Biology subjects

Singleton, K.

Publications and source records attributed to Singleton, K..

4 recordsLinked to original sources

bioRxiv2023

Systemic Metabolic and Mitochondrial Defects in Rett Syndrome Models

Genes mutated in monogenic neurodevelopmental disorders are broadly expressed. This observation supports the concept that monogenic neurodevelopmental disorders are systemic diseases that profoundly impact neurodevelopment. We tested the systemic disease model focusing on Rett syndrome, which is caused by mutations in MECP2. Transcriptomes and proteomes of organs and brain regions from Mecp2-null mice as well as diverse MECP2-null male and female human cells were assessed. Widespread changes in the steady-state transcriptome and proteome were identified in brain regions and organs of presymptomatic Mecp2-null male mice as well as mutant human cell lines. The extent of these transcriptome and proteome modifications was similar in cortex, liver, kidney, and skeletal muscle and more pronounced than in the hippocampus and striatum. In particular, Mecp2- and MECP2-sensitive proteomes were enriched in synaptic and metabolic annotated gene products, the latter encompassing lipid metabolism and mitochondrial pathways. MECP2 mutations altered pyruvate-dependent mitochondrial respiration while maintaining the capacity to use glutamine as a mitochondrial carbon source. We conclude that mutations in Mecp2/MECP2 perturb lipid and mitochondrial metabolism systemically limiting cellular flexibility to utilize mitochondrial fuels.

neuroscience↗

bioRxiv2022

EARLY AND MID-GESTATION ZIKA VIRUS (ZIKV) INFECTION IN THE OLIVE BABOON (PAPIO ANUBIS) LEADS TO FETAL CNS PATHOLOGY BY TERM GESTATION

Zika virus (ZIKV) infection in pregnancy can produce catastrophic teratogenic damage to the developing fetus including microcephaly and congenital Zika syndrome (CZS). We previously described fetal CNS pathology occurring by three weeks post-ZIKV infection in Olive baboons at mid-gestation, including neuroinflammation, loss of radial glia (RG), RG fibers, neuroprogenitor cells (NPCs) resulting in disrupted NPC migration. In the present study, we explored fetal brain pathologies at term gestation resulting from ZIKV infection during either first or second trimester in the Olive baboon. In all dams, viremia resolved after 7 days post infection (dpi). One first trimester infected dam aborted at 5 dpi. All dams developed IgM and IgG response to ZIKV with ZIKV IgG detected in fetal serum. Substantial placental pathology and inflammation was observed including disruption of syncytiotrophoblast layers, delayed villous maturation, partially or fully thrombosed vessels, calcium mineralization and fibrin deposits. In the uterus, ZIKV was detected in [3/4] first trimester but not in second trimester infected dams. While ZIKV was not detected in any fetal tissue at term, all fetuses exhibited varying degrees of neuropathology. Fetal brains from ZIKV infected dams exhibited a range of gross brain pathologies including irregularities of the major gyri and sulci of the cerebral cortex and cerebellar pathology. Frontal cortices of ZIKV fetuses showed a general disorganization of the six-layered cortex with degree of disorganization varying among the fetuses from the two groups. Frontal cortices from first but not second trimester infections exhibited increased microglia and astrocyte numbers (white matter) in both trimester infections. In the cerebellum, increased microglia were observed in both first and second trimester infected fetuses and decreased oligodendrocyte precursor cell populations in the cerebellar white matter in first trimester infections. In general, our observations are in accordance with those described in human ZIKV infected fetuses.

pathology↗

bioRxiv2020

MATERNAL ZIKA VIRUS (ZIKV) INFECTION FOLLOWING VAGINAL INOCULATION WITH ZIKV-INFECTED SEMEN IN THE TIMED-PREGNANT OLIVE BABOON

ZIKV infection is associated with pregnancy loss, fetal microcephaly and other malformations. While Aedes sp. of mosquito are the primary vector for ZIKV, sexual transmission of ZIKV is a significant route of infection. ZIKV has been documented in human, mouse and non-human primate (NHP) semen. It is critical to establish NHP models of vertical transfer of ZIKV that recapitulate human ZIKV pathogenesis. We hypothesized that vaginal deposition of ZIKV infected baboon semen would lead to maternal infection and vertical transfer in the olive baboon (Papio anubis). Timed pregnant baboons (n=6) were inoculated via vaginal deposition of baboon semen containing 106 ffu ZIKV (n=3, French Polynesian isolate:H/PF/2013, n=3 Puerto Rican isolate:PRVABC59) at mid-gestation (86-95 days gestation [dG]; term 183dG) on day (d) 0 (all dams), and then at 7 day intervals through three weeks. Maternal blood, saliva and cervico-vaginal washes were obtained at select days post-inoculation. Animals were euthanized at 28 days post initial inoculation (dpi; n=5) or 39 dpi (n=1) and maternal/fetal tissues collected. vRNA was quantified by qPCR. Viremia was achieved in 3/3 FP ZIKV infected dams and 2/3 PR ZIKV. ZIKV RNA was detected in cvw (5/6 dams;). ZIKV RNA was detected in lymph nodes, but not ovary, uterus, cervix or vagina in the FP ZIKV dams but was detected in uterus, vagina and lymph nodes. Placenta, amniotic fluid and all fetal tissues were ZIKV RNA negative in the FP infected dams whereas 2/3 PR infected dam placentas were ZIKV RNA positive. We conclude that ZIKV infected semen is a means of ZIKV transmission during pregnancy in primates. The PR isolate appeared more capable of wide spread dissemination to tissues, including placenta compared to the FP strain. IMPORTANCEDue to its established link to pregnancy loss, microcephaly and other major congenital anomalies, Zika virus (ZIKV) remains a worldwide health threat. Although mosquitoes are the primary means of ZIVK transmission, sexual transmission in human populations is well documented and provides a means for widespread dissemination of the virus. Differences in viremia, tissue distribution, immune responses and pregnancy outcome from sexually transmitted ZIKV compared to the subcutaneous route of infection are needed to better clinically manage ZIKV in pregnancy. Through our previous work, we have developed the olive baboon as a non-human primate model of ZIKV infection that is permissible to ZIKV infection via the subcutaneous route of inoculation and transfer of ZIKV to the fetus in pregnancy. The current study evaluated the course of ZIKV infection after vaginal inoculation of ZIKV in pregnant baboons at mid-gestation using baboon semen as the carrier and comparing two isolates of ZIKV, the French Polynesian isolate first associated with microcephaly and the Puerto Rican isolate, associated with an increased risk of microcephaly observed in the Americas.

physiology↗

bioRxiv2018

ZIKA VIRUS INFECTION AT MID-GESTATION RESULTS IN FETAL CEREBRAL CORTICAL INJURY AND FETAL DEATH IN THE OLIVE BABOON.

Zika virus (ZIKV) infection during pregnancy in humans is associated with an increased incidence of congenital anomalies including microcephaly as well as fetal death and miscarriage and collectively has been referred to a Congenital Zika Syndrome (CZS). Animal models for ZIKV infection in pregnancy have been developed including mice and macaques. While microcephaly has been achieved in mice via direct injection of ZIKV into the fetal brain or via interference with interferon signaling, in macaques the primary fetal CZS outcome are ocular defects. In the present study we develope the olive baboon (Papio anubis), as a model for the vertical transfer of ZIKV during pregnancy. We infected four mid-gestation, timed-pregnant baboons with the French Polynesian ZIKV isolate (104 ffu) and examined the acute phase of vertical transfer by stopping the study of one dam at 7 days post infection (dpi), two at 14 dpi and one at 21 dpi. All dams exhibited mild to moderate rash and conjunctivitis; three of four dams exhibited viremia at 7 dpi. Of the three dams studied to 14 to 21 days, only one still exhibited viremia on day 14. Vertical transfer of ZIKV to the fetus was found in two pregnancies; in one, vertical transfer was associated with fetal death at [~]14 dpi. In the other, vertical transfer was observed at 21 dpi. Both fetuses had ZIKV RNA in the fetal cerebral cortex as well as other tissues. The 21 dpi fetal cerebral cortex exhibited notable defects in radial glia, radial glial fibers, loss and or damage of immature oligodendrocytes and a loss in neuroprogenitor cells (NPCs). In addition, indices of pronounced neuroinflammation were observed including astrogliosis, increased microglia and IL-6 expression. The dams studied to 14 dpi (n=2) and 21 dpi (n=1) exhibited a anti-ZIKV IgM response and IgG response (21 dpi) that included transfer of the IgG to the fetal compartment (cord blood). The severity of systemic inflammatory response (cytokines and chemokines) reflected the vertical transfer of ZIKV in the two pregnancies. As such, these events likely represent the early mechanisms that lead to microcephaly and/or other CNS pathologies in a primate infected with ZIKV and are the first to be described in a non-human primate during the acute phase of ZIKV infection with a contemporaneous ZIKV strain. The baboon thus represents a major NHP for advancing as a model for ZIKV induced brain pathologies to contrast and compare to humans as well as other NHPs such as macaques.\n\nAUTHOR SUMMARYZika virus is endemic in the Americas, primarily spread through mosquitos and sexual contact. Zika virus infection during pregnancy in women is associated with a variety of fetal pathologies now referred to as Congenital Zika Syndrome (CZS), with the most severe pathology being fetal microcephaly. Developing model organisms that faithfully recreate Zika infection in humans is critical for future development of treatments and preventions. In our present study, we infected Olive baboons at mid-gestation with Zika virus and studied the acute period of viremia and transfer of Zika virus to the fetus during the first three weeks after infection to better understand the timing and mechanisms leading to CZS. We observed Zika virus transfer to fetuses resulting in fetal death in one pregnancy and in a second pregnancy, significant damage to the frontal cortex of the fetal brain consistent with development of microcephaly, closely resembling infection in pregnant women. Our baboon model differs from macaque non-human primate models where the primary fetal outcome during pregnancy following infection with contemporary strains of Zika virus is ocular pathology. Thus, the baboon provides a promising new non-human primate model to further compare and contrast the consequences of Zika virus infection in pregnancy to humans and macaques to better understand the disease.

neuroscience↗