PURPOSE. To develop an intravital imaging method that comprehensively shows the mouse conventional outflow pathway at high spatiotemporal resolution and to investigate the fine structures and dynamics within this pathway. METHODS. Intravital two-photon imaging was performed using Green, Prox1-reporter, and mito-Dendra2 mice. Schlemm's canal (SC) in human patients with glaucoma was histologically evaluated. RESULTS. The intravital two-photon imaging of Green mice ubiquitously expressing enhanced green fluorescent protein (EGFP) ("Green intravital imaging") demonstrated the perilimbal vein (PLV), collector channels (CCs), SC, and trabecular meshwork with and without a coverslip. A wide, tubular structure with septa was identified as SC in Prox1-reporter mice. Structures reminiscent of giant vacuoles and EGFP-positive vesicle flow were observed within SC. Based on the vesicle size, mitochondria in the vesicles, and platelet-specific intravital imaging findings, these EGFP-positive vesicles were identified as platelets. Moreover, platelet flow from the PLV into SC and from SC back to the PLV via CCs, as well as fast aqueous humor flow converging toward CCs, was observed. The quantitative analysis results suggested differences in aqueous flow velocity and flow patterns within SC. Platelets were also observed in SC of patients with glaucoma. CONCLUSIONS. Green intravital imaging comprehensively showed the proximal and distal conventional outflow pathway in mice at submicrometer spatial and 64.9-ms/frame temporal resolution, allowing observation of structures reminiscent of giant vacuoles. A subset of platelets transiently entered and exited SC via CCs. Within SC, aqueous humor exhibited fast flow converging toward the CCs, with differences in flow velocity and patterns. CCs may be involved in the heterogeneous dynamics of the aqueous humor.

Mouse ES cell populations contain a minor sub-population that expresses genes specifically expressed in 2-cell stage embryos. This sub-population consists of 2-cell-gene labeled cells (2CLCs) generated by the transient activation of the 2-cell specific genes initiated by the master regulator, Dux. However, the mechanism regulating the transient expression remains largely unclear. Here we reported a novel function of Zfp352, one of the 2-cell specific genes, in regulating the 2CLC sub-population. Zfp352 encodes zinc-finger transcription factor belonging to the Klf family. Dux transiently activates Zfp352 after the activation of Zscan4c in a subset of the 2CLC subpopulation. Interestingly, in the reporter assay, the transcriptional activation of Zscan4c by Dux is strongly repressed by the co-expression of Zfp352. However, the knockout of Zfp352 resulted in the repression of a subset of the 2-cell-specific genes. These data suggest the dual roles of Zfp352 in regulating the transient activation of the 2-cell-specific genes.

Pluripotent cells in mouse embryos, which first emerge in the inner cell mass of the blastocyst, undergo gradual transition marked by changes in gene expression, developmental potential, polarity, and morphology as they develop from the pre‐implantation until post‐implantation gastrula stage. Recent studies of cultured mouse pluripotent stem cells (PSCs) have clarified the presence of intermediate pluripotent stages between the naïve pluripotent state represented by embryonic stem cells (ESCs—equivalent to the pre‐implantation epiblast) and the primed pluripotent state represented by epiblast stem cells (EpiSCs—equivalent to the late post‐implantation gastrula epiblast). In this review, we discuss these recent findings in light of our knowledge on peri‐implantation mouse development and consider the implications of these new PSCs to understand their temporal sequence and the feasibility of using them as model system for pluripotency.

Adult erythropoiesis entails a series of well-coordinated events that produce mature red blood cells. One of such events is the mitochondria clearance that occurs cell-autonomously via autophagy-dependent mechanisms. Interestingly, recent studies have shown mitochondria transfer activities between various cell types. In the context of erythropoiesis, macrophages are known to interact closely with the early stages of erythroblasts to provide a specialized niche, termed erythroblastic islands (EBI). However, whether mitochondria transfer can occur in the EBI niche has not been explored. Here, we report that mitochondria transfer in the EBI niche occurs in vivo. We observed mitochondria transfer activities from the early stages of erythroblasts to macrophages in the reconstituted in vitro murine EBI via different modes, including tunnelling nanotubes (TNT). Moreover, we demonstrated that Wiskott-Aldrich syndrome protein (WASp) in macrophages mediates TNT formation and mitochondria transfer via the modulation of F-actin filamentation, thus promoting mitochondria clearance from erythroid cells, to potentially enhance their differentiation. Taken together, our findings provide novel insight into the mitochondria clearance machineries that mediate erythroid maturation.

The tumor suppressor folliculin (FLCN) suppresses nuclear translocation of TFE3, a master transcription factor for lysosomal biogenesis, via regulation of amino-acid-sensing Rag GTPases. However, the importance of this lysosomal regulation in mammalian physiology remains unclear. Following hematopoietic-lineage-specific Flcn deletion in mice, we found expansion of vacuolated phagocytes that accumulate glycogen in their cytoplasm, phenotypes reminiscent of lysosomal storage disorder (LSD). We report that TFE3 acts in a feedback loop to transcriptionally activate FLCN expression, and FLCN loss disrupts this loop, augmenting TFE3 activity. Tfe3 deletion in Flcn knockout mice reduces the number of phagocytes and ameliorates LSD-like phenotypes. We further reveal that TFE3 stimulates glycogenesis by promoting the expression of glycogenesis genes, including Gys1 and Gyg, upon loss of Flcn. Taken together, we propose that the FLCN-TFE3 feedback loop acts as a rheostat to control lysosome activity and prevents excessive glycogenesis and LSD-like phagocyte activation.

Key Points HSCs can be separated based on high or low mitochondrial mass. Higher mitochondrial mass is associated with quiescence and greater reconstitution capacity of HSCs.

Osteoclast differentiation is a dynamic differentiation process, which is accompanied by dramatic changes in metabolic status as well as in gene expression. Recent findings have revealed an essential connection between metabolic reprogramming and dynamic gene expression changes during osteoclast differentiation. However, the upstream regulatory mechanisms that drive these metabolic changes in osteoclastogenesis remain to be elucidated. Here, we demonstrate that induced deletion of a tumor suppressor gene, Folliculin (Flcn), in mouse osteoclast precursors causes severe osteoporosis in 3 weeks through excess osteoclastogenesis. Flcn-deficient osteoclast precursors reveal cell autonomous accelerated osteoclastogenesis with increased sensitivity to receptor activator of NF-κB ligand (RANKL). We demonstrate that Flcn regulates oxidative phosphorylation and purine metabolism through suppression of nuclear localization of the transcription factor Tfe3, thereby inhibiting expression of its target gene Pgc1. Metabolome studies revealed that Flcn-deficient osteoclast precursors exhibit significant augmentation of oxidative phosphorylation and nucleotide production, resulting in an enhanced purinergic signaling loop that is composed of controlled ATP release and autocrine/paracrine purinergic receptor stimulation. Inhibition of this purinergic signaling loop efficiently blocks accelerated osteoclastogenesis in Flcn-deficient osteoclast precursors. Here, we demonstrate an essential and novel role of the Flcn-Tfe3-Pgc1 axis in osteoclastogenesis through the metabolic reprogramming of oxidative phosphorylation and purine metabolism. © 2018 The Authors Journal of Bone and Mineral Research published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research (ASBMR).

a tab delimited flat file (SDRF file) describing the experimental details for human timecourse samples for the standard protocol of the HeliScopeCAGE protocol

List of DRA (http://trace.ddbj.nig.ac.jp/dra/index_e.html) accession numbers of the FANTOM5 samples, sequences and genomic coordinations. Files are in tab-delimited format, which includes * Library ID * FFID * BioSamples accession number * DRA experiment accession number * DRA run accession numbers * DRA analysis accession number for genomic coordination (BAM file) * DRA analysis accession number for CTSS (BED file) * Experiment method (CAGE/RNA-Seq/sRNA-Seq)

In the FANTOM5 project, transcription initiation events across the human and mouse genomes were mapped at a single base-pair resolution and their frequencies were monitored by CAGE (Cap Analysis of Gene Expression) coupled with single-molecule sequencing. Approximately three thousands of samples, consisting of a variety of primary cells, tissues, cell lines, and time series samples during cell activation and development, were subjected to a uniform pipeline of CAGE data production. The analysis pipeline started by measuring RNA extracts to assess their quality, and continued to CAGE library production by using a robotic or a manual workflow, single molecule sequencing, and computational processing to generate frequencies of transcription initiation. Resulting data represents the consequence of transcriptional regulation in each analyzed state of mammalian cells. Non-overlapping peaks over the CAGE profiles, approximately 200,000 and 150,000 peaks for the human and mouse genomes, were identified and annotated to provide precise location of known promoters as well as novel ones, and to quantify their activities.

Sample information (SDRF file) for human, including their details and details of their RNA extractions

List of DRA (http://trace.ddbj.nig.ac.jp/dra/index_e.html) accession numbers of the FANTOM5 samples, sequences and genomic coordinations. Files are in tab-delimited format, which includes * Library ID * FFID * BioSamples accession number * DRA experiment accession number * DRA run accession numbers * DRA analysis accession number for genomic coordination (BAM file) * DRA analysis accession number for CTSS (BED file) * Experiment method (CAGE/RNA-Seq/sRNA-Seq)

The ring finger protein PCGF6 (polycomb group ring finger 6) interacts with RING1A/B and E2F6 associated factors to form a non-canonical PRC1 (polycomb repressive complex 1) known as PCGF6-PRC1. Here, we demonstrate that PCGF6-PRC1 plays a role in repressing a subset of PRC1 target genes by recruiting RING1B and mediating downstream mono-ubiquitination of histone H2A. PCGF6-PRC1 bound loci are highly enriched for promoters of germ cell-related genes in mouse embryonic stem cells (ESCs). Conditional ablation of Pcgf6 in ESCs leads to robust de-repression of such germ cell-related genes, in turn affecting cell growth and viability. We also find a role for PCGF6 in pre- and peri-implantation mouse embryonic development. We further show that a heterodimer of the transcription factors MAX and MGA recruits PCGF6 to target loci. PCGF6 thus links sequence specific target recognition by the MAX/MGA complex to PRC1-dependent transcriptional silencing of germ cell-specific genes in pluripotent stem cells.

CAGE peak based expression table (RLE normalized) for human samples

a tab delimited flat file (SDRF file) describing the experimental details for mouse tissue samples for the low quantity version of the HeliScopeCAGE protocol

a tab delimited flat file (SDRF file) describing the experimental details for mouse quality control samples for the standard protocol of the HeliScopeCAGE protocol

Sample information (SDRF file) for human, including their details and details of their RNA extractions

In general, cell fate is determined primarily by transcription factors, followed by epigenetic mechanisms fixing the status. While the importance of transcription factors controlling cell fate has been well characterized, epigenetic regulation of cell fate maintenance remains to be elucidated. Here we provide an obvious fate conversion case, in which the inactivation of polycomb-medicated epigenetic regulation results in conversion of T-lineage progenitors to the B-cell fate. In T-cell-specific Ring1A/B-deficient mice, T-cell development was severely blocked at an immature stage. We found that these developmentally arrested T-cell precursors gave rise to functional B cells upon transfer to immunodeficient mice. We further demonstrated that the arrest was almost completely canceled by additional deletion of Pax5. These results indicate that the maintenance of T-cell fate critically requires epigenetic suppression of the B-lineage gene program.

Although it is generally accepted that cellular differentiation requires changes to transcriptional networks, dynamic regulation of promoters and enhancers at specific sets of genes has not been previously studied en masse. Exploiting the fact that active promoters and enhancers are transcribed, we simultaneously measured their activity in 19 human and 14 mouse time courses covering a wide range of cell types and biological stimuli. Enhancer RNAs, then messenger RNAs encoding transcription factors, dominated the earliest responses. Binding sites for key lineage transcription factors were simultaneously overrepresented in enhancers and promoters active in each cellular system. Our data support a highly generalizable model in which enhancer transcription is the earliest event in successive waves of transcriptional change during cellular differentiation or activation.