Quantification of spatiotemporal patterns of Ras isoform expression during development

Abstract

Ras proteins are important signalling hubs frequently dysregulated in cancer and in a group of developmental disorders called Rasopathies. Three Ras genes encode four proteins that differentially contribute to these phenotypes. Using quantitative real-time PCR (qRT-PCR) we have measured the gene expression profiles of each of the Ras isoforms in a panel of mouse tissues derived from a full developmental time course spanning embryogenesis through to adulthood. In most tissues and developmental stages we observe a relative contribution of KRas4B > > NRas ≥ KRas4A > HRas to total Ras expression with KRas4B typically representing 60–99% of all Ras transcripts. KRas4A is the most dynamically regulated Ras isoform with significant up-regulation of expression observed pre-term in stomach, intestine, kidney and heart. The expression patterns assist interpretation of the essential role of KRas in development and the preponderance of KRas mutations in cancer.

Capturing the primordial Kras mutation initiating urethane carcinogenesis

“…While a number of factors could contribute to this variation in mutagenesis [59][60][61] , one notable difference is that Kras mRNA levels are higher in the lung compared with these other tissues, suggestive of increased transcription. In fact, the lung was found to have the second highest levels of Kras mRNA of 15 adult murine tissues analyzed, second only to the brain 35 . Kras expression in the mouse lung also correlates with strain susceptibility to urethane carcinogenesis 62,63 .…”

“…Mutational strand asymmetry has been observed for other mutational processes 32,33 and correlated with the transcriptional status of mutated genes 34 . Kras mRNA levels determined by quantitative RT-PCR (RT-qPCR) 35 or RNA-seq 36 have been reported to be higher in the murine lung compared with the liver. In agreement, we validated the higher expression of Kras mRNA in lung compared with liver and pancreas by RT-qPCR ( Fig.…”

Expression patterns and immunohistochemical analysis of ERK, HRAS and MEK1 proteins during ovarian prehierarchical follicular development in Zi geese (Anser cygnoides)

“…HRAS showed a significant noticeable trend of expression levels by decreasing exponentially from PF to SYF (p  0.05), which suggest that HRAS may have dynamic functional activities during the prehierarchical follicle development. Previous studies reported the spatial and temporal HRAS mRNA transcripts during mice development expressed in a stage development and tissue specific manner with the highest expression in the adult brain (Newlaczyl et al, 2017). Moreover, higher expression of MEK1 was observed in SWF suggesting that MEK1 may have an active role by either suppressing or promoting the development of prehierarchical follicle.…”

Protein isoforms. Origin, structure and functions.

“…Quantification of spatiotemporal patterns of Ras isoforms expression during development showed a relative contribution of KRas4B > > NRas ≥ KRas4A > HRas to the total Ras expression with KRas4B typically representing 60-99 % of all Ras transcripts. KRas4A was the most dynamically regulated Ras isoform with significant up-regulation of the expression observed in stomach, intestine, kidney and heart [21]. The functional divergence may be explained, at least partially, by different membrane compartmentalization of the Ras isoforms [22].…”