Parathyroid hormone-related protein

Parathyroid hormone-related protein (or PTHrP) is a protein member of the parathyroid hormone family secreted by mesenchymal stem cells. It is occasionally secreted by cancer cells (breast cancer, certain types of lung cancer including squamous-cell lung carcinoma). However, it also has normal functions in bone, tooth, vascular and other tissues.

PTHLH
Available structures
PDBOrtholog search: PDBe RCSB
Identifiers
AliasesPTHLH, BDE2, HHM, PLP, PTHR, PTHRP, parathyroid hormone-like hormone, parathyroid hormone like hormone
External IDsOMIM: 168470 MGI: 97800 HomoloGene: 2113 GeneCards: PTHLH
Gene location (Human)
Chr.Chromosome 12 (human)[1]
Band12p11.22Start27,958,084 bp[1]
End27,972,733 bp[1]
RNA expression pattern


More reference expression data
Orthologs
SpeciesHumanMouse
Entrez

5744

19227

Ensembl

ENSG00000087494

n/a

UniProt

P12272

P22858

RefSeq (mRNA)

NM_002820
NM_198964
NM_198965
NM_198966

NM_008970

RefSeq (protein)

NP_002811
NP_945315
NP_945316
NP_945317

n/a

Location (UCSC)Chr 12: 27.96 – 27.97 Mbn/a
PubMed search[2][3]
Wikidata
View/Edit HumanView/Edit Mouse

Function

PTHrP acts as an endocrine, autocrine, paracrine, and intracrine hormone. It regulates endochondral bone development by maintaining the endochondral growth plate at a constant width. It also regulates epithelial–mesenchymal interactions during the formation of the mammary glands.

Tooth eruption

PTHrP is critical in intraosseous phase of tooth eruption where it acts as a signalling molecule to stimulate local bone resorption. Without PTHrP, the bony crypt surrounding the tooth follicle will not resorb, and therefore the tooth will not erupt. In the context of tooth eruption, PTHrP is secreted by the cells of the reduced enamel epithelium.

Mammary glands

It aids in normal mammary gland development.[4][5] It is necessary for maintenance of the mammary bud. Loss of PTHrP or its receptor causes the mammary bud cell fate to change back into epidermis. In lactation, it may regulate in conjunction with the calcium sensing receptor the mobilization and transfer of calcium to the milk, as well as placental transfer of calcium.

Humoral hypercalcemia of malignancy

PTHrP is related in function to the "normal" parathyroid hormone. When a tumor secretes PTHrP, this can lead to hypercalcemia.[6] As this is sometimes the first sign of the malignancy, hypercalcemia caused by PTHrP is considered a paraneoplastic phenomenon. PTHR1 is responsible for most cases of humoral hypercalcemia of malignancy.

PTHrP shares the same N-terminal end as parathyroid hormone and therefore it can bind to the same receptor, the Type I PTH receptor (PTHR1). PTHrP can simulate most of the actions of PTH including increases in bone resorption and distal tubular calcium reabsorption, and inhibition of proximal tubular phosphate transport. PTHrP lacks the normal feedback inhibition as PTH. [7]

However, PTHrP is less likely than PTH to stimulate 1,25-dihydroxyvitamin D production. Therefore, PTHrP does not increase intestinal calcium absorption.

Genetics

Four alternatively spliced transcript variants encoding two distinct isoforms have been observed. There is also evidence for alternative translation initiation from non-AUG (CUG and GUG) start sites, in-frame and downstream of the initiator AUG codon, to give rise to nuclear forms of this hormone.[8]

Discovery

The protein was first isolated in 1987 by T. J. Martin's team at the University of Melbourne. Miao et al. showed that disruption of the PTHrP gene in mice caused a lethal phenotype and distinct bone abnormalities, suggesting that PTHrP has a physiological function.

Interactions

Parathyroid hormone-related protein has been shown to interact with KPNB1[9][10] and Arrestin beta 1.[11]

gollark: ```lisp (let (partition_rec xs pred acc) (cond ((= xs '()) acc) (true (partition_rec (tail xs) pred (cond ((pred (head xs)) (list (cons (head xs) (head acc)) (snd acc))) (true (list (head acc) (cons (head xs) (snd acc)))) ))) )) (let (qsort xs cont) (cond ((= xs '()) (cont '())) (true (do (let h (head xs)) (let t (tail xs)) (let part_result (partition_rec t (lambda (x) (< x h)) '(() ()))) (qsort (head part_result) (lambda (ls) (qsort (snd part_result) (lambda (rs) (cont (+ ls (list h) rs)))))) )) ))```These all have to be done tail recursively or it could overflow.
gollark: Continuation passing style quicksort in a hilariously slow interpreter.
gollark: It manages *1* second, which is great.
gollark: When writing osmarkslisp™, I cared about performance to the extent that it would sort a list of 200 integers in under 5 seconds.
gollark: `b"%s"`?

See also

References
  1. GRCh38: Ensembl release 89: ENSG00000087494 - Ensembl, May 2017
  2. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  3. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. Hens JR, Dann P, Zhang JP, Harris S, Robinson GW, Wysolmerski J (March 2007). "BMP4 and PTHrP interact to stimulate ductal outgrowth during embryonic mammary development and to inhibit hair follicle induction". Development. 134 (6): 1221–30. doi:10.1242/dev.000182. PMID 17301089.
  5. Hens JR, Wysolmerski JJ (2005). "Key stages of mammary gland development: molecular mechanisms involved in the formation of the embryonic mammary gland". Breast Cancer Research. 7 (5): 220–4. doi:10.1186/bcr1306. PMC 1242158. PMID 16168142.
  6. Broadus AE, Mangin M, Ikeda K, Insogna KL, Weir EC, Burtis WJ, Stewart AF (September 1988). "Humoral hypercalcemia of cancer. Identification of a novel parathyroid hormone-like peptide". The New England Journal of Medicine. 319 (9): 556–63. doi:10.1056/NEJM198809013190906. PMID 3043221.
  7. Stewart, Andrew F. (2005-01-27). "Clinical practice. Hypercalcemia associated with cancer". The New England Journal of Medicine. 352 (4): 373–379. doi:10.1056/NEJMcp042806. ISSN 1533-4406. PMID 15673803.
  8. "Entrez Gene: PTHLH parathyroid hormone-like hormone".
  9. Cingolani G, Bednenko J, Gillespie MT, Gerace L (December 2002). "Molecular basis for the recognition of a nonclassical nuclear localization signal by importin beta". Molecular Cell. 10 (6): 1345–53. doi:10.1016/S1097-2765(02)00727-X. PMID 12504010.
  10. Lam MH, Hu W, Xiao CY, Gillespie MT, Jans DA (March 2001). "Molecular dissection of the importin beta1-recognized nuclear targeting signal of parathyroid hormone-related protein". Biochemical and Biophysical Research Communications. 282 (2): 629–34. doi:10.1006/bbrc.2001.4607. PMID 11401507.
  11. Conlan LA, Martin TJ, Gillespie MT (September 2002). "The COOH-terminus of parathyroid hormone-related protein (PTHrP) interacts with beta-arrestin 1B". FEBS Letters. 527 (1–3): 71–5. doi:10.1016/S0014-5793(02)03164-2. PMID 12220636.

Further reading

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