Transcription factor Tcf4 is the preferred heterodimerization partner for Olig2 in oligodendrocytes and required for differentiation

Abstract Development of oligodendrocytes and myelin formation in the vertebrate central nervous system is under control of several basic helix-loop-helix transcription factors such as Olig2, Ascl1, Hes5 and the Id proteins. The class I basic helix-loop-helix proteins Tcf3, Tcf4 and Tcf12 represent potential heterodimerization partners and functional modulators for all, but have not been investigated in oligodendrocytes so far. Using mouse mutants, organotypic slice and primary cell cultures we here show that Tcf4 is required in a cell-autonomous manner for proper terminal differentiation and myelination in vivo and ex vivo. Partial compensation is provided by the paralogous Tcf3, but not Tcf12. On the mechanistic level Tcf4 was identified as the preferred heterodimerization partner of the central regulator of oligodendrocyte development Olig2. Both genetic studies in the mouse as well as functional studies on enhancer regions of myelin genes confirmed the relevance of this physical interaction for oligodendrocyte differentiation. Considering that alterations in TCF4 are associated with syndromic and non-syndromic forms of intellectual disability, schizophrenia and autism in humans, our findings point to the possibility of an oligodendroglial contribution to these disorders.

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MIST1 and PTF1 Collaborate in Feed-Forward Regulatory Loops That Maintain the Pancreatic Acinar Phenotype in Adult Mice

Molecular and Cellular Biology ◽

10.1128/mcb.00370-16 ◽

2016 ◽

Vol 36 (23) ◽

pp. 2945-2955 ◽

Cited By ~ 17

Author(s):

Mei Jiang ◽

Ana C. Azevedo-Pouly ◽

Tye G. Deering ◽

Chinh Q. Hoang ◽

Daniel DiRenzo ◽

...

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Acinar Cell ◽

Pancreatic Acinar Cell ◽

Physical Interaction ◽

Transcriptional Enhancer ◽

Feed Forward ◽

Basic Helix Loop Helix ◽

Helix Loop Helix

Much remains unknown regarding the regulatory networks formed by transcription factors in mature, differentiated mammalian cells in vivo , despite many studies of individual DNA-binding transcription factors. We report a constellation of feed-forward loops formed by the pancreatic transcription factors MIST1 and PTF1 that govern the differentiated phenotype of the adult pancreatic acinar cell. PTF1 is an atypical basic helix-loop-helix transcription factor complex of pancreatic acinar cells and is critical to acinar cell fate specification and differentiation. MIST1, also a basic helix-loop-helix transcription factor, enhances the formation and maintenance of the specialized phenotype of professional secretory cells. The MIST1 and PTF1 collaboration controls a wide range of specialized cellular processes, including secretory protein synthesis and processing, exocytosis, and homeostasis of the endoplasmic reticulum. PTF1 drives Mist1 transcription, and MIST1 and PTF1 bind and drive the transcription of over 100 downstream acinar genes. PTF1 binds two canonical bipartite sites within a 0.7-kb transcriptional enhancer upstream of Mist1 that are essential for the activity of the enhancer in vivo . MIST1 and PTF1 coregulate target genes synergistically or additively, depending on the target transcriptional enhancer. The frequent close binding proximity of PTF1 and MIST1 in pancreatic acinar cell chromatin implies extensive collaboration although the collaboration is not dependent on a stable physical interaction.

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Modulation of Basic Helix-Loop-Helix Transcription Complex Formation by Id Proteins during Neuronal Differentiation

Journal of Biological Chemistry ◽

10.1074/jbc.m107713200 ◽

2001 ◽

Vol 277 (11) ◽

pp. 9118-9126 ◽

Cited By ~ 62

Author(s):

Annika Jögi ◽

Paula Persson ◽

Anna Grynfeld ◽

Sven Påhlman ◽

Håkan Axelson

Keyword(s):

Complex Formation ◽

Neuronal Differentiation ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Id Proteins

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The ER–Golgi intermediate compartment is a key membrane source for the LC3 lipidation step of autophagosome biogenesis

eLife ◽

10.7554/elife.00947 ◽

2013 ◽

Vol 2 ◽

Cited By ~ 226

Author(s):

Liang Ge ◽

David Melville ◽

Min Zhang ◽

Randy Schekman

Keyword(s):

Autophagosome Formation ◽

Functional Studies ◽

A Cell ◽

Intermediate Compartment ◽

Membrane Isolation ◽

Necessary And Sufficient ◽

Organelle Membrane ◽

Catabolic Process

Autophagy is a catabolic process for bulk degradation of cytosolic materials mediated by double-membraned autophagosomes. The membrane determinant to initiate the formation of autophagosomes remains elusive. Here, we establish a cell-free assay based on LC3 lipidation to define the organelle membrane supporting early autophagosome formation. In vitro LC3 lipidation requires energy and is subject to regulation by the pathways modulating autophagy in vivo. We developed a systematic membrane isolation scheme to identify the endoplasmic reticulum–Golgi intermediate compartment (ERGIC) as a primary membrane source both necessary and sufficient to trigger LC3 lipidation in vitro. Functional studies demonstrate that the ERGIC is required for autophagosome biogenesis in vivo. Moreover, we find that the ERGIC acts by recruiting the early autophagosome marker ATG14, a critical step for the generation of preautophagosomal membranes.

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Collagen fibrous scaffolds for sustained delivery of growth factors for meniscal tissue engineering

Nanomedicine ◽

10.2217/nnm-2021-0313 ◽

2022 ◽

Author(s):

Jihye Baek ◽

Kwang Il Lee ◽

Ho Jong Ra ◽

Martin K Lotz ◽

Darryl D D'Lima

Keyword(s):

Tissue Engineering ◽

Growth Factors ◽

Sustained Release ◽

Ex Vivo ◽

Synovial Cell ◽

Growth Factor Delivery ◽

Meniscal Tissue ◽

A Cell

Aim: To mimic the ultrastructural morphology of the meniscus with nanofiber scaffolds coupled with controlled growth factor delivery to modulate cellular performance for tissue engineering of menisci. Methods: The authors functionalized collagen nanofibers by conjugating heparin to the following growth factors for sustained release: PDGF-BB, TGF-β1 and CTGF. Results: Incorporating growth factors increased human meniscal and synovial cell viability, proliferation and infiltration in vitro, ex vivo and in vivo; upregulated key genes involved in meniscal extracellular matrix synthesis; and enhanced generation of meniscus-like tissue. Conclusion: The authors' results indicate that functionalizing collagen nanofibers can create a cell-favorable micro- and nanoenvironment and can serve as a system for sustained release of bioactive factors.

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Regulation of cilia abundance in multiciliated cells

eLife ◽

10.7554/elife.44039 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 18

Author(s):

Rashmi Nanjundappa ◽

Dong Kong ◽

Kyuhwan Shim ◽

Tim Stearns ◽

Steven L Brody ◽

...

Keyword(s):

Progenitor Cells ◽

Surface Area ◽

Ex Vivo ◽

Compensatory Mechanism ◽

Multiciliated Cells ◽

Culture Model ◽

A Cell ◽

Dependent Mechanism

Multiciliated cells (MCC) contain hundreds of motile cilia used to propel fluid over their surface. To template these cilia, each MCC produces between 100-600 centrioles by a process termed centriole amplification. Yet, how MCC regulate the precise number of centrioles and cilia remains unknown. Airway progenitor cells contain two parental centrioles (PC) and form structures called deuterosomes that nucleate centrioles during amplification. Using an ex vivo airway culture model, we show that ablation of PC does not perturb deuterosome formation and centriole amplification. In contrast, loss of PC caused an increase in deuterosome and centriole abundance, highlighting the presence of a compensatory mechanism. Quantification of centriole abundance in vitro and in vivo identified a linear relationship between surface area and centriole number. By manipulating cell size, we discovered that centriole number scales with surface area. Our results demonstrate that a cell-intrinsic surface area-dependent mechanism controls centriole and cilia abundance in multiciliated cells.

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Cortical Thinning and Hydrocephalus in Mice Lacking the Immunoglobulin Superfamily Member CDO

Molecular and Cellular Biology ◽

10.1128/mcb.26.10.3764-3772.2006 ◽

2006 ◽

Vol 26 (10) ◽

pp. 3764-3772 ◽

Cited By ~ 26

Author(s):

Wei Zhang ◽

Min-Jeong Yi ◽

Xiaoping Chen ◽

Francesca Cole ◽

Robert S. Krauss ◽

...

Keyword(s):

Neuronal Differentiation ◽

Myogenic Differentiation ◽

Immunoglobulin Superfamily ◽

Cortical Thinning ◽

Helix Loop Helix ◽

Neuronal Precursor Cells ◽

A Cell ◽

Multiple Cell

ABSTRACT CDO is a cell surface immunoglobulin superfamily member that positively regulates myogenic differentiation in vitro and in vivo and signals to posttranslationally activate myogenic basic helix-loop-helix (bHLH) transcription factors. The Cdo gene is also expressed in the dorsal aspect and midline structures of the developing central nervous system, and mice lacking CDO on the C57BL/6 background display holoprosencephaly with ∼80% penetrance, resulting in perinatal lethality. We report here that a fraction of Cdo −/− mice from this background have additional defects in brain development, including hydrocephalus and cortical thinning. Primary neural progenitor cultures from E14.5 Cdo −/− mutants display reduced proliferation, which may underlie the thinning. The cortical preplate and cortices of mutant animals also show reduced staining for β-tubulin III, indicating defective neuronal differentiation. CDO levels are strongly increased in cultured C17.2 neuronal precursor cells stimulated to differentiate; modulation of CDO levels in these cells by overexpression or interfering RNA approaches enhances or diminishes differentiation, respectively. Cotransfection of CDO enhances the activity of the neurogenic bHLH factor, neurogenin1, in reporter assays and enhances heterodimerization of neurogenin1 and E47. These results indicate that CDO promotes neuronal differentiation and support the hypothesis that CDO coordinates differentiation of multiple cell lineages by regulating the activity of tissue-specific bHLH factors.

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Tcf12, A Member of Basic Helix-Loop-Helix Transcription Factors, Mediates Bone Marrow Mesenchymal Stem Cell Osteogenic Differentiation In Vitro and In Vivo

Stem Cells ◽

10.1002/stem.2491 ◽

2016 ◽

Vol 35 (2) ◽

pp. 386-397 ◽

Cited By ~ 17

Author(s):

Siqi Yi ◽

Miao Yu ◽

Shuang Yang ◽

Richard J. Miron ◽

Yufeng Zhang

Keyword(s):

Bone Marrow ◽

Stem Cell ◽

Transcription Factors ◽

Mesenchymal Stem Cell ◽

Osteogenic Differentiation ◽

Basic Helix Loop Helix ◽

Helix Loop Helix

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The Basic Helix-Loop-Helix TAL1/SCL and Its Partners E47 and LMO2 Act Upstream of the VE-Cadherin Gene in Endothelial Cells.

Blood ◽

10.1182/blood.v108.11.1795.1795 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1795-1795

Author(s):

Virginie Deleuze ◽

Elias Chalhoub ◽

Rawan El-Hajj ◽

Christiane Dohet ◽

Mikael Le Clech ◽

...

Keyword(s):

Endothelial Cells ◽

Ectopic Expression ◽

Cell Junctions ◽

Small Interfering Rnas ◽

Hek 293 ◽

Basic Helix Loop Helix ◽

Helix Loop Helix ◽

Cell Cell

Abstract The basic helix-loop-helix protein TAL-1/SCL, essential for the formation of the hematopoietic system, is also required for vascular development and more particularly for embryonic angiogenesis. We previously reported that TAL-1 acts as a positive factor for post-natal angiogenesis by stimulating endothelial morphogenesis. To understand how TAL-1 modulates angiogenesis, we investigated the functional consequences of TAL-1 silencing, mediated by small-interfering RNAs, in human primary endothelial cells (ECs). We found that TAL-1 knockdown impaired in vitro EC tubulomorphogenesis (in 2-D on Matrigel or 3-D in collagen I gel), with the notable absence of cell-cell contacts, a prerequisite for morphogenesis initiation. This cellular deficiency was associated with a dramatic reduction in the vascular-endothelial (VE)-cadherin at intercellular junctions, the major component of endothelial adherens junctions. In contrast, PECAM (or CD31) was present at cell-cell junctions at the same levels as control cells. Importantly, silencing of two known TAL-1-partners in hematopoietic cells, E47 or LMO2, produce the same effects as TAL-1. Accordingly, silencing of TAL-1, as well as E47 and LMO2, provoked down-regulation of VE-cadherin at both the mRNA and protein levels. Transient transfection experiments in HUVECs showed that TAL-1 and E47 regulate the VE-cadherin promoter through a specialized E-box element. Finally, endogenous VE-cadherin transcription could be directly activated in non-endothelial HEK-293 cells that neither express TAL-1 or LMO2, by the sole concomitant ectopic expression of TAL-1, E47 and LMO2. Overall, our data demonstrate that a multiprotein complex containing at least TAL-1, LMO2 and E47 act upstream of the VE-cadherin gene. We are currently performing chromatin immunoprecipitation (ChIP) to investigate whether the TAL-1-containing complex binds in vivo the VE-cadherin promoter. This study identifies VE-cadherin as an upstream TAL-1-target gene in the endothelial lineage, and provides a first clue in TAL-1 function in the control of angiogenesis.

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