Biomedical Updates


Aluminum Impairs Protein-Folding

As we have long been aware, aluminum is notorious as a neurotoxic metal. A new Japanese study set out to determine whether endoplasmic reticulum (ER) stress is involved in aluminum-induced cell death (apoptosis) in astrocytes, star-shaped glial cells in the brain and spinal cord.1 When mitochondrial RNA (mRNA) was analyzed by reverse transcription-PCR* following exposure of aluminum glycinate to primary cultured astrocytes, gene expression analysis revealed some interesting measurements. Among these was that an inositol-requiring protein (beta) measure reflecting unfolded protein response (UPR) was up-regulated in astrocytes exposed to aluminum, while a different inositol-requiring protein (alpha) was up-regulated by a positive control material.


* Reverse transcription polymer chain reaction is a laboratory technique commonly used in molecular biology to generate many copies of a DNA sequence, a process termed “amplification,” in order to rapidly identify those sequences.


Yet exposure to aluminum glycinate, in contrast to the positive control material, seemed to down-regulate mRNA expression of many genes, including the ER resident molecular chaperones and binding chaperones.

The down-regulation or non-activation of the molecular chaperones, whose expressions are known to be protective by increasing protein folding, may spell doom for the adaptive response that is responsible for genetic repair. The results of this study demonstrate that aluminum may induce apoptosis in astrocytes via ER stress by impairing the protein-folding machinery. Can osmolytes be of any benefit? Time will tell.

Reference

  1. Aremu DA, Ezomo OF, Meshitsuka S. Gene expression in primary cultured astrocytes affected by aluminum: alteration of chaperons involved in protein folding. Environ Health Prev Med 2011 Jan;16(1):16-24.

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