-competent proviral genomes contribute to viral rebound in an infected individual. The majority of available techniques can only assess the integration site or the proviral genome, but not both, preventing reliable evaluation of HIV reservoirs.
Topics: CD4-Positive T-Lymphocytes; Cell Proliferation; HIV Infections; HIV-1; Hematopoietic Stem Cells; Host Microbial Interactions; Humans; Proviruses; Viral Load; Virus Latency; Virus Replication
PubMed: 31973022
DOI: 10.3390/v12020127 -
Journal of Experimental Botany Oct 2021Organogenesis in plants is primarily postembryonic and relies on a strict balance between cell division and cell expansion. The root is a particularly well-suited model... (Review)
Review
Organogenesis in plants is primarily postembryonic and relies on a strict balance between cell division and cell expansion. The root is a particularly well-suited model to study cell proliferation in detail since the two processes are spatially and temporally separated for all the different tissues. In addition, the root is amenable to detailed microscopic analysis to identify cells progressing through the cell cycle. While it is clear that cell proliferation activity is restricted to the root apical meristem (RAM), understanding cell proliferation kinetics and identifying its parameters have required much effort over many years. Here, we review the main concepts, experimental settings, and findings aimed at obtaining a detailed knowledge of how cells proliferate within the RAM. The combination of novel tools, experimental strategies, and mathematical models has contributed to our current view of cell proliferation in the RAM. We also discuss several lines of research that need to be explored in the future.
Topics: Cell Cycle; Cell Division; Cell Proliferation; Kinetics; Meristem; Plant Roots
PubMed: 34159378
DOI: 10.1093/jxb/erab303 -
Journal of Cellular and Molecular... Jan 2021Previously, we identified differentially expressed proteins, including ADFP, between lung adenocarcinoma (LAC) tissue and paired normal bronchioloalveolar epithelium. In...
Previously, we identified differentially expressed proteins, including ADFP, between lung adenocarcinoma (LAC) tissue and paired normal bronchioloalveolar epithelium. In this study, we investigated the role of ADFP in LAC. ADFP levels in the serum of patients with lung cancer and benign diseases were measured by enzyme-linked immunosorbent assays (ELISA). shRNA was used to knock-down or overexpress ADFP in A549 and NCI-H1299 cells. The biological function of ADFP and its underlying mechanisms was evaluated in vivo and in vitro. ADFP was highly expressed in the serum of lung cancer patients, especially those with LAC. ADFP promoted cell proliferation and up-regulated the p-Akt/Akt ratio in A549 and NCI-H1299 cells in vitro. Furthermore, in nude mice, ADFP promoted tumour formation with high levels of p-Akt/Akt, Ki67 and proliferating cell nuclear antigen (PCNA). Similar to the effect of ADFP knock-down, MK-2206 (a phosphorylation inhibitor of Akt) reduced A549 and NCI-H1299 cell proliferation. In ADFP-overexpressing A549 and NCI-H1299 cells, proliferation was suppressed by MK-2206 and returned to the control level. ADFP did not regulate invasion, migration or adhesion in LAC cells. Together, these results suggest that ADFP promotes LAC cell proliferation in vitro and in vivo by increasing Akt phosphorylation level.
Topics: A549 Cells; Adenocarcinoma of Lung; Animals; Cell Line, Tumor; Female; Flow Cytometry; Humans; Lung Neoplasms; Mice; Mice, Inbred BALB C; Mice, Nude; Perilipin-2; Proliferating Cell Nuclear Antigen; Proto-Oncogene Proteins c-akt; Real-Time Polymerase Chain Reaction; Wound Healing
PubMed: 33249703
DOI: 10.1111/jcmm.16136 -
Current Biology : CB Jun 2022Photosynthesis shapes the symbiotic relationships between cnidarians and Symbiodiniaceae algae-with many cnidarian hosts requiring symbiont photosynthate for...
Photosynthesis shapes the symbiotic relationships between cnidarians and Symbiodiniaceae algae-with many cnidarian hosts requiring symbiont photosynthate for survival-but little is known about how photosynthesis impacts symbiosis establishment. Here, we show that during symbiosis establishment, infection, proliferation, and maintenance can proceed without photosynthesis, but the ability to do so is dependent on specific cnidarian-Symbiodiniaceae relationships. The evaluation of 31 pairs of symbiotic relationships (five species of Symbiodiniaceae in sea anemone, coral, and jellyfish hosts) revealed that infection can occur without photosynthesis. A UV mutagenesis method for Symbiodiniaceae was established and used to generate six photosynthetic mutants that can infect these hosts. Without photosynthesis, Symbiodiniaceae cannot proliferate in the sea anemone Aiptasia or jellyfish Cassiopea but can proliferate in the juvenile polyps of the coral Acropora. After 6 months of darkness, Breviolum minutum is maintained within Aiptasia, indicating that Symbiodiniaceae maintenance can be independent of photosynthesis. Manipulating photosynthesis provides insights into cnidarian-Symbiodiniaceae symbiosis.
Topics: Animals; Anthozoa; Dinoflagellida; Photosynthesis; Sea Anemones; Symbiosis
PubMed: 35504283
DOI: 10.1016/j.cub.2022.04.021 -
Veterinary Immunology and... May 2020CellTrace Violet™ is a commonly used fluorescent dye used with flow cytometry to identify cell proliferation. Activated equine lymphocytes were examined using flow...
CellTrace Violet™ is a commonly used fluorescent dye used with flow cytometry to identify cell proliferation. Activated equine lymphocytes were examined using flow cytometry, microscopy and tritiated thymidine proliferation assays. CellTrace Violet™ was incorporated into the equine lymphocytes effectively. Equine lymphocytes proliferated when activated with pokeweed mitogen, but did not proliferate when previously stained with CellTrace Violet™. Serial dilutions of CellTrace Violet™ did not eliminate the inhibition of activated lymphocytes. Equine lymphocyte viability was greater than 90 % for both stained and unstained cells. Based on these data, CellTrace Violet™ is not recommended for the assessment of lymphocyte proliferation in equine cells. The mechanism of inhibition of equine lymphocyte proliferation by CellTrace Violet™ is unknown.
Topics: Animals; Cell Proliferation; Cell Survival; Concanavalin A; Flow Cytometry; Fluorescent Dyes; Horses; Lymphocyte Activation; Lymphocytes; Pokeweed Mitogens
PubMed: 32229340
DOI: 10.1016/j.vetimm.2020.110037 -
BMC Genomics Apr 2024Hox gene family is an important transcription factor that regulates cell process, and plays a role in the process of adipocytes differentiation and fat deposition....
BACKGROUND
Hox gene family is an important transcription factor that regulates cell process, and plays a role in the process of adipocytes differentiation and fat deposition. Previous transcriptome sequencing studies have indicated that the Homeobox A9 gene (HOXA9) is a candidate gene for regulating the process of bovine lipid metabolism, but the function and specific mechanism of action remain unclear. Therefore, this study aims to explore the role of HOXA9 in the proliferation, differentiation and apoptosis of bovine preadipocytes through gain-of-function and lose-of-function.
RESULT
It found HOXA9 highly expressed in bovine adipose tissue, and its expression level changed significantly during adipocytes differentiation process. It gave a hint that HOXA9 may be involved in the process of bovine lipid metabolism. The results of HOXA9 gain-of-function experiments indicated that HOXA9 appeared to act as a negative regulator not only in the differentiation but also in the proliferation of bovine preadipocytes, which is mainly reflected that overexpression of HOXA9 down-regulate the mRNA and protein expression level of PPARγ, CEBPα and FABP4 (P < 0.05). The mRNA expression level of CDK1, CDK2, PCNA, CCNA2, CCNB1, CCND1 and CCNE2, as well as the protein expression of CDK2 also significantly decreased. The decrease of lipid droplets content was the main characteristic of the phenotype (P < 0.01), which further supported the evidence that HOXA9 was a negative regulator of preadipocytes differentiation. The decrease of cell proliferation rate and EdU positive rate, as well as the limitation of transition of preadipocytes from G0/G1 phase to S phase also provided evidence for the inhibition of proliferation. Apart from this above, we noted an interesting phenomenon that overexpression of HOXA9 showed in a significant upregulation of both mRNA and protein level of apoptosis markers, accompanied by a significant increase in cell apoptosis rate. These data led us not to refute the fact that HOXA9 played an active regulatory role in apoptosis. HOXA9 loss-of-function experiments, however, yielded the opposite results. Considering that HOXA9 acts as a transcription factor, we predicted its target genes. Dual luciferase reporter assay system indicated that overexpression of HOXA9 inhibits activity of PCNA promoter.
CONCLUSION
Taken together, we demonstrated for the first time that HOXA9 played a role as a negative regulatory factor in the differentiation and proliferation of preadipocytes, but played a positive regulatory role in apoptosis, and it may play a regulatory role by targeting PCNA. This study provides basic data for further exploring the regulatory network of intramuscular fat deposition in bovine.
Topics: Animals; Cattle; Genes, Homeobox; Adipocytes; Proliferating Cell Nuclear Antigen; Cell Differentiation; Cell Proliferation; Transcription Factors; Apoptosis; RNA, Messenger; Adipogenesis
PubMed: 38605318
DOI: 10.1186/s12864-024-10231-3 -
Cold Spring Harbor Perspectives in... Jul 2021The molecular basis of the persistence of experienced T lymphocytes, also known as "memory T lymphocytes," is still enigmatic. We are beginning to understand their... (Review)
Review
The molecular basis of the persistence of experienced T lymphocytes, also known as "memory T lymphocytes," is still enigmatic. We are beginning to understand their considerable heterogeneity and topographic compartmentalization into memory T cells circulating through the body and those residing in a particular tissue. In some tissues, like murine spleen, subpopulations of memory T cells proliferating in the absence of antigen (homeostatic proliferation) have been described. Other populations are maintained resting in terms of transcription, mobility, and proliferation in dedicated survival niches organized by stromal cells. The survival of these memory T cells is conditional on being in such a niche, where they can persist for a lifetime. Circulating memory T lymphocytes of distinct immune responses slowly decline in numbers over time. The rules governing their entry into and exit from blood, as well as their lifestyle outside of the blood and their relation to resident memory T cells are poorly understood. Homeostasis of circulating, proliferating, and resting memory T cells is obviously controlled by different rheostats: tissue-exit and tissue-entry signals for circulating and proliferation-inducing signals for proliferating memory T cells. For tissue-resident, resting memory T cells, it is the availability of their survival niche. Apparently, this mechanism (i.e., the link between memory T cell and stromal cell) is so robust that it provides efficient T-cell memory over a lifetime in tissues such as the bone marrow.
Topics: Animals; Cell Survival; Homeostasis; Humans; Immunologic Memory; Memory T Cells
PubMed: 33903153
DOI: 10.1101/cshperspect.a038083