Inactive forms of the catalytic subunit of protein kinaseA are expressed in the brain of higher primates

• Published in: The FEBS journal 2008-01, Vol.275 (2), p.250-262
• Main Authors: Larsen, Anja CV, Kvissel, Anne-Katrine, Hafte, Tilahun T, Avellan, Cecilia IA, Eikvar, Sissel, Rootwelt, Terje, Oerstavik, Sigurd, Skalhegg, Bjoern S
• Format: Article
• Language: English
• Subjects: Macaca mulatta; Primates
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/j.1742-4658.2007.06195.x

It is well documented that the beta -gene of the catalytic (C) subunit of protein kinaseA encodes a number of splice variants. These splice variants are equipped with a variable N-terminal end encoded by alternative use of several exons located 5' to exon 2 in the human, bovine and mouse C beta gene. In the present study, we demonstrate the expression of six novel human C beta mRNAs that lack 99bp due to loss of exon 4. The novel splice variants, designated C beta Delta 4, were identified in low amounts at the mRNA level in NTera2-N cells. We developed a method to detect C beta Delta 4 mRNAs in various cells and demonstrated that these variants were expressed in human and Rhesus monkey brain. Transient expression and characterization of the C beta Delta 4 variants demonstrated that they are catalytically inactive both invitro against typical protein kinaseA substrates such as kemptide and histone, and invivo against the cAMP-responsive element binding protein. Furthermore, co-expression of C beta Delta 4 with the regulatory subunit (R) followed by kinase activity assay with increasing concentrations of cAMP and immunoprecipitation with extensive washes with cAMP (1mm) and immunoblotting demonstrated that the C beta Delta 4 variants associate with both RI and RII in a cAMP-independent fashion. Expression of inactive C subunits which associate irreversibly with R may imply that C beta Delta 4 can modulate local cAMP effects in the brain by permanent association with R subunits even at saturating concentrations of cAMP.