Affymetrix gene expression array (mouse 2.0) of sorted undifferentiated spermatogonia in inducible Miwi2 knock-out model
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ABSTRACT: Undifferentiated spermatogonia were sorted from Miwi2Tom/FL; ERT-Cre/+ (Miwi2-iKO) and Miwi2Tom/+; ERT-Cre/+ (Miwi2-CTL) mice injected with tamoxifen two weeks after last tamoxifen injection to understand an impact of acute Miwi2 deletion on spermatogenic homeostasis.
Project description:In mice, the PIWI-piRNA pathway is essential to re-establish transposon silencing during male germline reprogramming. The cytoplasmic PIWI protein MILI mediates piRNA-guided transposon RNA cleavage as well as piRNA amplification. MIWI2-bound piRNAs and its nuclear localization are proposed to be dependent upon MILI function. Here, we demonstrate the existence of a piRNA biogenesis pathway that in the absence of MILI that sustains partial MIWI2 function and reprogramming activity.
Project description:Defective germline reprogramming in Miwi2- and Dnmt3l-deficient mice results in the failure to reestablish transposon silencing, meiotic arrest and progressive loss of spermatogonia. Here we sought to understand the molecular basis for this spermatogonial dysfunction. Through a combination of imaging, conditional genetics and transcriptome analysis, we demonstrate that germ cell elimination in the respective mutants arises due to defective germline reprogramming rather than a function for the respective factors within spermatogonia. In both Miwi2-/- and Dnmt3l-/- spermatogonia the intracisternal-A particle (IAP) family of endogenous retroviruses is de-repressed, but in contrast to meiotic cells DNA damage is not observed. Instead we find that unmethylated IAP promoters rewire the spermatogonial transcriptome by driving expression of neighboring host genes. In summary, defective reprogramming deregulates the spermatogonial transcriptome that may underlie spermatogonial dysfunction.
Project description:GFRa1-GFP positive, Miwi2-tdTom negative and GFRa1-GFP negative, Miwi2-tdTom positive single cells from the testes of 2 adult, 2 aged and 3 busulfan-treated mice were sorted with FACS and cDNA libraries prepared with the SMARTseq2 protocol. Single-cell libraries were sequenced
Project description:Samples were prepared from 100 GFRa1-GFP positive, Miwi2-tdTom negative and 100 GFRa1-GFP negative, Miwi2-tdTom positive cells that were sorted with FACS. cDNA libraries were prepared with the SMARTseq2 protocol. Adult, control samples had four biological replicates while the aged and busulfan-treated samples were in triplicate. There were 2 technical replicates per biological sample.
Project description:The PIWI protein MIWI2 and its associated PIWI-interacting RNAs (piRNAs) instruct DNA methylation of young active transposable elements (TEs) in the male germline. Here we show that MIWI2 associates with TEX15 in foetal gonocytes. TEX15 is predominantly a nuclear protein that is not required for piRNA biogenesis but is essential for piRNA-directed TE de novo methylation and silencing. In summary, TEX15 is an essential executor of mammalian piRNA-directed DNA methylation.
Project description:To study the adult population of spermatogonial stem cells marked with the expression of Miwi2, we generated the Miwi2-Tomato reporter knock-in allele. To further explore the molecular identity of Miwi2-TomPos spermatogonia, we performed comparative gene expression analysis between two population hierarchically related, an upstream population of Miwi2-TomHi c-KitNeg spermatogonia and their Miwi2-TomHi c-KitPos descendants. The analysis revealed enrichment for many genes that have been associated with SSC/SPC (Spermatogonial Stem Cells/ Spermatogonial Precursor Cells) phenotype or function.
Project description:We examined the construction of the piRNA system in the restricted developmental window in which methylation patterns are set during mammalian embryogenesis. We find robust expression of two Piwi family proteins, MIWI2 and MILI. Their associated piRNA profiles reveal differences from Drosophila wherein large piRNA clusters act as master regulators of silencing. Instead, in mammals, dispersed transposon copies initiate the pathway, producing primary piRNAs, which predominantly join MILI in the cytoplasm. MIWI2, whose nuclear localization and association with piRNAs depend upon MILI, is enriched for secondary piRNAs antisense to the elements that it controls. The Piwi pathway lies upstream of known mediators of DNA methylation, since piRNAs are still produced in Dnmt3L mutants, which fail to methylate transposons. This implicates piRNAs as specificity determinants of DNA methylation in germ cells. Examination of total small RNA and MILI associated piRNAs in embryonic and post-birth mouse testes, MIWI2-associated piRNAs in embryonic testes.
Project description:Gonocytes were FACS sorted from testes of E16.5 Miwi2 Tom/+ embryos using the tdTomato reporter knocked into the Miwi2 locus. RNA was isolated from sorted cells and transcript expression analyzed by microarray measurement.
Project description:Piwi proteins and piRNAs have conserved functions in transposonM- silencing. The murine Piwi proteins Mili and Miwi2 direct epigeneticM- LINE1 (L1) and intracisternal A particle (IAP) transposon silencingM- during genome reprogramming in the embryonic male germline. PiwiM- proteins are proposed to be piRNA-guided endonucleases that initiateM- secondary piRNA biogenesis . However the actual contribution of theirM- endonuclease activities to piRNA biogenesis and transposon silencingM- remain unknown. To investigate the role of Piwi-catalyzedM- endonucleolytic activity, we engineered point mutations in the mouseM- that substitute the second D to an A in the catalytic triad (DDH) ofM- Mili and Miwi2, generating the MiliDAH and Miwi2DAH alleles,M- M- respectively. Analysis of Mili-bound piRNAs from homozygous MiliDAHM- fetal gonadocytes revealed the failure of transposon piRNA amplification resulting in the stark reduction of piRNA bound withinM- Miwi2 ribonuclear particles (RNPs). We find that Mili-mediated piRNA amplification is selectively required for L1 but not IAP silencing.M- The defective piRNA pathway in MiliDAH mice results in spermatogenic failure and sterility. Surprisingly, homozygous Miwi2DAH mice areM- fertile, transposon silencing is established normally and no defectsM- in secondary piRNA biogenesis are observed. In addition, the hallmarks of piRNA amplification are observed in Miwi2-deficient gonadocytes. WeM- conclude that cycles of intra-Mili secondary piRNA biogenesis fuelM- piRNA amplification that is selectively required for L1 silencing.M-
Project description:Mibrobial Patterns can induce trained innate immunity in macrophages. We tested whether innate memory can be elicited by stimulating macrophages with a house dust mite extract for 24h before washout, and analyzed the gene expression after 5 days post-exposure.