University of Georgia
Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors

Author: Donna Huber

UGA’s Rozario receives NIH Director’s New Innovator Award

Donna Huber on March 24, 2021

By Alan Flurry

(Photo courtesy of Tania Rozario)

University of Georgia faculty member Tania Rozario has received a $2 million grant from the National Institutes of Health Director’s New Innovator Award Program, which supports early-career investigators of exceptional creativity who propose high-risk, high-reward research projects.

Rozario is an assistant professor with a joint appointment in the Franklin College of Arts and Sciences Department of Genetics and the Center for Tropical and Emerging Global Diseases.

Among the study of tropical diseases worldwide—and particularly among the parasites that cause disease—worms are a largely neglected disease agent, despite being a source of widespread problems that affect both health and economic output. Even within the study of worms, parasitic flatworms like tapeworms represent an understudied group. However, free-living flatworms like planarians are the focus of significant research because of the organism’s dynamic regenerative capacity, which presents intriguing parallels to their parasitic cousins.

Planarian flatworms cut in two will make two new worms, and cut into 10 pieces will result in 10 worms. They are the Ferrari of regenerators, according to Rozario.

“As part of its normal life cycle, a tapeworm sheds large parts of its body and then regrows this lost tissue,” Rozario said. “It has this natural regenerative-like ability, which is very promising from a basic biology standpoint, to understand how stem cells and regeneration functions in these worms.”

Taking advantage of both extensive past research and the much more sophisticated tools of today, Rozario envisions a melding of developmental biology with parasitology as a new approach to understand the parasite. She is using the rat tapeworm, Hymenolepis diminuta, to re-establish a model organism that had been a favorite model among parasitologists in the early-mid 20th century but was left behind by the molecular biology revolution.

Flatworms have incredible capacity for regeneration, according to Tania Rozario, who studies them as agents of parasitic disease. For example, this rat tapeworm is capable of growing thousands of segments and can regenerate segments following amputation.

 

“One of the major drivers is trying to understand the diversity of the stem cell milieu in these tapeworms,” Rozario said. “We’ll try to parse out the interaction between the diversity of stem cells present and the local signals that then allow the worms to regenerate and make thousands of segments. These interactions are likely crucial for development of both female and male reproductive structures, which exist in each segment of the animal.”

“Dr. Rozario brings a new and exciting area of research to UGA, and her enthusiasm for her research is phenomenal,” said Nancy Manley, Distinguished Research Professor and department head for genetics. “Her success in getting this prestigious award speaks to her talent and the quality of her science. We are enthusiastic to have her as our newest colleague.”

“I am excited that Dr. Rozario has joined us at UGA,” said Dennis Kyle, GRA Eminent Scholar in antiparasitic drug discovery and director of the Center for Tropical and Emerging Global Diseases. “Her pioneering work is ushering in a new era whereby tapeworms can serve as model organisms. The prestigious NIH Director’s Pioneer Award is evidence of the creative approach she is undertaking to better understand these interesting parasites.”

“It’s important that we study the monsters in our midst so that we can learn from organisms in our environment that have these really out-there, unique physiological capabilities,” Rozario said. “We can learn about how they have evolved strategies to thrive in their specific niche, but they can also teach us something more fundamental about biology that could be broadly applicable.”

microscopy of tapeworms
In these Hymenolepis diminuta tapeworm necks, dividing cells—including stem cells—are depicted through color-marking in the image. (Image courtesy of Tania Rozario)

Lysosomal cholesterol accumulation contributes to the movement phenotypes associated with NUS1 haploinsufficiency

Donna Huber on March 17, 2021

Purpose: Variants in NUS1 are associated with a congenital disorder of glycosylation, developmental and epileptic encephalopathies, and are possible contributors to Parkinson disease pathogenesis. How the diverse functions of the NUS1-encoded Nogo B receptor (NgBR) relate to these different phenotypes is largely unknown. We present three patients with de novo heterozygous variants in NUS1 that cause a complex movement disorder, define pathogenic mechanisms in cells and zebrafish, and identify possible therapy.

Methods: Comprehensive functional studies were performed using patient fibroblasts, and a zebrafish model mimicking NUS1 haploinsufficiency.

Results: We show that de novo NUS1 variants reduce NgBR and Niemann-Pick type C2 (NPC2) protein amount, impair dolichol biosynthesis, and cause lysosomal cholesterol accumulation. Reducing nus1 expression 50% in zebrafish embryos causes abnormal swim behaviors, cholesterol accumulation in the nervous system, and impaired turnover of lysosomal membrane proteins. Reduction of cholesterol buildup with 2-hydroxypropyl-ß-cyclodextrin significantly alleviates lysosomal proteolysis and motility defects.

Conclusion: Our results demonstrate that these NUS1 variants cause multiple lysosomal phenotypes in cells. We show that the movement deficits associated with nus1 reduction in zebrafish arise in part from defective efflux of cholesterol from lysosomes, suggesting that treatments targeting cholesterol accumulation could be therapeutic.

Seok-Ho Yu, Tong Wang, Kali Wiggins, Raymond J. Louie, Emilio F. Merino, Cindy Skinner, Maria B. Cassera, Kirsten Meagher, Paul Goldberg, Neggy Rismanchi, Dillon Chen, Michael J. Lyons, Heather Flanagan-Steet & Richard Steet. Genet Med. 2021 Mar 17. doi: 10.1038/s41436-021-01137-6.

Deletion of a Golgi protein in Trypanosoma cruzi reveals a critical role for Mn2+ in protein glycosylation needed for host cell invasion and intracellular replication

Donna Huber on March 15, 2021

Trypanosoma cruzi is a protist parasite and the causative agent of American trypanosomiasis or Chagas disease. The parasite life cycle in its mammalian host includes an intracellular stage, and glycosylated proteins play a key role in host-parasite interaction facilitating adhesion, invasion and immune evasion. Here, we report that a Golgi-localized Mn2+-Ca2+/H+ exchanger of T. cruzi (TcGDT1) is required for efficient protein glycosylation, host cell invasion, and intracellular replication. The Golgi localization was determined by immunofluorescence and electron microscopy assays. TcGDT1 was able to complement the growth defect of Saccharomyces cerevisiae null mutants of its ortholog ScGDT1 but ablation of TcGDT1 by CRISPR/Cas9 did not affect the growth of the insect stage of the parasite. The defect in protein glycosylation was rescued by Mn2+ supplementation to the growth medium, underscoring the importance of this transition metal for Golgi glycosylation of proteins.

Ramakrishnan S, Unger LM, Baptista RP, Cruz-Bustos T, Docampo R (2021) Deletion of a Golgi protein in Trypanosoma cruzi reveals a critical role for Mn2+ in protein glycosylation needed for host cell invasion and intracellular replication. PLoS Pathog 17(3): e1009399. https://doi.org/10.1371/journal.ppat.1009399

RGS10 physically and functionally interacts with STIM2 and requires store-operated calcium entry to regulate proinflammatory gene expression in microglia

Donna Huber on March 8, 2021

Chronic activation of microglia is a driving factor in the progression of neuroinflammatory diseases, and mechanisms that regulate microglial inflammatory signaling are potential targets for novel therapeutics. Regulator of G protein Signaling 10 is the most abundant RGS protein in microglia, where it suppresses inflammatory gene expression and reduces microglia-mediated neurotoxicity. In particular, microglial RGS10 downregulates the expression of pro-inflammatory mediators including cyclooxygenase 2 (COX-2) following stimulation with lipopolysaccharide (LPS). However, the mechanism by which RGS10 affects inflammatory signaling is unknown and is independent of its canonical G protein targeted mechanism. Here, we sought to identify non-canonical RGS10 interacting partners that mediate its anti-inflammatory mechanism. Through RGS10 co-immunoprecipitation coupled with mass spectrometry, we identified STIM2, an endoplasmic reticulum (ER) localized calcium sensor and a component of the store-operated calcium entry (SOCE) machinery, as a novel RGS10 interacting protein in microglia. Direct immunoprecipitation experiments confirmed RGS10-STIM2 interaction in multiple microglia and macrophage cell lines, as well as in primary cells, with no interaction observed with the homologue STIM1. We further determined that STIM2, Orai channels, and the Ca2+--dependent phosphatase calcineurin are essential for LPS-induced COX-2 production in microglia, and this pathway is required for the inhibitory effect of RGS10 on COX-2. Additionally, our data demonstrated that RGS10 suppresses SOCE triggered by ER calcium depletion and that ER calcium depletion, which induces SOCE, amplifies proinflammatory genes. In addition to COX-2, we also show that RGS10 suppresses the expression of proinflammatory cytokines in microglia in response to thrombin and LPS stimulation, and all of these effects require SOCE. Collectively, the physical and functional links between RGS10 and STIM2 suggest a complex regulatory network connecting RGS10, SOCE, and pro-inflammatory gene expression in microglia, with broad implications in the pathogenesis and treatment of chronic neuroinflammation.

Menbere Wendimu, Mohammed Alqinyah, Stephen Vella, Phillip Dean, Faris Almutairi, Roseanne Davila Rivera, Shima Rayatpisheh, James Wohlschlegel, Silvia Moreno, Shelley B Hooks. Cell Signal. 2021 Mar 8;109974. doi: 10.1016/j.cellsig.2021.109974

Reduced Trypanosoma cruzi-specific humoral response and enhanced T cell immunity after treatment interruption with benznidazole in chronic Chagas disease

Donna Huber on March 7, 2021

Background: Interruption of benznidazole therapy due to the appearance of adverse effects, which is presumed to lead to treatment failure, is a major drawback in the treatment of chronic Chagas disease.

Methods: Trypanosoma cruzi-specific humoral and T cell responses, T cell phenotype and parasite load were measured to compare the outcome in 33 subjects with chronic Chagas disease treated with an incomplete benznidazole regimen and 58 subjects treated with the complete regimen, during a median follow-up period of 48 months.

Results: Both treatment regimens induced a reduction in the T. cruzi-specific antibody levels and similar rates of treatment failure when evaluated using quantitative PCR. Regardless of the regimen, polyfunctional CD4+ T cells increased in the subjects, with successful treatment outcome defined as a decrease of T. cruzi-specific antibodies. Regardless of the serological outcome, naive and central memory T cells increased after both regimens. A decrease in CD4+ HLA-DR+ T cells was associated with successful treatment in both regimens. The cytokine profiles of subjects with successful treatment showed fewer inflammatory mediators than those of the untreated T. cruzi-infected subjects. High levels of T cells expressing IL-7 receptor and low levels of CD8+ T cells expressing the programmed cell death protein 1 at baseline were associated with successful treatment following benznidazole interruption.

Conclusions: These findings challenge the notion that treatment failure is the sole potential outcome of an incomplete benznidazole regimen and support the need for further assessment of the treatment protocols for chronic Chagas disease.

Melisa D Castro Eiro, María A Natale, María G Alvarez, Huifeng Shen, Rodolfo Viotti, Bruno Lococo, Jacqueline Bua, Myriam Nuñez, Graciela L Bertocchi, María C Albareda, Gonzalo Cesar, Rick L Tarleton, Susana A Laucella. J Antimicrob Chemother. 2021 Mar 7;dkab054. doi: 10.1093/jac/dkab054

Trainee Spotlight: Nathan Chasen

Donna Huber on March 5, 2021

Nathan Chasen is a post-doctoral fellow in Drew Etheridge’s laboratory (submitted photo)

Nathan Chasen, a postdoctoral fellow in Drew Etheridge’s laboratory, is originally from Richmond, Virginia. After receiving his undergraduate degree from Emory University, he worked as a research technician at UGA. He then decided to attend UGA for graduate school. Under the mentorship of Silvia Moreno, Chasen received two American Heart Association Predoctoral Fellowship Awards and earned his Ph.D. in December of 2017.

Why did you choose UGA? 

I chose UGA because it is one of the best places in the world to study parasites for both the quality of the work and the collaborative research environment.

What is your research focus/project and why are you interested in the topic? 

My current research focus is the poorly understood endocytic organelle of the parasite Trypanosoma cruzi, which is the causal agent of Chagas disease.

What are your future professional plans?  

I plan to establish an academic lab that continues to unravel the nature of this neglected parasite, using state-of-the-art molecular tools and microscopy methods.

What is your favorite thing about UGA and Athens? 

The area is a great low-cost living area, with little traffic and essentially everything you need within a 15-minute drive, including great food and a lively downtown area. The ability to live affordably within a short bike ride of campus is also a plus.

 

Support trainees like Nathan by giving today to the Center for Tropical & Emerging Global Diseases.

[button size=’large’ style=” text=’Give Now’ icon=” icon_color=’BA0C2F’ link=’https://ctegd.uga.edu/give/’ target=’_self’ color=” hover_color=” border_color=” hover_border_color=” background_color=” hover_background_color=” font_style=” font_weight=” text_align=’center’ margin=”]

 

Whole blood and blood components from vertebrates differentially affect egg formation in three species of anautogenous mosquitoes

Donna Huber on February 24, 2021

Background: Most female mosquitoes are anautogenous and must blood feed on a vertebrate host to produce eggs. Prior studies show that the number of eggs females lay per clutch correlates with the volume of blood ingested and that protein is the most important macronutrient for egg formation. In contrast, how whole blood, blood fractions and specific blood proteins from different vertebrates affect egg formation is less clear. Since egg formation is best understood in Aedes aegypti, we examined how blood and blood components from different vertebrates affect this species and two others: the malaria vector Anopheles gambiae and arbovirus vector Culex quinquefasciatus.

Methods: Adult female mosquitoes were fed blood, blood fractions and purified major blood proteins from different vertebrate hosts. Markers of reproductive response including ovary ecdysteroidogenesis, yolk deposition into oocytes and number of mature eggs produced were measured.

Results: Ae. aegypti, An. gambiae and C. quinquefasciatus responded differently to meals of whole blood, plasma or blood cells from human, rat, chicken and turkey hosts. We observed more similarities between the anthropophiles Ae. aegypti and An. gambiae than the ornithophile C. quinquefasciatus. Focusing on Ae. aegypti, the major plasma-derived proteins (serum albumin, fibrinogen and globulins) differentially stimulated egg formation as a function of vertebrate host source. The major blood cell protein, hemoglobin, stimulated yolk deposition when from pigs but not humans, cows or sheep. Serum albumins from different vertebrates also variably affected egg formation. Bovine serum albumin (BSA) stimulated ovary ecdysteroidogenesis, but more weakly induced digestive enzyme activities than whole blood. In contrast, BSA-derived peptides and free amino acids had no stimulatory effects on ecdysteroidogenesis or yolk deposition into oocytes.

Conclusions: Whole blood, blood fractions and specific blood proteins supported egg formation in three species of anautogenous mosquitoes but specific responses varied with the vertebrate source of the blood components tested.

Harrison, R.E., Brown, M.R. & Strand, M.R. Whole blood and blood components from vertebrates differentially affect egg formation in three species of anautogenous mosquitoes. Parasites Vectors 14, 119 (2021). https://doi.org/10.1186/s13071-021-04594-9

Silvia Moreno elected as American Academy of Microbiology Fellow

Donna Huber on February 18, 2021

Silvia Moreno
Photo credit: Dorothy Kozlowski

University of Georgia researcher, a member of the Center for Tropical and Emerging Global Diseases and a Distinguished Research Professor in cellular biology, has been elected as a 2021 American Academy of Microbiology Fellow. Holding courtesy appointments in microbiology and infectious diseases, Silvia N. Moreno also serves as director of the NIH-funded Training in Tropical and Emerging Global Diseases program.

“This is an honor that represents the hard work and commitment of the members of my lab, past and present,” said Moreno.

Her research focuses on the parasite Toxoplasma gondii, which can cause encephalitis and cardiogenic shock in immunocompromised patients and can result in devastating birth defects in children born from infected pregnant women. Almost a third of the human population is infected. The parasite also infects cats, dogs and cattle.

In particular, Moreno’s laboratory is interested in discovering unique metabolic differences that can be used as targets for chemotherapy as current treatment options are for only one phase of the disease and have harmful side effects.

In 2018, she was named a corresponding member of the Latin American Academy of Sciences. Since 2015, she has been leading the Training in Tropical and Emerging Global Diseases program which is funded by an NIH T32 training grant. In the most recent competing renewal of the grant, CTEGD was awarded $1.9 million.

Under Moreno’s leadership the program has expanded to provide fellowships to seven graduate students and two post-doctoral fellows, a mini-sabbatical program for faculty members of local colleges with a higher proportion of diversity students to offer undergraduates and faculty research experience, and organize a number of professional development workshops.

Moreno joins more than 2,500 AAM fellows who are elected through a highly selective, peer-reviewed process, based on their record of scientific achievement and original contributions that have advanced the field of microbiology. Of the 150 researchers nominated this year, only 65 were elected to the 2021 Fellowship Class.

Evaluation of changes in drug susceptibility and population genetic structure in Haemonchus contortus following worm replacement as a means to reverse the impact of multiple-anthelmintic resistance on a sheep farm

Donna Huber on February 18, 2021

A population of Haemonchus contortus that was highly resistant to benzimidazoles and avermectin/milbemycins with a subpopulation that was resistant to levamisole, was replaced with a susceptible laboratory isolate of H. contortus in a flock of sheep. The anthelmintic susceptibility and population genetics of the newly established population were evaluated for 3.5 years using in vivo, in vitro, and molecular methods. Successful replacement of the resistant population with a susceptible population was confirmed using phenotypic and genotypic measurements; larval development assay indicated full anthelmintic susceptibility; albendazole treatment yielded 98.7% fecal egg count reduction; pyrosequence genotyping of single nucleotide polymorphisms in positions 167 and 200 of the isotype-1 beta tubulin gene were present at 0.0 and 1.7%, respectively; microsatellite genotyping indicated the background haplotype was similar to the susceptible isolate; and haplotypes of the isotype-1 beta tubulin gene were similar to the susceptible isolate. To sustain the susceptibility of the new population, targeted selective treatment was implemented using albendazole. Surprisingly, within 1.5 years post-replacement, the population reverted to a resistant phenotype. Resistance to albendazole, ivermectin, and moxidectin was confirmed via fecal egg count reduction test, larval development assay, and pyrosequencing-based genotyping. Targeted selective treatment was then carried out using levamisole. However, within one year, resistance was detected to levamisole. Population genetics demonstrated a gradual change in the genetic structure of the population until the final population was similar to the initial resistant population. Genetic analyses showed a lack of diversity in the susceptible isolate, suggesting the susceptible isolate had reduced environmental fitness compared to the resistant population, providing a possible explanation for the rapid reversion to resistance. This work demonstrates the power of combining molecular, in vitro, and in vivo assays to study phenotypic and genotypic changes in a field population of nematodes, enabling improved insights into the epidemiology of anthelmintic resistance.

Melissa M George, Adriano F Vatta, Sue B Howell, Bob E Storey, Ciaran J McCoy, Adrian J Wolstenholme, Elizabeth M Redman, John S Gilleard, Ray M Kaplan. International Journal for Parasitology: Drugs and Drug Resistance. 15, April 2021, 134-143. https://doi.org/10.1016/j.ijpddr.2021.02.004

MdBVe46 is an envelope protein that is required for virion formation by Microplitis demolitor bracovirus

Donna Huber on February 16, 2021

Bracoviruses (BVs) are endogenized nudiviruses that braconid parasitoid wasps have coopted for functions in parasitizing hosts. Microplitis demolitor is a braconid wasp that produces Microplitis demolitor bracovirus (MdBV) and parasitizes the larval stage of the moth Chrysodeixis includens. Some BV core genes are homologs of genes also present in baculoviruses while others are only known from nudiviruses or other BVs. In this study, we had two main goals. The first was to separate MdBV virions into envelope and nucleocapsid fractions before proteomic analysis to identify core gene products that were preferentially associated with one fraction or the other. Results indicated that nearly all MdBV baculovirus-like gene products that were detected by our proteomic analysis had similar distributions to homologs in the occlusion-derived form of baculoviruses. Several core gene products unknown from baculoviruses were also identified as envelope or nucleocapsid components. Our second goal was to functionally characterize a core gene unknown from baculoviruses that was originally named HzNVorf64-like. Immunoblotting assays supported our proteomic data that identified HzNVorf64-like as an envelope protein. We thus renamed HzNVorf64-like as MdBVe46, which we further hypothesized was important for infection of C. includens. Knockdown of MdBVe46 by RNA interference (RNAi) greatly reduced transcript and protein abundance. Knockdown of MdBVe46 also altered virion morphogenesis, near-fully inhibited infection of C. includens, and significantly reduced the proportion of hosts that were successfully parasitized by M. demolitor.

Michael J Arvin, Ange Lorenzi, Gaelen R Burke, Michael R Strand. J Gen Virol. 2021 Feb 16. doi: 10.1099/jgv.0.001565.