Cysteine-rich with EGF-like domain protein 2 is a protein that in humans is encoded by the CRELD2 gene found on chromosome 22q13.[1][2] It is a known homolog of CRELD1 [5]. CRELD2's identifying feature is a tryptophan-aspartic acid domain [6]. It is a multifunctional glycoprotein that is approximately 60 kilodaltons and can reside in the ER or Golgi and be secreted spontaneously [5]. It is implicated in numerous ER-stress related diseases including chronic liver disease, cardiovascular disease, kidney disease, and cancer [9][14].

Structure edit

 
Structure of CRELD2

CRELD2 can present itself in a variety of isoforms with similar motifs but different functions [4]. Common motifs include EGF/calcium binding EGF domains and furin cysteine-rich domains [5]. The C-terminal of this protein includes the following specific amino acid sequence necessary for retention and secretion: (R/H)EDL [11]. The N-terminal has multiple CXXC motifs which are vital for translocation and isomerase activity [6]. CpG islands are present in the functional promoter region upstream of CRELD2. In this functional promoter region, GC nucleotides are abundant and a TATA box is absent [4]. An ERSE (ER Stress Responsible Element) is also present in CRELD2 and is conserved in numerous species [5].

Function edit

 
The mechanism of CRELD2 retention during normal conditions and CRELD2 secretion under ER stress conditions

The CXXC motif at the N-terminal of CRELD2 suggests that it plays a role in the quality control of ER proteins. At the C-terminal, the four amino acids (R/H)EDL modulate the secretion of CRELD2. CRELD2 can bind to KDEL receptors in the Golgi and be retrogradely transported to the ER [7]. The presence of ER Stress Responsible Elements implies a regulatory role of CRELD2 during ER stress [10]. CRELD2 may function to promote ER stress tolerance or assist in recovery from acute stress [23].The CRELD family is also implicated in developmental events [4].

Tissue Expression edit

Throughout the life span of an individual, CRELD2 displays ubiquitous expression. Expression of CRELD2 is found in most, if not all, tissues including: skeletal muscle, heart, liver, kidney, and placenta [3]. The expression of CRELD2 differs in adult tissue and fetal tissue. In adult tissue, CRELD2 is mainly expressed in pancreatic tissue, stomach tissue, duodenal tissue, salivary gland tissue, thyroid gland tissue, appendix tissue, and tracheal tissue. Fetal expression of CRELD2 occurs primarily in the following tissues: lung, liver, thymus, spleen, and heart. Expression of CRELD2 can be induced by inducing ER stress via chemicals such as Tm, Tg, and BFA.

CRELD2 in Diseases edit

Chronic Liver Disease edit

In adult mice, exposure to arsenic during gestation led to high levels of CRELD2 expression in the liver. Expression of CRELD2 in the livers of mice also increased following 24 hours of intraperitoneal Tm infusion. Furthermore, in older mice with a knockout for Grp78, alcohol resulted in an increase of methylation at CpG islands in genes involved in CRELD2 expression [12]. Based on these studies utilizing mice models, CRELD2 is implicated in maintenance of liver homeostasis [23].

Chronic Vascular Diseases edit

CRELD2 has been highly implicated in chronic vascular diseases based on multiple studies. In cardiomyocytes of neonatal rats, administration of Tm led to increased levels of CRELD2 mRNA. When an ER-stress inhibitor, salubrinal, was administered, the observed effect was reversed [8]. In another study, the aortic zone exhibited elevated CRELD2 expression which confirmed the presence of a mutation in the 3’ untranslated region of FBN1 and associated ER stress response. Furthermore, aneurysmal samples from humans displayed high levels of CRELD2 [15].

Cartilage and Bone Metabolism edit

CRELD is implicated in the homeostasis of cartilage and bone development based on numerous examples. In a mutant Matn3 model of multiple epiphyseal dysplasia, CRELD2 was found to be expressed at the highest levels in chondrocytes [25]. In mouse models of ER-stress related growth plate diseases, CRELD2 expression was observed in hypertrophic zones. In addition, when ER stress was induced in cartilage treated with interleukin-1alpha, CRELD2 involvement was observed. Moreover, during osteogenic differentiation of mesenchymal stem cells mediated via bone morphogenic protein 9, CRELD2 displays high levels of up-regulation [16][17][18][19][20].

Cancer edit

ER stress, and thus CRELD2, are associated with the development of numerous types of cancer and tumor progression. Tumor angiogenesis can be promoted by CRELD2 up-regulating MB114 cell invasion. Additionally, CRELD2 was implicated as target of androgen receptors in prostate cancer. In renal cell carcinoma patients, CRELD2 expression was correlated with a poor prognosis. Furthermore, the presence of the CRELD2 gene and expression of the CRELD2 protein was linked to decreased chances of disease-free survival in cases of hepatocellular carcinoma. Another example implication the role of CRELD2 in cancer is exhibited in breast cancer [26]. Tumor progression was promoted by high levels of CRELD2, while lack of adequate CRELD2 expression suppressed tumor growth [21].

CRELD2 as a Biomarker edit

Due to its association with ER stress, CRELD2 can be utilized as a biomarker in ER-stress related diseases. For example, prosthetic joint infection can be detected via the presence of CRELD2 in synovial fluid [24]. Also, in males with NASH, decreased serum CRELD2 concentration led to higher levels of disease progression. Lastly, CRELD2 in the urine can be used as a biomarker for ER-stress related kidney diseases.

References edit

  1. Rupp PA, Fouad GT, Egelston CA, Reifsteck CA, Olson SB, Knosp WM, Glanville RW, Thornburg KL, Robinson SW, Maslen CL. Jul 2002. Identification, genomic organization and mRNA expression of CRELD1, the founding member of a unique family of matricellular proteins. https://doi.org/10.1016/S0378-1119(02)00696-0
  2. Entrez gene: CRELD2. https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=79174
  3. Tang, Q., Liu, Q., Li, Y., Mo, L., & He, J. (2023). CRELD2, endoplasmic reticulum stress, and human diseases. Frontiers in endocrinology, 14, 1117414. https://doi.org/10.3389/fendo.2023.1117414
  4. Maslen CL, Babcock D, Redig JK, Kapeli K, Akkari YM, Olson SB. CRELD2: gene mapping, alternatesplicing, and comparative genomic identification of the promoter region. Gene (2006) 382:111–20. doi: 10.1016/j.gene.2006.06.016
  5. Oh-hashi K, Koga H, Ikeda S, Shimada K, Hirata Y, Kiuchi K. CRELD2 is a novel endoplasmic reticulum stress-inducible gene. Biochem Biophys Res Commun (2009) 387(3):504–10. doi: 10.1016/j.bbrc.2009.07.047
  6. Oh-hashi K, Kunieda R, Hirata Y, Kiuchi K. Biosynthesis and secretion of mouse cysteine-rich with EGF-like domains 2. FEBS Lett (2011) 585(15):2481–7. doi: 10.1016/j.febslet.2011.06.029
  7. Newstead S, Barr F. Molecular basis for KDEL-mediated retrieval of escaped ER-resident proteins - SWEET talking the COPs. J Cell Sci (2020) 133(19):jcs250100. doi: 10.1242/jcs.250100
  8. Liu CL, Zhong W, He YY, Li X, Li S, He KL. Genome-wide analysis of tunicamycin-induced endoplasmic reticulum stress response and the protective effect of endoplasmic reticulum inhibitors in neonatal rat cardiomyocytes. Mol Cell Biochem (2016) 413(1-2):57–67. doi: 10.1007/s11010-015-2639-0
  9. Kim Y, Park SJ, Manson SR, Molina CA, Kidd K, Thiessen-Philbrook H, et al.. Elevated urinary CRELD2 is associated with endoplasmic reticulum stress-mediated kidney disease. JCI Insight (2017) 2(23):e92896. doi: 10.1172/jci.insight.92896
  10. Oh-Hashi K, Fujimura K, Norisada J, Hirata Y. Expression analysis and functional characterization of the mouse cysteine-rich with EGF-like domains 2. Sci Rep (2018) 8(1):12236. doi: 10.1038/s41598-018-30362-4
  11. Munro S, Pelham HR. A c-terminal signal prevents secretion of luminal ER proteins. Cell (1987) 48(5):899–907. doi: 10.1016/0092-8674(87)90086-9
  12. Takemoto H, Yoshimori T, Yamamoto A, Miyata Y, Yahara I, Inoue K, et al.. Heavy chain binding protein (BiP/GRP78) and endoplasmin are exported from the endoplasmic reticulum in rat exocrine pancreatic cells, similar to protein disulfide-isomerase. Arch Biochem Biophys (1992) 296(1):129–36. doi: 10.1016/0003-9861(92)90554-A
  13. Marciniak SJ, Chambers JE, Ron D. Pharmacological targeting of endoplasmic reticulum stress in disease. Nat Rev Drug Discovery (2022) 21(2):115–40. doi: 10.1038/s41573-021-00320-3
  14. Ren J, Bi Y, Sowers JR, Hetz C, Zhang Y. Endoplasmic reticulum stress and unfolded protein response in cardiovascular diseases. Nat Rev Cardiol (2021) 18(7):499–521. doi: 10.1038/s41569-021-00511-w
  15. Navas-Madroñal M, Rodriguez C, Kassan M, Fité J, Escudero JR, Cañes L, et al.. Enhanced endoplasmic reticulum and mitochondrial stress in abdominal aortic aneurysm. Clin Sci (Lond) (2019) 133(13):1421–38. doi: 10.1042/CS20190399
  16. Hughes A, Oxford AE, Tawara K, Jorcyk CL, Oxford JT. Endoplasmic reticulum stress and unfolded protein response in cartilage pathophysiology; contributing factors to apoptosis and osteoarthritis. Int J Mol Sci (2017) 18(3):665. doi: 10.3390/ijms18030665
  17. Guo J, Ren R, Sun K, He J, Shao J. PERK signaling pathway in bone metabolism: Friend or foe? Cell Prolif (2021) 54(4):e13011. doi: 10.1111/cpr.13011
  18. Rellmann Y, Eidhof E, Dreier R. Review: ER stress-induced cell death in osteoarthritic cartilage. Cell Signal (2021) 78:109880. doi: 10.1016/j.cellsig.2020.109880
  19. Zhang J, Weng Y, Liu X, Wang J, Zhang W, Kim SH, et al.. Endoplasmic reticulum (ER) stress inducible factor cysteine-rich with EGF-like domains 2 (Creld2) is an important mediator of BMP9-regulated osteogenic differentiation of mesenchymal stem cells. PLoS One (2013) 8(9):e73086. doi: 10.1371/journal.pone.0073086
  20. Duxfield A, Munkley J, Briggs MD, Dennis EP. CRELD2 is a novel modulator of calcium release and calcineurin-NFAT signalling during osteoclast differentiation. Sci Rep (2022) 12(1):13884. doi: 10.1038/s41598-022-17347-0
  21. Salvagno C, Mandula JK, Rodriguez PC, Cubillos-Ruiz JR. Decoding endoplasmic reticulum stress signals in cancer cells and antitumor immunity. Trends Cancer (2022) 8(11):930–943. doi: 10.1016/j.trecan.2022.06.006
  22. Yarmohammadi F, Hayes AW, Karimi G. The therapeutic effects of berberine against different diseases: A review on the involvement of the endoplasmic reticulum stress. Phytother Res (2022) 36(8):3215–31. doi: 10.1002/ptr.7539
  23. Kern P, Balzer NR, Blank N, Cygon C, Wunderling K, Bender F, et al.. Creld2 function during unfolded protein response is essential for liver metabolism homeostasis. FASEB J (2021) 35(10):e21939. doi: 10.1096/fj.202002713RR
  24. Chen MF, Chang CH, Yang LY, Hsieh PH, Shih HN, Ueng SWN, et al.. Synovial fluid interleukin-16, interleukin-18, and CRELD2 as novel biomarkers of prosthetic joint infections. Bone Joint Res (2019) 8(4):179–88. doi: 10.1302/2046-3758.84.BJR-2018-0291.R1
  25. Hartley CL, Edwards S, Mullan L, Bell PA, Fresquet M, Boot-Handford RP, et al.. Armet/Manf and Creld2 are components of a specialized ER stress response provoked by inappropriate formation of disulphide bonds: Implications for genetic skeletal diseases. Hum Mol Genet (2013) 22(25):5262–75. doi: 10.1093/hmg/ddt383
  26. Boyle ST, Poltavets V, Kular J, Pyne NT, Sandow JJ, Lewis AC, et al. ROCK-mediated selective activation of PERK signalling causes fibroblast reprogramming and tumour progression through a CRELD2-dependent mechanism. Nat Cell Biol (2020) 22(7):882–95. doi: 10.1038/s41556-020-0523-y


External links edit

Further reading edit


  1. ^ Rupp PA, Fouad GT, Egelston CA, Reifsteck CA, Olson SB, Knosp WM, Glanville RW, Thornburg KL, Robinson SW, Maslen CL (Jul 2002). "Identification, genomic organization and mRNA expression of CRELD1, the founding member of a unique family of matricellular proteins". Gene. 293 (1–2): 47–57. doi:10.1016/S0378-1119(02)00696-0. PMID 12137942.
  2. ^ "Entrez Gene: CRELD2 cysteine-rich with EGF-like domains 2".