The wide and growing range of lamin B‑related diseases: from laminopathies to cancer

B-type lamins are fundamental components of the nuclear lamina, a complex structure that acts as a scafold for organization and function of the nucleus. Lamin B1 and B2, the most represented isoforms, are encoded by LMNB1 and LMNB2 gene, respectively. All B-type lamins are synthesized as precursors and undergo sequential post-translational modifcations to generate the mature protein. B-type lamins are involved in a wide range of nuclear functions, including DNA replication and repair, regulation of chromatin and nuclear stifness. Moreover, lamins B1 and B2 regulate several cellular processes, such as tissue development, cell cycle, cellular proliferation, senescence, and DNA damage response. During embryogenesis, B-type lamins are essential for organogenesis, in particular for brain development. As expected from the numerous and pivotal functions of B-type lamins, mutations in their genes or fuctuations in their expression levels are critical for the onset of several diseases. Indeed, a growing range of human disorders have been linked to lamin B1 or B2, increasing the complexity of the group of diseases collectively known as laminopathies. This review highlights the recent fndings on the biological role of B-type lamins under physiological or pathological conditions, with a particular emphasis on brain disorders and cancer

The open body: a “new” book

At the beginning of the ‘300, Mondino de’ Liuzzi, a physician from Bologna, was the first anatomist who started again the dissection of human body neglected from the III century. He hinted at the existence of the conflict between book and body, between “auctoritas” and the direct observation of the human body . The Mondino’s masterwork “Anothomia” remained the key book up to the middle of the sixth century, when Andrea Vesalio wrote “De Umani Corporis Fabrica,” in which the body (cadaver) eventually became the main player of the book . During the years, the technologic evolution led to the wrong conviction that dissection could be dismissed, albeit, still in our day, doctors in training feel the need to associate the direct experience on the cadaver with the very valuable digital means and the modern imaging technologies even in 3D. Thinking to Anatomy as an already fully well known discipline is a mistake. The most advanced methodologies for surgical access, namely the minimally invasive surgery, require the evolution of the traditional anatomical knowledge. The Human Anatomy Institute of the University of Bologna, among the first in Italy, has recognized this need. Thanks to the generosity of the people enrolled in the Body donation programme for research and teaching, our Institute allows medical students to practice dissection on cadavers, beginning as Freshman, then Sophomore, Junior and Senior. The sharing of Bologna’s experience could be the chance to think about the perspectives offered by the dissection of the corpse: a wide range of possibilities spanning from research projects to advanced training courses in collaboration with clinicians and surgeons belonging to different branches. Moreover the practice of corpse dissection is extremely important for the recruitment of young graduates in Medicine which, by means of the experience vested acting as “tutor of anatomy”, acquire interest in the field of research of morphological sciences, spanning from macroscopic up to the cellular and molecular level. Hic mors gaudet succurrere vitae: the motto, reported in dissection room of most of the Italian anatomical institutes, represents the synthesis of the experience of an ancient discipline which, nowadays , has the chance to rewrite a new chapter dedicated to modern frontiers of scientific research and medical education

Diacylglycerol kinase (DGK) involvement in K562 erythroleukemia cell proliferation

Nuclear phosphoinositide metabolism has been widely described as involved in many regulatory mechanisms including cell cycle and cell proliferation (1). Our recent studies demonstrated that an increase of nuclear Diacylglycerol (DAG) regulated the G2/M progression of erythroleukemia cells, K562 (2). As nuclear DAG can be synthesized by Phospholipases C (PLC) located in the nucleus, it can also be converted to Phosphatidic acid (PA) by a class of proteins called Diacylglycerol Kinases (DGK), which phosphorylate it utilizing ATP as a source of phosphate. PA levels in the nuclear compartments peak after G2/M progression, controlling cell cycle progression (1). We found that a particular DGK isoform, DGKa, is highly localized in the nuclear compartment of K562 cells. Then, we decided to investigate if this isozyme could be involved in cell proliferation of K562 cells, stimulating the exit from G2/M checkpoint through the production of PA in the nuclear compartment. Our data show that inhibition of DGK activity by two specific inhibitors, DI (R59022) and DII (R59949), blocks K562 cell proliferation. This effect is probably due to nuclear DGKa, indeed its modulation can affect cell proliferation too. Moreover, many cell cycle related proteins seem to be targeted by DGK activity. These evidences suggest a role for DGKa in the control of cell cycle progression acting on nuclear DAG levels and increase our knowledge about the importance of PI metabolism in the nuclei of eucaryotic cells

Re‐examination of the mechanisms regulating nuclear inositol lipid metabolism

Although inositol lipids constitute only a very minor proportion of total cellular lipids, they have received immense attention by scientists since it was discovered that they play key roles in a wide range of important cellular processes. In the late 1980s, it was suggested that these lipids are also present within the cell nucleus. Albeit the early reports about the intranuclear localization of phosphoinositides were met by skepticism and disbelief, compelling evidence has subsequently been accumulated convincingly showing that a phosphoinositide cycle is present at the nuclear level and may be activated in response to stimuli that do not activate the inositol lipid metabolism localized at the plasma membrane. Very recently, intriguing new data have highlighted that some of the mechanisms regulating nuclear inositol lipid metabolism differ in a substantial way from those operating at the cell periphery. Here, we provide an overview of recent findings regarding the regulation of both nuclear phosphatidylinositol 3‐kinase and phosphoinositide‐specific phospholipase C‐β1

PLC-beta 1 regulates the expression of miR-210 during mithramycin-mediated erythroid differentiation in K562 cells

PLC-beta 1 (PLCβ1) inhibits erythroid differentiation induced by mithramycin (MTH) by targeting miR-210 expression. MicroRNA-210 (miR-210) has been reported to be upregulated in various types of human malignancy suggesting that it has an important role in tumorigenesis. Inhibition of miR-210 affects the erythroid differentiation pathway and it occurs to a greater extent in MTH-treated cells. In this paper we have analyzed the effect of MTH on human K562 cells differentiation. Overexpression of PLCβ1 suppresses the differentiation of K562 elicited by MTH as demonstrated by the absence of γ-globin expression. Inhibition of PLCβ1 expression is capable to promote the differentiation process leading to a recovery of γ-globin gene even in the absence of MTH. Our experimental evidences suggest that PLCβ1 signalling regulates erythropoiesis through miR-210. Indeed overexpression of PLCβ1 leads to a decrease of miR-210 expression after MTH treatment. Moreover miR-210 is up-regulated through both proliferation and differentiation events when PLCβ1 expression is down-regulated. Therefore we suggest a novel role for PLCβ1 in regulating miR-210 and our data hint at the fact that, in human K562 erythroleukemia cells, the modulation of PLCβ1 expression is able to exert an impairment of normal erythropoiesis as assessed by γ-globin expression

How Inflammation Pathways Contribute to Cell Death in Neuro-Muscular Disorders

Neuro-muscular disorders include a variety of diseases induced by genetic mutations resulting in muscle weakness and waste, swallowing and breathing difficulties. However, muscle alterations and nerve depletions involve specific molecular and cellular mechanisms which lead to the loss of motor-nerve or skeletal-muscle function, often due to an excessive cell death. Morphological and molecular studies demonstrated that a high number of these disorders seem characterized by an upregulated apoptosis which significantly contributes to the pathology. Cell death involvement is the consequence of some cellular processes that occur during diseases, including mitochondrial dysfunction, protein aggregation, free radical generation, excitotoxicity and inflammation. The latter represents an important mediator of disease progression, which, in the central nervous system, is known as neuroinflammation, characterized by reactive microglia and astroglia, as well the infiltration of peripheral monocytes and lymphocytes. Some of the mechanisms underlying inflammation have been linked to reactive oxygen species accumulation, which trigger mitochondrial genomic and respiratory chain instability, autophagy impairment and finally neuron or muscle cell death. This review discusses the main inflammatory pathways contributing to cell death in neuro-muscular disorders by highlighting the main mechanisms, the knowledge of which appears essential in developing therapeutic strategies to prevent the consequent neuron loss and muscle wasting

BMP-2 induced expression of PLC beta1 that is a positive regulator of osteoblast differentiation

C2C12 is an immortalized mouse myoblast cell line. The cells readily proliferate in high-serum conditions, and differentiate and fuse in low-serum conditions. While this cell line is a very useful tool to study aspects of myogenesis, metabolism and muscle biology, however, treatment of C2C12 cells with bone morphogenic protein (BMPs) induces cells to differentiate into osteoblasts. Osteoblast differentiation is controlled by diversified signaling proteins and transcription factors, essentially BMP-2, Osterix (Osx/Sp7) and Runx2, finally associating with the expression of late osteoblast marker genes, like ALPL and Bglap. These peculiarities make C2C12 progenitor cells a skillful prototype to investigate the molecular mechanism that control cell destiny specification and terminal differentiation. In the current investigation, we took improvement of the differentiation peculiarities of the mouse C2C12 cell line to analyze whether changes in PLCbeta1 expression and its nuclear localization might regulate or affect their terminal osteogenic differentiation. We demonstrated that overexpression of PLCβ1 enhances the osteogenic differentiation of C2C12 elicited by BMP-2 as demonstrated by the presence of osteoblast marker genes expression. In the present study we also showed that miR-214 suppressed osteogenic differentiation through the regulation of nuclear PLCβ1 by targeting Osterix

Specific ablation of phospholipase Cγ1 in forebrain causes manic-like behavior

It is well known that manic episodes are one of the major diagnostic symptoms in a spectrum of neuropsychiatric disorders that include schizophrenia, obsessive-compulsive disorder and bipolar disorder (BD). Despite a possible association between BD and the gene encoding phospholipase Cγ1 (PLCG1), its etiological basis remains unclear. Here, we report that mice lacking phospholipase Cγ1 (PLCγ1) in the forebrain (Plcg1f/f; CaMKII) exhibit hyperactivity, decreased anxiety-like behavior, reduced depressive-related behavior, hyperhedonia, hyperphagia, impaired learning and memory and exaggerated startle responses. Inhibitory transmission in hippocampal pyramidal neurons and striatal dopamine receptor D1-expressing neurons of Plcg1-deficient mice was significantly reduced. The decrease in inhibitory transmission is likely due to a reduced number of γ-aminobutyric acid (GABA)-ergic boutons, which may result from impaired localization and/or stabilization of postsynaptic CaMKII (Ca2+/calmodulin-dependent protein kinase II) at inhibitory synapses. Moreover, mutant mice display impaired brain-derived neurotrophic factor-tropomyosin receptor kinase B-dependent synaptic plasticity in the hippocampus, which could account for deficits of spatial memory. Lithium and valproate, the drugs presently used to treat mania associated with BD, rescued the hyperactive phenotypes of Plcg1f/f; CaMKII mice. These findings provide evidence that PLCγ1 is critical for synaptic function and plasticity and that the loss of PLCγ1 from the forebrain results in manic-like behavior