Expression and localization of protein kinase C theta isoform in mouse testis

Differential expression of protein kinase C α and δ in testes of mouse at various stages of development

Protein kinase C (PKC) describes a family of serine/threonine protein kinases, and multiple isoforms are expressed in various mammalian tissues. In the present study, we examined the expression of PKC-alpha and PKC-delta at protein and mRNA level in mouse testis by Western blotting and RT-PCR. We also examined the expression of both PKC isoenzymes in the developing mouse testis. In testes of mouse at various developmental stages, both the protein and the mRNA of PKC-alpha were uniformly distributed; but PKC-delta expression occurred in the testes of 3-week-old mice, perhaps even at a relatively late stage in spermatid development. The results suggest that each isoenzyme may have different functional roles in processing and modulating physiological cellular responses of spermatogenesis.

Expression of Constitutive Endothelial, Neuronal and Inducible Nitric Oxide Synthase in the Testis and Epididymis of Horse

The expression of three isoforms of nitric oxide synthase (NOS) were examined in the testis and epididymis of a thoroughbred horse. Immunohistochemical studies demonstrated the presence of eNOS immunostaining in some germ cells in the seminiferous tubules and in vascular endothelial cells in the interstitial tissues. Interstitial cells, most likely Leydig cells, were also intensely immunopositive for eNOS. The pattern of immunostaining for nNOS was similar to that for eNOS in the testis. Weak expression of iNOS was detected in the seminiferous tubules of the testis, but intense expression was found in interstitial cells. Inducible NOS was also strongly detected in stereocilia, sperm, epithelium and connective tissue of the epididymis of normal horses. These findings suggest that three isoforms of NOS are expressed in the testis and epididymis of horse and that they play important roles in the biology of interstitial cells that produce testosterone, as well as in spermatogenesis in the seminiferous tubules.

Localization of protein kinase C theta immunoreactivity to interstitial cells of Cajal in guinea-pig gastrointestinal tract

In the gastrointestinal tract, interstitial cells of Cajal (ICC) are located between nerve fibres and muscle cells and have a role in neuromuscular transmission and muscle contractility. Protein kinase C (PKC) is involved in modulation of muscle contractility by neurotransmitters, but it is not known if PKC has a role in ICC. There are 11 different PKC isoforms. The presence of PKC isoforms in ICC in guinea-pig gastrointestinal tract was examined using fluorescence immunohistochemistry and confocal microscopy. Segments of guinea-pig stomach, duodenum, ileum, proximal and distal colon were fixed in zambonis fixative. Frozen sections and wholemounts were incubated with anti-PKC antibodies (alpha, beta, delta, epsilon, gamma, iota, lambda, mu, theta) followed by fluorescent secondary antibody. Only PKC theta (theta) immunoreactivity was found in ICC. None of the other PKC isoforms (alpha, beta, delta, epsilon, gamma, iota, lambda, mu) localized to the ICC. PKC theta immunoreactivity was prominent in ICC located between the circular and longitudinal muscle layers (ICC-MY) in all regions except stomach and within the circular muscle (ICC-IM) in the large intestine. PKC theta was not present in ICC in the deep muscular plexus in either duodenum or ileum. PKC theta immunoreactivity was present in the cell body and proximal processes of the ICC. The cells containing PKC theta also contained cKit confirming the cells were ICC. ICC-MY in the ileum also contained the neurokinin (NK) 1 receptor. In conclusion, PKC theta is present in pacemaker ICC, but its function is not yet known. Functional studies will be needed to determine the role of this kinase in ICC. Knowing the second messenger cascades and being able to manipulate subpopulations of ICC will add to our understanding of the molecular and cell biology of ICC networks within the gastrointestinal tract and may ultimately help in understanding the aetiology of some gastrointestinal motor pathologies.

PKCtheta II, a new isoform of protein kinase C specifically expressed in the seminiferous tubules of mouse testis

Protein kinase C (PKC) theta, a Ca(2+)-independent isoform of PKC, has been known to be expressed in skeletal muscle and T cells. In the present study, we isolated and characterized a smaller transcript expressed in the mouse testis, the cDNA of which is referred hereafter as PKCthetaII and the original PKCtheta as PKCthetaI. The cDNA clone of PKCthetaII has 2184 base pairs and 464 amino acids in the possible open reading frame, consisting of the 5' unique sequence of 20 amino acids and the PKCthetaI sequence of 444 amino acids. Genomic DNA analysis revealed that transcription of PKCthetaII is initiated from the PKCthetaII-specific exon, which is located between exons 7 and 8 of the PKCtheta gene, indicating that alternative splicing is the mechanism by which PKCthetaII is generated. PKCthetaII is expressed exclusively in the testis in an age-dependent manner with sexual maturation. In situ hybridization and reverse transcription-polymerase chain reaction of microdissected tissues clearly demonstrated that PKCthetaII is expressed in the seminiferous tubules of the mouse testis. Consistent with its molecular structure lacking the C1 regulatory domain, PKCthetaII is constitutively active as determined by an in vitro kinase assay, being independent of PKC activators, e.g. phosphatidylserine and phorbol ester. PKCthetaII may play a crucial role in spermatogenesis or some related function of the testis.