A novel insulin analog with unique properties: LysB3,GluB29 insulin induces prominent activation of insulin receptor substrate 2, but marginal phosphorylation of insulin receptor substrate 1.
The potentially enhanced mitogenic activity of insulin analogs represents a safety risk that requires detailed analysis of new analogs considered for therapeutic applications. We assessed the signaling properties and mitogenic potency of two novel rapid-acting insulin analogs, Lys(B3),Glu(B29) insulin (HMR 1964) and Lys(B3),Ile(B28) insulin (HMR 1153) using myoblasts and cardiomyocytes. In myoblasts, both binding and internalization were two- to threefold higher for Asp(B10) insulin and HMR 1153 when compared with HMR 1964 and regular insulin. This finding correlated with a prominent Shc/IGF-I receptor interaction, tyrosine phosphorylation of Shc, activation of extracellular signal-regulated protein kinase (ERK)-1 and -2, and stimulation of DNA synthesis by HMR 1153 and Asp(B10) insulin. In contrast, HMR 1964 produced a marginal activation of the Shc/ERK kinase cascade and was equipotent to insulin in stimulating DNA synthesis in myoblasts. Further, the in vivo growth-promoting activity of this analog was found to be identical to that of regular human insulin. In myoblasts, HMR 1964 produced a minor activation of insulin receptor substrate (IRS)-1 tyrosine phosphorylation, but a prominent activation of IRS-2, with a significantly stronger effect than insulin in human myoblasts. Predominant activation of IRS-2 was also observed in adult cardiomyocytes where HMR 1964 increased 3-O-methylglucose transport and the activation of Akt and glycogen synthase kinase-3 to the same extent as human insulin. We concluded that 1) the mitogenic properties of insulin analogs may result from a series of initial receptor interactions, including internalization and phosphorylation; 2) the mitogenic and metabolic potential of HMR 1964 is identical to that of insulin; and 3) predominant activation of IRS-2 may open new avenues for optimized insulin therapies.
Rakatzi
Irini
I
Department of Clinical Biochemistry and Pathobiochemistry, German Diabetes Research Institute, Düsseldorf, Germany.
Ramrath
Stefanie
S
Ledwig
Daniela
D
Dransfeld
Olaf
O
Bartels
Thomas
T
Seipke
Gerhard
G
Eckel
Jürgen
J
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000367:Age Factors; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D006801:Humans; D007004:Hypoglycemic Agents / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008934:Mitogens / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000166:cytology; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D051381:Rats; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D007004:Hypoglycemic Agents; C526292:IRS1 protein, human; C526297:IRS2 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526296:Irs1 protein, rat; C526299:Irs2 protein, rat; D008934:Mitogens; D010750:Phosphoproteins; D011506:Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; C528035:Shc1 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014443:Tyrosine