Insulin


 

Description

Insulin is a peptide hormone produced by beta (β) cells of the pancreatic islets considered to be the main anabolic hormone of the body. Insulin is synthesized as a single-chain precursor, preproinsulin, that contains an N-terminal signal sequence and a connecting peptide (C-peptide) linking the A and B chains of the insulin molecule (proinsulin) (Steiner, Cunningham et al. 1967, Dodson and Steiner 1998). Within the endoplasmic reticulum of the β cell, proinsulin is exposed to several specific endopeptidases which excise the C peptide, thereby generating the mature form of insulin; insulin and free C peptide are packaged in the Golgi into secretory granules which accumulate in the cytoplasm for release when systemic glucose level increase. Insulin is not only a biomarker used in the identification of pathologies associated with glucose metabolism such as Type 1 and Type 2 diabetes; the secretion of insulin rises with age, which is related to both increasing body fat mass and ageing itself (Thorens, Rodriguez et al. 2019). Similarly, levels of circulating C peptide are being considered as potential biomarkers for certain cancers and atherosclerotic disease (Murphy, Cross et al. 2015, Cardellini, Farcomeni et al. 2017, Khan, Sobki et al. 2018). Figure 1 demonstrates that while the A and B chains of HUM and RHE insulin have the same sequences, MAR insulin has significant aminoacid differences with HUM insulin. We found one Luminex kit (Biorad) that had reactivity with MAR samples, but no reagents able to recognize MAR C peptide.

 

Alignment

Protein alignment for human, rhesus macaque and marmoset insulin:

image of Protein alignment for human, rhesus macaque and marmoset Insulin

 

Protein alignment for marmoset, owl monkey, and squirrel monkey insulin:

Protein alignment for marmoset, owl monkey, and squirrel monkey insulin

 

References

  • Cardellini, M., A. Farcomeni, M. Ballanti, M. Morelli, F. Davato, I. Cardolini, G. Grappasonni, S. Rizza, V. Guglielmi, O. Porzio, C. Pecchioli, R. Menghini, A. Ippoliti and M. Federici (2017). "C-peptide: A predictor of cardiovascular mortality in subjects with established atherosclerotic disease." Diab Vasc Dis Res 14(5): 395-399.
  • Dodson, G. and D. Steiner (1998). "The role of assembly in insulin's biosynthesis." Curr Opin Struct Biol 8(2): 189-194.
  • Khan, H. A., S. H. Sobki, A. Ekhzaimy, I. Khan and M. A. Almusawi (2018). "Biomarker potential of C-peptide for screening of insulin resistance in diabetic and non-diabetic individuals." Saudi J Biol Sci 25(8): 1729-1732.
  • Murphy, N., A. J. Cross, W. Y. Huang, V. Rajabzadeh-Heshejin, F. Stanczyk, R. Hayes and M. J. Gunter (2015). "A prospective evaluation of C-peptide levels and colorectal adenoma incidence." Cancer Epidemiol 39(2): 160-165.
  • Steiner, D. F., D. Cunningham, L. Spigelman and B. Aten (1967). "Insulin biosynthesis: evidence for a precursor." Science 157(3789): 697-700.
  • Thorens, B., A. Rodriguez, C. Cruciani-Guglielmacci, L. Wigger, M. Ibberson and C. Magnan (2019). "Use of preclinical models to identify markers of type 2 diabetes susceptibility and novel regulators of insulin secretion - A step towards precision medicine." Mol Metab 27S: S147-S154.

 

Status

Mice have been immunized with recombinant marmoset protein.