The fidgetin family: Shaking things up among the microtubule-severing enzymes.

The microtubule cytoskeleton is required for several crucial cellular processes, including chromosome segregation, cell polarity and orientation, and intracellular transport. These functions rely on microtubule stability and dynamics, which are regulated by microtubule-binding proteins (MTBPs). One such type of regulator is the microtubule-severing enzymes (MSEs), which are ATPases Associated with Diverse Cellular Activities (AAA+ ATPases). The most recently identified family are the fidgetins, which contain three members: fidgetin, fidgetin-like 1 (FL1), and fidgetin-like 2 (FL2). Of the three known MSE families, the fidgetins have the most diverse range of functions in the cell, spanning mitosis/meiosis, development, cell migration, DNA repair, and neuronal function. Furthermore, they offer intriguing novel therapeutic targets for cancer, cardiovascular disease, and wound healing. In the two decades since their first report, there has been great progress in our understanding of the fidgetins; however, there is still much left unknown about this unusual family. This review aims to consolidate the present body of knowledge of the fidgetin family of MSEs and to inspire deeper exploration into the fidgetins and the MSEs as a whole.

Fidgetin-like 2 depletion enhances cell migration by regulating GEF-H1, RhoA, and FAK.

The microtubule (MT) cytoskeleton and its dynamics play an important role in cell migration. Depletion of the microtubule-severing enzyme Fidgetin-like 2 (FL2), a regulator of MT dynamics at the leading edge of migrating cells, leads to faster and more efficient cell migration. Here we examine how siRNA knockdown of FL2 increases cell motility. Förster resonance energy transfer biosensor studies shows that FL2 knockdown decreases activation of the p21 Rho GTPase, RhoA, and its activator GEF-H1. Immunofluorescence studies reveal that GEF-H1 is sequestered by the increased MT density resulting from FL2 depletion. Activation of the Rho GTPase, Rac1, however, does not change after FL2 knockdown. Furthermore, FL2 depletion leads to an increase in focal adhesion kinase activation at the leading edge, as shown by immunofluorescence studies, but no change in actin dynamics, as shown by fluorescence recovery after photobleaching. We believe these results expand our understanding of the role of MT dynamics in cell migration and offer new insights into RhoA and Rac1 regulation.

Evaluation of novel highly specific antibodies to cancer testis antigen Centrin-1 for radioimmunoimaging and radioimmunotherapy of pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) accounts for >90% of pancreatic malignancies, and has median survival of <6 months. There is an urgent need for diagnostic and therapeutic options for PDAC. Centrin1 (CETN1) is a novel member of Cancer/Testis Antigens, with a 25-fold increase of CETN1 gene expression in PDX from PDAC patients. The absence of selective anti-CETN1 antibodies is hampering CETN1 use for diagnosis and therapy. Here we report the generation of highly specific for CETN1 antibodies and their evaluation for radioimmunoimaging and radioimmunotherapy (RIT) of experimental PDAC. METHODS: The antibodies to CETN1 were generated via mice immunization with immunogenic peptide distinguishing CETN1 from CETN2. Patient tumor microarrays were used to evaluate the binding of the immune serum to PDAC versus normal pancreas. The antibodies were tested for their preferential binding to CETN1 over CETN2 by ELISA. Mice bearing PDAC MiaPaCa2 xenografts were imaged with microSPECT/CT and treated with 213 Bi- and 177 Lu-labeled antibodies to CETN1. RESULTS: Immune serum bind to 50% PDAC cases on patient tumor microarrays with no specific binding to normal pancreas. Antibodies demonstrated preferential binding to CETN1 versus CETN2. Antibody 69-11 localized to PDAC xenografts in mice in vivo and ex vivo. RIT of PDAC xenografts with 213 Bi-labeled antibodies was effective, safe, and CETN1-specific. CONCLUSIONS: The results demonstrate the ability of these novel antibodies to detect CETN1 both in vitro and in vivo; as well, the RIT treatment of experimental PDAC when radiolabeled with 213 Bi is highly efficient and safe. Further evaluation of these novel reagents for diagnosis and treatment of PDAC is warranted.

A potential case of remission of Parkinson's disease.

We present the case of a 78-year-old male who, 16 years ago, was diagnosed with Parkinson's disease (PD) by a neurologist. He initially presented with left-hand tremor, stooped posture, shuffling gait, and frequent falls, which eventually progressed to bilateral motor symptoms after 3 years. Since 2012, his symptoms and signs have almost completely remitted, and he has been off all pharmacotherapy for that time. The accuracy of the initial PD diagnosis is supported by an appropriate clinical presentation, history of positive response to Sinemet, and an abnormal SPECT DaT scan; thus this case suggests the possibility of remission of symptoms in some patients. We propose that the patient's long history of meditation practice may have been one contributing factor of this improvement as meditation has been shown to release dopamine in the striatum.