Mutations in FBXL4, encoding a mitochondrial protein, cause early-onset mitochondrial encephalomyopathy.

Whole-exome sequencing and autozygosity mapping studies, independently performed in subjects with defective combined mitochondrial OXPHOS-enzyme deficiencies, identified a total of nine disease-segregating FBXL4 mutations in seven unrelated mitochondrial disease families, composed of six singletons and three siblings. All subjects manifested early-onset lactic acidemia, hypotonia, and developmental delay caused by severe encephalomyopathy consistently associated with progressive cerebral atrophy and variable involvement of the white matter, deep gray nuclei, and brainstem structures. A wide range of other multisystem features were variably seen, including dysmorphism, skeletal abnormalities, poor growth, gastrointestinal dysmotility, renal tubular acidosis, seizures, and episodic metabolic failure. Mitochondrial respiratory chain deficiency was present in muscle or fibroblasts of all tested individuals, together with markedly reduced oxygen consumption rate and hyperfragmentation of the mitochondrial network in cultured cells. In muscle and fibroblasts from several subjects, substantially decreased mtDNA content was observed. FBXL4 is a member of the F-box family of proteins, some of which are involved in phosphorylation-dependent ubiquitination and/or G protein receptor coupling. We also demonstrate that FBXL4 is targeted to mitochondria and localizes in the intermembrane space, where it participates in an approximately 400 kDa protein complex. These data strongly support a role for FBXL4 in controlling bioenergetic homeostasis and mtDNA maintenance. FBXL4 mutations are a recurrent cause of mitochondrial encephalomyopathy onset in early infancy.

Reversible Photoregulation of Cell-Cell Adhesions With Opto-E-cadherin.

The cell-cell adhesion molecule E-cadherin has been intensively studied due to its prevalence in tissue function and its spatiotemporal regulation during epithelial-to-mesenchymal cell transition. Nonetheless, regulating and studying the dynamics of it has proven challenging. We developed a photoswitchable version of E-cadherin, named opto-E-cadherin, which can be toggled OFF with blue light illumination and back ON in the dark. Herein, we describe easy-to-use methods to test and characterise opto-E- cadherin cell clones for downstream experiments. Key features • This protocol describes how to implement optogenetic cell-cell adhesion molecules effectively (described here on the basis of opto-E-cadherin), while highlighting possible pitfalls. • Utilises equipment commonly found in most laboratories with high ease of use. • Phenotype screening is easy and done within a few hours (comparison of cell clusters in the dark vs. blue light in an aggregation assay). • Three different functionality assay systems are described. • After the cell line is established, all experiments can be performed within three days.

Reversible photoregulation of cell-cell adhesions with opto-E-cadherin.

E-cadherin-based cell-cell adhesions are dynamically and locally regulated in many essential processes, including embryogenesis, wound healing and tissue organization, with dysregulation manifesting as tumorigenesis and metastasis. However, the lack of tools that would provide control of the high spatiotemporal precision observed with E-cadherin adhesions hampers investigation of the underlying mechanisms. Here, we present an optogenetic tool, opto-E-cadherin, that allows reversible control of E-cadherin-mediated cell-cell adhesions with blue light. With opto-E-cadherin, functionally essential calcium binding is photoregulated such that cells expressing opto-E-cadherin at their surface adhere to each other in the dark but not upon illumination. Consequently, opto-E-cadherin provides remote control over multicellular aggregation, E-cadherin-associated intracellular signalling and F-actin organization in 2D and 3D cell cultures. Opto-E-cadherin also allows switching of multicellular behaviour between single and collective cell migration, as well as of cell invasiveness in vitro and in vivo. Overall, opto-E-cadherin is a powerful optogenetic tool capable of controlling cell-cell adhesions at the molecular, cellular and behavioural level that opens up perspectives for the study of dynamics and spatiotemporal control of E-cadherin in biological processes.

Efficient Purification of Cowpea Chlorotic Mottle Virus by a Novel Peptide Aptamer.

The cowpea chlorotic mottle virus (CCMV) is a plant virus explored as a nanotechnological platform. The robust self-assembly mechanism of its capsid protein allows for drug encapsulation and targeted delivery. Additionally, the capsid nanoparticle can be used as a programmable platform to display different molecular moieties. In view of future applications, efficient production and purification of plant viruses are key steps. In established protocols, the need for ultracentrifugation is a significant limitation due to cost, difficult scalability, and safety issues. In addition, the purity of the final virus isolate often remains unclear. Here, an advanced protocol for the purification of the CCMV from infected plant tissue was developed, focusing on efficiency, economy, and final purity. The protocol involves precipitation with PEG 8000, followed by affinity extraction using a novel peptide aptamer. The efficiency of the protocol was validated using size exclusion chromatography, MALDI-TOF mass spectrometry, reversed-phase HPLC, and sandwich immunoassay. Furthermore, it was demonstrated that the final eluate of the affinity column is of exceptional purity (98.4%) determined by HPLC and detection at 220 nm. The scale-up of our proposed method seems to be straightforward, which opens the way to the large-scale production of such nanomaterials. This highly improved protocol may facilitate the use and implementation of plant viruses as nanotechnological platforms for in vitro and in vivo applications.

Urologic Presentations and Management Options in Pediatric Mitochondrial Disease.

OBJECTIVE: To review the evaluation and management of urologic pathology related to mitochondiral diseases (MD) in childhood. METHODS: A retrospective review was performed of patients with MD from 1/1/2000 - 10/8/2020 who were referred for urologic evaluation at a single pediatric hospital. Clinical and demographic information was reviewed including symptomatology, urodynamic evaluation, and medical/surgical management. RESULTS: 15 patients were identified for inclusion. Median age of presentation was 5 years and median follow up was 4 years. Patients presented with numerous urologic concerns including urinary retention/incomplete emptying, incontinence, and recurrent urinary tract infection. Urodynamics demonstrated elevated median bladder capacity at 172% of expected as calculated by age. Detrusor sphincter dyssynergia (DSD) was present in 6 (50%). Progression to surgical intervention occurred in 67% at a median time of 3.5 years after initial referral. This included suprapubic tube (SPT) placement and sacral neuromodulation (SNM). CONCLUSION: Patients in this study were found to have a spectrum of lower urinary tract dysfunction (LUTD) with elevated bladder capacity being common. No singular urodynamic feature prevailed although DSD was found in 50%. Progression of symptoms over time was also common. Most patients (67%) did go on to surgical intervention including SPT and SNM. Clinicians should be aware of the possibility of LUTD in children with MD and they should be promptly referred to pediatric urology when LUTD is suspected.

Innervation modulates the functional connectivity between pancreatic endocrine cells.

The importance of pancreatic endocrine cell activity modulation by autonomic innervation has been debated. To investigate this question, we established an in vivo imaging model that also allows chronic and acute neuromodulation with genetic and optogenetic tools. Using the GCaMP6s biosensor together with endocrine cell fluorescent reporters, we imaged calcium dynamics simultaneously in multiple pancreatic islet cell types in live animals in control states and upon changes in innervation. We find that by 4 days post fertilization in zebrafish, a stage when islet architecture is reminiscent of that in adult rodents, prominent activity coupling between beta cells is present in basal glucose conditions. Furthermore, we show that both chronic and acute loss of nerve activity result in diminished beta-beta and alpha-beta activity coupling. Pancreatic nerves are in contact with all islet cell types, but predominantly with beta and delta cells. Surprisingly, a subset of delta cells with detectable peri-islet neural activity coupling had significantly higher homotypic coupling with other delta cells suggesting that some delta cells receive innervation that coordinates their output. Overall, these data show that innervation plays a vital role in the maintenance of homotypic and heterotypic cellular connectivity in pancreatic islets, a process critical for islet function.

A dimerization-dependent mechanism regulates enzymatic activation and nuclear entry of PLK1.

Polo-like kinase 1 (PLK1) is a crucial regulator of cell cycle progression. It is established that the activation of PLK1 depends on the coordinated action of Aurora-A and Bora. Nevertheless, very little is known about the spatiotemporal regulation of PLK1 during G2, specifically, the mechanisms that keep cytoplasmic PLK1 inactive until shortly before mitosis onset. Here, we describe PLK1 dimerization as a new mechanism that controls PLK1 activation. During the early G2 phase, Bora supports transient PLK1 dimerization, thus fine-tuning the timely regulated activation of PLK1 and modulating its nuclear entry. At late G2, the phosphorylation of T210 by Aurora-A triggers dimer dissociation and generates active PLK1 monomers that support entry into mitosis. Interfering with this critical PLK1 dimer/monomer switch prevents the association of PLK1 with importins, limiting its nuclear shuttling, and causes nuclear PLK1 mislocalization during the G2-M transition. Our results suggest a novel conformational space for the design of a new generation of PLK1 inhibitors.

Non-mitotic functions of polo-like kinases in cancer cells.

Inhibitors of mitotic protein kinases are currently being developed as non-neurotoxic alternatives of microtubule-targeting agents (taxanes, vinca alkaloids) which provide a substantial survival benefit for patients afflicted with different types of solid tumors. Among the mitotic kinases, the cyclin-dependent kinases, the Aurora kinases, the kinesin spindle protein and Polo-like kinases (PLKs) have emerged as attractive targets of cancer therapeutics. The functions of mammalian PLK1-5 are traditionally linked to the regulation of the cell cycle and to the stress response. Especially the key role of PLK1 and PLK4 in cellular growth and proliferation, their overexpression in multiple types of human cancer and their druggability, make them appealing targets for cancer therapy. Inhibitors for PLK1 and PLK4 are currently being tested in multiple cancer trials. The clinical success of microtubule-targeting agents is attributed not solely to the induction of a mitotic arrest in cancer cells, but also to non-mitotic effects like targeting intracellular trafficking on microtubules. This raises the question whether new cancer targets like PLK1 and PLK4 regulate critical non-mitotic functions in tumor cells. In this article we summarize the important roles of PLK1-5 for the regulation of non-mitotic signaling. Due to these functions it is conceivable that inhibitors for PLK1 or PLK4 can target interphase cells, which underscores their attractive potential as cancer drug targets. Moreover, we also describe the contribution of the tumor-suppressors PLK2, PLK3 and PLK5 to cancer cell signaling outside of mitosis. These observations highlight the urgent need to develop highly specific ATP-competitive inhibitors for PLK4 and for PLK1 like the 3rd generation PLK-inhibitor Onvansertib to prevent the inhibition of tumor-suppressor PLKs in- and outside of mitosis. The remarkable feature of PLKs to encompass a unique druggable domain, the polo-box-domain (PBD) that can be found only in PLKs offers the opportunity for the development of inhibitors that target PLKs exclusively. Beyond the development of mono-specific ATP-competitive PLK inhibitors, the PBD as drug target will support the design of new drugs that eradicate cancer cells based on the mitotic and non-mitotic function of PLK1 and PLK4.

Weight Trajectory in Refugee Children after Resettling in the United States: A Pilot Study.

BACKGROUND: The objective of this study is to describe the weight trajectory of refugee children after resettlement in the US. METHODS: A pilot study was conducted, utilizing longitudinal data obtained from the electronic health record of 129 children between 2 and 18 years of age (54% female, mean age 10 years) from the 3 primary countries of origin presenting to a refugee clinic (Bhutan, N = 71; Burma, N = 36, and Iraq, N = 22).. Mixed effects model analyses were utilized to characterize weight trajectory with calculation of a per year change in BMI-z score, adjusting for baseline BMI-z score, age, and time. RESULTS: There was a significant increase in BMI-z (mean 0.15 units/year, p=0.04) among refugee children during their initial period after resettlement. Female children from Bhutan demonstrated the most rapid increase in weight, with a mean BMI-z gain of 1.00 units/year. CONCLUSION: Female children from Bhutan demonstrated rapid weight gain after resettlement in the US. Further studies are needed to describe weight trajectory trends and evaluate possible reasons for rapid weight gain in this population.

Passive immunization.

Passive immunization employs preformed antibodies provided to an individual that can prevent or treat infectious diseases. There are several situations in which passive immunization can be used: for persons with congenital or acquired immunodeficiency, prophylactic administration when there is a likelihood of exposure to a particular infection, or treatment of a disease state already acquired by the individual. Passive immunization is limited by short duration (typically weeks to months), variable response, and adverse reactions. This article focuses on specific immunoglobulins for preventing or treating infectious diseases, as these are the most likely scenarios one might encounter in primary care practice.

Diagnosis of childhood cancer.

Childhood cancer is uncommon but remains the leading cause of disease-related death in children. Symptoms are often vague or insidious; they may suggest a more common alternative diagnosis, and they are quite different from those associated with adult malignancy. The skilled office practitioner must consider cancer as a diagnosis when symptoms/signs persist or when multiple symptoms point toward a possible diagnosis of malignancy. Early diagnosis is critical, as survival rates have increased dramatically over the past decades. Prolonged delay in diagnosis is common, especially for brain tumors and certain lymphomas (Hodgkin disease). When one encounters symptoms suspicious for a childhood malignancy, it is imperative that the child be referred to a pediatric cancer center. These centers possess not only the ability to further evaluate and manage children with malignancy, but also are able to provide support for patients and their families. This evaluation may include further imaging, but often involves obtaining tissue for histologic review. This will require appropriate tumor or bone marrow biopsy, preferably before the start of treatment. Depending upon the type of suspected malignancy, direct tumor biopsy can be facilitated by imaging-guided biopsy (ultrasound, CT, or MRI), which spares the patient additional surgery. This optimally is performed by a skilled team: hematologist/oncologist, surgeon, radiologist, and pathologist. Best results depend upon early referral by the thoughtful practitioner.

Successful liver transplant for unresectable hepatoblastoma.

BACKGROUND: Treatment of children with stage III and IV hepatoblastoma has shown little improvement with 5-year survival rates of 64% and 25%, respectively (J Clin Oncol 2000;18:2665-75). A timely and organized treatment program including preoperative chemotherapy combined with living donor liver transplantation and postoperative chemotherapy has been used seeking improved long-term survival in stage III and IV cases. METHODS: A retrospective review of 8 patients with stage III and IV hepatoblastoma unresectable by conventional resection were treated with complete hepatectomy and transplantation. Approval was obtained from our institutional review board. RESULTS: Since August of 2001, we have treated 6 patients with stage III hepatoblastoma and 2 patients with initial stage IV hepatoblastoma. These patients (age, 23 months-9 years) had all received extensive chemotherapy or prior resections. After chemotherapy, none had gross tumor documented outside of the liver at time of transplantation. All underwent hepatectomy including vena cava resection, in selected cases, with living donor orthotopic liver transplantation. All patients had at least 2 cycles of postoperative chemotherapy. Of 8 patients, 6 are alive and well with normalized alpha-fetoprotein levels. There were 2 late deaths from recurrent disease. Length of follow-up ranged from 7 to 53 months. CONCLUSION: Complete hepatectomy with living donor liver transplantation provides optimal surgical treatment in unresectable stage III and initial stage IV disease confined to the liver at resection. This series indicates that children tolerate complete hepatectomy, transplantation, and postoperative chemotherapy well. Referral to a transplant center during the first 3 cycles of chemotherapy appears to offers the best opportunity for long-term survival.