Multinucleated Giant Cells’ Incidence, Immune Markers, and Significance: A Study of 172 Cases of Papillary Thyroid Carcinoma

Multinucleated giant cells (MGCs) are often detected in cases of papillary thyroid carcinoma (PTC). Their origin and significance, however, has not been established. One possibility is that they form in response to injury induced by fine needle aspiration biopsy (FNAB). Other hypotheses are that the chemically-altered colloid produced by PTC induces MGCs to act as colloidophages, or else MGCs are a non-specific immune response ingesting neoplastic follicle cells. We assigned 172 cases of PTC a semi-quantitative score for MGCs. Cases with “many” MGCs were immunohistochemically stained for AEI/AEIII, CD68, and CD163 to assess for epithelial vs histiocytic differentiation, and for thyroglobulin and TTF-1 to assess for MGC ingestion of colloid or thyroid follicle cells respectively. Overall, we identified MGCs in 100/172 (58.1%) PTC specimens; in 45 (26.2%), “many” MGCs were found, while in 55 (31.9%) MGCs were “few.” The mean sizes of PTC in cases with many as opposed to rare/no MGCs was 2.50 cm vs 1.8 [P = 0.003]. The cases of PTC with many MGCs had higher multifocality (26/45 vs 51/127 [P = 0.06]), extrathyroidal extension (21/45 vs 36/127 [P = 0.03]), and recurrence (8/45 vs 9/127 [P = 0.08]), than did cases with rare or no MGCs. The majority of patients both with and without numerous MGCs had previous histories of FNA or hemilobectomy: 40/45 and 99/127 respectively (P = 0.062). The majority of MGCs were positive for CD68 (45/45), CD163 (44/45), thyroglobulin (34/45) and negative for AEI/AEIII (44/45) and TTF-1 (44/45). These results indicate that MGCs in PTC are of histiocytic origin. Cases of PTC with many MGCs have a significantly greater likelihood of extrathyroidal extension and greater tumor size than cases with few/no MGCs. MGCs appear to be functioning largely as colloidophages

Two Cellular Protein Kinases, DNA-PK and PKA, Phosphorylate the Adenoviral L4-33K Protein and Have Opposite Effects on L1 Alternative RNA Splicing

Accumulation of the complex set of alternatively processed mRNA from the adenovirus major late transcription unit (MLTU) is subjected to a temporal regulation involving both changes in poly (A) site choice and alternative 3′ splice site usage. We have previously shown that the adenovirus L4-33K protein functions as an alternative splicing factor involved in activating the shift from L1-52,55K to L1-IIIa mRNA. Here we show that L4-33K specifically associates with the catalytic subunit of the DNA-dependent protein kinase (DNA-PK) in uninfected and adenovirus-infected nuclear extracts. Further, we show that L4-33K is highly phosphorylated by DNA-PK in vitro in a double stranded DNA-independent manner. Importantly, DNA-PK deficient cells show an enhanced production of the L1-IIIa mRNA suggesting an inhibitory role of DNA-PK on the temporal switch in L1 alternative RNA splicing. Moreover, we show that L4-33K also is phosphorylated by protein kinase A (PKA), and that PKA has an enhancer effect on L4-33K-stimulated L1-IIIa splicing. Hence, we demonstrate that these kinases have opposite effects on L4-33K function; DNA-PK as an inhibitor and PKA as an activator of L1-IIIa mRNA splicing. Taken together, this is the first report identifying protein kinases that phosphorylate L4-33K and to suggest novel regulatory roles for DNA-PK and PKA in adenovirus alternative RNA splicing

A cyclic GMP signalling module that regulates gliding motility in a malaria parasite.

The ookinete is a motile stage in the malaria life cycle which forms in the mosquito blood meal from the zygote. Ookinetes use an acto-myosin motor to glide towards and penetrate the midgut wall to establish infection in the vector. The regulation of gliding motility is poorly understood. Through genetic interaction studies we here describe a signalling module that identifies guanosine 3', 5'-cyclic monophosphate (cGMP) as an important second messenger regulating ookinete differentiation and motility. In ookinetes lacking the cyclic nucleotide degrading phosphodiesterase delta (PDEdelta), unregulated signalling through cGMP results in rounding up of the normally banana-shaped cells. This phenotype is suppressed in a double mutant additionally lacking guanylyl cyclase beta (GCbeta), showing that in ookinetes GCbeta is an important source for cGMP, and that PDEdelta is the relevant cGMP degrading enzyme. Inhibition of the cGMP-dependent protein kinase, PKG, blocks gliding, whereas enhanced signalling through cGMP restores normal gliding speed in a mutant lacking calcium dependent protein kinase 3, suggesting at least a partial overlap between calcium and cGMP dependent pathways. These data demonstrate an important function for signalling through cGMP, and most likely PKG, in dynamically regulating ookinete gliding during the transmission of malaria to the mosquito

Quantification of dynamic protein complexes using Renilla luciferase fragment complementation applied to protein kinase A activities in vivo

The G protein-coupled receptor (GPCR) superfamily represents the most important class of pharmaceutical targets. Therefore, the characterization of receptor cascades and their ligands is a prerequisite to discovering novel drugs. Quantification of agonist-induced second messengers and downstream-coupled kinase activities is central to characterization of GPCRs or other pathways that converge on GPCR-mediated signaling. Furthermore, there is a need for simple, cell-based assays that would report on direct or indirect actions on GPCR-mediated effectors of signaling. More generally, there is a demand for sensitive assays to quantify alterations of protein complexes in vivo. We describe the development of a Renilla luciferase (Rluc)-based protein fragment complementation assay (PCA) that was designed specifically to investigate dynamic protein complexes. We demonstrate these features for GPCR-induced disassembly of protein kinase A (PKA) regulatory and catalytic subunits, a key effector of GPCR signaling. Taken together, our observations show that the PCA allows for direct and accurate measurements of live changes of absolute values of protein complex assembly and disassembly as well as cellular imaging and dynamic localization of protein complexes. Moreover, the Rluc-PCA has a sufficiently high signal-to-background ratio to identify endogenously expressed Gαs protein-coupled receptors. We provide pharmacological evidence that the phosphodiesterase-4 family selectively down-regulates constitutive β-2 adrenergic- but not vasopressin-2 receptor-mediated PKA activities. Our results show that the sensitivity of the Rluc-PCA simplifies the recording of pharmacological profiles of GPCR-based candidate drugs and could be extended to high-throughput screens to identify novel direct modulators of PKA or upstream components of GPCR signaling cascades