Ole Øyen

Human testis cDNA for the regulatory subunit RIIα of CAMP-dependent protein kinase encodes an alternate amino-terminal region

Phosphorylations catalysed by cAMP‐dependent protein kinase are essential for sperm motility, and type II cAMP‐dependent protein kinase in mature sperm has been shown to be firmly bound to the flagellum via the regulatory subunit, RII. The present study documents high‐levelled expression of a human, testis‐specific RIIα mRNA (2.0 kb) analogous to the rat mRNA which is induced in haploid germ cells [(1988) FEBS Lett. 229, 391–394]. We report the molecular cloning of a full‐length human cDNA corresponding to this unique testis mRNA, and the presence of an alternate amino‐terminal region (amino acids 45–75) of the predicted RIIα protein (404 amino acids) compared with the previously published mouse and rat sequences. However, this alternate region is also shown to be present in RIIα mRNA (7.0 kb) of human somatic cells. Our data indicate the divergent amino‐terminal sequence to be due to species differences, suggesting an active evolutionary pressure on this particular region, which could be involved in subcellular attachment of RIIα and thereby localization of kinase activity to certain targets within the cell.

Molecular cloning of the human transmembrane secretory component (poly-Ig receptor) and its mRNA expression in human tissues.

A 2.5 kilobase (kb) cDNA clone containing 92% of the coding region for human transmembrane secretory component (SC) or poly-Ig receptor, was isolated from a mammary gland cDNA library. The cDNA clone encoded a protein of 693 amino acids which showed 99% homology with the primary amino acid sequence of human free SC as reported by Eiffert et al. (1), and 54% homology with the deduced amino acid sequence of rabbit transmembrane SC for which cDNA was cloned by Mostov et al. (2). Northern blot analysis showed mRNA expression in various human exocrine tissues in good agreement with our previous immunohistochemical studies of SC.

Molecular cloning, cDNA structure and deduced amino acid sequence for a type I regulatory subunit of cAMP-dependent protein kinase from human testis

A 1.5 kilobase (kb) cDNA clone containing the entire coding region for a regulatory subunit of type I cAMP-dependent protein kinase (RI) was isolated from a human testis cDNA library. The cDNA clone encodes a protein of 381 amino acids that shows 98% and 97% homology to the bovine skeletal muscle RI and rat brain RI, respectively. Northern blot analysis demonstrates two major mRNA-species (1.5 and 3.0 kb) in human testis and one mRNA-species (3.0 kb) in human T-lymphocytes.

A unique mRNA species for a regulatory subunit of cAMP-dependent protein kinase is specifically induced in haploid germ cells.

Cyclic AMP (cAMP) and its action by way of cAMP‐dependent protein kinase is important for sperm motility. Previous studies on germ cells have demonstrated a selective decrease in the amount of type I cAMP‐dependent protein kinase during spermatid development, and that type II was the major form present in elongating spermatids and in mature sperm. This would indicate activation of a gene in haploid germ cells, encoding a regulatory subunit of type II protein kinase. However, haploid expression of such a gene has so far not been shown. In the present study we demonstrate high‐levelled expression of a unique mRNA species for a specific regulatory subunit of type II cAMP‐dependent protein kinase at late stages of spermatogenesis, i.e. during spermatid elongation.

Regulation of mRNA levels for cellular retinol binding protein in rat sertoli cells by cyclic AMP and retinol

The levels of mRNA for cellular retinol binding protein (CRBP) were studied in primary rat Sertoli cell cultures treated with cAMP analogues and retinol. In the presence of cyclic AMP analogues a dose- and time-dependent reduction (70-90%) of the levels of mRNA for CRBP was observed. Retinol concentrations above 10 nM induced a dose- and time-dependent increase (2-3 fold) in mRNA levels for CRBP. Assuming that CRBP is important for vitamin A action, our data indicate that both cAMP and retinol itself modulate the sensitivity of the Sertoli cells for retinol.

Molecular cloning, cDNA structure and deduced amino acid sequence for the hormone-induced regulatory subunit (RIIβ) of cAMP-dependent protein kinase from rat ovarian granulosa cells

Abstract The regulatory subunit of cAMP-dependent protein kinase designated RIIβ (RII51) has previously been shown to be the product of a separate gene. This was accomplished by the molecular cloning of a partial cDNA clone estimated to lack 30–45 nucleotides of the 5′ end of the coding region. We hereby report the isolation of a cDNA clone for RIIβ from rat granulosa cells, extending 43 nucleotides further 5′ cmpared with the previously published cDNA sequence, and from which the entire amino acid sequence (415 residues) of the rat RIIβ protein can be deduced. A cAMP regulated mRNA of 3.2 kilobases (kb) for RIIβ was detected by the isolated cDNA in rat Sertoli cells.