Expression of insulin-like growth factor I in developing lens is compartmentalized.

Caldés, Trinidad; Alemany, Jorge; Robcis, Henri L.; Pablo, Flora de

doi:10.1016/s0021-9258(18)54777-3

Cited by 41 publications

(1 citation statement)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In several in vitro studies, IGF-I and IGF-II promote the proliferation of preadipocytes, chondrocytes and fibroblasts (Cynober et al, 1985;Butterwith and Goddard, 1991;Leach and Rosselot, 1992). Moreover, in fibroblasts, IGF-I and IGF-II increase net protein accretion (Caldes et al, 1991). GH treatment in chicken hepatocytes induces IGF-I production (O'Neill et al, 1990).…”

Section: Insulin-like Growth Factor Axismentioning

confidence: 99%

The Endocrine Regulation of Chicken Growth

Kim¹

2010

Asian Australas. J. Anim. Sci

View full text Add to dashboard Cite

The somatotropic axis plays a key role in proliferation and differentiation of avian organs during both pre-and posthatching periods. This review discusses the complexity of regulation of the endocrine system for chicken development and growth by growth hormone (GH), insulin-like growth factor (IGF), and IGF binding protein (IGFBP). In addition, the thyrotropic axis, including thyrotropin-releasing hormone (TRH) and thyroid hormones (T 4 and T 3 ), is also involved in the GH-secreting pattern. In mammals, IGF-I and -II are always sequestered in a 150 kDa non-covalent ternary complex. This complex consists of one molecule each of IGF-I or IGF-II, IGFBP-3 or IGFBP-5 and an acid labile subunit (ALS). Chick ALS is identified in different strains for the first time, and further investigation of the expression of ALS on developmental stage and ALS effect on IGF bioavailability may be addressed in the future.

show abstract

Section: Insulin-like Growth Factor Axismentioning

confidence: 99%

The Endocrine Regulation of Chicken Growth

Kim¹

2010

Asian Australas. J. Anim. Sci

View full text Add to dashboard Cite

show abstract

A role for endogenous TGF? and associated signaling pathways in the differentiation of lens fiber cells

2001

View full text Add to dashboard Cite

TGFalpha is hypothesized to be an endogenous regulator of lens fiber terminal differentiation. With immunofluorescence, TGFalpha was localized to differentiating cells in the lens epithelium and superficial fiber cell mass of the adult chicken. A similar pattern of localization was also noted when differentiating epithelial cells were cultured. Immunoneutralization of endogenous TGFalpha inhibited the accumulation of filensin, a unique intermediate filament protein subunit restricted to developing vertebrate lens fibers. ELISA assays quantified the effects of TGFalpha on filensin expression. Surprisingly, inhibition of the TGFalpha receptors' tyrosine kinase activity with nanomolar concentrations of PD153035 increased the accumulation of differentiated characteristics in the presence or absence of ligand. Morphologically, PD153035-treated cells grew as aggregated masses and spread less well onto the substrate. Accompanying these morphologic changes was a complete inhibition of cell division. Post-receptor signaling events were examined with cAMP assays and Western blotting. TGFalpha did not affect cAMP levels while isoproterenol, an additional mediator of lens cell differentiation, caused significant increases in cAMP levels. Activation of ERK2 via dual phosphorylation was noted in response to TGFalpha but not isoproterenol. PD153035 reduced, but did not eliminate, ERK2 phosphorylation in response to TGFalpha. Phosphorylation of the CREB transcription factor was also observed in response to TGFalpha or isoproterenol. These data indicate that endogenous ligands can influence the expression of differentiated characteristics in cultured chick lens cells. A focus of multiple signaling pathways affecting filensin expression is the CREB transcription factor. While increased ERK2 activation may be involved in stimulating cell division, lower levels of persistent ERK2 activation promotes differentiation thus indicating some form of signaling pathway compartmentalization. This could also mean that additional receptors for TGFalpha not inhibited by PD153035 are responsible for promoting differentiation in chick lens cells.

show abstract

Orthograde transport and release of insulin‐like growth factor I from the inferior olive to the cerebellum

Nieto-Bona

Garcia-Segura

Torres‐Alemán

1993

J of Neuroscience Research

View full text Add to dashboard Cite

Insulin‐like growth factor I (IGF‐I) and its receptor are expressed in functionally related areas of the rat brain such as the inferior olive and the cerebellar cortex. A marked decrease of IGF‐I levels in cerebellum is found when inferior olive neurons are lesioned. In addition, Purkinje cells in the cerebellar cortex depend on this growth factor to survive and differentiate in vitro. Thus, we consider it possible that IGF‐I forms part of a putative trophic circuitry encompassing the inferior olive and the cerebellar cortex and possibly other functionally connected areas. To test this hypothesis we have studied whether IGF‐I may be taken up, transported, and released from the inferior olive to the cerebellum. We have found that 125I‐IGF‐I is taken up by inferior olive neurons in a receptor‐mediated process and orthogradely transported to the cerebellum. Thus, radioactivity found in the cerebellar lobe contralateral to the injection site in the inferior olive was immunoprecipitated by an anti‐IGF‐I antibody, co‐eluted with 125I‐IGF‐I in an HPLC column, and co‐migrated with 125I‐IGF‐I in an SDS‐urea polyacrylamide gel electrophoresis. Time‐course studies indicated that orthograde axonal transport is relatively rapid since 30 min after the injection, radiolabeled IGF‐I was already detected in the contralateral cerebellum. Furthermore, transport of IGF‐i from the inferior olive is specific since when 125I‐neurotensin was injected in the inferior olive or when 125I‐IGF‐I was injected in the pontine nucleus, no radiactivity was found in the contralateral cerebellum. In addition, no specific transport of 125I‐IGF‐I was found in climbing fiber‐deafferented rats or when excess unlabeled IGF‐I was co‐injected with 125I‐IGF‐I. We next studied whether IGF‐I is released by inferior olive neurons. We found that the release of IGF‐I from cerebellar slices of normal rats was significantly greater in response to depolarizing stimuli than that from slices obtained of climbing fiber‐deafferented animals. Indeed, in vitro release of IGF‐I in response to KCI or veratridine was almost completely abolished in the latter. These data suggest that IGF‐I is taken up by inferior olive neurons through IGF‐I receptors and transported to the cerebellum through their axons without any major modification. Moreover, the release of IGF‐I from the cerebellum after depolarization depends on the presence of climbing fiber afferents. Altogether these results indicate that the olivo‐cerebellar pathway is able to take up, orthogradely transport, and release IGF‐I. Since a similar process has been described in the visual system for basic fibroblast growth factor (bFGF), we propose that IGF‐I, bFGF, and possibly other growth factors may constitute afferent trophic signals involved in plastic mechanisms within specific neural circuitries. © 1993 Wiley‐Liss, Inc.

show abstract

Expression of insulin-like growth factor I in developing lens is compartmentalized.

Cited by 41 publications

References 38 publications

The Endocrine Regulation of Chicken Growth

The Endocrine Regulation of Chicken Growth

A role for endogenous TGF? and associated signaling pathways in the differentiation of lens fiber cells

Orthograde transport and release of insulin‐like growth factor I from the inferior olive to the cerebellum

Contact Info

Product

Resources

About