Very little is known about regulatory mechanisms of PDI transcription in eukaryotes, in part because abundantly expressed PDI seems regulated at the level of protein expression, translocation and perhaps post-translational modifications [54].
Some of these novel microRNAs are both abundantly expressed and developmentally regulated.
For instance, imprinted genes, which are epigenetically regulated, are abundantly expressed in foetal and placental tissues and are apparently absent in non-placental organisms [ 24, 25 ].
Building on prior evidence that lincRNAs are abundantly expressed and spatio-temporally regulated within the brain during development and adulthood (Mercer et al., 2008; Qureshi et al., 2010; Cabili et al., 2011; Ramos et al., 2013), we concentrated on the candidate lincRNAs that were expressed in the brain or in neural progenitors.
Linkage analysis studies showed that this family carries a null mutation predicted to disrupt specifically the NC11-303 ishortm (shoft) of COL18A1 common to vascular basement membranes, which is distinct from a long form splice variant expressed abundantly in the liver and heart and regulated by a different promoter [41].
In the previously cited reference Lukiw reported that: "miR-9, miR-124a, miR-125b, miR-128, miR-132 and miR-219 are abundantly represented in fetal hippocampus, are differentially regulated in aged brain, and an alteration in specific micro-RNA complexity occurs in Alzheimer hippocampus".
In osteoblast, we demonstrate that Arl6ip5 abundantly expresses in osteoblastic cells and is regulated by bone metabolism-related hormones and growth factors.
ZmrpP0 is relatively abundantly expressed in unfertilized egg cells but down regulated in zygotes by 18 hour after in-vitro fertilization [27].
In normal tissues, MALAT1 expresses in a tissue specific patterns, for example, Malat1 is the most abundantly expressed lincRNA in differentiating neurons, and is up regulated in cerebellum, hippocampus and brain stem of human alcoholics [ 17].
