Conversion of neurons and glia to external-cell fates in the external sensory organs of Drosophila hamlet mutants by a cousin-cousin cell-type respecification

Metazoans differentially express multiple Hox transcription factors to specify diverse cell fates along the developing anterior-posterior axis. Two challenges arise when trying to understand how the Hox transcription factors regulate the required target genes for morphogenesis: First, how does each Hox factor differ from one another to accurately activate and repress target genes required for the formation of distinct segment and regional identities? Second, how can a Hox factor that is broadly expressed in many tissues within a segment impact the development of specific organs by regulating target genes in a cell type-specific manner? In this review, we highlight how recent genomic, interactome, and cis-regulatory studies are providing new insights into answering these two questions. Collectively, these studies suggest that Hox factors may differentially modify the chromatin of gene targets as well as utilize numerous interactions with additional co-activators, co-repressors, and sequence-specific transcription factors to achieve accurate segment and cell type-specific transcriptional outcomes.

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A novel subtype of pineal projection neurons expressing melanopsin share a common developmental program with classical projection neurons

10.1101/712091 ◽

2019 ◽

Author(s):

Dora Sapède ◽

Clair Chaigne ◽

Patrick Blader ◽

Elise Cau

Keyword(s):

Pineal Organ ◽

Hybrid Cell ◽

Projection Neuron ◽

Projection Neurons ◽

Cell Type ◽

Cell Fates ◽

Neuron Population ◽

Neuronal Populations ◽

Developmental Program

SummaryThe zebrafish pineal organ is a photoreceptive structure containing two main neuronal populations (photoreceptors and projections neurons). Here we describe a new pineal cell type that harbors both characteristics of projection neurons and photoreceptors. Indeed, a subpopulation of projection neurons expresses the melanopsin gene opn4xa suggesting photoreceptive properties. This population of hybrid cell fates, share a similar behaviour regarding dependency for BMP and Notch signalling pathways with classical non-photosensitive projection neurons (PNs) suggesting they are closer to the PN population. We describe two distinct types of activity within PNs: an achromatic LIGHT OFF activity in opn4xa− PNs and a LIGHT ON activity elicited by green and blue light in opn4xa+ PNs. Altogether the discovery and characterization of opn4xa+ PNs suggest a previously unanticipated heterogeneity in the projection neuron population.

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Sibling cell fate in the Drosophila adult external sense organ lineage is specified by prospero function, which is regulated by Numb and Notch

Development ◽

10.1242/dev.126.10.2083 ◽

1999 ◽

Vol 126 (10) ◽

pp. 2083-2092 ◽

Cited By ~ 9

Author(s):

G.V. Reddy ◽

V. Rodrigues

Keyword(s):

Transcription Factor ◽

Notch Signaling ◽

Cell Fate ◽

Sense Organ ◽

Sensory Organ ◽

Sensory Organs ◽

Cell Fates ◽

Homeodomain Transcription Factor ◽

Intrinsic Signal ◽

Sensory Organ Precursors

Specification of cell fate in the adult sensory organs is known to be dependent on intrinsic and extrinsic signals. We show that the homeodomain transcription factor Prospero (Pros) acts as an intrinsic signal for the specification of cell fates within the mechanosensory lineage. The sensory organ precursors divide to give rise to two secondary progenitors - PIIa and PIIb. Pros is expressed in PIIb, which gives rise to the neuron and thecogen cells. Loss of Pros function affects the identity of PIIb and neurons fail to differentiate. Pros misexpression is sufficient for the transformation of PIIa to PIIb fate. The expression of Pros in the normal PIIb cell appears to be regulated by Notch signaling.

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Transcriptomic Profiling of Developing Melanocortin Neurons Reveals a Role for Prdm12 in Energy Balance

10.1101/753434 ◽

2019 ◽

Author(s):

Xiameng Chen ◽

Steven C. Wyler ◽

Li Li ◽

Amanda G. Arnold ◽

Rong Wan ◽

...

Keyword(s):

Energy Balance ◽

Adult Brain ◽

Hypothalamic Nucleus ◽

Cell Type ◽

Cell Fates ◽

Intrinsic Factors ◽

Physiological Processes ◽

Neuronal Precursors ◽

Transcription Regulators ◽

Cell Type Specific

AbstractThe hypothalamus is a critical regulator of many physiological processes essential for life. In the adult brain, each anatomically-defined hypothalamic nucleus consists of functionally heterogeneous neuronal subpopulations that dictate distinct survival behaviors. Nevertheless, how rich neuronal identities are established in the developing hypothalamus remains poorly understood.Despite their opposing actions on food intake, POMC and NPY/AgRP neurons in the arcuate nucleus of the hypothalamus (ARH) are derived from the same progenitors that give rise to ARH neurons. However, the mechanism whereby common neuronal precursors subsequently adopt either the anorexigenic (POMC) or the orexigenic (NPY/AgRP) identity remains elusive.We hypothesize that POMC and NPY/AgRP cell fates are specified and maintained by distinct intrinsic factors. In search of them, we profiled the transcriptomes of developing POMC and NPY/AgRP neurons with whole-genome RNA sequencing (RNA-seq). Moreover, cell-type-specific transcriptomic analyses revealed transcription regulators that are selectively enriched in either population, but whose developmental functions are unknown in these neurons.Among them, we found the expression of the PR domain-containing factor 12 (Prdm12) was enriched in POMC neurons but was absent in NPY/AgRP neurons. Selective ablation of Prdm12 in postmitotic POMC neurons led to early-onset obesity, accelerated linear growth, as well as impaired glucose tolerance, which recapitulates symptoms of POMC/MC4R deficiency in humans. These findings, therefore, establish a previously-unrecognized role for Prdm12 in energy balance. Furthermore, the combination of cell-type-specific genomic and genetic analyses provides a means to dissect cellular and functional diversity in the developing hypothalamus as well as the developmental origins of diverse survival behaviors.

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Mutual antagonism between signals secreted by adjacent wingless and engrailed cells leads to specification of complementary regions of the Drosophila parasegment

Development ◽

10.1242/dev.126.18.4107 ◽

1999 ◽

Vol 126 (18) ◽

pp. 4107-4115 ◽

Cited By ~ 3

Author(s):

U. Gritzan ◽

V. Hatini ◽

S. DiNardo

Keyword(s):

Cell Type ◽

Cell Fates ◽

Symmetric Pattern ◽

Mutual Antagonism ◽

Dependent Signal

Specialized groups of cells known as organizers govern the establishment of cell type diversity across cellular fields. Segmental patterning within the Drosophila embryonic epidermis is one paradigm for organizer function. Here cells differentiate into smooth cuticle or distinct denticle types. At parasegment boundaries, cells expressing Wingless confront cells co-expressing Engrailed and Hedgehog. While Wingless is essential for smooth cell fates, the signals that establish denticle diversity are unknown. We show that wg mutants have residual mirror-symmetric pattern that is due to an Engrailed-dependent signal specifying anterior denticle fates. The Engrailed-dependent signal acts unidirectionally and Wg activity imposes this asymmetry. Reciprocally, the Engrailed/Hedgehog interface imposes asymmetry on Wg signaling. Thus, a bipartite organizer, with each signal acting essentially unidirectionally, specifies segmental pattern.

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Four distinct regulatory regions of the cut locus and their effect on cell type specification in Drosophila.

Genetics ◽

10.1093/genetics/127.1.151 ◽

1991 ◽

Vol 127 (1) ◽

pp. 151-159 ◽

Cited By ~ 11

Author(s):

S Liu ◽

E McLeod ◽

J Jack

Keyword(s):

Regulatory Region ◽

Malpighian Tubules ◽

The Other ◽

Cell Type ◽

Cut Locus ◽

Sensory Organs ◽

Regulatory Regions ◽

Tissue Specific ◽

Specific Effects ◽

Type Specification

Abstract The cut gene in Drosophila is necessary in at least one cell type, the external sensory organs, for proper cell type specification and morphogenesis. It is also expressed in a variety of other tissues, where its function is less well characterized. Previous work has demonstrated that mutations affecting all the tissues map in the transcribed and translated portion of the gene, while mutations that are tissue specific in their effects map in the 140 kb upstream of the most 5' exon known. Within that 140 kb, the mutations fall into four subregions, two of which contain mutations affecting unique sets of tissues and the other two of which contain mutations that affect a third set. Our examination of the defects of mutants, their complementation behavior, and their effect on the distribution of the cut protein in embryos, alters the picture in three important ways. First, some mutations convert the cells of the Malpighian tubules into what appear to be gut cells, suggesting that cut is necessary for cell type specification and morphogenesis in a variety of tissues. Second, mutations in each of the four subregions in the 140 kb of upstream DNA cause a different set of phenotypes, suggesting that the regulatory region contains at least four separate units with different tissue specific functions. And third, mutations have now been identified that map in the transcribed and translated portion of the gene but that have tissue specific effects.

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Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053711 ◽

1982 ◽

Vol 40 ◽

pp. 210-211

Author(s):

M.J. Murphy ◽

R.R. Price ◽

J.C. Sloman

Keyword(s):

Cultured Cells ◽

Human Tumor ◽

Cell Type ◽

Tumor Mass ◽

Initial Cell ◽

Cloning Assay ◽

Human Tumor Cloning ◽

The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

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Some Observations on Changes in Denervated Taste Buds of Circumvallate Papillae of Rabbits

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100063457 ◽

1969 ◽

Vol 27 ◽

pp. 308-309

Author(s):

Sunao Fujimoto ◽

Raymond G. Murray ◽

Assia Murray

Keyword(s):

Taste Buds ◽

Taste Bud ◽

Cell Type ◽

Dark Cells ◽

Type Iii ◽

Circumvallate Papillae ◽

Taste Bud Cells ◽

Light Cells

Taste bud cells in circumvallate papillae of rabbit have been classified into three groups: dark cells; light cells; and type III cells. Unilateral section of the 9th nerve distal to the petrosal ganglion was performed in 18 animals, and changes of each cell type in the denervated buds were observed from 6 hours to 10 days after the operation.Degeneration of nerves is evident at 12 hours (Fig. 1) and by 2 days, nerves are completely lacking in the buds. Invasion by leucocytes into the buds is remarkable from 6 to 12 hours but then decreases. Their extrusion through the pore is seen. Shrinkage and disturbance in arrangement of cells in the buds can be seen at 2 days. Degenerated buds consisting of a few irregular cells and remnants of degenerated cells are present at 4 days, but buds apparently normal except for the loss of nerve elements are still present at 6 days.

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Dendritic cells of the human epidermis: immuno-electron microscopic studies of la antigen reactivity

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100084090 ◽

1978 ◽

Vol 36 (2) ◽

pp. 644-645

Author(s):

G. Rowden ◽

M. G. Lewis ◽

T. M. Phillips

Keyword(s):

Dendritic Cells ◽

Langerhans Cells ◽

Cell Types ◽

Cell Type ◽

Electron Microscopic ◽

La Antigen ◽

Microscopic Studies ◽

A Cell ◽

C3 Receptors ◽

Antigen Reactivity

Langerhans cells of mammalian stratified squamous epithelial have proven to be an enigma since their discovery in 1868. These dendritic suprabasal cells have been considered as related to melanocytes either as effete cells, or as post divisional products. Although grafting experiments seemed to demonstrate the independence of the cell types, much confusion still exists. The presence in the epidermis of a cell type with morphological features seemingly shared by melanocytes and Langerhans cells has been especially troublesome. This so called "indeterminate", or " -dendritic cell" lacks both Langerhans cells granules and melanosomes, yet it is clearly not a keratinocyte. Suggestions have been made that it is related to either Langerhans cells or melanocyte. Recent studies have unequivocally demonstrated that Langerhans cells are independent cells with immune function. They display Fc and C3 receptors on their surface as well as la (immune region associated) antigens.

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