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21 results on '"Ray, Poulomi"'

12. FGF and BMP signaling are required for specifying pre-chondrogenic identity in neural crest derived mesenchyme and initiating the chondrogenic program

Author

Kumar, Megha, Ray, Poulomi, and Chapman, Susan C.

Subjects
animal structures, Gene Expression Regulation, Developmental, SOX9 Transcription Factor, Chick Embryo, Models, Biological, Article, Microspheres, Fibroblast Growth Factors, Mesoderm, Neural Crest, embryonic structures, Bone Morphogenetic Proteins, Animals, Chondrogenesis, In Situ Hybridization, Signal Transduction
Abstract

The pharyngeal endoderm is hypothesized as the source of local signals that specify the identity of neural crest-derived mesenchyme in the arches. Sox9 is induced and maintained in prechondrogenic cells during condensation formation and endochondral ossification. Using explant culture, we determined that pharyngeal endoderm was sufficient, but not necessary for specifying prechondrogenic identity, as surrounding tissues including the otic vesicle can compensate for signals from the pharyngeal endoderm. Multiple Fgf genes are expressed specifically in the pharyngeal endoderm subjacent to the neural crest-derived mesenchyme. Fibroblast growth factor (FGF) signaling is both sufficient and required for specification of Sox9 expression and specification of prechondrogenic identity, as demonstrated by the addition of recombinant FGF protein or the FGF receptor inhibitor (SU5402) to explanted tissue, respectively. However, FGF signaling cannot maintain Sox9 expression or initiate the chondrogenic program as indicated by the absence of Col2a1 transcripts. Bone morphogenetic protein (BMP) 4 signaling can induce and maintain Sox9 expression in isolated mesenchyme, but only in combination with FGF signaling induce Col2a1 expression, and thus, chondrogenesis. Given the spatiotemporal expression patterns of FGFs and BMPs in the pharyngeal arches, we suggest that this may represent a general mechanism of local signals specifying prechondrogenic identity and initiation of the chondrogenic program.

Published
2012

15. Multiaxial Polarity Determines Individual Cellular and Nuclear Chirality.

Author

Ray, Poulomi, Singh, Ajay, Wan, Leo, Raymond, Michael, Kaur, Gurleen, and Fredericks, Michael

Subjects
*CHIRALITY, *POLARITY (Physics), *EMBRYOLOGY, *CELL morphology, *EPITHELIAL cells
Abstract

Intrinsic cell chirality has been implicated in the left-right (LR) asymmetry of embryonic development. Impaired cell chirality could lead to severe birth defects in laterality. Previously, we detected cell chirality with an in vitro micropatterning system. Here, we demonstrate for the first time that chirality can be quantified as the coordination of multiaxial polarization of individual cells and nuclei. Using an object labeling, connected component based method, we characterized cell chirality based on cell and nuclear shape polarization and nuclear positioning of each cell in multicellular patterns of epithelial cells. We found that the cells adopted a LR bias the boundaries by positioning the sharp end towards the leading edge and leaving the nucleus at the rear. This behavior is consistent with the directional migration observed previously on the boundary of micropatterns. Although the nucleus is chirally aligned, it is not strongly biased towards or away from the boundary. As the result of the rear positioning of nuclei, the nuclear positioning has an opposite chirality to that of cell alignment. Overall, our results have revealed deep insights of chiral morphogenesis as the coordination of multiaxial polarization at the cellular and subcellular levels. [ABSTRACT FROM AUTHOR]

Published
2017
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20. EARLY SKELETAL MORPHOGENESIS: THE ROLE OF PHARYNGEAL ENDODERM DERIVED SIGNALING DURING SPECIFICATION OF CRANIOFACIAL SKELETON AND INTERPLAY OF MECHANICAL FORCES AND MOLECULAR SIGNALING DURING SKELETAL CONDENSATION

Author

Ray, Poulomi

Subjects
Developmental Biology
Abstract

This study examines the fundamental principles governing the early stages of skeletal morphogenesis. I specifically investigate the specification of mesenchymal progenitor cells to a skeletal fate. Using explant culture system, I determine that the pharyngeal endoderm was sufficient, but not necessary for specifying pre-chondrogenic identity. FGF signaling is both sufficient and required for specification of Sox9 expression and specification of prechondrogenic identity, as demonstrated by the addition of recombinant FGF protein or the FGF receptor inhibitor (SU5402) to explanted tissue, respectively. However, FGF signaling cannot maintain Sox9 expression or initiate the chondrogenic program as indicated by the absence of Col2a1 transcripts. BMP4 signaling induces and maintains Sox9 expression in the isolated mesenchyme, but only in combination with FGF signaling is capable of inducing Col2a1 expression, and thus, chondrogenesis. I propose that this represents a general mechanism of local signals specifying pre-chondrogenic identity and initiation of the chondrogenic program. Additionally, I determine how specified mesenchymal cells integrate mechanical and molecular information from their environment forming a cartilage condensation. The classical model defines condensation based on increased cell density. Based on our results, we propose a revised model for skeletal condensation, which is based on differential cell shape changes and independent of increasing cell density. By disrupting cytoskeletal reorganization, I demonstrate that tension dependent dynamic cell shape changes drive condensation and modulate the response of the condensing cells to FGF, BMP and TGF-β pathways. Rho Kinase driven actomyosin contractions and myosin II generated differential cell cortex tension drive the cell shape changes and negatively TGF-β pathway. Dorsal and ventral condensations undergo distinct cell shape changes regulated by BMP. This study elucidates the fundamental principles of interplay between mechanical forces and molecular signaling, in a self-organizing system, generating shape and form.

Published
2013

21. Cell chirality: emergence of asymmetry from cell culture.

Author

Wan LQ, Chin AS, Worley KE, and Ray P

Subjects
Cell Culture Techniques, In Vitro Techniques, Body Patterning, Embryonic Development
Abstract

Increasing evidence suggests that intrinsic cell chirality significantly contributes to the left-right (LR) asymmetry in embryonic development, which is a well-conserved characteristic of living organisms. With animal embryos, several theories have been established, but there are still controversies regarding mechanisms associated with embryonic LR symmetry breaking and the formation of asymmetric internal organs. Recently, in vitro systems have been developed to determine cell chirality and to recapitulate multicellular chiral morphogenesis on a chip. These studies demonstrate that chirality is indeed a universal property of the cell that can be observed with well-controlled experiments such as micropatterning. In this paper, we discuss the possible benefits of these in vitro systems to research in LR asymmetry, categorize available platforms for single-cell chirality and multicellular chiral morphogenesis, and review mathematical models used for in vitro cell chirality and its applications in in vivo embryonic development. These recent developments enable the interrogation of the intracellular machinery in LR axis establishment and accelerate research in birth defects in laterality.This article is part of the themed issue 'Provocative questions in left-right asymmetry'., (© 2016 The Author(s).)

Published
2016
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