Regulatory mechanisms on the early process of mouse spermatogenesis investigated by digital gene expression tag profiling analysis
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ABSTRACT: A detailed understanding of the gene regulation mechanisms in premeiosis cells is germane to understanding normal spermatogenesis. The genome-wide expression profiles of type B spermatogonia and primary spermatocytes in mouse were investigated using Solexa/Illumina’s digital gene expression (DGE) system, a tag based high-throughput transcriptome sequencing method, and the developmental process of early spermatogenesis was analyzed systematically. The results suggested that the expression pattern of mouse type B spermatogonia and primary spermatocytes was changed dramatically, especially the genes related to junction assembly, regulation of actin cytoskeleton and pluripotency. The change of the expression levels of these pathways’ main components may be affected by corresponding miRNAs through post-transcriptional regulation. The analysis results will benefit for better understanding the molecular mechanism of early spermatogenesis process. Using DGE technology to examine gene expression pattern's change between mouse type B spermatogonia and primary spermatocytes cell types.
Project description:A detailed understanding of the gene regulation mechanisms in premeiosis cells is germane to understanding normal spermatogenesis. The genome-wide expression profiles of type B spermatogonia and primary spermatocytes in mouse were investigated using Solexa/Illumina’s digital gene expression (DGE) system, a tag based high-throughput transcriptome sequencing method, and the developmental process of early spermatogenesis was analyzed systematically. The results suggested that the expression pattern of mouse type B spermatogonia and primary spermatocytes was changed dramatically, especially the genes related to junction assembly, regulation of actin cytoskeleton and pluripotency. The change of the expression levels of these pathways’ main components may be affected by corresponding miRNAs through post-transcriptional regulation. The analysis results will benefit for better understanding the molecular mechanism of early spermatogenesis process.
Project description:The piRNA pathway is studied in great detail in Drosophila female germline. In this study we show that unlike the female germline where all Piwi proteins are expressed throughout oogenesis, Ago3 - a Piwi family protein shows a spatial expression male germline. To understand dynamics of piRNA pathway during spermatogonia and primary spermatocyte stages of male germline development, we used arrest mutants. The bag of marbles (bam) and benign gonial cell neoplasm (bgcn) mutants have only early mitotic dividing germline cells in the testes due to failure to progress to primary spermatocyte stage, the cannonball (can) and spermatocyte arrest (sa) mutant germline cells cannot progress beyond primary spermatocyte stage. To investigate the dynamics of the piRNA pathway during spermatogenesis in spermatogonia and primary spermatocyte stages, we used testicular tissues from these stage-specific arrested mutants. While we used entire bam and bgcn mutant testes for spermatogonia purification, we while we manually removed the apical regions of can and sa mutant testes to exclude mitotically dividing undifferentiated germline cells for primary spermatocytes purification. Our results show that piRNAs mapping to transposons are more abundant in spermatogonia, whereas those mapping to Suppressor of Stellate [Su(Ste)] and AT-chX are mostly expressed in primary spermatocytes. Furthermore we observed that transposon-mapping piRNAs with ping-pong signature are more abundant in spermatogonia albeit still detectable in primary spermatocytes where Ago3 is not expressed. These results suggest that robust piRNA production via ping-pong cycle takes place in spermatogonia, and to a lesser extent in primary spermatocytes even in the absence of Ago3. Consistently, piRNAs from ago3 mutant testes also exhibit the ping-pong signature, confirming that a non-canonical ping-pong cycle is acting during spermatogenesis. Our study provides a developmental dimension to the piRNA pathway and uncovers a new mechanism used in the male germline to silence transposons. The difference in piRNA from spermatogonia and primary spermatocyte stages was studied by comparing small RNAs from bam and bgcn mutant testis, which represent spermatogonia stages with the small RNAs from apex removed can and sa testis, representing primary spermatocyte stages. In the study we also studied effect of loss of Piwi family proteins Aub and Ago3, which have different spatial expression during male germline development.
Project description:Spermatogenesis is a complex sperm-generating process involving the mitosis of spermatogonia, meiosis of spermatocytes and spermiogenesis of spermatids. Elucidating the phosphorylation-based regulations should advance our understanding of the underlying molecular mechanisms. Here we present an integrative study of phosphorylation events in the testis. Large-scale phosphoproteome profiling in the adult mouse testis identified 17,829 phosphorylation sites in 3,955 phosphoproteins.
Project description:Vertebrate spermatogonial stem cells maintain sperm production over the lifetime of an animal but fertility declines with age. While morphological studies have informed our understanding of typical spermatogenesis, the molecular and cellular mechanisms underlying the maintenance and decline of spermatogenesis are not yet understood. We used single-cell RNA sequencing to generate a developmental atlas of the aging zebrafish testis. All testes contained spermatogonia, but we observed a progressive decline in spermatogenesis that correlates with age. Testes from some older males only contained spermatogonia and a reduced population of spermatocytes. Spermatogonia in older males are transcriptionally distinct from spermatogonia in testes capable of robust spermatogenesis. Immune cells including macrophages and lymphocytes drastically increase in abundance in testes that cannot complete spermatogenesis. Our developmental atlas reveals the cellular changes as the testis ages and defines a molecular roadmap for the regulation of spermatogenesis.
Project description:Prophase I of male meiosis involves dynamic chromosome segregation processes during early spermatogenesis, including synapsis, meiotic recombination, and cohesion. Genetic defects in genes participating in these processes consistently cause reproduction failure in mice. To identify candidate genes responsible for infertility in humans, we performed expression profiling of mouse spermatogenic cells undergoing meiotic prophase I. Cell fractions enriched in spermatogonia, leptotene/zygotene spermatocytes, or pachytene spermatocytes were separately isolated from mouse testes for RNA extraction. To minimize the contamination of other cell types, we fractionated the testicular cells undergoing the first round of spermatogenesis using Percoll gradient procedure. The cell fractions were characterized by morphological analysis by phase contrast microscopy and Nomarski interference microscopy, and then expression of cell lineage- and spermatogenesis stage-specific genes were examined by RT-PCR. The most enriched fractions for spermatogonia (fraction2 from day8), leptotene/zygotene spermatocytes (fraction5 from day12), and pachytene spermatocytes (fraction8 from day15) were subjected to hybridization on Affymetrix microarrays.
Project description:The piRNA pathway is studied in great detail in Drosophila female germline. In this study we show that unlike the female germline where all Piwi proteins are expressed throughout oogenesis, Ago3 - a Piwi family protein shows a spatial expression male germline. To understand dynamics of piRNA pathway during spermatogonia and primary spermatocyte stages of male germline development, we used arrest mutants. The bag of marbles (bam) and benign gonial cell neoplasm (bgcn) mutants have only early mitotic dividing germline cells in the testes due to failure to progress to primary spermatocyte stage, the cannonball (can) and spermatocyte arrest (sa) mutant germline cells cannot progress beyond primary spermatocyte stage. To investigate the dynamics of the piRNA pathway during spermatogenesis in spermatogonia and primary spermatocyte stages, we used testicular tissues from these stage-specific arrested mutants. While we used entire bam and bgcn mutant testes for spermatogonia purification, we while we manually removed the apical regions of can and sa mutant testes to exclude mitotically dividing undifferentiated germline cells for primary spermatocytes purification. Our results show that piRNAs mapping to transposons are more abundant in spermatogonia, whereas those mapping to Suppressor of Stellate [Su(Ste)] and AT-chX are mostly expressed in primary spermatocytes. Furthermore we observed that transposon-mapping piRNAs with ping-pong signature are more abundant in spermatogonia albeit still detectable in primary spermatocytes where Ago3 is not expressed. These results suggest that robust piRNA production via ping-pong cycle takes place in spermatogonia, and to a lesser extent in primary spermatocytes even in the absence of Ago3. Consistently, piRNAs from ago3 mutant testes also exhibit the ping-pong signature, confirming that a non-canonical ping-pong cycle is acting during spermatogenesis. Our study provides a developmental dimension to the piRNA pathway and uncovers a new mechanism used in the male germline to silence transposons.
Project description:Alternative Cleavage and Polyadenylation (APA) often results in production of mRNA isoforms with either longer or shorter 3’UTRs from the same genetic locus, potentially impacting mRNA translation, localization and stability. Developmentally regulated APA can thus make major contributions to cell-type-specific gene expression programs as cells differentiate. During Drosophila spermatogenesis, approximately 500 genes undergo APA when proliferating spermatogonia differentiate into spermatocytes, producing transcripts with shortened 3’ UTRs, leading to profound stage-specific changes in the proteins expressed. The molecular mechanisms that specify usage of upstream polyadenylation sites in spermatocytes are thus key to understanding the changes in cell state. Here, we show that upregulation of PCF11 and Cbc, the two components of Cleavage Factor II (CFII), orchestrates APA during Drosophila spermatogenesis. Knock down of PCF11 or cbc in spermatocytes caused dysregulation of APA, with many transcripts normally cleaved at a proximal site in spermatocytes now cleaved at their distal site, as in spermatogonia. Forced overexpression of CFII components in spermatogonia switched cleavage of some transcripts to the proximal site normally used in spermatocytes. Our findings reveal a developmental mechanism where changes in expression of specific cleavage factors can direct cell-type-specific APA at selected genes.
Project description:Alternative Cleavage and Polyadenylation (APA) often results in production of mRNA isoforms with either longer or shorter 3’UTRs from the same genetic locus, potentially impacting mRNA translation, localization and stability. Developmentally regulated APA can thus make major contributions to cell-type-specific gene expression programs as cells differentiate. During Drosophila spermatogenesis, approximately 500 genes undergo APA when proliferating spermatogonia differentiate into spermatocytes, producing transcripts with shortened 3’ UTRs, leading to profound stage-specific changes in the proteins expressed. The molecular mechanisms that specify usage of upstream polyadenylation sites in spermatocytes are thus key to understanding the changes in cell state. Here, we show that upregulation of PCF11 and Cbc, the two components of Cleavage Factor II (CFII), orchestrates APA during Drosophila spermatogenesis. Knock down of PCF11 or cbc in spermatocytes caused dysregulation of APA, with many transcripts normally cleaved at a proximal site in spermatocytes now cleaved at their distal site, as in spermatogonia. Forced overexpression of CFII components in spermatogonia switched cleavage of some transcripts to the proximal site normally used in spermatocytes. Our findings reveal a developmental mechanism where changes in expression of specific cleavage factors can direct cell-type-specific APA at selected genes.
Project description:Alternative Cleavage and Polyadenylation (APA) often results in production of mRNA isoforms with either longer or shorter 3’UTRs from the same genetic locus, potentially impacting mRNA translation, localization and stability. Developmentally regulated APA can thus make major contributions to cell-type-specific gene expression programs as cells differentiate. During Drosophila spermatogenesis, approximately 500 genes undergo APA when proliferating spermatogonia differentiate into spermatocytes, producing transcripts with shortened 3’ UTRs, leading to profound stage-specific changes in the proteins expressed. The molecular mechanisms that specify usage of upstream polyadenylation sites in spermatocytes are thus key to understanding the changes in cell state. Here, we show that upregulation of PCF11 and Cbc, the two components of Cleavage Factor II (CFII), orchestrates APA during Drosophila spermatogenesis. Knock down of PCF11 or cbc in spermatocytes caused dysregulation of APA, with many transcripts normally cleaved at a proximal site in spermatocytes now cleaved at their distal site, as in spermatogonia. Forced overexpression of CFII components in spermatogonia switched cleavage of some transcripts to the proximal site normally used in spermatocytes. Our findings reveal a developmental mechanism where changes in expression of specific cleavage factors can direct cell-type-specific APA at selected genes.
Project description:Spermatogenesis is a complicated and poorly understood process that relies on the precise regulation of the self-renewal and differentiation of spermatogonia. In many organisms, microRNAs (miRNAs) are involved in multiple developmental processes as critical regulators of transcriptional and post-transcriptional gene silencing. This study investigated the expression pattern of miRNAs in type B spermatogonia cells (BSc) and primary spermatocytes (PSc) of mice, using a high-throughput small RNA sequencing system.