Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.

Since the initial description of apoptosis, a number of different forms of cell death have been described. In this review we will focus on classic caspase-dependent apoptosis and its variations that contribute to diseases. Over fifty years of research have clarified molecular mechanisms involved in apoptotic signaling as well and shown that alterations of these pathways lead to human diseases. Indeed both reduced and increased apoptosis can result in pathology. More recently these findings have led to the development of therapeutic approaches based on regulation of apoptosis, some of which are in clinical trials or have entered medical practice.

Sjögren-Larsson syndrome (SLS) is an inherited neurocutaneous disorder characterized by mental retardation, spasticity and ichthyosis. SLS patients have a profound deficiency in fatty aldehyde dehydrogenase (FALDH) activity. We have now cloned the human FALDH cDNA and show that it maps to the SLS locus on chromosome 17p11.2. Sequence analysis of FALDH amplified from fibroblast mRNA and genomic DNA from 3 unrelated SLS patients reveals distinct mutations, including deletions, an insertion and a point mutation. The cloning of FALDH and the identification of mutations in SLS patients opens up possibilities for developing therapeutic approaches to ameliorate the neurologic and cutaneous symptoms of the disease.

The p53 tumor suppressor gene is one of the most frequently mutated genes in human cancers. 1 p53 is a sequence-specific transcription factor and plays a critical role in activating the expression of genes involved in cell cycle arrest or apoptosis under conditions of genotoxic stress. 2,3 For over two decades, p53 was thought to be the only gene of its kind in the vertebrate genomes. This strong conviction, which was widely accepted in the p53 field, has now been proven to be incorrect. Two genes, referred to as p63 and p73, have been found to encode proteins that share a significant amino-acid identity in the transactivation domain, the DNA binding domain, and the oligomerization domain with p53. In the short period since their cloning, a number of investigators have reported on the structure, the function and the regulation of p63 and p73. This review summarizes the current information on the p63 and the p73 genes, with a focus on the differences between the three members in this newly defined p53-gene family.Keywords: p73; p53; c-Abl; apoptosis Abbreviations: HPV-16, human papilloma virus-16; IGFBP, Insulin-like growth factor binding proteins; IR, ionizing irradiation; MEFs, mouse embryo ®broblasts; MMS, methylmethane sulfonate; OD, oligomerization domain; SAM, sterile alpha motif; TA, transactivation domain; DN p63, N-terminal deleted p63 variants Alternative splicing of p63 and p73The p53 gene generates a single mRNA with a single open reading frame. In contrast, both the p63 and the p73 genes generate several differentially spliced variants. With the p73 gene, alternative splicings not only add or delete coding sequences, but also alter the reading frame. Hence, the p63 and the p73 genes can each encode several different proteins. Most notably, both the p63 and the p73 genes encode alternatively spliced C-terminal regions that are not found in the p53 protein (Figure 1).The p63 gene encodes at least six open reading frames: from the usage of two different promoters/ATG in combination with three alternatively spliced C-terminal ends (Figure 1). The three isoforms (TA-a, TA-b and TAg) are produced by a 5'-promoter and alternative splicing at the 3' end of the gene. These three isoforms contain the coding sequence for the N-terminal transactivation (TA) domain. Each of these three splice variants can also be expressed from an internal promoter upstream of exon 3', that provides a different ATG to initiate translation downstream of the TA domain. These N-terminal deleted p63 isoforms are referred to as DN-alpha, DN-beta and DNgamma. These DN p63 isoforms do not activate transcription but instead can inhibit the transactivation functions of the full length p63 proteins and of p53. 4 The p73 gene generates at least six open reading frames with alternatively spliced 3-region. Initially, two isoforms of p73 were identified: 5 the full length alphaisoform and a C-terminal shortened beta-isoform resulting from the alternative splicing of exon 13. Four other spliced forms of p73 have since been identified in...

Bats are natural reservoir hosts and sources of infection of several microorganisms, many of which cause severe human diseases. Because of contact between bats and other animals, including humans, the possibility exists for additional interspecies transmissions and resulting disease outbreaks. The purpose of this article is to supply an overview on the main pathogens isolated from bats that have the potential to cause disease in humans.

Additional complexity in p73: induction by mitogens in lymphoid cells and identification of two new splicing variants e and z Dear Editor, p53 is a sequence specific transcription factor which transactivates several genes important in the apoptotic pathway, such as p21, mdm2, gadd45, bax and caspases. 1,2 Lack of apoptosis, with inappropriate cell proliferation in cancer is correlated with a high frequency of p53 mutations, in some tumours reaching 50%. Perhaps surprisingly, in view of the importance of p53 in regulating cell death and its strong phylogenetic conservation, only recently have homologous genes been identified.These (p63 and p73) show up to 63% aminoacid identity with p53 in the DNA binding, oligomerization and transcription activation domains, suggesting a similar mechanism of action to p53. 3±7 p63 is expressed as six different forms. 4 These use one of the two alternative transcription initiation sites, each transcript then being expressed as one of three alternatively spliced variants (a, b, g). Since the transcripts using the downstream ATG lack the first three exons coding for the transactivation domain, they act as natural dominant negative mutants of full length p63 and of p53. 4 The p73 gene comprises 14 exons and we have shown previously that in addition to the full length a form and the alternatively spliced transcript lacking exon 13 (b) other splice variants, lacking exon 11 (g) and exons 11, 12 and 13 (d) are also produced. 8 Stimulation of the T lymphoblastoid cell line, Jurkat, and human peripheral blood lymphocytes (PBL) with phytoemagglutinin (PHA) causes a 3 and 2.6-fold increase respectively in p73 expression by Northern blotting after 24 h (panel A). This is associated with induction of 34.7% and 21.2% of apoptotic cells respectively. No p53 was detected in Jurkat cells after PHA treatment (not shown).In order to discriminate the differential induction of the four p73 isoforms we performed an RT±PCR using isoformspecific primers on RNA extracted from cells treated under the same conditions. Panel B shows upregulation of a, b, g and d in PHA-treated PBL and Jurkat cells. Densitometric comparison of these with the housekeeping gene GAPDH showed that the increase in expression of each isoform were comparable (not shown).In addition, a new isoform was amplified from normal PBL. Cloning and sequencing of this p73e identified it as a splicing variant lacking exons 11 and 13 (panel C). To confirm the existence of p73e, we screened a panel of normal and tumour cell lines. As also shown in panel B, p73e was also present in the human hepatoma line HepG2, and a sixth isoform z was identified in the MCF7 human breast cancer cell line and in a human skin biopsy. p73 z is a further splice variant which lacks exons 11 and 12, and results in the loss of 96 aminoacids, the sequence continuing with the C-terminus of the a form (panel C). In p73e, loss of exon 11 deletes 50 aminoacids with a frame shift to the reading frame of the g isoform; splicing of exon 13 deletes an additional 31 aminoacids...

The life expectancy for pancreatic cancer patients has seen no substantial changes in the last 40 years as very few and mostly just palliative treatments are available. As the five years survival rate remains around 5%, the identification of novel pharmacological targets and development of new therapeutic strategies are urgently needed. Here we demonstrate that inhibition of the G protein-coupled receptor GPR55, using genetic and pharmacological approaches, reduces pancreatic cancer cell growth in vitro and in vivo and we propose that this may represent a novel strategy to inhibit pancreatic ductal adenocarcinoma (PDAC) progression. Specifically, we show that genetic ablation of Gpr55 in the KRAS/TP53/Pdx1-Cre (KPC) mouse model of PDAC significantly prolonged survival. Importantly, KPC mice treated with a combination of the GPR55 antagonist Cannabidiol (CBD) and gemcitabine (GEM, one of the most used drugs to treat PDAC), survived nearly three times longer compared to mice treated with vehicle or GEM alone. Mechanistically, knockdown or pharmacologic inhibition of GPR55 reduced anchorage-dependent and independent growth, cell cycle progression, activation of mitogen-activated protein kinase (MAPK) signalling and protein levels of ribonucleotide reductases in PDAC cells. Consistent with this, genetic ablation of Gpr55 reduced proliferation of tumour cells, MAPK signalling and ribonucleotide reductase M1 levels in KPC mice. Combination of CBD and GEM inhibited tumour cell proliferation in KPC mice and it opposed mechanisms involved in development of resistance to GEM in vitro and in vivo. Finally, we demonstrate that the tumour suppressor p53 regulates GPR55 protein expression through modulation of the microRNA miR34b-3p. Our results demonstrate the important role played by GPR55 downstream of p53 in PDAC progression. Moreover our data indicate that combination of CBD and GEM, both currently approved for medical use, might be tested in clinical trials as a novel promising treatment to improve PDAC patients' outcome.

Cajal Bodies are one of many specialised organelles contained in the eukaryotic cell nucleus, and are involved in a number of functions, including regulation of replication-dependent histone gene transcription. In normal diploid cells their number varies between 0 and 4 depending on the cell cycle phase, although in cancer cell lines their number is extremely variable and it has been suggested that it correlates with cell ploidy. Here we show that in mammalian cells, as in Drosophila, two distinct though functionally related bodies exist: a histone gene locus body and a Cajal Body. The first one can be detected using FLASH or NPAT as markers while the second is labelled using antibodies against Coilin. Only the number of FLASH/NPAT histone gene locus bodies correlates with ploidy and only these organelles appear to be regulated during the cell cycle. Finally, we show that the two organelles completely co-localize during the S phase of the cell cycle.