Transthyretin expression in the postischemic brain

PLoS One. 2019 Sep 3;14(9):e0221555. doi: 10.1371/journal.pone.0221555. eCollection 2019.

Abstract

The unknown role of the carrier protein transthyretin (TTR) in mechanisms of functional recovery in the postischemic brain prompted us to study its expression following experimental stroke. Male C57/B6 mice (age 9 to 10 weeks) were subjected to permanent focal ischemia induced by photothrombosis (PT) and brain tissues were analyzed for ttr expression and TTR levels at 24 hours, 48 hours, 7 days and 14 days following the insult by RT-PCR, Western blot and immunohistochemistry. Fourteen days after PT, non-specific TTR-like immunoreactive globules were found in the ischemic core and surrounding peri-infarct region by immunohistochemistry that could not be allocated to DAPI positive cells. No TTR immunoreactivity was found when stainings were performed with markers for neurons (Neuronal Nuclei, NeuN), reactive astrocytes (glial fibrillary acidic protein, GFAP) or microglia (cluster of differentiation 68, CD68). In addition, we could not find TTR by immunoblotting in protein extracts obtained from the ischemic territory nor ttr expression by RT-PCR at all time points following PT. In all experiments, ttr expression in the choroid plexus and TTR in the mouse serum served as positive controls and recombinant legumain peptide as negative control. Together, our results indicate that TTR is not synthesized in brain resident cells in the ischemic infarct core and adjacent peri-infarct area. Thus, it seems unlikely that in situ synthesized TTR is involved in mechanisms of tissue reorganization during the first 14 days following PT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / metabolism
  • Brain / metabolism*
  • Brain / pathology
  • Brain Ischemia / genetics*
  • Brain Ischemia / metabolism*
  • Brain Ischemia / pathology
  • Choroid Plexus / metabolism
  • Choroid Plexus / pathology
  • Disease Models, Animal
  • Gene Expression
  • Immunohistochemistry
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Microglia / metabolism
  • Neurons / metabolism
  • Prealbumin / cerebrospinal fluid
  • Prealbumin / genetics*
  • Prealbumin / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism

Substances

  • Prealbumin
  • RNA, Messenger
  • Ttr protein, mouse

Grants and funding

This study was supported by National Funds by FCT - Foundation for Science and Technology (grant SFRH/BD/104679/2014) (DT), the ‘‘Programa Operacional do Centro, Centro 2020” through the funding of the ICON project (Interdisciplinary Challenges on Neurodegeneration; CENTRO-01-0145-FEDER-000013) (IG and CS), Health Sciences Research Center (CICS-UBI) through National Funds by FCT - (UID / Multi / 00709/2019) (IG and CS), the Swedish Brain Fund (No. FO2019-0254 and FO2018-0316) (KR), ALF Skåne (KR), Sparbanksstiftelsen Färs & Frosta (KR), the Crafoord Foundation (KR), Sveriges Stroke Riksförbundet (KR), the Hans-Christian and Alice Wachtmeister Foundation (KR) and the Stiftelsen Sven-Olof Jansons livsverk (KR). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.