NDM29, a RNA polymerase III-dependent non coding RNA, promotes amyloidogenic processing of APP and amyloid β secretion.

Neuroblastoma Differentiation Marker 29 (NDM29) is a RNA polymerase (pol) III-transcribed non-coding (nc) RNA whose synthesis drives neuroblastoma (NB) cell differentiation to a nonmalignant neuron-like phenotype. Since in this process a complex pattern of molecular changes is associated to plasma membrane protein repertoire we hypothesized that the expression of NDM29 might influence also key players of neurodegenerative pathways. In this work we show that the NDM29-dependent cell maturation induces amyloid precursor protein (APP) synthesis, leading to the increase of amyloid β peptide (Aβ) secretion and the concomitant increment of Aβ x-42/Aβ x-40 ratio. We also demonstrate that the expression of NDM29 RNA, and the consequent increase of Aβ formation, can be promoted by inflammatory stimuli (and repressed by anti-inflammatory drugs). Moreover, NDM29 expression was detected in normal human brains although an abnormal increased synthesis of this ncRNA is induced in patients affected by neurodegenerative diseases. Therefore, the complex of events triggered by NDM29 expression induces a condition that favors the formation of Aβ peptides in the extracellular space, as it may occur in Alzheimer's Disease (AD). In addition, these data unexpectedly show that a pol III-dependent small RNA can act as key regulator of brain physiology and/or pathology suggesting that a better knowledge of this portion of the human transcriptome might provide hints for neurodegeneration studies.