Affordable Access

Publisher Website

Type II keratins precede type I keratins during early embryonic development

European Journal of Cell Biology
Publication Date
DOI: 10.1016/j.ejcb.2005.04.001
  • Intermediate Filaments
  • Keratins
  • Pre-Implantation Embryo
  • Promiscuous Keratin Filaments
  • Ebs
  • Biology


Abstract We and others have recently demonstrated that the keratin (K) gene family in mammals is even more complex than previously thought [Eur. J. Cell Biol. 83, 19–26]. To address the function of keratins during early development, precise information on their spatio-temporal expression is required. Here, we examined the expression of selected mouse keratins from pre-implantation to mid-gestational embryonic stages using RT-PCR and immunofluorescence. At E0.5, transcripts encoding K5, K6, K7, K8, K14, K15, K18, and K19 are apparently absent. We report on a post-transcriptional regulation of type I keratins, preventing filament formation in 8- to 16-cell stage embryos. In these embryos, mRNAs coding for K7, K8, K18, and K19 are present, but only K7 and K8 are translated into protein which is deposited in aggregates. Following the accumulation of K18 protein at E3.5, keratin filaments are formed. Delayed onset of type I keratin protein expression was additionally observed in later embryonic stages for K5 and K14. K5 protein expression starts in the forelimb surface ectoderm as early as E9.25, while the expression of its partner, K14, begins at E9.75. From E9.25 to E9.75, K5 forms atypical filaments with K18. Remarkably, in embryonic K5 −/− mice, K14 formed normal filaments until E12.5 despite the absence of its partner K5, due to the presence of K8. Following periderm formation, K14-containing filaments disappeared and K14 became localized in aggregates in basal keratinocytes. Despite the absence of a keratin cytoskeleton, there was no cytolysis. We suggest that the formation of the first embryonic cytoskeleton from soluble keratins is regulated by unknown mechanisms. Whether the premature expression of type II keratins relates to their proposed role in TNF- and Fas-mediated signalling is presently unknown.

There are no comments yet on this publication. Be the first to share your thoughts.


Seen <100 times

More articles like this

Type II keratins precede type I keratins during ea...

on European Journal of Cell Biolo... August 2005

Differential expression of inhibin subunits and fo...

on Developmental Biology December 1992

Differential expression of inhibin subunits and fo...

on Developmental Biology Jan 01, 1992

Expression of unusually large keratins during term...

on The Journal of Cell Biology Jan 11, 1984
More articles like this..