Synthesis and secretion of transferrin by isolated ciliary epithelium of rabbit

Bertazolli-Filho, Rubens; Laicine, Eduardo Miguel; Haddad, Antônio

doi:10.1016/s0006-291x(03)00825-8

Cited by 14 publications

(10 citation statements)

References 29 publications

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“…We also speculate that the down-regulation of the ILM protein synthesis in early human life is essential, since a continuous high rate of synthesis of ILM proteins with a very slow degradation would eventually lead to a very thick extracellular matrix sheet that would interfere with the transparency of the eye. It is of note that soluble proteins in the vitreous, such as transferrin and a2 macroglobulin that are also synthesized by the ciliary body (Bertazolli-Filho et al, 2003;Kubota et al, 2004) are not downregulated in the adult eye, thus, it appears that only the slowly metabolized ECM proteins of the eye have a developmentally regulated synthesis.…”

Section: Age-dependent Changes In the Morphology Of The Ilmmentioning

confidence: 99%

Age-dependent changes in the structure, composition and biophysical properties of a human basement membrane

2010

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Section: Age-dependent Changes In the Morphology Of The Ilmmentioning

confidence: 99%

Age-dependent changes in the structure, composition and biophysical properties of a human basement membrane

2010

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“…Transferrin, a protein typical for serum, is present in large quantities in VB. It is synthesized by the ciliary body, 34,39 and its concentration in VB remains steady from embryogenesis to old age. 22 A similar time course was detected for fibronectin.…”

Section: Vitreous and The Origin Of Vb Proteins In The Eyementioning

confidence: 99%

Origin and turnover of ECM proteins from the inner limiting membrane and vitreous body

Halfter

Dong

et al. 2008

Eye

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The inner limiting membrane (ILM) and the vitreous body (VB) are two major extracellular matrix (ECM) structures that are essential for early eye development. The ILM is considered to be the basement membrane of the retinal neuroepithelium, yet in situ hybridization and chick/quail transplant experiments in organcultured eyes showed that all components critical for ILM assembly, such as laminin or collagen IV, are not synthesized by the retina. Rather, ILM proteins, with the exception of agrin, originate from the lens or (and) ciliary body and are shed into the vitreous. The VB serves as a reservoir providing high concentrations of ILM proteins for the instant assembly of new ILM during rapid embryonic eye growth. The function of the retina in ILM assembly is to provide the cellular receptor proteins for the binding of the ILM proteins from the vitreous. The VB is a gelatinous ECM structure that fills the vitreous cavity of the eye. Its major structural proteins, collagen II and fibrillin, originate primarily from the ciliary body. Reverse transcription-PCR and western blotting show that the rate of synthesis of structural, monomeric ILM and VB proteins, such as laminin, collagen IV and II is very high during embryogenesis and very low in the adult. The downregulation of ILM and VB protein synthesis occurs during early postnatal life, and both ILM and VB are from then on maintained throughout life with minimum turnover. Our data explain why ILM and VB do not regenerate after vitrectomy and ILM peeling.

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“…The existence of an intrinsic vitreous transferrin has been demonstrated (12) and many studies were subsequently carried out to determine its origins. Many eye components have been considered to be potential sources of vitreous transferrin, including the retina (4), lens (5) and ciliary epithelium (6). Regarding the aqueous humor, the intrinsic transferrin could reach it either by migration from the vitreous and/or by secretion from the lens and ciliary epithelium.…”

Section: Discussionmentioning

confidence: 99%

“…Even though the main source of transferrin in the body is the liver, many extra-hepatic sources exist. Several eye sites are capable of synthesizing and secreting transferrin, including the retina (4), lens (5) and ciliary epithelium (6). Both the lens and the ciliary epithelium face the posterior chamber, which means that the secreted transferrin becomes a constituent of the AH.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and secretion of transferrin by a bovine trabecular meshwork cell line

Bertazolli-Filho

Laicine

Haddad

2007

Braz J Med Biol Res

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The trabecular meshwork (TM) is the main outflow pathway in the mammalian eye. Oxidative damage to TM cells has been suggested to be an important cause of impairment of TM functions, leading to deficient drainage of aqueous humor, with deleterious consequences to the eye. Transferrin, a metalloprotein involved in iron transport, has been characterized as an intrinsic eye protein. Since transferrin is implicated in the control of oxidative stress, the objective of the present study was to determine if a bovine TM cell line (CTOB) synthesizes and secretes transferrin. The CTOB cell line was cultured in the presence of 35 S-methionine and the incubation medium was submitted to immunoprecipitation. Total RNAs from CTOB and isolated bovine TM (freshly isolated, incubated or not) were subjected to the reverse transcription-polymerase chain reaction and the amplification products were sequenced. Also, both CTOB and histological TM preparations were processed for transferrin immunolocalization. A labeled peptide of about 80 kDa, the expected size for transferrin, was immunopurified from CTOB samples obtained from the incubation assays. The reverse transcription-polymerase chain reaction and sequencing experiments detected the presence of transferrin mRNA in CTOB and isolated bovine TM. Reactivity to antibodies against transferrin was observed both in CTOB and TM. The results obtained in all of these experiments indicated that the TM is capable of synthesizing and secreting transferrin. The possible implications for the physiology of the eye are discussed.

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Synthesis and secretion of transferrin by isolated ciliary epithelium of rabbit

Cited by 14 publications

References 29 publications

Age-dependent changes in the structure, composition and biophysical properties of a human basement membrane

Age-dependent changes in the structure, composition and biophysical properties of a human basement membrane

Origin and turnover of ECM proteins from the inner limiting membrane and vitreous body

Synthesis and secretion of transferrin by a bovine trabecular meshwork cell line

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