Alternative RNA processing

In addition to affecting the efficiency of promoter utilization, eukaryotic cells employ alternative RNA processing to control gene expression. This can result when alternative promoters, intron-exon splice sites, or polyadenylation sites are used. Occasionally, heterogeneity within a cell results, but more commonly the same primary transcript is processed differendy in different tissues. A few examples of each of these types of regulation are presented below. 

Interestingly, Chisaka et al. (1992) targeted the Hox-1.6 gene in a different manner and observed some distinct phenotypic effects. Alternate RNA processing allows the Hox-1.6 gene to encode two different proteins, one with the homeodomain and one without it. The experiments... 

Rosenfeld, M.G., Amara, S.G. and Evans, R.M. Alternative RNA processing events as a critical developmental regulatory strategy in nenroendocrine gene expression (1984) Biochem. Soc. Symp. 49, 27-44... 

Amara, G.S., Jonas, V., Rosenfeld, M.G., Ong, E.S., Evans, R.M. Alternative RNA processing in calcitonin gene expression generates mRNAs encoding different polypeptide products, Nature 1982, 298, 240-244. 

Leff, S. D., M. G. Rosenfeld, and R. M. Evans, Complex transcriptional units Diversity in gene expression by alternative RNA processing. Ann. Rev. Biochem. 55 1091-1117, 1986. 

Early, P., Rogers, J., Davis, M., Calame, K., Bond, M., Wall, R., Hood, L. (1980b). T vo mRNAs can be produced from a single immunoglobulin p gene by alternative RNA processing pathways. Cell 20,313-319. 

Maki, R., Roeder, W., Traunecker, A., Sidman, C., Wabl, M., Raschke, W., Tonegawa, S. (1981). The role of DNA rearrangement and alternative RNA processing in the expression of immunoglobulin delta genes. Cell 24, 353-365. 

Lou, H. . andGagcl. K. F. 1998.. Alternative RNA processing Its mb in regulating expression of calatonln/calcitoniii gene-related peptiib I Endocrinol. 156 401 405. 

Examples of all three types of alternative RNA processing occur during sexual differentiation in Drosophila (see Figure 12-14). Commonly, one mRNA is produced from a complex transcription unit in some cell types, and an alternative mRNA is made in other cell types. For example, differences in RNA splicing of the primary fibronectin transcript in fibroblasts and hepatocytes determines whether or not the secreted protein Includes domains that adhere to cell surfaces (see Figure 4-15). 

The four basic modes of alternative RNA processing include selective splicing, use of an alternate 50 donor site, use of an alternate 30 acceptor site, and use of an alternate polyadenylation site. 

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