- Email: [email protected]
Guest editors’ introduction
Archives of Biochemistry and Biophysics 504 (2010) 1–2
Contents lists available at ScienceDirect
Archives of Biochemistry and Biophysics journal homepage: www.elsevier.com/locate/yabbi
Guest editors’ introduction
Guest editorial This highlight issue on carotenoids represents the fourth such in a series published at nearly 3 year intervals in concert with the occurrence of the Gordon Research Conference on carotenoids. The first highlight issue was published in January of 2001 and subsequent highlight issues appeared in October of 2004 and September of 2007. Between January 17 and 22 of 2010, the seventh triennial gathering of researchers from around the globe occurred in Ventura where the advances in the science of carotenoids and their functions were the focus of intense discussion. The highlight issues although timed to coincide with the GRC are not proceedings of these conferences. These highlight issues serve as an opportunity for researchers to layout the progress in this field through the presentation of original research papers and reviews at a time when many have invested a significant effort, ‘taking stock’ and assessing the state of carotenoid science. All of the papers published in this highlight issue have undergone the rigorous peer review process distinctive of ABB publications. The past highlight issues have become significant resources to carotenoid scientists and researchers as well as for those new to the subject and wishing to understand the breadth and scope of carotenoid science. We hope that this Fourth Highlight Issue on carotenoids will stand well among those issues with timely and significant presentations on the developments in this exciting field of study. That carotenoids in the human diet are associated with improved health and they have been implicated as exerting their effects through anti-oxidant activity, up- and down-regulation of proteins, induction of apoptosis, as well as photo-protection of tissues experiencing actinic stress is widely known. Naturally occurring carotenoids have, for most of the past century, been grouped as either pro-vitamin or non-pro-vitamin A carotenoids. This reflects the human perspective and significance that vitamin A has for human health and the essential role of vitamin A in development and growth, as well as vision. The discovery of the genes responsible for cleavage of carotenoids via the production of the cleavage enzymes, beta-carotene-15,150 -monooxygenase (BCMO1) and beta-carotene-90 ,100 -monooxygenase (BCMO2), has opened a new chapter in this story. The site of BCMO expression and action are naturally of great importance. Shmarakov et al. [1] have followed BCMO1 and BCMO2 expression in the livers of wild type and BCMO1-deficient mice demonstrating the importance of the liver as a cellular site for beta-carotene metabolism. The broader importance of intact carotenoids as well as their apo-carotenoid cleavage products in humans, both related and unrelated to their pro-vitamin A function, has become increasingly evident during the last 10 years. How important the eccentric cleavage of betacarotene is to its metabolism, and to the regulation of vitamin A 0003-9861/$ - see front matter Ó 2010 Published by Elsevier Inc. doi:10.1016/j.abb.2010.10.003
generally, is now a problem that can be specifically investigated. Apo-13-carotenone, formed by the BCMO2 eccentric cleavage of beta-carotene acts is shown by the work of Eroglu et al. [2] to be a potent antagonist of activated RxR-a a retinoic acid receptor. RXR’s are nuclear receptor proteins that can modulate the transcriptional activity of target genes by binding to gene promoters. Fucoxanthin, the abundant xanthophyll found in brown algae, and as such, a component of the Asian diet has come under investigation to provide us an understanding of the basis for health claims associated with its consumption. Hosokawa et al. [3] describes evidence that fucoxanthin can differentially influence mRNA expression in adipocytes of lean versus obese mice providing a molecular clue to its role. In a review of the action of lycopene in atherosclerosis prevention, Palozza et al. [4] describes the progress that has been made in relating the influence of lycopene on atherosclerosis at a molecular level through the study of its effects on critical pathways in cell lines. The importance of carotenes in dermal tissues and their role as photoprotectants has been a challenging problem to address. Although carotenoids have been used to treat individuals with extreme dermal sensitivity to light for several decades the natural levels of individual carotenoids and their functionality has been hard to address in vivo, especially humans. In their paper, Scarmo et al. [5] provide new evidence on this role of carotenes in the skin. The practical hurdles associated with wide scale in vivo measurement of carotenoids in skin have benefitted through the innovative use of resonance Raman spectroscopy as developed by Gellerman. In their review, Gellerman and Ermakov provide a picture of the specificity and quantitative use of Raman spectroscopy for assessing dermal carotenoid levels [6]. The presence of high concentrations of lutein and zeaxanthin, the principle components of the macular pigment, pose several challenging problems to researchers. In particular, how are these carotenoids specifically transported and accumulated within the human macula? And, what function do these carotenoids serve within the retina? Bone et al. [7], show that the responsiveness of the macular pigment to modulation by diet is influenced by dose during supplementation studies. Li et al. [8] provide in vitro evidence that the xanthophylls of the macular pigment function as singlet oxygen scavengers. Electron Spin Resonance Spectroscopy (EPR) can be a probe of the localization of carotenoids in membranes and their accessibility by oxygen. Subczynski et al. [9] give us an elegant description of the use of EPR to assess the potential location of lipophilic carotenoids within membrane structures of the retina and their influence on those membranes. In addition to chlorophylls, several carotenoids are among the natural pigments essential in the photosynthetic light harvesting proteins of higher plants and other photosynthetic organisms. The functions of carotenoids in light harvesting complexes are
2
Guest editors’ introduction / Archives of Biochemistry and Biophysics 504 (2010) 1–2
much less clearly understood than those of the chlorophylls. Recognition that the natural, minor elaborations in the structural motifs of the xanthophyll end-groups can regulate the roles played by specific xanthophylls has been explored in a paper by Betterle et al. [10]. They show us evidence that binding of zeaxanthin to the antenna protein monomer, LHCB6, uniquely increases photoprotection by down-regulating both the chlorophyll singlet state and consequent singlet oxygen production. In their review, [11], Ruban and Johnson address the distinct functions of the xanthophyll components in the light harvesting proteins of higher plants. They present a persuasive argument that xanthophyll hydrophobicity/polarity can explain the need for xanthophyll variety within the light harvesting proteins. This work sheds further light on the recently demonstrated diverse functions of these carotenoids within the photosynthetic proteins. Photoprotection by carotenoids is a dominant and widely observed natural theme. Zhu et al.’s study of the cyanobacterium Synechococcus sp. helps define more clearly the role that xanthophyll carotenoids have in protection against photoinhibition and oxidative stress [12]. Studying this cyanobacterium they have been able to demonstrate that mRNA levels of most genes involved in carotenogenisis increase after exposure to high levels of light. Independent of the origin of radical oxygen species (ROS) within cells, the ability of carotenoids to intercept and ameliorate their effects is a major role believed essential to their ability to act as protectants and anti-oxidants. In their paper, Edge et al. [13] present pulse radiolysis data that carotenoid species are able to protect guanosine in vitro against oxidation by ROS. Vallabhaneni et al. [14] teach us about the expression of the carotenoid dioxygenase enzymes (CCD’s) of the grass species maize, rice, and sorghum and how the CCD’s in turn regulate the essential physiological and developmental roles occupied by carotenoids and apocarotenoids. In particular, the mapping of CCD’s to specific chromosome locations opens a door to the metabolic engineering of maize endosperm. Abscisic acid, a product produced in higher plants from the precursors of carotenoid synthesis, plays a critical role in drought resistance. In a second paper, Vallabhaneni and Wurtzel [15] have investigated expression of the genes that control abscisic acid levels in maize root in response to dehydration and rehydration. We see that the supply of carotenoid precursors, essential for carotenoid biosynthesis, has broad importance to the development and survival of plants. In a review, Rodriguez-Concepcion [16] describes progress that has been made in understanding how manipulation of how the methylerythritol (MEP) pathway impacts carotenoid biosynthesis. The underlying central importance of MEP-derived precursors fundamentally influences the biosynthesis of other isoprenoids as well as carotenoids. In many parts of the world, food production is limited by the effects of parasitic fungi that damage or kill infected plants. Rice, in particular, is one of the food plants infected by Striga infection. Jamil et al. [17] demonstrate that the ability of carotenoid biosynthesis inhibitors to influence the success of Striga germination may have potential to reduce the damage done by this parasite. The commercial significance of carotenoids in their role as pigments in plants and animals cannot be overstated. They influence consumer acceptance of products as well as the viability of the organisms. Altering and improving pigmentation in plants, particularly flowers has been a major motivation into the study of carotenoid biosynthesis. In their review of the regulation of carotenoid pigmentation in flowers, Zhu et al. [18] describe a number of different regulatory mechanisms including the transcriptional regulation of genes essential to carotenoid biosynthesis and also the mechanisms responsible for control of carotenoid storage. The presence of diet derived carotenoid pigments in animals and their metabolism is important to coloration that is especially significant
among birds where pigmentation influences success in mate selection and breeding. Carotenoid levels are also an indicator of the health status in birds. LaFountain et al. [19] show us that after a century of study, the identity of pigments in bird plumage remains an important and vigorous topic of research. They provide us fresh insight into avian carotenoid metabolism. In their paper they describe the presence of a novel methoxy carotenoid in the plumage of the brilliant, burgundy-colored Pompadour Continga (Xipholena punicea), see cover photo. The presence of dietary carotenoids in body tissues of wild mallard ducklings is shown to have a relationship with their health status and parasite burden in the paper by Butler and McGraw [20]. Toomey and McGraw [21] present a description of the effects of dietary carotenoid intake on the accumulation of carotenoids in the oil-droplets in the retinas wild house finches. Their data indicate highly specific mechanisms of retinal carotenoid metabolism and accumulation, as well as differential rates of turnover among different retinal carotenoids. The breadth of the natural occurrence of carotenoids, the diversity of their functions, and the host of scientific disciplines essential to their study is evidenced in the papers of this Fourth Highlight Issue on Carotenoids. It is this vigor and cross-disciplinary character in the study of carotenoids that many of us find so appealing to our fundamental curiosity. We are confident that these characteristics will continue to attract and inspire young scientists and researchers, as well as veteran scientists to join us in the pursuit of understanding this colorful, ubiquitous, and sometimes even confusing class of phytopigments. They promise to improve our health, increase our ability to produce greater quantities of nutritious foods, as well as enliven our lives with their brilliant palette. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21]
Shmarakov et al., Arch. Biochem. Biophys. 504 (2010) 3–10. Harrison, Arch. Biochem. Biophys. 504 (2010) 11–16. Hosokawa et al., Arch. Biochem. Biophys. 504 (2010) 17–25. Palozza et al., Arch. Biochem. Biophys. 504 (2010) 26–33. Scarmo et al., Arch. Biochem. Biophys. 504 (2010) 34–39. Gellerman, Ermakov, Arch. Biochem. Biophys. 504 (2010) 40–49. Bone et al., Arch. Biochem. Biophys. 504 (2010) 50–55. Li et al., Arch. Biochem. Biophys. 504 (2010) 56–60. Subczynski et al., Arch. Biochem. Biophys. 504 (2010) 61–66. Betterle, Arch. Biochem. Biophys. 504 (2010) 67–77. Ruban, Johnson, Arch. Biochem. Biophys. 504 (2010) 78–85. Zhu, Arch. Biochem. Biophys. 504 (2010) 86–99. Edge et al., Arch. Biochem. Biophys. 504 (2010) 100–103. Vallabhaneni et al., Arch. Biochem. Biophys. 504 (2010) 104–111. Vallabhaneni, Wurtzel, Arch. Biochem. Biophys. 504 (2010) 112–117. Rodriguez-Concepcion, Arch. Biochem. Biophys. 504 (2010) 118–122. Jamil et al., Arch. Biochem. Biophys. 504 (2010) 123–131. Zhu et al., Arch. Biochem. Biophys. 504 (2010) 132–141. LaFountain et al., Arch. Biochem. Biophys. 504 (2010) 142–153. Butler, McGraw, Arch. Biochem. Biophys. 504 (2010) 154–160. Toomey, McGraw, Arch. Biochem. Biophys. 504 (2010) 161–168.
John T. Landrum Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States E-mail address: landrumj@fiu.edu Xiang-Dong Wang Nutrition and Cancer Biology Laboratory, Jean Mayer USDA HNRCA at Tufts University, 711 Washington Street, Boston, MA 02111-1524, United States E-mail address: [email protected] Eleanore T. Wurtzel Department of Biological Sciences, Lehman College, The City University of New York, NY 10468, United States E-mail address: [email protected]
Contents lists available at ScienceDirect
Archives of Biochemistry and Biophysics journal homepage: www.elsevier.com/locate/yabbi
Guest editors’ introduction
Guest editorial This highlight issue on carotenoids represents the fourth such in a series published at nearly 3 year intervals in concert with the occurrence of the Gordon Research Conference on carotenoids. The first highlight issue was published in January of 2001 and subsequent highlight issues appeared in October of 2004 and September of 2007. Between January 17 and 22 of 2010, the seventh triennial gathering of researchers from around the globe occurred in Ventura where the advances in the science of carotenoids and their functions were the focus of intense discussion. The highlight issues although timed to coincide with the GRC are not proceedings of these conferences. These highlight issues serve as an opportunity for researchers to layout the progress in this field through the presentation of original research papers and reviews at a time when many have invested a significant effort, ‘taking stock’ and assessing the state of carotenoid science. All of the papers published in this highlight issue have undergone the rigorous peer review process distinctive of ABB publications. The past highlight issues have become significant resources to carotenoid scientists and researchers as well as for those new to the subject and wishing to understand the breadth and scope of carotenoid science. We hope that this Fourth Highlight Issue on carotenoids will stand well among those issues with timely and significant presentations on the developments in this exciting field of study. That carotenoids in the human diet are associated with improved health and they have been implicated as exerting their effects through anti-oxidant activity, up- and down-regulation of proteins, induction of apoptosis, as well as photo-protection of tissues experiencing actinic stress is widely known. Naturally occurring carotenoids have, for most of the past century, been grouped as either pro-vitamin or non-pro-vitamin A carotenoids. This reflects the human perspective and significance that vitamin A has for human health and the essential role of vitamin A in development and growth, as well as vision. The discovery of the genes responsible for cleavage of carotenoids via the production of the cleavage enzymes, beta-carotene-15,150 -monooxygenase (BCMO1) and beta-carotene-90 ,100 -monooxygenase (BCMO2), has opened a new chapter in this story. The site of BCMO expression and action are naturally of great importance. Shmarakov et al. [1] have followed BCMO1 and BCMO2 expression in the livers of wild type and BCMO1-deficient mice demonstrating the importance of the liver as a cellular site for beta-carotene metabolism. The broader importance of intact carotenoids as well as their apo-carotenoid cleavage products in humans, both related and unrelated to their pro-vitamin A function, has become increasingly evident during the last 10 years. How important the eccentric cleavage of betacarotene is to its metabolism, and to the regulation of vitamin A 0003-9861/$ - see front matter Ó 2010 Published by Elsevier Inc. doi:10.1016/j.abb.2010.10.003
generally, is now a problem that can be specifically investigated. Apo-13-carotenone, formed by the BCMO2 eccentric cleavage of beta-carotene acts is shown by the work of Eroglu et al. [2] to be a potent antagonist of activated RxR-a a retinoic acid receptor. RXR’s are nuclear receptor proteins that can modulate the transcriptional activity of target genes by binding to gene promoters. Fucoxanthin, the abundant xanthophyll found in brown algae, and as such, a component of the Asian diet has come under investigation to provide us an understanding of the basis for health claims associated with its consumption. Hosokawa et al. [3] describes evidence that fucoxanthin can differentially influence mRNA expression in adipocytes of lean versus obese mice providing a molecular clue to its role. In a review of the action of lycopene in atherosclerosis prevention, Palozza et al. [4] describes the progress that has been made in relating the influence of lycopene on atherosclerosis at a molecular level through the study of its effects on critical pathways in cell lines. The importance of carotenes in dermal tissues and their role as photoprotectants has been a challenging problem to address. Although carotenoids have been used to treat individuals with extreme dermal sensitivity to light for several decades the natural levels of individual carotenoids and their functionality has been hard to address in vivo, especially humans. In their paper, Scarmo et al. [5] provide new evidence on this role of carotenes in the skin. The practical hurdles associated with wide scale in vivo measurement of carotenoids in skin have benefitted through the innovative use of resonance Raman spectroscopy as developed by Gellerman. In their review, Gellerman and Ermakov provide a picture of the specificity and quantitative use of Raman spectroscopy for assessing dermal carotenoid levels [6]. The presence of high concentrations of lutein and zeaxanthin, the principle components of the macular pigment, pose several challenging problems to researchers. In particular, how are these carotenoids specifically transported and accumulated within the human macula? And, what function do these carotenoids serve within the retina? Bone et al. [7], show that the responsiveness of the macular pigment to modulation by diet is influenced by dose during supplementation studies. Li et al. [8] provide in vitro evidence that the xanthophylls of the macular pigment function as singlet oxygen scavengers. Electron Spin Resonance Spectroscopy (EPR) can be a probe of the localization of carotenoids in membranes and their accessibility by oxygen. Subczynski et al. [9] give us an elegant description of the use of EPR to assess the potential location of lipophilic carotenoids within membrane structures of the retina and their influence on those membranes. In addition to chlorophylls, several carotenoids are among the natural pigments essential in the photosynthetic light harvesting proteins of higher plants and other photosynthetic organisms. The functions of carotenoids in light harvesting complexes are
2
Guest editors’ introduction / Archives of Biochemistry and Biophysics 504 (2010) 1–2
much less clearly understood than those of the chlorophylls. Recognition that the natural, minor elaborations in the structural motifs of the xanthophyll end-groups can regulate the roles played by specific xanthophylls has been explored in a paper by Betterle et al. [10]. They show us evidence that binding of zeaxanthin to the antenna protein monomer, LHCB6, uniquely increases photoprotection by down-regulating both the chlorophyll singlet state and consequent singlet oxygen production. In their review, [11], Ruban and Johnson address the distinct functions of the xanthophyll components in the light harvesting proteins of higher plants. They present a persuasive argument that xanthophyll hydrophobicity/polarity can explain the need for xanthophyll variety within the light harvesting proteins. This work sheds further light on the recently demonstrated diverse functions of these carotenoids within the photosynthetic proteins. Photoprotection by carotenoids is a dominant and widely observed natural theme. Zhu et al.’s study of the cyanobacterium Synechococcus sp. helps define more clearly the role that xanthophyll carotenoids have in protection against photoinhibition and oxidative stress [12]. Studying this cyanobacterium they have been able to demonstrate that mRNA levels of most genes involved in carotenogenisis increase after exposure to high levels of light. Independent of the origin of radical oxygen species (ROS) within cells, the ability of carotenoids to intercept and ameliorate their effects is a major role believed essential to their ability to act as protectants and anti-oxidants. In their paper, Edge et al. [13] present pulse radiolysis data that carotenoid species are able to protect guanosine in vitro against oxidation by ROS. Vallabhaneni et al. [14] teach us about the expression of the carotenoid dioxygenase enzymes (CCD’s) of the grass species maize, rice, and sorghum and how the CCD’s in turn regulate the essential physiological and developmental roles occupied by carotenoids and apocarotenoids. In particular, the mapping of CCD’s to specific chromosome locations opens a door to the metabolic engineering of maize endosperm. Abscisic acid, a product produced in higher plants from the precursors of carotenoid synthesis, plays a critical role in drought resistance. In a second paper, Vallabhaneni and Wurtzel [15] have investigated expression of the genes that control abscisic acid levels in maize root in response to dehydration and rehydration. We see that the supply of carotenoid precursors, essential for carotenoid biosynthesis, has broad importance to the development and survival of plants. In a review, Rodriguez-Concepcion [16] describes progress that has been made in understanding how manipulation of how the methylerythritol (MEP) pathway impacts carotenoid biosynthesis. The underlying central importance of MEP-derived precursors fundamentally influences the biosynthesis of other isoprenoids as well as carotenoids. In many parts of the world, food production is limited by the effects of parasitic fungi that damage or kill infected plants. Rice, in particular, is one of the food plants infected by Striga infection. Jamil et al. [17] demonstrate that the ability of carotenoid biosynthesis inhibitors to influence the success of Striga germination may have potential to reduce the damage done by this parasite. The commercial significance of carotenoids in their role as pigments in plants and animals cannot be overstated. They influence consumer acceptance of products as well as the viability of the organisms. Altering and improving pigmentation in plants, particularly flowers has been a major motivation into the study of carotenoid biosynthesis. In their review of the regulation of carotenoid pigmentation in flowers, Zhu et al. [18] describe a number of different regulatory mechanisms including the transcriptional regulation of genes essential to carotenoid biosynthesis and also the mechanisms responsible for control of carotenoid storage. The presence of diet derived carotenoid pigments in animals and their metabolism is important to coloration that is especially significant
among birds where pigmentation influences success in mate selection and breeding. Carotenoid levels are also an indicator of the health status in birds. LaFountain et al. [19] show us that after a century of study, the identity of pigments in bird plumage remains an important and vigorous topic of research. They provide us fresh insight into avian carotenoid metabolism. In their paper they describe the presence of a novel methoxy carotenoid in the plumage of the brilliant, burgundy-colored Pompadour Continga (Xipholena punicea), see cover photo. The presence of dietary carotenoids in body tissues of wild mallard ducklings is shown to have a relationship with their health status and parasite burden in the paper by Butler and McGraw [20]. Toomey and McGraw [21] present a description of the effects of dietary carotenoid intake on the accumulation of carotenoids in the oil-droplets in the retinas wild house finches. Their data indicate highly specific mechanisms of retinal carotenoid metabolism and accumulation, as well as differential rates of turnover among different retinal carotenoids. The breadth of the natural occurrence of carotenoids, the diversity of their functions, and the host of scientific disciplines essential to their study is evidenced in the papers of this Fourth Highlight Issue on Carotenoids. It is this vigor and cross-disciplinary character in the study of carotenoids that many of us find so appealing to our fundamental curiosity. We are confident that these characteristics will continue to attract and inspire young scientists and researchers, as well as veteran scientists to join us in the pursuit of understanding this colorful, ubiquitous, and sometimes even confusing class of phytopigments. They promise to improve our health, increase our ability to produce greater quantities of nutritious foods, as well as enliven our lives with their brilliant palette. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21]
Shmarakov et al., Arch. Biochem. Biophys. 504 (2010) 3–10. Harrison, Arch. Biochem. Biophys. 504 (2010) 11–16. Hosokawa et al., Arch. Biochem. Biophys. 504 (2010) 17–25. Palozza et al., Arch. Biochem. Biophys. 504 (2010) 26–33. Scarmo et al., Arch. Biochem. Biophys. 504 (2010) 34–39. Gellerman, Ermakov, Arch. Biochem. Biophys. 504 (2010) 40–49. Bone et al., Arch. Biochem. Biophys. 504 (2010) 50–55. Li et al., Arch. Biochem. Biophys. 504 (2010) 56–60. Subczynski et al., Arch. Biochem. Biophys. 504 (2010) 61–66. Betterle, Arch. Biochem. Biophys. 504 (2010) 67–77. Ruban, Johnson, Arch. Biochem. Biophys. 504 (2010) 78–85. Zhu, Arch. Biochem. Biophys. 504 (2010) 86–99. Edge et al., Arch. Biochem. Biophys. 504 (2010) 100–103. Vallabhaneni et al., Arch. Biochem. Biophys. 504 (2010) 104–111. Vallabhaneni, Wurtzel, Arch. Biochem. Biophys. 504 (2010) 112–117. Rodriguez-Concepcion, Arch. Biochem. Biophys. 504 (2010) 118–122. Jamil et al., Arch. Biochem. Biophys. 504 (2010) 123–131. Zhu et al., Arch. Biochem. Biophys. 504 (2010) 132–141. LaFountain et al., Arch. Biochem. Biophys. 504 (2010) 142–153. Butler, McGraw, Arch. Biochem. Biophys. 504 (2010) 154–160. Toomey, McGraw, Arch. Biochem. Biophys. 504 (2010) 161–168.
John T. Landrum Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States E-mail address: landrumj@fiu.edu Xiang-Dong Wang Nutrition and Cancer Biology Laboratory, Jean Mayer USDA HNRCA at Tufts University, 711 Washington Street, Boston, MA 02111-1524, United States E-mail address: [email protected] Eleanore T. Wurtzel Department of Biological Sciences, Lehman College, The City University of New York, NY 10468, United States E-mail address: [email protected]