MKL1 deficiency results in a severe neutrophil motility defect due to impaired actin polymerization
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ABSTRACT:
PROVIDER: PRJNA555994 | ENA |
REPOSITORIES: ENA
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Project description:Megakaryoblastic leukemia 1 (MKL1) promotes the regulation of essential cell processes, including actin cytoskeletal dynamics by co-activating serum response factor. Recently, the first human case with MKL1 deficiency, leading to a novel primary immunodeficiency, was identified. We report a second family with two siblings with a homozygous frameshift mutation in MKL1. The index case deceased as an infant from progressive and severe pneumonia by Pseudomonas aeruginosa and poor wound healing. The younger sib was preemptively transplanted shortly after birth. The immunodeficiency was marked by a pronounced actin polymerization defect and a strongly reduced motility and chemotactic response by MKL1-deficient neutrophils. Apart from the lack of MKL1, subsequent proteomic and transcriptomic analyses of patient neutrophils revealed actin and several actin-related proteins to be downregulated, confirming a role for MKL1 as transcriptional co-regulator. Degranulation was enhanced upon suboptimal neutrophil activation, while production of reactive oxygen species was normal. Neutrophil adhesion was intact but without proper spreading. The latter could explain the observed failure in firm adherence and transendothelial migration under flow conditions. No apparent defect in phagocytosis and bacterial killing was found. Also monocyte-derived macrophages showed intact phagocytosis; lymphocyte counts and proliferative capacity were normal. Non-hematopoietic primary patient fibroblasts demonstrated defective differentiation into myofibroblasts but normal migration and filamentous actin (F-actin) content, most probably due to compensatory mechanisms of MKL2, which is not expressed in neutrophils. Our findings extend current insight into the severe immune dysfunction in MKL1 deficiency, with cytoskeletal dysfunction and defective extravasation of neutrophils as most prominent features.
2020-03-16 | GSE134644 | GEO
Project description:Characterize the genes regulated by MKL1/SRF complex in human megakaryocytes (MKs) derived from cord blood or cytapheresis : Using a knock down approach by small interference of MKL1 in MK progenitors, we observed a decrease in the percentage of cells with actin polymerization after adhesion on various substrates, an increase of mean ploidy level and apoptosis. Furthermore, MKL1 inhibition induced a major defect in pro-platelet formation and MKs migration. These results clearly demonstrate that MKL1 is involved in the cytoskeleton organization and maturation of MKs as well as in platelet formation. The goal of gene profiling was to identify new potential MKL1/SRF targets the expression level of which was down regulated after MKL1 inhibition: Human CD34+ cells isolated from cord blood or cytapheresis were transduced by a control lentivirus (designed as SCR; scramble) or by the lentivirus encoding for shRNA of MKL1 (designed as shMKL1) both containing a GFP expressed under the control of PGK promoter. The cells were than grown in serum free medium supplemented by thrombopoietin leading to a generation of megakaryocytes. At day 9 of culture (80% of MKs), the GFP positive cells were sorted, RNAs were extracted and submitted to hybridization as described in annex protocols. Two lists of genes (one for cord blood samples and one for cytapheresis samples) deregulated after the repression of MKL1 were done comparing the intensity of hybridization between SCR and shMKL1 samples. The common list of genes deregulated in MKs from cord blood and cytapheresis after the repression of MKL1 was than generated.
2009-09-14 | E-TABM-640 | biostudies-arrayexpress
Project description:Actins and regulators of actin dynamics generate contractile forces providing major mechanical and structural support for the cell. Whether and how they actively participate in cell fate control is not clear. Here, we report the actin responsive transcription factor complex MKL1/SRF, the major transcriptional regulator of large numbers of actin cytoskeletal genes, as an important regulator of genomic accessibility and cell fate outcome. Somatic cells with weaker MKL1/SRF activity progress toward pluripotency efficiently while sustained MKL1/SRF activity at a level seen in typical fibroblasts is sufficient to stall cells on their trajectory toward pluripotency. This altered cell fate outcome is associated with an overactive actin cytoskeleton, which connects to chromatin via the LINC complex, preventing its conversion into a relaxed, open conformation that allows sufficient accessibility to pluripotency-inducing transcription factors. Interfering with actin polymerization at appropriate times promotes pluripotency induction. Thus, we reveal a previously unappreciated aspect of cell fate control exerted by the actin based cytoskeletal system.
2019-03-01 | GSE120399 | GEO
Project description:We identified two isoforms of human MKL1 that differ in their N-terminal domains. Since MKL1 is a transcriptional coactivator of SRF and regulates many SRF target genes, we wanted to analyze if transcription is differentially regulated by the two isoforms upon stimulation of the Rho-actin-MKL1-SRF pathway. Activity of the Rho-actin-MKL1 pathway was induced in EcR293 cell lines stably over-expressing the empty vector control, a 5’UTR-full length MKL1_S construct, or a 5’UTR-full length MKL1_L construct by LPA treatment.
2015-05-14 | E-GEOD-47209 | biostudies-arrayexpress
Project description:Cellular differentiation is regulated through activation and repression of defined transcription factors. A hallmark of differentiation is a pronounced change in cell shape, which is determined by dynamics of the actin cytoskeleton. In de-differentiated fat (DFAT) cells and 3T3-L1 cells, we showed that treatment with the ROCK inhibitor Y-27632, by inducing remodeling of the actin cytoskelton, causes adipocyte differentiation. In addition, we found that depletion of MKL1, an actin binding transcriptional coactivator, elicits adipogenesis. To investigate whether regulation of MKL1 by actin cytoskeleton dynamics drives adipocyte differentiation, we compared the gene expression changes resulting from DFAT cells after treatment with Y-27632 and transfection of Mkl1 siRNA. Using Affymetrix mouse genome array, we compared global gene expression profiles in DFAT cells after treatment with Y-27632 and transfection with Mkl1 siRNA to search for particular biological functions in genes of which expression intensities were increased and decreased.
2014-03-28 | E-GEOD-52334 | biostudies-arrayexpress
Project description:We identified two isoforms of human MKL1 that differ in their N-terminal domains. Since MKL1 is a transcriptional coactivator of SRF and regulates many SRF target genes, we wanted to analyze if transcription is differentially regulated by the two isoforms upon stimulation of the Rho-actin-MKL1-SRF pathway.
2015-05-14 | GSE47209 | GEO
Project description:Cellular differentiation is regulated through activation and repression of defined transcription factors. A hallmark of differentiation is a pronounced change in cell shape, which is determined by dynamics of the actin cytoskeleton. In de-differentiated fat (DFAT) cells and 3T3-L1 cells, we showed that treatment with the ROCK inhibitor Y-27632, by inducing remodeling of the actin cytoskelton, causes adipocyte differentiation. In addition, we found that depletion of MKL1, an actin binding transcriptional coactivator, elicits adipogenesis. To investigate whether regulation of MKL1 by actin cytoskeleton dynamics drives adipocyte differentiation, we compared the gene expression changes resulting from DFAT cells after treatment with Y-27632 and transfection of Mkl1 siRNA.
2014-03-28 | GSE52334 | GEO
Project description:The mechanisms underlying cancer metastasis remain poorly understood. Here, we report that TFAM deficiency rapidly and stably induced spontaneous lung metastasis in mice with liver cancer. Interestingly, unexpected polymerization of nuclear actin was observed in TFAM-knockdown HCC cells when cytoskeleton was examined. Polymerization of nuclear actin is causally linked to the high-metastatic ability of HCC cells by modulating chromatin accessibility and coordinating the expression of genes associated with extracellular matrix remodeling, angiogenesis, and cell migration. Mechanistically, TFAM deficiency blocked the TCA cycle and increased the intracellular malonyl-CoA levels. Malonylation of mDia2, which drives actin assembly, promotes its nuclear translocation. Importantly, inhibition of malonyl-CoA production or nuclear actin polymerization significantly impeded the spread of HCC cells in mice. Moreover, TFAM was significantly downregulated in metastatic HCC tissues and was associated with overall survival and time to tumor recurrence of HCC patients. Taken together, our study connects mitochondria to the metastasis of human cancer via uncovered mitochondria-to-nucleus retrograde signaling, indicating that TFAM may serve as an effective target to block HCC metastasis.
2022-06-23 | MTBLS4307 | MetaboLights
Project description:Megakaryoblastic Leukemia 1 and 2 (MKL1 and 2) are coactivators of the transcription factor Serum Response Factor (SRF). We recently showed that depletion of MKL1 and 2 abolished HCC xenograft growth, associated with oncogene-induced senescence. To identify suitable MKL target genes mediating these effects, we performed microarray analyses using HuH7 hepatocellular carcinoma cells stably expressing shRNA against MKL1/2 (HuH7 MKL1/2 KD). We therefore used a Affymetrix oligonucleotide array and filtered for genes whose expression in HuH7 MKL1/2 KD cells was reduced by a factor of at least 2.5 as compared to control HuH7 cells.
2017-01-01 | GSE88974 | GEO
Project description:The aim of the experiment is to investigate whether megakaryoblastic leukemia factor-1 (MKL1) induces tenascin-C in normal mammary epithelial HC11 and tumor mammary epithelial 4T1 cell lines, as well as to identify other genes that are transcriptionally regulated by MKL1. For this purpose, we compared the transcriptomes of HC11 and 4T1 cell lines stably expressing the full length (FL) MKL1 protein (HC11-FL and 4T1-FL cell lines) to respective control cell lines stably transfected with an empty vector (HC11-control and 4T1-control cell lines).
2011-06-10 | E-MEXP-3232 | biostudies-arrayexpress