Identification of a light-regulated MYB gene from an Arabidopsis transcription factor gene collection

Seven different MYB-related genes have been isolated from a genomic Arabidopsis library with probes based on MYB DNA-binding motifs. The predicted amino acid sequence of these genes showed high similarity in the MYB domain but outside this region virtually no similarities were found. The set of MYB-related genes was used to identify differentially expressed genes following the transfer of etiolated seedlings to light. This differential screen resulted in the selection of the ATM4 gene which is induced by light within one hour of exposure of etiolated or dark-adapted seedlings.     

Global genome splicing analysis reveals an increased number of alternatively spliced genes with aging

Alternative splicing (AS) is a key regulatory mechanism for the development of different tissues; however, not much is known about changes to alternative splicing during aging. Splicing events may become more frequent and widespread genome‐wide as tissues age and the splicing machinery stringency decreases. Using skin, skeletal muscle, bone, thymus, and white adipose tissue from wild‐type C57BL6/J male mice (4 and 18 months old), we examined the effect of age on splicing by AS analysis of the differential exon usage of the genome. The results identified a considerable number of AS genes in skeletal muscle, thymus, bone, and white adipose tissue between the different age groups (ranging from 27 to 246 AS genes corresponding to 0.3–3.2% of the total number of genes analyzed). For skin, skeletal muscle, and bone, we included a later age group (28 months old) that showed that the number of alternatively spliced genes increased with age in all three tissues (P < 0.01). Analysis of alternatively spliced genes across all tissues by gene ontology and pathway analysis identified 158 genes involved in RNA processing. Additional analysis of AS in a mouse model for the premature aging disease Hutchinson–Gilford progeria syndrome was performed. The results show that expression of the mutant protein, progerin, is associated with an impaired developmental splicing. As progerin accumulates, the number of genes with AS increases compared to in wild‐type skin. Our results indicate the existence of a mechanism for increased AS during aging in several tissues, emphasizing that AS has a more important role in the aging process than previously known.