Structural proteins of the mammalian lens: A review with emphasis on changes in development, aging and cataract

Harding, John J.; Dilley, Keith J.

doi:10.1016/0014-4835(76)90033-6

Cited by 466 publications

(137 citation statements)

References 256 publications

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“…However, AGE levels are also dependent on protein turnover rates [5,15,46,47]. Lens protein [1,48] and cartilage collagen [30] essentially do not turn over, whereas skin collagen has a turnover faster than cartilage and lens [37]. While cartilage and skin collagen are relatively comparable in glucose concentrations and oxidative stress as determinants of AGE levels, the difference in protein turnover is clearly reflected in the higher CML, CEL and pentosidine levels in cartilage compared with skin collagen (Table 1).…”

Section: Maillard Reaction Products In Cartilage Compared With Skin Amentioning

confidence: 99%

Age-related accumulation of Maillard reaction products in human articular cartilage collagen

Verzijl

DeGroot

Oldehinkel³

et al. 2000

Biochemical Journal

239

100

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Non-enzymic modification of tissue proteins by reducing sugars, the so-called Maillard reaction, is a prominent feature of aging. In articular cartilage, relatively high levels of the advanced glycation end product (AGE) pentosidine accumulate with age. Higher pentosidine levels have been associated with a stiffer collagen network in cartilage. However, even in cartilage, pentosidine levels themselves represent 1 cross-link per 20 collagen molecules, and as such cannot be expected to contribute substantially to the increase in collagen network stiffness. In the present study, we investigated a broad range of Maillard reaction products in cartilage collagen in order to determine whether pentosidine serves as an adequate marker for AGE levels. Not only did the well-characterized AGEs pentosidine, N ε -(carboxymethyl)lysine, and N ε -(carboxyethyl)lysine increase with age in cartilage collagen (all P 0.0001), but also general measures of AGE cross-linking, such as browning and fluorescence (both P 0.0001), increased. The levels of these AGEs are all higher in cartilage collagen than in skin collagen. INTRODUCTIONDuring aging, long-lived proteins such as collagen and eye lens proteins are non-enzymically modified by reducing sugars. The major initial product is fructose-lysine (FL) [1,2], which results from glycation of ε-amino groups on lysine residues. In subsequent Maillard or browning reactions, products known as advanced glycation end products (AGEs) are formed from FL [3,4], and accumulate with age in long-lived proteins [1,2,[5][6][7][8]. These AGEs include structurally characterized adducts, such as N ε -(carboxymethyl)lysine (CML) [1][2][3] and N ε -(carboxyethyl)-lysine (CEL) [9], fluorescent cross-links, such as pentosidine formed between lysine and arginine residues [5,10], as well as chemically unidentified compounds which result in proteinbound browning or fluorescence, and cross-linking [11][12][13][14].In comparison with other collagen-rich tissues such as skin, cartilage contains relatively large amounts of pentosidine [5,15]. Pentosidine levels in articular cartilage increase linearly with age [6-8], as was previously described for skin collagen [16] and lens proteins [10]. Pentosidine is also present in the proteoglycans in articular cartilage [17], but appears to be localized predominantly in the collagen component of the tissue [7]. Age-related accumulation of AGE cross-links in articular cartilage collagen may result in increased stiffening of the collagen network, as was shown after in itro ribosylation of cartilage [7]. Thus AGE cross-linking in i o may contribute to the age-related impairment of the ability of articular collagen to resist mechanically induced damage and eventually cartilage degeneration [18][19][20].Abbreviations used : AGE, advanced glycation end product ; CEL, N ε -(carboxyethyl)lysine ; CML, N ε -(carboxymethyl)lysine ; FL, fructose-lysine. 1 To whom correspondence should be addressed (e-mail JM.TeKoppele!pg.tno.nl).As a functional measure of glycation the digestibility o...

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Section: Maillard Reaction Products In Cartilage Compared With Skin Amentioning

confidence: 99%

Age-related accumulation of Maillard reaction products in human articular cartilage collagen

Verzijl

DeGroot

Oldehinkel³

et al. 2000

Biochemical Journal

239

100

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“…It is tempting to suggest that the similarities between Eand d-crystallin reflect specific requirements for the proper functioning of lens proteins in the avian and reptilian lenses, which are characterized by a very soft consistency and great plasticity in relation to their unique accomodative properties It is remarkable that the major lens proteins in the duck, and in many other birds and reptiles, are the products of five unrelated gene families: a-, pi?-, 6-, E-and 48-kDa crystallins [I, 81, while in mammalian lenses only two gene families (a and P / y ) take care of the crystallin production [25] The scattered occurrence of E-crystallin among avian species is also intriguing. While it is found in considerable amounts in some species, like duck, it is apparently absent in others, like chicken.…”

Section: Discussionmentioning

confidence: 99%

ɛ‐Crystallin, a novel avian and reptilian eye lens protein

Stapel

Zweers

Dodemont

et al. 1985

European Journal of Biochemistry

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Gel filtration of Peking duck eye lens proteins reveals a component eluting just behind δ‐crystallin and comprising approximately 10% of the total soluble protein. The native Mr of this additional component is estimated to be 120000; it appears to be composed of three identical chains of Mr 38000 and pl 7.5. Circular dichroic spectroscopy showed a relatively high α‐helical content. No immunological cross‐reactivity is found with α‐, β‐, γ‐ or δ‐crystallins, and partial amino acid sequence determinations likewise failed to reveal any similarity with other known crystallins. We conclude that this protein represents another and novel family of eye lens proteins, for which we propose the designation ɛ‐crystallin. ɛ‐Crystallin is translated from a 1450‐base mRNA, which has been partially purified. ɛ‐Crystallin is found scattered among avian and reptilian taxa, but not in other vertebrates. Its rate of evolutionary change seems to be as slow as that of α‐ and β‐crystallins.

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“…The membrane proteins can be separated fi'om the other protein constituents of lens fiber cells because of their differential solubilization properties. Treatment of the fiber cells with buffer removes the watersoluble crystallins and subsequent extraction with 8M urea solubilizes the cytoskeleton resulting in a crystallin-free, cytoskeleton-free membrane preparation (Broekhuyse, 1981;Harding and Dilley, 1976;Bloemendal, 1981Bloemendal, , 1982. The protein patterns are quite similar for buffer-washed membranes isolated in the presence or absence of calcium (cf.…”

Section: Characterization Of Lehs Of Fiber Membrane Proteinsmentioning

confidence: 99%

EDTA-extractable proteins from calf lens fiber membranes are phosphorylated by Ca2+-phospholipid-dependent protein kinase

Raaij

Feijen

Snoek

1987

Experimental Eye Research

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A dist, inct group of EDTA-extractable proteins (EEP), being a major protein component of calf" let, s fiber membranes, is botmd to these membranes in a ca}vium-dependet)t amy. Both purified and membrane-bound EE~P can be phosphorylated in vitro by a C~'z*-nctivated, phospholipiddependent protein kinase (protei~ kinase C). In general, this protein kinase preferentially phosphorylates serilm and threonine residues of protein substrates. Pflosphoamino-aeid analysis of the two major bands of EEP phosphory|ated by protein kinase C, representing the 33 (h30 + 34000 EE |) proteins and the 30700-31 800 pr~)teins, respectively, revea|ed differences in the phosphoaminoaeid patterns. For the 33 000 + 34 0(X) EEP proteins, only phosphothreonine was detected whereas tbr the 30700-31 8(~) proteins, the label was incorporated in both threonine and serine residues. No label was fouzltt on tyrosine resid~Jes. T))ese resu}ts implicate differences in the primary structure of the individual EEI) proteinn. Regarding previous observations that EEP is a main protein component of lens fiber junctions and of the many covering epithelial and endothelial ceils, and considering the fact that protein kinase C is involved in cell-cell communication, growth and differentiation processes we suggest that a correlation exists between phosphorylation-dephosphorylation of EEP and the regulation of a ~umber of cellular processes.

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Structural proteins of the mammalian lens: A review with emphasis on changes in development, aging and cataract

Cited by 466 publications

References 256 publications

Age-related accumulation of Maillard reaction products in human articular cartilage collagen

Age-related accumulation of Maillard reaction products in human articular cartilage collagen

ɛ‐Crystallin, a novel avian and reptilian eye lens protein

EDTA-extractable proteins from calf lens fiber membranes are phosphorylated by Ca2+-phospholipid-dependent protein kinase

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