Haptoglobin-related protein

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HPR
Identifiers
AliasesHPR, A-259H10.2, HP
External IDsOMIM: 140210 HomoloGene: 122206 GeneCards: HPR
Orthologs
SpeciesHumanMouse
Entrez

3250

n/a

Ensembl

ENSG00000261701

n/a

UniProt

P00739

n/a

RefSeq (mRNA)

NM_020995
NM_001384360

n/a

RefSeq (protein)

NP_066275

n/a

Location (UCSC)Chr 16: 72.06 – 72.08 Mbn/a
PubMed search[2]n/a
Wikidata
View/Edit Human

Haptoglobin-related protein (Hpr) is a serum protein that binds to haemoglobin of red blood cells and is present only in primates.[3] It acts as a molecule of innate immunity in association with apolipoprotein L1 (ApoL 1)-containing high-density lipoprotein (HDL) particles.[4] In humans, together with related serum protein, haptoglobin, it acts as a cell-killing agent as part of the trypanolytic factor against the protozoan parasite Trypanosoma brucei thereby providing natural resistance to African sleeping sickness.[5] It is produced from the gene HPR that is located on the long arm of chromosome 16 within the HP (for haptoglobin) gene cluster.[6]

History[edit]

Haptoglobin was discovered as a "plasma substance" in 1938 by French biochemists Max-Fernand Jayle and Michel Polonovski.[7][8] The gene (later denoted as HP or Hp) was identified by British biochemist Oliver Smithies and his mentor, Canadian geneticist Norma Ford Walker in 1956.[9][10] Smithies and Walker discovered that the gene could exist in two allelic autosomal genes, Hp1and Hp2.[11] Additional allele and associated genes were subsequently identified.[12]

In 1983, Italian geneticist Riccardo Cortese and his team, led by Giovanni Raugei, sequenced the human Hp gene and discovered that there is a closely related gene in the vicinity.[13] As they reported: "Southern blot analysis provides evidence for the presence of more than one haptoglobin gene per haploid genome and confirms that there is restriction site polymorphism at this locus."[14] The next year, Smithies team, then at the University of Wisconsin, US, identified the same new gene and gave the name Hpr (for haptoglobin-related).[15] The protein, Hpr, was determined by New York University Medical Center scientists Madhavi Muranjan, Victor Nussenzweig and Stephen Tomlinson in 1998.[16]

Structure[edit]

Hpr is 45-kDa in molecular size. It is structurally similar to haptoglobin with over 90% amino acid identity but in lesser concentration in the blood.[16] Like haptoglobin, it is composed of α- and β-chain which are connected through a disulfide bond.[17] It lacks a glycosylation site and a cysteine involved in inter-α-chain bonding that are present in haptoglobin. Haptoglobin has either 1 (Hp1 genotype) or 2 (Hp2 genotype) of such cysteines. The α-chain of Hpr contains a hydrophobic signal peptide, which is absent in haptoglobin. The signal peptide makes Hpr associated with ApoL 1.[4]

The HPR gene originated from duplication of the HP gene and is present at 2.2 kilobase pairs downstream of the HP gene on the long arm of chromosome 16 in humans.[6][16] HPR is 94% similar in DNA sequence to HP gene.[5] The gene is also present in apes and Old World monkeys in which it is created from a gene triplication (additional HP gene is present) during early evolution of the primate group.[3] Some humans have additional copy of HPR gene.[5] The gene product has 28-amino acid differences, 16 of which occur in the β chain. HPR has longer intron, 9.5 kilobase pairs compared to 1.3 kilobase pairs of that of haptoglobin. It contains a retrovirus-like element that is not found in haptoglobin.[18]

Function[edit]

Haptoglobin is known to be a high affinity-binding protein for haemoglobin during red blood cell destruction (haemolysis). Since Hpr is an accessory protein, it was initially believed that it that does not bind haemoglobin.[16] However, an experiment in 2006 showed that it binds to haemoglobin with same affinity as haptoglobin.[4] Unlike haptoglobin which binds to the scavenger receptor CD163, a protein on macrophages that is critical for eliminating bacterial infection,[19] Hpr has no affinity for the receptor indicating that its primary role is different.[16][20]

The major function of Hpr is protection from infection with Trypanosoma brucei to provide natural resistance to African sleeping sickness.[5] Together with haptolglobin and apoliproproteins, it makes up a trypanolytic factor TLF 1 in the blood of primates that can kill invading the animal strain of T. brucei (specifically T. b. brucei).[21] However, chimpanzees have mutated Hpr so that their serum cannot kill T. b. brucei.[22] The human strains, T. b. rhodesiense and T. b. gambiense have acquired resistance to TLF indicating an evolutionary arms race between primates and the protozoan parasite.[23] Hpr is also involved in TLF 2 in which its function is not yet understood.[5]

References[edit]

  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000261701 – Ensembl, May 2017
  2. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  3. ^ a b McEvoy SM, Maeda N (1988-10-25). "Complex events in the evolution of the haptoglobin gene cluster in primates". The Journal of Biological Chemistry. 263 (30): 15740–15747. doi:10.1016/S0021-9258(19)37650-1. ISSN 0021-9258. PMID 3170608.
  4. ^ a b c Nielsen MJ, Petersen SV, Jacobsen C, Oxvig C, Rees D, Møller HJ, et al. (2006-10-15). "Haptoglobin-related protein is a high-affinity hemoglobin-binding plasma protein". Blood. 108 (8): 2846–2849. doi:10.1182/blood-2006-05-022327. ISSN 0006-4971. PMID 16778136.
  5. ^ a b c d e Hardwick RJ, Ménard A, Sironi M, Milet J, Garcia A, Sese C, et al. (2014). "Haptoglobin (HP) and Haptoglobin-related protein (HPR) copy number variation, natural selection, and trypanosomiasis". Human Genetics. 133 (1): 69–83. doi:10.1007/s00439-013-1352-x. ISSN 1432-1203. PMC 3898332. PMID 24005574.
  6. ^ a b Koda Y, Soejima M, Yoshioka N, Kimura H (1998). "The haptoglobin-gene deletion responsible for anhaptoglobinemia". American Journal of Human Genetics. 62 (2): 245–252. doi:10.1086/301701. ISSN 0002-9297. PMC 1376878. PMID 9463309.
  7. ^ Shih AW, McFarlane A, Verhovsek M (2014). "Haptoglobin testing in hemolysis: measurement and interpretation". American Journal of Hematology. 89 (4): 443–447. doi:10.1002/ajh.23623. ISSN 1096-8652. PMID 24809098.
  8. ^ "Haptoglobins". New England Journal of Medicine. 266 (11): 569–570. 1962-03-15. doi:10.1056/NEJM196203152661115. ISSN 0028-4793.
  9. ^ Smithies O, Walker NF (1956-09-29). "Notation for serum-protein groups and the genes controlling their inheritance". Nature. 178 (4535): 694–695. Bibcode:1956Natur.178..694S. doi:10.1038/178694a0. ISSN 0028-0836. PMID 13369501.
  10. ^ Mäkelä O, Eriksson A, Lehtovaara R (2008-08-06). "On the inheritance of the haptoglobin serum groups". Acta Genetica et Statistica Medica. 9 (2): 149–166. doi:10.1159/000151092. ISSN 0365-2785. JSTOR 45103594. PMID 14420139.
  11. ^ Giblett ER (1964-01-01). "Variant Haptoglobin Phenotypes". Cold Spring Harbor Symposia on Quantitative Biology. 29: 321–326. doi:10.1101/SQB.1964.029.01.034. ISSN 0091-7451. PMID 14278478.
  12. ^ Van der straten A, Cabezón T, Resibois A, Bollen A (1985-01-01), Peeters H (ed.), Structure of the Human Haptoglobin Pseudogene, Protides of the Biological Fluids, vol. 33, Elsevier, pp. 151–155, doi:10.1016/B978-0-08-033215-4.50039-X, ISBN 978-0-08-033215-4, retrieved 2024-01-26
  13. ^ Bensi G, Raugei G, Klefenz H, Cortese R (1985). "Structure and expression of the human haptoglobin locus". The EMBO Journal. 4 (1): 119–126. doi:10.1002/j.1460-2075.1985.tb02325.x. PMC 554159. PMID 4018023.
  14. ^ Raugei G, Bensi G, Colantuoni V, Romano V, Santoro C, Costanzo F, et al. (1983-09-10). "Sequence of human haptoglobin cDNA: evidence that the alpha and beta subunits are coded by the same mRNA". Nucleic Acids Research. 11 (17): 5811–5819. doi:10.1093/nar/11.17.5811. ISSN 0305-1048. PMC 326319. PMID 6310515.
  15. ^ Maeda N, Yang F, Barnett DR, Bowman BH, Smithies O (1984). "Duplication within the haptoglobin Hp2 gene". Nature. 309 (5964): 131–135. Bibcode:1984Natur.309..131M. doi:10.1038/309131a0. ISSN 1476-4687. PMID 6325933.
  16. ^ a b c d e Muranjan M, Nussenzweig V, Tomlinson S (1998-02-13). "Characterization of the human serum trypanosome toxin, haptoglobin-related protein". The Journal of Biological Chemistry. 273 (7): 3884–3887. doi:10.1074/jbc.273.7.3884. ISSN 0021-9258. PMID 9461571.
  17. ^ Imrie HJ, Fowkes FJ, Migot-Nabias F, Luty AJ, Deloron P, Hajduk SL, et al. (2012). "Individual variation in levels of haptoglobin-related protein in children from Gabon". PLOS ONE. 7 (11): e49816. Bibcode:2012PLoSO...749816I. doi:10.1371/journal.pone.0049816. ISSN 1932-6203. PMC 3502254. PMID 23185445.
  18. ^ Maeda N (1985-06-10). "Nucleotide sequence of the haptoglobin and haptoglobin-related gene pair. The haptoglobin-related gene contains a retrovirus-like element". The Journal of Biological Chemistry. 260 (11): 6698–6709. doi:10.1016/S0021-9258(18)88836-6. ISSN 0021-9258. PMID 2987228.
  19. ^ Fabriek BO, van Bruggen R, Deng DM, Ligtenberg AJ, Nazmi K, Schornagel K, et al. (January 2009). "The macrophage scavenger receptor CD163 functions as an innate immune sensor for bacteria" (PDF). Blood. 113 (4): 887–92. doi:10.1182/blood-2008-07-167064. PMID 18849484. S2CID 4811741.
  20. ^ Skytthe MK, Sørensen AL, Hennig D, Sandberg MB, Rasmussen LM, Højrup P, et al. (2022-10-03). "Haptoglobin-related protein in human plasma correlates to haptoglobin concentrations and phenotypes". Scandinavian Journal of Clinical and Laboratory Investigation. 82 (6): 461–466. doi:10.1080/00365513.2022.2122076. ISSN 0036-5513. PMID 36129375. S2CID 252406321.
  21. ^ Drain J, Bishop JR, Hajduk SL (2001-08-10). "Haptoglobin-related protein mediates trypanosome lytic factor binding to trypanosomes". The Journal of Biological Chemistry. 276 (32): 30254–30260. doi:10.1074/jbc.M010198200. ISSN 0021-9258. PMID 11352898.
  22. ^ Seed JR, Sechelski JB, Loomis MR (1990). "A survey for a trypanocidal factor in primate sera". The Journal of Protozoology. 37 (5): 393–400. doi:10.1111/j.1550-7408.1990.tb01163.x. ISSN 0022-3921. PMID 2120433.
  23. ^ Capewell P, Cooper A, Clucas C, Weir W, Macleod A (2015). "A co-evolutionary arms race: trypanosomes shaping the human genome, humans shaping the trypanosome genome". Parasitology. 142 (Suppl 1): S108–119. doi:10.1017/S0031182014000602. ISSN 1469-8161. PMC 4413828. PMID 25656360.

External links[edit]

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