Vitellogenin

Last updated
Vitellinogen, open beta-sheet
Identifiers
SymbolDUF1943
Pfam PF09172
InterPro IPR015255
SCOP2 1lsh / SCOPe / SUPFAM
Available protein structures:
Pfam   structures / ECOD  
PDB RCSB PDB; PDBe; PDBj
PDBsum structure summary

Vitellogenin (VTG or less popularly known as VG) (from Latin vitellus, yolk, and genero, I produce) is a precursor of egg yolk that transports protein and some lipid from the liver through the blood to the growing oocytes where it becomes part of the yolk. Normally, it is only found in the blood or hemolymph of females, and can therefore be used as a biomarker in vertebrates of exposure to environmental estrogens which stimulate elevated levels in males as well as females. [1] "Vitellogenin" is a synonymous term for the gene and the expressed protein. The protein product is classified as a glycolipoprotein, having properties of a sugar, fat and protein. It belongs to a family of several lipid transport proteins.

Contents

Vitellogenin is an egg yolk precursor found in the females of nearly all oviparous species including fish, amphibians, reptiles, birds, most invertebrates, and monotremes. [2] Vitellogenin is the precursor of the lipoproteins and phosphoproteins that make up most of the protein content of yolk. In the presence of estrogenic endocrine disruptive chemicals (EDCs), male fish can express the gene in a dose dependent manner. This gene expression in male fish can be used as a molecular marker of exposure to estrogenic EDCs. [3]

Function

Vitellogenin provides the major egg yolk protein that is a source of nutrients during early development of egg-laying (oviparous) vertebrates and invertebrates. Although vitellogenin also carries some lipid for deposition in the yolk, the primary mechanism for deposition of yolk lipid is instead via VLDLs, at least in birds and reptiles. [4] Vitellogenin precursors are multi-domain apolipoproteins (proteins that bind to lipids to form lipoproteins), that are cleaved into distinct yolk proteins. Different vitellogenin proteins exist, which are composed of variable combinations of yolk protein components; however, the cleavage sites are conserved.[ citation needed ]

Components

In vertebrates, a complete vitellogenin is composed of:

N-terminal lipid transport domain

Vitellogenin lipid transport domain, N-terminal
Identifiers
SymbolVitellogenin_N
Pfam PF01347
InterPro IPR001747
SMART SM00638
PROSITE PS51211
SCOP2 1llv / SCOPe / SUPFAM
OPM superfamily 254
OPM protein 1lsh
Available protein structures:
Pfam   structures / ECOD  
PDB RCSB PDB; PDBe; PDBj
PDBsum structure summary

This particular domain represents a conserved region found in several lipid transport proteins, including vitellogenin, microsomal triglyceride transfer protein and apolipoprotein B-100. [7]

Vesicle trafficking

This particular domain, the Vitellogenin lipid transport domain, is also found in the Microsomal triglyceride transfer protein (MTTP) and in Apolipoprotein B. It aids cell trafficking and export of cargo.[ citation needed ]

Microsomal triglyceride transfer protein (MTTP)

Microsomal triglyceride transfer protein (MTTP) is an endoplasmic reticulum lipid transfer protein involved in the biosynthesis and lipid loading of apolipoprotein B. MTTP is also involved in the late stage of CD1d trafficking in the lysosomal compartment, CD1d being the MHC I-like lipid antigen presenting molecule. [8]

Apolipoprotein B

Apolipoprotein B can exist in two forms: B-100 and B-48. Apolipoprotein B-100 is present on several lipoproteins, including very low-density lipoproteins (VLDL), intermediate density lipoproteins (IDL) and low density lipoproteins (LDL), and can assemble VLDL particles in the liver. [9] Apolipoprotein B-100 has been linked to the development of atherosclerosis.

ApoB is ancestrally universal to all animals, as homologs are found in choanoflagellates. The insect homolog is called apolipophorin I/II. [10]

Human proteins containing this domain

APOB (see native LDL-ApoB structure at 37°C on YouTube); [11] MTTP;

Honey bees

Honey bees deposit vitellogenin molecules in fat bodies in their abdomen and heads. The fat bodies apparently act as a food storage reservoir. The glycolipoprotein vitellogenin has additional functionality as it acts as an antioxidant to prolong Queen bee and forager lifespan as well as a hormone that affects future foraging behavior. [12] The health of a honey bee colony is dependent upon the vitellogenin reserves of the nurse bees – the foragers having low levels of vitellogenin. As expendable laborers, the foragers are fed just enough protein to keep them working their risky task of collecting nectar and pollen. Vitellogenin levels are important during the nest stage and thus influence honey bee worker division of labor.[ citation needed ]

A nurse bee's vitellogenin titer that developed in the first four days after emergence, affects its subsequent age to begin foraging and whether it preferentially forages for nectar or pollen. If young workers are short on food their first days of life, they tend to begin foraging early and preferentially for nectar. If they are moderately fed, they forage at normal age preferentially for nectar. If they are abundantly fed, immediately after emergence, their vitellogenin titer is high and they begin foraging later in life, preferentially collecting pollen. Pollen is the only available protein source for honey bees. [13]

Juvenile hormone feedback loop

For the majority of the investigated insect species it has been documented that juvenile hormone stimulates the transcription of the vitellogenin genes and the consequent control of vitellogenin production (cf. Engelmann, 1983; Wyatt and Davey, 1996). [14] [15]

The vitellogenin expression is part of a regulatory feedback loop that enables vitellogenin and juvenile hormone to mutually suppress each other. Vitellogenin and juvenile hormone likely work antagonistically in the honey bee to regulate the honey bees development and behavior. Suppression of one leads to high titers of the other. [16]

It is likely that the balance between vitellogenin and juvenile hormone levels is also involved in swarming behavior. [17]

Juvenile hormone levels drop in honey bee colonies pre-swarming and it is expected that vitellogenin levels would therefore rise. One may surmise, that swarming bees would want to pack along as much vitellogenin as possible to extend their lifespan and to be able to quickly build a new nest. [ citation needed ]

Evolution

Vertebrates started off with a single copy of the vitellogenin gene, and the bird-mammalian and amphibian lineages each experienced duplications that gave rise to the modern genes. With the exception of monotremes, mammals have all their vitellogenin genes turned into pseudogenes, although the region syntenic to bird VIT1-VIT2-VIT3 can still be found and aligned. [18] In monotremes just one of the genes remained functional. [19]

See also

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Vitellogenesis is the process of yolk protein formation in the oocytes during sexual maturation. The term vitellogenesis comes from the Latin vitellus. Yolk proteins, such as Lipovitellin and Phosvitin, provides maturing oocytes with the metabolic energy required for development. Vitellogenins are the precursor proteins that lead to yolk protein accumulation in the oocyte. In vertebrates, estrogen and vitellogenin production have a positive correlation. When estrogen production in the ovary is increased via the activation of the hypothalmo-pituitary axis it leads to heightened vitellogenin production in the liver. Vitellogenin production in the liver is the first step of vitellogenesis. Once Vitellogenins are released into the blood stream where they are then transported to the growing oocyte where they lead to yolk protein production. The transport of vitellogenins into the maturing oocyte is done via endocytosis mediated by a receptor which is a low-density lipoprotein receptor (LDLR). Yolk is a lipoprotein composed of proteins, phospholipids and neutral fats along with a small amount of glycogen. The yolk is synthesised in the liver of the female parent in soluble form. Through circulation it is transported to the follicle cells that surround the maturing ovum, and is deposited in the form of yolk platelets and granules in the ooplasm. The mitochondria and Golgi complex are said to bring about the conversion of the soluble form of yolk into insoluble granules or platelets.

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References

  1. ↑ "Definition of VITELLOGENIN".
  2. ↑ Robinson, Richard (18 March 2008). "For Mammals, Loss of Yolk and Gain of Milk Went Hand in Hand". PLOS Biology. 6 (3): e77. doi: 10.1371/journal.pbio.0060077 . PMC   2267822 . PMID   20076706.
  3. ↑ Tran, Thi Kim Anh; Yu, Richard Man Kit; Islam, Rafiquel; Nguyen, Thi Hong Tham; Bui, Thi Lien Ha; Kong, Richard Yuen Chong; O'Connor, Wayne A.; Leusch, Frederic D.L.; Andrew-Priestley, Megan; MacFarlane, Geoff R. (May 2019). "The utility of vitellogenin as a biomarker of estrogenic endocrine disrupting chemicals in molluscs". Environmental Pollution. 248: 1067–1078. Bibcode:2019EPoll.248.1067T. doi:10.1016/j.envpol.2019.02.056. hdl: 10072/386355 . PMID   31091639. S2CID   92464394.
  4. ↑ Price, E. R. (2017). "The physiology of lipid storage and use in reptiles". Biological Reviews. 92 (3): 1406–1426. doi: 10.1111/brv.12288 . PMID   27348513. S2CID   7570705.
  5. ↑ Finn, Roderick Nigel (1 June 2007). "Vertebrate Yolk Complexes and the Functional Implications of Phosvitins and Other Subdomains in Vitellogenins1". Biology of Reproduction. 76 (6): 926–35. doi: 10.1095/biolreprod.106.059766 . PMID   17314313.
  6. ↑ Thompson, James R.; Banaszak, Leonard J. (July 2002). "Lipid−Protein Interactions in Lipovitellin". Biochemistry. 41 (30): 9398–409. doi:10.1021/bi025674w. PMID   12135361.
  7. ↑ Anderson TA, Levitt DG, Banaszak LJ (July 1998). "The structural basis of lipid interactions in lipovitellin, a soluble lipoprotein". Structure. 6 (7): 895–909. doi: 10.1016/S0969-2126(98)00091-4 . PMID   9687371.
  8. ↑ Sagiv, Yuval; Bai, Li; Wei, Datsen G.; Agami, Reuven; Savage, Paul B.; Teyton, Luc; Bendelac, Albert (16 April 2007). "A distal effect of microsomal triglyceride transfer protein deficiency on the lysosomal recycling of CD1d". The Journal of Experimental Medicine. 204 (4): 921–8. doi:10.1084/jem.20061568. PMC   2118556 . PMID   17403933.
  9. ↑ Olofsson SO, Borèn J (November 2005). "Apolipoprotein B: a clinically important apolipoprotein which assembles atherogenic lipoproteins and promotes the development of atherosclerosis". Journal of Internal Medicine. 258 (5): 395–410. doi: 10.1111/j.1365-2796.2005.01556.x . PMID   16238675. S2CID   19885776.
  10. ↑ Huebbe P, Rimbach G (August 2017). "Evolution of human apolipoprotein E (APOE) isoforms: Gene structure, protein function and interaction with dietary factors". Ageing Research Reviews. 37: 146–161. doi:10.1016/j.arr.2017.06.002. PMID   28647612. S2CID   3758905.
  11. ↑ Kumar V, Butcher SJ, Öörni K, Engelhardt P, Heikkonen J, et al. (2011) Three-Dimensional cryoEM Reconstruction of Native LDL Particles to 16Å Resolution at Physiological Body Temperature.
  12. ↑ Oliver, Randy (August 2007). "Fat Bees Part 1". American Bee Journal.[ verification needed ]
  13. ↑ Randy, Oliver (Aug 2007). "Fat Bees - Part 1". American Bee Journal: 714.
  14. ↑ Engelmann F (1983). "Vitellogenesis controlled by juvenile hormone". In Downer RG, Laufer H (eds.). Endocrinology of Insects. New York: Alan R. Liss. pp. 259–270.
  15. ↑ Wyatt GR, Davey KG (1996). "Cellular and Molecular Actions of Juvenile Hormone. II. Roles of Juvenile Hormone in Adult Insects". Advances in Insect Physiology Volume 26. Vol. 26. pp. 1–155. doi:10.1016/S0065-2806(08)60030-2. ISBN   9780120242269.
  16. ↑ Hrassnigg, Norbert; Crailsheim, Karl (2005). "Differences in drone and worker physiology in honeybees (Apis mellifera)" (PDF). Apidologie. 36 (2): 255–277. doi: 10.1051/apido:2005015 .
  17. ↑ Zeng, Zhijiang; Huang, Zachary Y.; Qin, Yuchuan; Pang, Huizhong (1 April 2005). "Hemolymph Juvenile Hormone Titers in Worker Honey Bees under Normal and Preswarming Conditions". Journal of Economic Entomology. 98 (2): 274–278. doi: 10.1603/0022-0493-98.2.274 . PMID   15889713. S2CID   198130721.
  18. ↑ Brawand, David; Wahli, Walter; Kaessmann, Henrik; Phillippe, Hervé (18 March 2008). "Loss of Egg Yolk Genes in Mammals and the Origin of Lactation and Placentation". PLOS Biology. 6 (3): e63. doi: 10.1371/journal.pbio.0060063 . PMC   2267819 . PMID   18351802.
  19. ↑ Yang Zhou, Linda Shearwin-Whyatt, Guojie Zhang et al.: Platypus and echidna genomes reveal mammalian biology and evolution. In: Nature . 6 January 2021. doi:10.1038/s41586-020-03039-0. See also:

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