Structure-Function Analysis of the Conserved Histone Chaperone Spt6

Chromatin structure is crucial to regulate access to the genome for processes such as a transcription, recombination, DNA repair, and DNA replication. Spt6, a key factor involved in regulating chromatin structure, is conserved throughout eukaryotes. Spt6 has been shown to function in many aspects of gene expression, including nucleosome assembly, transcription initiation and elongation, and mRNA processing and export. In addition, Spt6 has several conserved domains; however, little is known about their functions. I have performed a structure-function analysis of Spt6 using three separate approaches. First, I employed a random insertion mutagenesis that has identified sixty-seven mutants. While these mutants did not provide information regarding known domains, some have phenotypes that may prove useful for future study. Second, in a collaborative project with Romier lab, I studied the functional roles of the Spt6 SH2 domains. I have shown that deletion of the region of Spt6 encoding the SH2 domains causes severe mutant phenotypes without affecting Spt6 protein levels, demonstrating the importance of the SH2 domains of Spt6. Third, in an additional collaboration with the Romier lab, I showed that mutations that alter the region of Spt6 that interacts with the conserved transcription factor Spn1 impair Spt6 functions in vivo. Overall, this multi-pronged structure-function analysis of Spt6 has provided new insights into the tandem SH2 domains of Spt6, the Spt6-Spn1 interaction, and the uses and limitations of insertion mutagenesis. In addition, I have attempted to explore a possible role for Spt6 in transcription-associated mutagenesis. After employing several types of in vivo assays, I conclude that a possible role for Spt6 in transcription-associated mutagenesis is uncertain, as the results (with respect to a role for Spt6) reproducibly vary depending on the assay used. Thus, understanding this aspect of Spt6 biology awaits better assays and understanding of transcription-associated mutagenesis. Overall, the work in this dissertation will serve to further elucidate the mechanisms of Spt6 in chromatin regulation, transcription, and DNA damage repair

Clinical Oncology Society of Australia: Position statement on cancer-related malnutrition and sarcopenia

© 2020 The Authors. Nutrition & Dietetics published by John Wiley & Sons Australia, Ltd on behalf of Dietitians Australia. This position statement describes the recommendations of the Clinical Oncology Society of Australia (COSA) regarding management of cancer-related malnutrition and sarcopenia. A multidisciplinary working group completed a review of the literature, focused on evidence-based guidelines, systematic reviews and meta-analyses, to develop recommendations for the position statement. National consultation of the position statement content was undertaken through COSA members. All people with cancer should be screened for malnutrition and sarcopenia in all health settings at diagnosis and as the clinical situation changes throughout treatment and recovery. People identified as “at risk” of malnutrition or with a high-risk cancer diagnosis or treatment plan should have a comprehensive nutrition assessment; people identified as “at risk” of sarcopenia should have a comprehensive evaluation of muscle status using a combination of assessments for muscle mass, muscle strength and function. All people with cancer-related malnutrition and sarcopenia should have access to the core components of treatment, including medical nutrition therapy, targeted exercise prescription and physical and psychological symptom management. Treatment for cancer-related malnutrition and sarcopenia should be individualised, in collaboration with the multidisciplinary team (MDT), and tailored to meet needs at each stage of cancer treatment. Health services should ensure a broad range of health care professionals across the MDT have the skills and confidence to recognise malnutrition and sarcopenia to facilitate timely referrals and treatment. The position statement is expected to provide guidance at a national level to improve the multidisciplinary management of cancer-related malnutrition and sarcopenia

BDNF increases survival of retinal dopaminergic neurons after prenatal compromise. Invest Ophthalmol Vis Sci

PURPOSE. Chronic placental insufficiency (CPI) severe enough to cause growth restriction (GR) results in alterations to the retina, including a reduction in tyrosine hydroxylase immunoreactive (TH-IR)-dopaminergic amacrine cells. Brain-derived neurotrophic factor (BDNF) plays a role in the development of the retinal dopaminergic network and may therefore be an appropriate therapy for restoring dopaminergic cells after prenatal compromise. This study was conducted (1) to establish whether BDNF and its receptor NTRK2 (Trk B) are altered in the retina after CPI and (2) to explore the potential of BDNF to enhance dopaminergic cell survival in organotypic retinal cultures from prenatally compromised animals. METHODS. CPI was induced in pregnant guinea pigs at 30 days' gestation (dg; term, ϳ67 dg) via unilateral ligation of the uterine artery. Fetuses were euthanatized at 60 dg and the retinas prepared for enzyme-linked immunosorbent assay (ELISA) analysis of BDNF protein levels and for immunohistochemistry to localize BDNF and NTRK2. Organotypic cultures of retinas from GR and control fetuses at 50 to 52 dg were treated with BDNF, and dopaminergic amacrine cells counts were assessed. RESULTS. Retinal BDNF protein levels and the intensity of BDNFimmunoreactivity (IR) in the ganglion cell layer were reduced (P Ͻ 0.05) in GR fetuses compared with control fetuses. Addition of BDNF to organotypic cultures increased (P Ͻ 0.05) the survival and neurite growth of dopaminergic neurons from both control and GR fetuses. CONCLUSIONS. Alterations to BDNF levels may underlie reductions in dopaminergic amacrine cells observed after CPI. The addition of BDNF has the potential to increase survival and neurite growth of dopaminergic amacrine cells. (Invest Ophthalmol Vis Sci

Vulnerability of Dopaminergic Amacrine Cells and Optic Nerve Myelination to Prenatal Endotoxin Exposure

PURPOSE. Intrauterine infection has been linked to preterm delivery and neurologic injury. The purpose of this study was to investigate the effects of fetal inflammation induced by exposure to endotoxin on the structure and neurochemistry of the retina and optic nerve. METHODS. The bacterial endotoxin, lipopolysaccharide (LPS), was administered to fetal sheep at ϳ0.65 of the ϳ147-day gestation period via repeated bolus doses (1 g/kg per day) over 5 days, with fetal retinas and optic nerves assessed 10 days after the first LPS exposure. RESULTS. In the retina, the total number of tyrosine hydroxylase immunoreactive (TH-IR), dopaminergic amacrine cells was reduced (P Ͻ 0.05) in LPS-exposed compared with control fetuses. There was no difference in the number of ChAT-, substance P-, or NADPH-d-positive amacrine cells. The total number of myelinated axons in the optic nerve was not different (P Ͼ 0.05) between groups; however, the myelin sheath was thinner (P Ͻ 0.05) in LPS-exposed fetuses. CONCLUSIONS. Prenatal exposure to repeated doses of endotoxin results in alterations to the retina and optic nerve with specific effects on dopaminergic neurons and myelination, respectively. These findings could have implications for visual function. (Invest Ophthalmol Vis Sci. 2007;48:472-478