From biosynthesis and beyond-Loss or overexpression of the cytokinin synthesis gene, iptA, alters cytokinesis and mitochondrial and amino acid metabolism in Dictyostelium discoideum.

Cytokinins (CKs) are a class of growth-promoting signaling molecules that affect multiple cellular and developmental processes. These phytohormones are well studied in plants, but their presence continues to be uncovered in organisms spanning all kingdoms, which poses new questions about their roles and functions outside of plant systems. Cytokinin production can be initiated by one of two different biosynthetic enzymes, adenylate isopentenyltransfases (IPTs) or tRNA isopentenyltransferases (tRNA-IPTs). In this study, the social amoeba, Dictyostelium discoideum, was used to study the role of CKs by generating deletion and overexpression strains of its single adenylate-IPT gene, iptA. The life cycle of D. discoideum is unique and possesses both single- and multicellular stages. Vegetative amoebae grow and divide while food resources are plentiful, and multicellular development is initiated upon starvation, which includes distinct life cycle stages. CKs are produced in D. discoideum throughout its life cycle and their functions have been well studied during the later stages of multicellular development of D. discoideum. To investigate potential expanded roles of CKs, this study focused on vegetative growth and early developmental stages. We found that iptA-deficiency results in cytokinesis defects, and both iptA-deficiency and overexpression results in dysregulated tricarboxylic acid (TCA) cycle and amino acid metabolism, as well as increased levels of adenosine monophosphate (AMP). Collectively, these findings extend our understanding of CK function in amoebae, indicating that iptA loss and overexpression alter biological processes during vegetative growth that are distinct from those reported during later development.

PML and PML-like exonucleases restrict retrotransposons in jawed vertebrates.

We have uncovered a role for the promyelocytic leukemia (PML) gene and novel PML-like DEDDh exonucleases in the maintenance of genome stability through the restriction of LINE-1 (L1) retrotransposition in jawed vertebrates. Although the mammalian PML protein forms nuclear bodies, we found that the spotted gar PML ortholog and related proteins in fish function as cytoplasmic DEDDh exonucleases. In contrast, PML proteins from amniote species localized both to the cytoplasm and formed nuclear bodies. We also identified the PML-like exon 9 (Plex9) genes in teleost fishes that encode exonucleases. Plex9 proteins resemble TREX1 but are unique from the TREX family and share homology to gar PML. We also characterized the molecular evolution of TREX1 and the first non-mammalian TREX1 homologs in axolotl. In an example of convergent evolution and akin to TREX1, gar PML and zebrafish Plex9 proteins suppressed L1 retrotransposition and could complement TREX1 knockout in mammalian cells. Following export to the cytoplasm, the human PML-I isoform also restricted L1 through its conserved C-terminus by enhancing ORF1p degradation through the ubiquitin-proteasome system. Thus, PML first emerged as a cytoplasmic suppressor of retroelements, and this function is retained in amniotes despite its new role in the assembly of nuclear bodies.

Haploinsufficient tumor suppressor PRP4K is negatively regulated during epithelial-to-mesenchymal transition.

The pre-mRNA processing factor 4 kinase (PRP4K, also known as PRPF4B) is an essential gene. However, reduced PRP4K expression is associated with aggressive breast and ovarian cancer phenotypes including taxane therapy resistance, increased cell migration and invasion in vitro, and cancer metastasis in mice. These results are consistent with PRP4K being a haploinsufficient tumor suppressor. Increased cell migration and invasion is associated with epithelial-to-mesenchymal transition (EMT), but how reduced PRP4K levels affect normal epithelial cell migration or EMT has not been studied. Depletion of PRP4K by small hairpin RNA (shRNA) in non-transformed mammary epithelial cell lines (MCF10A, HMLE) reduced or had no effect on 2D migration in the scratch assay but resulted in greater invasive potential in 3D transwell assays. Depletion of PRP4K in mesenchymal triple-negative breast cancer cells (MDA-MB-231) resulted in both enhanced 2D migration and 3D invasion, with 3D invasion correlated with higher fibronectin levels in both MDA-MB-231 and MCF10A cells and without changes in E-cadherin. Induction of EMT in MCF10A cells, by treatment with WNT-5a and TGF-ß1, or depletion of eukaryotic translation initiation factor 3e (eIF3e) by shRNA, resulted in significantly reduced PRP4K expression. Mechanistically, induction of EMT by WNT-5a/TGF-ß1 reduced PRP4K transcript levels, whereas eIF3e depletion led to reduced PRP4K translation. Finally, reduced PRP4K levels after eIF3e depletion correlated with increased YAP activity and nuclear localization, both of which are reversed by overexpression of exogenous PRP4K. Thus, PRP4K is a haploinsufficient tumor suppressor negatively regulated by EMT, that when depleted in normal mammary cells can increase cell invasion without inducing full EMT.

The Joel-Cohen laparotomy: A dilapidating access source of wide and complex suprapubic incisional hernia.

PURPOSE: This retrospective study aims to describe morphological and therapeutic peculiarities of the suprapubic incisional hernia (SIH) encountered after a Joël-Cohen laparotomy. PATIENTS AND METHOD: Serie-report: 9 patients had an SIH, 2 were sub-umbilical and did not concern the suprapubic scar, 3 were central, 2 on the whole length of the suprapubic scar, and 2 were bilateral in one case associated to a sub-umbilical incisional hernia. RESULTS: SIH were wide openings, with a hernial fascia constituted from the anterior fascia, without connexion with the parietal peritoneum, in a sub-umbilical position above the suprapubic scar, or through the suprapubic scar. Rectus muscle was ruptured or sclerosed. There were 2 distinct defects, an anterior one through the anterior fascia, and a posterior one between the rectus muscles. The parietal peritoneum was retracted leaving bare the posterior side of the rectus muscles. There was an interstitial retro-fascial space, so the SIH was bisaccular. When releasing the parietal peritoneum was not feasible, the prosthesis was placed in a retro-fascial space. When the parietal peritoneum was released, the prosthesis was placed in a preperitoneal space. The anterior defect closure was not always completely feasible, fulfilled with a Vicryl prosthesis. One patient presents an abdominal wall bulging in case of efforts. CONCLUSION: SIH after a Joël-Cohen laparotomy is wide and dilapidating. The cure is difficult. This technique should be reserved to real emergency obstetrical procedure. We highlight the importance of the parietal peritoneum closure after gynecological or obstetric surgery.

Tinker, Tailor, Tumour Suppressor: The Many Functions of PRP4K.

Pre-mRNA processing factor 4 kinase (PRP4K, also known as PRPF4B) is an essential kinase first identified in the fission yeast Schizosaccharomyces pombe that is evolutionarily conserved from amoebae to animals. During spliceosomal assembly, PRP4K interacts with and phosphorylates PRPF6 and PRPF31 to facilitate the formation of the spliceosome B complex. However, over the past decade additional evidence has emerged that PRP4K has many diverse cellular roles beyond splicing that contribute to tumour suppression and chemotherapeutic responses in mammals. For example, PRP4K appears to play roles in regulating transcription and the spindle assembly checkpoint (SAC), a key pathway in maintaining chromosomes stability and the response of cancer cells to taxane-based chemotherapy. In addition, PRP4K has been revealed to be a haploinsufficient tumour suppressor that promotes aggressive cancer phenotypes when partially depleted. PRP4K is regulated by both the HER2 and estrogen receptor, and its partial loss increases resistance to the taxanes in multiple malignancies including cervical, breast and ovarian cancer. Moreover, ovarian and triple negative breast cancer patients harboring tumours with low PRP4K expression exhibit worse overall survival. The depletion of PRP4K also enhances both Yap and epidermal growth factor receptor (EGFR) signaling, the latter promoting anoikis resistance in breast and ovarian cancer. Finally, PRP4K is negatively regulated during epithelial-to-mesenchymal transition (EMT), a process that promotes increased cell motility, drug resistance and cancer metastasis. Thus, as we discuss in this review, PRP4K likely plays evolutionarily conserved roles not only in splicing but in a number of cellular pathways that together contribute to tumour suppression.

Adding Some "Splice" to Stress Eating: Autophagy, ESCRT and Alternative Splicing Orchestrate the Cellular Stress Response.

Autophagy is a widely studied self-renewal pathway that is essential for degrading damaged cellular organelles or recycling biomolecules to maintain cellular homeostasis, particularly under cellular stress. This pathway initiates with formation of an autophagosome, which is a double-membrane structure that envelopes cytosolic components and fuses with a lysosome to facilitate degradation of the contents. The endosomal sorting complexes required for transport (ESCRT) proteins play an integral role in controlling autophagosome fusion events and disruption to this machinery leads to autophagosome accumulation. Given the central role of autophagy in maintaining cellular health, it is unsurprising that dysfunction of this process is associated with many human maladies including cancer and neurodegenerative diseases. The cell can also rapidly respond to cellular stress through alternative pre-mRNA splicing that enables adaptive changes to the cell's proteome in response to stress. Thus, alternative pre-mRNA splicing of genes that are involved in autophagy adds another layer of complexity to the cell's stress response. Consequently, the dysregulation of alternative splicing of genes associated with autophagy and ESCRT may also precipitate disease states by either reducing the ability of the cell to respond to stress or triggering a maladaptive response that is pathogenic. In this review, we summarize the diverse roles of the ESCRT machinery and alternative splicing in regulating autophagy and how their dysfunction can have implications for human disease.

Laparoscopic tension-free repair of anterior abdominal wall incisional and ventral hernias with an intraperitoneal Gore-Tex mesh: prospective study and review of the literature.

BACKGROUND: Recurrence rates after repair of incisional and ventral hernias range from 18% to 52%. Prosthetic open repair has decreased this rate, but the wide fascial dissection it requires increases the complication rate. Laparoscopic repair is a safe and effective alternative. PATIENTS AND METHODS: A prospective study was performed including 86 patients (63 women and 23 men) with a mean age of 54 years (range 29-79 years) having incisional or ventral hernias who underwent laparoscopic repair in our institution between July 1994 and October 2001. The majority of the patients were obese with a mean body mass index of 31.7 kg/m2. The abdominal wall defect size ranged from 2 X 1 cm to 20 X 13 cm. In all cases, a Gore-Tex mesh (Dual Mesh, W.L. Gore & Associates, Flagstaff, AZ, USA) was used in sizes ranging from 10 X 15 cm to 20 X 30 cm. RESULTS: Nineteen repairs were performed for recurrent hernias (12 incisional and 7 ventral). The mean operative time was 110.3 minutes (range 50-240 minutes). There was one open conversion (1.2%), one intraoperative complication (1.2%), and no deaths. There were no wound or mesh infections. Immediate postoperative complications occurred in 9 patients (10.6%) and late complications occurred in 16 patients (18.8%). The average hospital stay was 4.8 days (range 2-19 days). During a mean follow-up of 37 months (range 6-73 months), there were 6 hernia recurrences (7%). CONCLUSION: Laparoscopic repair of incisional hernia and ventral hernia appears to be safe, especially with the use of Gore-Tex mesh, and is proving to be effective as it decreases pain, complications, hospital stay, and recurrences.

[Digestive complications of biliary gallstone lost during laparoscopic cholecystectomy]. / Complications digestives d'un calcul biliaire perdu pendant une cholécystectomie sous coelioscopie.

A patient was admitted because of an intestinal obstruction. Eight years before, he underwent a laparoscopic cholecystectomy. Abdominal ultrasonography and small bowel series showed a gallstone in the small bowel that computed tomography scan failed to identify. Laparotomy showed a Meckel's diverticula and a biliary stone in the terminal ileum. In the literature, it has been shown that gallstone lost during laparoscopic cholecystectomy may be responsible for intraperitoneal abscess. In the contact of intestine, the stone may induce an obstructive abscess, a communicating abscess, a digestive fistula or a biliary ileus. During the postoperative course of laparoscopic cholecystectomy, these patients suffer from abdominal pain and fever lasting from few days to several months. Imaging shows the biliary gallstone mechanical complications induced by the stone. To avoid such complications, biliary gallstone that falls into the peritoneum during laparoscopic cholecystectomy should be removed under laparoscopy.

[Urogenital expression of a tumor of the terminal ileum]. / Tumeur de l'iléon terminal à expression urogénitale.

Malignant tumors of the small bowel are usually associated with digestive and general symptoms. We report the case of a 26-year-old patient who presented with right lumbar pain and right testicular pain. Final diagnosis was lymphoma of the terminal ileum involving the right pelvic ureter and the right vas deferens. We discuss frequency and mechanisms of this very unusual extension of malignant small bowel tumors.