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Role of high mobility group protein-1 (HMG1) in amyloid-beta homeostasis

Kazuyuki Takata1, Yoshihisa Kitamura, Jun-ichi Kakimura

  • 1Department of Neurobiology, Kyoto Pharmaceutical University, Japan.

Biochemical and Biophysical Research Communications
|February 5, 2003
PubMed

Insights

High mobility group protein-1 (HMG1) hinders microglial clearance of amyloid-beta (Abeta) and stabilizes Abeta oligomers. Increased HMG1 in Alzheimer

Area of Science:

  • Neuroscience
  • Cell Biology
  • Biochemistry

Background:

  • Alzheimer's disease (AD) is characterized by amyloid-beta (Abeta) plaques and activated microglia.
  • Microglial Abeta clearance is crucial, with factors like transforming growth factor-beta1 (TGF-beta1) playing a role.
  • The precise interaction between microglia and Abeta deposition in AD remains incompletely understood.

Purpose of the Study:

  • To investigate the role of high mobility group protein-1 (HMG1) in microglial Abeta uptake and oligomerization.
  • To determine the effect of HMG1 on Abeta (1-42) clearance in the presence and absence of TGF-beta1.
  • To examine HMG1 expression and localization in Alzheimer's disease brains.

Main Methods:

  • Assessing microglial uptake of Abeta (1-42) with and without HMG1 and TGF-beta1.
  • Investigating HMG1 binding to Abeta (1-42) and its effect on oligomerization.
  • Quantifying HMG1 protein levels in cytosolic and particulate fractions of AD brain tissue.
  • Examining the colocalization of HMG1 and Abeta in senile plaques via immunohistochemistry.

Main Results:

  • High mobility group protein-1 (HMG1) significantly inhibited microglial uptake of Abeta (1-42), irrespective of TGF-beta1 presence.
  • HMG1 was found to bind to Abeta (1-42), promoting the stabilization of Abeta oligomers.
  • Elevated HMG1 protein levels were observed in both cytosolic and particulate fractions of Alzheimer's disease brains.
  • HMG1 and Abeta were found to be colocalized within senile plaques, often associated with microglia.

Conclusions:

  • HMG1 plays a role in modulating extracellular Abeta (1-42) homeostasis.
  • HMG1 appears to influence Abeta (1-42) oligomerization, potentially contributing to AD pathogenesis.
  • The findings suggest HMG1 as a potential regulator of Abeta deposition and microglial response in Alzheimer's disease.

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