Diverging gain-of-function mechanisms of two novel KRAS mutations associated with Noonan and cardio-facio-cutaneous syndromes

Cirstea, I. C.; Gremer, L.; Dvorsky, R.; Zenker, M.; Piekorz, R. P.; Zhang, S. -C.; Ahmadian, M. R.

doi:10.1093/hmg/dds426

Journal Article

FZJ-2013-05988

Diverging gain-of-function mechanisms of two novel KRAS mutations associated with Noonan and cardio-facio-cutaneous syndromes

Cirstea, I. C. ; Gremer, L.FZJ* ; Dvorsky, R. ; Zhang, S. -. ; Piekorz, R. P. ; Zenker, M. ; Ahmadian, M. R. (Corresponding author)

2013
Oxford Univ. Press Oxford

Human molecular genetics 22(2), 262 - 270 (2013) [10.1093/hmg/dds426]

This record in other databases:

Please use a persistent id in citations: doi:10.1093/hmg/dds426

Abstract: Activating somatic and germline mutations of closely related RAS genes (H, K, N) have been found in various types of cancer and in patients with developmental disorders, respectively. The involvement of the RAS signalling pathways in developmental disorders has recently emerged as one of the most important drivers in RAS research. In the present study, we investigated the biochemical and cell biological properties of two novel missense KRAS mutations (Y71H and K147E). Both mutations affect residues that are highly conserved within the RAS family. KRASY71H showed no clear differences to KRASwt, except for an increased binding affinity for its major effector, the RAF1 kinase. Consistent with this finding, even though we detected similar levels of active KRASY71H when compared with wild-type protein, we observed an increased activation of MEK1/2, irrespective of the stimulation conditions. In contrast, KRASK147E exhibited a tremendous increase in nucleotide dissociation generating a self-activating RAS protein that can act independently of upstream signals. As a consequence, levels of active KRASK147E were strongly increased regardless of serum stimulation and similar to the oncogenic KRASG12V. In spite of this, KRASK147E downstream signalling did not reach the level triggered by oncogenic KRASG12V, especially because KRASK147E was downregulated by RASGAP and moreover exhibited a 2-fold lower affinity for RAF kinase. Here, our findings clearly emphasize that individual RAS mutations, despite being associated with comparable phenotypes of developmental disorders in patients, can cause remarkably diverse biochemical effects with a common outcome, namely a rather moderate gain-of-function.

Classification: