BTB-zinc Finger Research Articles

Isoforms of terminal selector Mamo control axon guidance during adult Drosophila memory center construction via Semaphorin-1a

In animals undergoing metamorphosis, the appearance of the nervous system is coincidently transformed by the morphogenesis of neurons. Such morphogenic alterations are exemplified in three types of intrinsic neurons in the Drosophila memory center. In contrast to the well-characterized remodeling of γ neurons, the morphogenesis of α/β and α’/β′ neurons has not been adequately explored. Here, we show that mamo, a BTB-zinc finger transcription factor that acts as a terminal selector for α’/β′ neurons, controls the formation of the correct axonal pattern of α’/β′ neurons. Intriguingly, specific Mamo isoforms are preferentially expressed in α’/β′ neurons to regulate the expression of axon guidance molecule Semaphorin-1a. This action directs proper axon guidance in α’/β′ neurons, which is also crucial for wiring of α’/β’ neurons with downstream neurons. Taken together, our results provide molecular insights into how neurons establish correct axonal patterns in circuitry assembly during adult memory center construction.

The BTB-ZF gene Bm-mamo regulates pigmentation in silkworm caterpillars

The color pattern of insects is one of the most diverse adaptive evolutionary phenotypes. However, the molecular regulation of this color pattern is not fully understood. In this study, we found that the transcription factor Bm-mamo is responsible for black dilute (bd) allele mutations in the silkworm. Bm-mamo belongs to the BTB zinc finger family and is orthologous to mamo in Drosophila melanogaster. This gene has a conserved function in gamete production in Drosophila and silkworms and has evolved a pleiotropic function in the regulation of color patterns in caterpillars. Using RNAi and clustered regularly interspaced short palindromic repeats (CRISPR) technology, we showed that Bm-mamo is a repressor of dark melanin patterns in the larval epidermis. Using in vitro binding assays and gene expression profiling in wild-type and mutant larvae, we also showed that Bm-mamo likely regulates the expression of related pigment synthesis and cuticular protein genes in a coordinated manner to mediate its role in color pattern formation. This mechanism is consistent with the dual role of this transcription factor in regulating both the structure and shape of the cuticle and the pigments that are embedded within it. This study provides new insight into the regulation of color patterns as well as into the construction of more complex epidermal features in some insects.

The BTB-ZF gene Bm-mamo regulates pigmentation in silkworm caterpillars.

The color pattern of insects is one of the most diverse adaptive evolutionary phenotypes. However, the molecular regulation of this color pattern is not fully understood. In this study, we found that the transcription factor Bm-mamo is responsible for black dilute (bd) allele mutations in the silkworm. Bm-mamo belongs to the BTB zinc finger family and is orthologous to mamo in Drosophila melanogaster. This gene has a conserved function in gamete production in Drosophila and silkworms and has evolved a pleiotropic function in the regulation of color patterns in caterpillars. Using RNAi and clustered regularly interspaced short palindromic repeats (CRISPR) technology, we showed that Bm-mamo is a repressor of dark melanin patterns in the larval epidermis. Using in vitro binding assays and gene expression profiling in wild-type and mutant larvae, we also showed that Bm-mamo likely regulates the expression of related pigment synthesis and cuticular protein genes in a coordinated manner to mediate its role in color pattern formation. This mechanism is consistent with the dual role of this transcription factor in regulating both the structure and shape of the cuticle and the pigments that are embedded within it. This study provides new insight into the regulation of color patterns as well as into the construction of more complex epidermal features in some insects.

Antagonistic role of the BTB-zinc finger transcription factors Chinmo and Broad-Complex in the juvenile/pupal transition and in growth control.

During development, the growing organism transits through a series of temporally regulated morphological stages to generate the adult form. In humans, for example, development progresses from childhood through to puberty and then to adulthood, when sexual maturity is attained. Similarly, in holometabolous insects, immature juveniles transit to the adult form through an intermediate pupal stage when larval tissues are eliminated and the imaginal progenitor cells form the adult structures. The identity of the larval, pupal, and adult stages depends on the sequential expression of the transcription factors chinmo, Br-C, and E93. However, how these transcription factors determine temporal identity in developing tissues is poorly understood. Here, we report on the role of the larval specifier chinmo in larval and adult progenitor cells during fly development. Interestingly, chinmo promotes growth in larval and imaginal tissues in a Br-C-independent and -dependent manner, respectively. In addition, we found that the absence of chinmo during metamorphosis is critical for proper adult differentiation. Importantly, we also provide evidence that, in contrast to the well-known role of chinmo as a pro-oncogene, Br-C and E93 act as tumour suppressors. Finally, we reveal that the function of chinmo as a juvenile specifier is conserved in hemimetabolous insects as its homolog has a similar role in Blatella germanica. Taken together, our results suggest that the sequential expression of the transcription factors Chinmo, Br-C and E93 during larva, pupa an adult respectively, coordinate the formation of the different organs that constitute the adult organism.

NuRD complex recruitment to Thpok mediates CD4+ T cell lineage differentiation.

Although BTB-zinc finger (BTB-ZF) transcription factors control the differentiation of multiple hematopoietic and immune lineages, how they function is poorly understood. The BTB-ZF factor Thpok controls intrathymic CD4+ T cell development and the expression of most CD4+ and CD8+ lineage genes. Here, we identify the nucleosome remodeling and deacetylase (NuRD) complex as a critical Thpok cofactor. Using mass spectrometry and coimmunoprecipitation in primary T cells, we show that Thpok binds NuRD components independently of DNA association. We locate three amino acid residues within the Thpok BTB domain that are required for both NuRD binding and Thpok functions. Conversely, a chimeric protein merging the NuRD component Mta2 to a BTB-less version of Thpok supports CD4+ T cell development, indicating that NuRD recruitment recapitulates the functions of the Thpok BTB domain. We found that NuRD mediates Thpok repression of CD8+ lineage genes, including the transcription factor Runx3, but is dispensable for Cd4 expression. We show that these functions cannot be performed by the BTB domain of the Thpok-related factor Bcl6, which fails to bind NuRD. Thus, cofactor binding critically contributes to the functional specificity of BTB-ZF factors, which control the differentiation of most hematopoietic subsets.

Long Noncoding RNA lncR17454 Regulates Metamorphosis of Silkworm Through let-7 miRNA Cluster.

A number of long noncoding RNAs (lncRNAs) have been identified in silkworm, but little is known about their functions. Recent study showed that the let-7 miRNA cluster (contains let-7, miR-2795, and miR-100) was transcribed from the last exon of lncRNA lncR17454 in silkworm. To investigate the functional role of lncR17454, dsRNAs of lncR17454 were injected into the hemolymph of 1-d-old third-instar larvae of Bombyx mori, repression of lncR17454 led to molting arrestment during the larval–larval and larval–pupal transition of silkworm, which was consistent to the result as let-7 knockdown in other studies. The expression level of mature let-7, miR-100, and miR-2795 decreased 40%, 36%, and 40%, respectively, while the mRNA level of two predicted target genes of let-7, the Broad Complex isoform 2 (BR-C-Z2) and the BTB-Zinc finger transcription repression factor gene Abrupt (Ab), increased significantly after lncR17454 knockdown. In contrast, when adding the 20-Hydroxyecdysone (20E) to silkworm BmN4 cell lines, the expression level of lncR17454 and let-7 cluster all increased significantly, but the expression of Abrupt, the predicted target gene of let-7, was repressed. Dual-luciferase reporter assays confirmed Abrupt was the real target of let-7. Here we found that the lncRNA lncR17454 can play regulator roles in the metamorphosis of silkworm through let-7 miRNA cluster and the ecdysone signaling pathway, which will provide new clues for lepidopteran pest control.

Modulating expression of a BTB-ZF transcription factor in adipose resident NKT cells alters function and disrupts metabolism regulation.

Abstract Natural killer T cells (NKTs) are potent modulators of the immune system that can regulate the function of other cell types largely through their rapid and robust production of a wide variety of cytokines. One tissue that relies on the interactions of NKT cells with various cell types is white adipose tissue. Adipose resident NKT cells (arNKTs) maintain tissue homeostasis and metabolism through anti-inflammatory interactions such as modulating macrophage functions and enhancing the proliferation and function of FoxP3-expressing Tregs. However, arNKTs are phenotypically distinct from other populations of NKT cells in their transcription factor expression. We have found that genetically modulating the expression of a BTB-ZF transcription factor in NKT cells alters the frequency and function of arNKTs, thereby altering weight gain and metabolic function. Our data show that sustained expression of the BTB-ZF transcription factor in arNKT cells leads to lower arNKT frequency, altered function, and enhanced weight gain in a model of obesity (60% high fat diet). While deletion of the transcription factor during NKT cell development leads to lower arNKT frequency, altered arNKT phenotype, and impaired weight gain when fed 60% high fat diet. Collectively, our data show that dynamic changes in the expression of a BTB-zinc finger transcription factor during NKT cell development and tissue-homing are required for normal arNKT cell function, and preservation of adipose tissue metabolism. Our findings imply that NKT cell inability to temporally regulate the expression of a single transcription factor may drive adipose tissue dysregulation and metabolic disease. Supported by NIH/NIAID R21 AI159066-01

Complex Interplay Between MAZR and Runx3 Regulates the Generation of Cytotoxic T Lymphocyte and Memory T Cells.

The BTB zinc finger transcription factor MAZR (also known as PATZ1) controls, partially in synergy with the transcription factor Runx3, the development of CD8 lineage T cells. Here we explored the role of MAZR as well as combined activities of MAZR/Runx3 during cytotoxic T lymphocyte (CTL) and memory CD8+ T cell differentiation. In contrast to the essential role of Runx3 for CTL effector function, the deletion of MAZR had a mild effect on the generation of CTLs in vitro. However, a transcriptome analysis demonstrated that the combined deletion of MAZR and Runx3 resulted in much more widespread downregulation of CTL signature genes compared to single Runx3 deletion, indicating that MAZR partially compensates for loss of Runx3 in CTLs. Moreover, in line with the findings made in vitro, the analysis of CTL responses to LCMV infection revealed that MAZR and Runx3 cooperatively regulate the expression of CD8α, Granzyme B and perforin in vivo. Interestingly, while memory T cell differentiation is severely impaired in Runx3-deficient mice, the deletion of MAZR leads to an enlargement of the long-lived memory subset and also partially restored the differentiation defect caused by loss of Runx3. This indicates distinct functions of MAZR and Runx3 in the generation of memory T cell subsets, which is in contrast to their cooperative roles in CTLs. Together, our study demonstrates complex interplay between MAZR and Runx3 during CTL and memory T cell differentiation, and provides further insight into the molecular mechanisms underlying the establishment of CTL and memory T cell pools.

Identification of ZBTB24 protein domains and motifs for heterochromatin localization and transcriptional activation.

Immunodeficiency, centromeric instability, facial anomalies (ICF) syndrome is a rare autosomal recessive disorder caused by mutations in either DNMT3B, ZBTB24, CDCA7, HELLS or an unknown gene(s). Among the known causative genes, ZBTB24 encodes a member of the BTB-zinc finger (ZF) transcription factor family. The protein possesses a BTB domain, an AT-hook and eight C2H2 ZF motifs. All ZBTB24 mutations reported in ICF patients are predicted to disrupt at least one ZF motif. Here, we show that both AT-hook and distinct ZF motifs, particularly the 6th motif, of human and mouse ZBTB24 proteins are important for their heterochromatin localization. On the other hand, the 6th and 7th ZF motifs, and not the AT-hook or the BTB domain, of the human and mouse proteins are essential for transcriptional activation of CDCA7, another ICF causative gene and a known target of ZBTB24. By deletion analysis of the human CDCA7 promoter, we show that two motifs for ZBTB24 binding are important for transcriptional activation of this gene. These results reveal the evolutionarily conserved domains and motifs important for the biological function of ZBTB24, which provides a basis for understanding the molecular mechanisms underlying the pathogenesis of ICF syndrome.

Mamo decodes hierarchical temporal gradients into terminal neuronal fate.

Temporal patterning is a seminal method of expanding neuronal diversity. Here we unravel a mechanism decoding neural stem cell temporal gene expression and transforming it into discrete neuronal fates. This mechanism is characterized by hierarchical gene expression. First, Drosophila neuroblasts express opposing temporal gradients of RNA-binding proteins, Imp and Syp. These proteins promote or inhibit chinmo translation, yielding a descending neuronal gradient. Together, first and second-layer temporal factors define a temporal expression window of BTB-zinc finger nuclear protein, Mamo. The precise temporal induction of Mamo is achieved via both transcriptional and post-transcriptional regulation. Finally, Mamo is essential for the temporally defined, terminal identity of α'/β' mushroom body neurons and identity maintenance. We describe a straightforward paradigm of temporal fate specification where diverse neuronal fates are defined via integrating multiple layers of gene regulation. The neurodevelopmental roles of orthologous/related mammalian genes suggest a fundamental conservation of this mechanism in brain development.

The mode of action of Fruitless: Is it an easy matter to switch the sex?

The fruitless (fru) locus was originally defined by a male sterile mutation that promotes male‐to‐male courtship while suppressing male‐to‐female courtship in Drosophila melanogaster. The fru promoter‐1 pre‐RNA generates a set of BTB‐zinc finger family FruM proteins expressed exclusively in the male neurons, leading to the formation of sexual dimorphisms in neurons via male‐specific neuroblast proliferation, male‐specific neural survival, male‐specific neuritegenesis or male‐specific arbor patterning. Such a wide spectrum of phenotypic effects seems to result from chromatin modifications, in which FruBM recruits Bonus, Histone deacetylase 1 (HDAC1) and/or Heterochromatin protein 1a (HP1a) to ~130 target sites. One established FruBM transcriptional target is the axon guidance protein gene robo1. Multiple transcriptional regulator‐binding sites are nested around the FruBM‐binding site, and mediate sophisticated modulation of the repressor activity of FruBM. FruBM also binds to the Lola‐Q transcriptional repressor to protect it from proteasome‐dependent degradation in male but not female neurons as FruBM exists only in male neurons, leading to the formation of sexually dimorphic neural structures. These findings shed light on the multilayered network of transcription regulation orchestrated by the master regulator FruBM.

Steroid Hormone Ecdysone Signaling Specifies Mushroom Body Neuron Sequential Fate via Chinmo

The functional variety in neuronal composition of an adult brain is established during development. Recent studies proposed that interactions between genetic intrinsic programs and external cues are necessary to generate proper neural diversity [1]. However, the molecular mechanisms underlying this developmental process are still poorly understood. Three main subtypes of Drosophila mushroom body (MB) neurons are sequentially generated during development and provide a good example of developmental neural plasticity [2]. Our present data propose that the environmentally controlled steroid hormone ecdysone functions as a regulator of early-born MB neuron fate during larval-pupal transition. We found that the BTB-zinc finger factor Chinmo acts upstream of ecdysone signaling to promote a neuronal fate switch. Indeed, Chinmo regulates the expression of the ecdysone receptor B1 isoform to mediate the production of γ and α'β' MB neurons. In addition, we provide genetic evidence for a regulatory negative feedback loop driving the α'β' to αβ MB neuron transition in which ecdysone signaling in turn controls microRNA let-7 depression of Chinmo expression. Thus, our results uncover a novel interaction in the MB neural specification pathway for temporal control of neuronal identity by interplay between an extrinsic hormonal signal and an intrinsic transcription factor cascade.

Broad-complex, tramtrack, and bric-à-brac (BTB) proteins: Critical regulators of development.

Broad-complex, Tramtrack, and Bric-à-brac/poxvirus and zinc finger (BTB/POZ) family proteins are a diverse family of proteins that are characterized by the presence of a common protein-protein interaction domain, known as the BTB domain. BTB proteins have been identified in poxviruses and many eukaryotes, and have diverse functions, ranging from transcriptional regulation and chromatin remodeling to protein degradation and cytoskeletal regulation. Specificity of function is determined in part by additional domains present in BTB family proteins, as well as by interaction partners. Studies of BTB proteins in Drosophila and mammalian systems have revealed the importance of these genes in multiple developmental contexts, as well as in cancer and neurological and musculoskeletal diseases. In this review, we discuss the functions of BTB/POZ proteins during development with an emphasis on BTB-zinc finger (BTB-ZF) proteins, which play critical roles in transcriptional regulation and chromatin remodeling.

BTB-Zinc Finger Oncogenes Are Required for Ras and Notch-Driven Tumorigenesis in Drosophila.

During tumorigenesis, pathways that promote the epithelial-to-mesenchymal transition (EMT) can both facilitate metastasis and endow tumor cells with cancer stem cell properties. To gain a greater understanding of how these properties are interlinked in cancers we used Drosophila epithelial tumor models, which are driven by orthologues of human oncogenes (activated alleles of Ras and Notch) in cooperation with the loss of the cell polarity regulator, scribbled (scrib). Within these tumors, both invasive, mesenchymal-like cell morphology and continual tumor overgrowth, are dependent upon Jun N-terminal kinase (JNK) activity. To identify JNK-dependent changes within the tumors we used a comparative microarray analysis to define a JNK gene signature common to both Ras and Notch-driven tumors. Amongst the JNK-dependent changes was a significant enrichment for BTB-Zinc Finger (ZF) domain genes, including chronologically inappropriate morphogenesis (chinmo). chinmo was upregulated by JNK within the tumors, and overexpression of chinmo with either RasV12 or Nintra was sufficient to promote JNK-independent epithelial tumor formation in the eye/antennal disc, and, in cooperation with RasV12, promote tumor formation in the adult midgut epithelium. Chinmo primes cells for oncogene-mediated transformation through blocking differentiation in the eye disc, and promoting an escargot-expressing stem or enteroblast cell state in the adult midgut. BTB-ZF genes are also required for Ras and Notch-driven overgrowth of scrib mutant tissue, since, although loss of chinmo alone did not significantly impede tumor development, when loss of chinmo was combined with loss of a functionally related BTB-ZF gene, abrupt, tumor overgrowth was significantly reduced. abrupt is not a JNK-induced gene, however, Abrupt is present in JNK-positive tumor cells, consistent with a JNK-associated oncogenic role. As some mammalian BTB-ZF proteins are also highly oncogenic, our work suggests that EMT-promoting signals in human cancers could similarly utilize networks of these proteins to promote cancer stem cell states.

The role of BTB-zinc finger transcription factors during T cell development and in the regulation of T cell-mediated immunity.

The proper regulation of the development and function of peripheral helper and cytotoxic T cell lineages is essential for T cell-mediated adaptive immunity. Progress made during the last 10-15years led to the identification of several transcription factors and transcription factor networks that control the development and function of T cell subsets. Among the transcription factors identified are also several members of the so-called BTB/POZ domain containing zinc finger (ZF) transcription factor family (BTB-ZF), and important roles of BTB-ZF factors have been described. In this review, we will provide an up-to-date overview about the role of BTB-ZF factors during T cell development and in peripheral T cells.

Reprogramming Donor T cells for Adoptive Immunotherapy

ImmunotherapyVol. 5, No. 12 CommentaryReprogramming donor T cells for adoptive immunotherapyMarkus Y MaparaMarkus Y MaparaDepartment of Medicine, Division of Hematoloy/Oncology & Columbia Center for Translational Immunology (CCTI), Columbia University, College of Physicians & Surgeons, 177Ft. Washington Avenue, MHB – 6GN435, New York, NY 10032, USA. Search for more papers by this authorEmail the corresponding author at mym2111@cumc.columbia.eduPublished Online:27 Nov 2013https://doi.org/10.2217/imt.13.139AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInReddit View articleKeywords: GVHDmemoryPLZFT cellsReferences1 Barnes DW, Loutit JF. Treatment of murine leukaemia with x-rays and homologous bone marrow. II. Br. J. Haematol.3,241–252 (1957).Crossref, Medline, CAS, Google Scholar2 Horowitz MM, Gale RP, Sondel PM et al. 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Immunol.184,6746–6755 (2010).Crossref, Medline, CAS, Google ScholarFiguresReferencesRelatedDetails Vol. 5, No. 12 Follow us on social media for the latest updates Metrics Downloaded 33 times History Published online 27 November 2013 Published in print December 2013 Information© Future Medicine LtdKeywordsGVHDmemoryPLZFT cellsFinancial & competing interests disclosureThis work was supported by the NIH RO1 HL093716. The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.No writing assistance was utilized in the production of this manuscript.PDF download

The BTB-zinc Finger Transcription Factor Abrupt Acts as an Epithelial Oncogene in Drosophila melanogaster through Maintaining a Progenitor-like Cell State

The capacity of tumour cells to maintain continual overgrowth potential has been linked to the commandeering of normal self-renewal pathways. Using an epithelial cancer model in Drosophila melanogaster, we carried out an overexpression screen for oncogenes capable of cooperating with the loss of the epithelial apico-basal cell polarity regulator, scribbled (scrib), and identified the cell fate regulator, Abrupt, a BTB-zinc finger protein. Abrupt overexpression alone is insufficient to transform cells, but in cooperation with scrib loss of function, Abrupt promotes the formation of massive tumours in the eye/antennal disc. The steroid hormone receptor coactivator, Taiman (a homologue of SRC3/AIB1), is known to associate with Abrupt, and Taiman overexpression also drives tumour formation in cooperation with the loss of Scrib. Expression arrays and ChIP-Seq indicates that Abrupt overexpression represses a large number of genes, including steroid hormone-response genes and multiple cell fate regulators, thereby maintaining cells within an epithelial progenitor-like state. The progenitor-like state is characterised by the failure to express the conserved Eyes absent/Dachshund regulatory complex in the eye disc, and in the antennal disc by the failure to express cell fate regulators that define the temporal elaboration of the appendage along the proximo-distal axis downstream of Distalless. Loss of scrib promotes cooperation with Abrupt through impaired Hippo signalling, which is required and sufficient for cooperative overgrowth with Abrupt, and JNK (Jun kinase) signalling, which is required for tumour cell migration/invasion but not overgrowth. These results thus identify a novel cooperating oncogene, identify mammalian family members of which are also known oncogenes, and demonstrate that epithelial tumours in Drosophila can be characterised by the maintenance of a progenitor-like state.

BTB-ZF factors recruit the E3 ligase cullin 3 to regulate lymphoid effector programs

The differentiation of several T and B cell effector programs in the immune system is directed by signature transcription factors that induce rapid epigenetic remodeling. We report that PLZF, the BTB-ZF transcription factor directing the innate-like effector program of NKT thymocytes 1,2 was prominently associated with cullin 3 (Cul3), an E3 ubiquitin ligase previously shown to use BTB domain-containing proteins as adaptors for substrate binding 3–7. PLZF transported Cul3 to the nucleus where the two proteins were associated within a chromatin modifying complex. Furthermore, PLZF expression resulted in selective changes of ubiquitination of multiple components of this complex. Cul3 was also found associated with another BTB-ZF transcription factor, Bcl6, which directs the B cell germinal center and the T follicular helper programs. Conditional deletion in mice demonstrated an essential role of Cul3 for the development of PLZF- and Bcl6-dependent lineages. We conclude that distinct lineage-specific BTB-ZF transcription factors recruit Cul3 to alter the ubiquitination pattern of their associated chromatin modifying complex. We propose that this novel function is essential to direct the differentiation of several T and B lymphocyte effector programs, and may also be involved in the oncogenic role of PLZF and Bcl6 in leukemias and lymphomas 8,9.

Adaptor Protein Self-Assembly Drives the Control of a Cullin-RING Ubiquitin Ligase

The E3 ligases recruit substrate proteins for targeted ubiquitylation. Recent insights into the mechanisms of ubiquitylation demonstrate that E3 ligases can possess active regulatory properties beyond those of a simple assembly scaffold. Here, we describe the dimeric structure of the E3 ligase adaptor protein SPOP (speckle-type POZ protein) in complex with the N-terminal domain of Cul3 at 2.4Å resolution. We find that SPOP forms large oligomers that can form heteromeric species with the closely related paralog SPOPL. In combination, SPOP and SPOPL (SPOP-like) form a molecular rheostat that can fine-tune E3 ubiquitin ligase activity by affecting the oligomeric state of the E3 complex. We propose that adaptor protein self-assembly provides a graded level of regulation of the SPOP/Cul3 E3 ligase toward its multiple protein substrates.

CtBP-interacting BTB Zinc Finger Protein (CIBZ) Promotes Proliferation and G1/S Transition in Embryonic Stem Cells via Nanog

Mouse embryonic stem cells (ESCs) require transcriptional regulation to ensure rapid proliferation that allows for self-renewal. However, the molecular mechanism by which transcriptional factors regulate this rapid proliferation remains largely unknown. Here we present data showing that CIBZ, a BTB domain zinc finger transcriptional factor, is a key transcriptional regulator for regulation of ESC proliferation. Here we show that deletion or siRNA knockdown of CIBZ inhibits ESC proliferation. Cell cycle analysis shows that loss of CIBZ delays the progression of ESCs through the G1 to S phase transition. Conversely, constitutive ectopic expression of exogenous CIBZ in ESCs promotes proliferation and accelerates G1/S transition. These findings suggest that regulation of the G1/S transition explains, in part, CIBZ-associated ESC proliferation. Our data suggest that CIBZ acts through the post-transcriptionally regulates the expression of Nanog, a positive regulator of ESC proliferation and G1/S transition, but does not affect Oct3/4 and Sox2 protein expression. Notably, constitutive overexpression of Nanog partially rescued the proliferation defect caused by CIBZ knockdown, indicating the role of CIBZ in ESC proliferation and G1/S transition at least in part depends on the Nanog protein level.