Association of SPARC (osteonectin, BM-40) with extracellular and intracellular components of the ciliated surface ectoderm ofXenopus embryos

Huynh, My Hang; Hong, Henry; Delovitch, Shayna; Desser, Sherwin S.; Ringuette, Maurice J.

doi:10.1002/1097-0169(200010)47:2<154::aid-cm6>3.0.co;2-l

Cited by 21 publications

(20 citation statements)

References 33 publications

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“…Later, SPARC is ideally positioned to play a role in the formation and maintenance of the basal lamina that is necessary for Schwann cell myelination (Fig. 6) (Court et al, 2006), similar to its role in basement membranes in other tissues and across multiple organisms (Fitzgerald and Schwarzbauer, 1998;Huynh et al, 2000;Bradshaw and Sage, 2001;Martinek et al, 2002). This may also explain why oligodendrocytes, whose myelin does not have a basal lamina, do not express SPARC.…”

Section: Discussionmentioning

confidence: 97%

SPARC is expressed by macroglia and microglia in the developing and mature nervous system

Vincent

Lau

Roskams

2008

Developmental Dynamics

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SPARC (secreted protein, acidic and rich in cysteine) is a matricellular protein that is highly expressed during development, tissue remodeling, and repair. SPARC produced by olfactory ensheathing cells (OECs) can promote axon sprouting in vitro and in vivo. Here, we show that in the developing nervous system of the mouse, SPARC is expressed by radial glia, blood vessels, and other pial-derived structures during embryogenesis and postnatal development. The rostral migratory stream contains SPARC that becomes progressively restricted to the SVZ in adulthood. In the adult CNS, SPARC is enriched in specialized radial glial derivatives (Mü ller and Bergmann glia), microglia, and brainstem astrocytes. The peripheral glia, Schwann cells, and OECs express SPARC throughout development and in maturity, although it appears to be down-regulated with maturation. These data suggest that SPARC may be expressed by glia in a spatiotemporal manner consistent with a role in cell migration, neurogenesis, synaptic plasticity, and angiogenesis.

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Section: Discussionmentioning

confidence: 97%

SPARC is expressed by macroglia and microglia in the developing and mature nervous system

Vincent

Lau

Roskams

2008

Developmental Dynamics

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“…SPARC has been demonstrated to decrease focal adhesion of tissue culture cells to a variety of different matrix substrata and inhibit the adhesion of migrating mesodermal cells during gastrulation in vivo (Murphy-Ullrich et al 1995). However, in epithelial tissues, SPARC may promote cell-cell adhesion (Huynh et al 2000). Therefore, in different tissues, SPARC may exhibit anti-adhesive or adhesive activities.…”

Section: Introductionmentioning

confidence: 97%

Evolutionary conservation and association of SPARC with the basal lamina in Drosophila

et al. 2002

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SPARC (secreted protein, acidic, rich in cysteine, also called BM40 and osteonectin) is a multifunctional calcium-binding glycoprotein whose modular organization has been highly conserved between invertebrates and vertebrates, indicating a conservation of function during metazoan evolution. Genome analysis has revealed a single copy of the DrosophilaSPARC ( dSPARC) gene. As a first step towards investigating the function of SPARC in Drosophila, we examined its spatiotemporal distribution during development. During embryogenesis, dSPARC mRNA transcripts are restricted to mesoderm derivatives, hemocytes, and the fat body. Immunostaining with anti- DrosophilaSPARC antibodies indicates that dSPARC secreted by the hemocytes and fat body cells is concentrated in basal laminae surrounding internal organs. During oogenesis, dSPARC transcripts are restricted to the somatic cells of the germarium and follicles. Consistent with embryonic development, the resultant protein is concentrated in basal laminae. Mutations in type IV collagen are associated with a dramatic decrease in dSPARC protein immunostaining in hemocytes. The data suggest that the production and assembly of dSPARC in the basal lamina is dependent on type IV collagen, and raise the possibility that dSPARC and type IV collagen interactions are a prerequisite to the assembly and structural integrity of basal laminae in Drosophila.

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“…Besides its wellcharacterized extracellular and pericellular functions, emerging data suggest that SPARC may also function inside cells (17). Indeed, intracellular SPARC is associated with tubulin in ciliated epithelial cells (18) and is found in the nuclei of endothelial and lens epithelial cells (19,20). Together, these reports indicate that SPARC might function intracellularly to influence diverse cellular activities.…”

Section: Introductionmentioning

confidence: 99%

Persistent Activation of the Fyn/ERK Kinase Signaling Axis Mediates Imatinib Resistance in Chronic Myelogenous Leukemia Cells through Upregulation of Intracellular SPARC

et al. 2010

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SPARC is an extracellular matrix protein that exerts pleiotropic effects on extracellular matrix organization, growth factor availability, cell adhesion, differentiation, and immunity in cancer. Chronic myelogenous leukemia (CML) cells resistant to the BCR-ABL inhibitor imatinib (IM-R cells) were found to overexpress SPARC mRNA. In this study, we show that imatinib triggers SPARC accumulation in a variety of tyrosine kinase inhibitor (TKI)-resistant CML cell lines. SPARC silencing in IM-R cells restored imatinib sensitivity, whereas enforced SPARC expression in imatinib-sensitive cells promoted viability as well as protection against imatinib-mediated apoptosis. Notably, we found that the protective effect of SPARC required intracellular retention inside cells. Accordingly, SPARC was not secreted into the culture medium of IM-R cells. Increased SPARC expression was intimately linked to persistent activation of the Fyn/ERK kinase signaling axis. Pharmacologic inhibition of this pathway or siRNA-mediated knockdown of Fyn kinase resensitized IM-R cells to imatinib. In support of our findings, increased levels of SPARC mRNA were documented in blood cells from CML patients after 1 year of imatinib therapy compared with initial diagnosis. Taken together, our results highlight an important role for the Fyn/ERK signaling pathway in imatinib-resistant cells that is driven by accumulation of intracellular SPARC.

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Association of SPARC (osteonectin, BM-40) with extracellular and intracellular components of the ciliated surface ectoderm ofXenopus embryos

Cited by 21 publications

References 33 publications

SPARC is expressed by macroglia and microglia in the developing and mature nervous system

SPARC is expressed by macroglia and microglia in the developing and mature nervous system

Evolutionary conservation and association of SPARC with the basal lamina in Drosophila

Persistent Activation of the Fyn/ERK Kinase Signaling Axis Mediates Imatinib Resistance in Chronic Myelogenous Leukemia Cells through Upregulation of Intracellular SPARC

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