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[P1.28]: Boundary cell specific adhesion molecule, PB–cadherin, is not required for maintenance the midbrain‐hindbrain border
Author(s) -
SaarimakiVire J.,
Turakainen H.,
Alitalo A.,
Sinjushi.,
Savilahti H.,
Partanen J.
Publication year - 2010
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/j.ijdevneu.2010.07.069
Subject(s) - library science , art , computer science
PB-cadherin belongs to the classical cadherin family of homotypic cell adhesion molecules. PB-cadherin is expressed in forebrain, midbrain–hindbrain boundary (MHB) and limb buds (Kitijama et. al., 1999). Little is still known of its functions. Short type PB-cadherin promotes survival of gonocytes in neonatal rats (Wu et al., 2005). Therefore, Pb-cadherin might participate in maintaining cell survival and stem cell population in other tissues. In midbrain–hindbrain specific FGFR1 knock-out embryos the border between midbrain and hindbrain is disrupted. Signaling trough FGFR1 may thus regulate cell adhesion properties at the MHB (Trokovic et al., 2003). Furthermore, there is a specific FGFR1 -dependent slowly proliferating boundary cell population between midbrain and rhombomere 1. These boundary cells may be important for development of the isthmic construction and separation of the two brain regions (Trokovic 2005, Kala 2008). The expression of PB-cadherin started in MHB at E8.0 and PB-cadherin was expressed in the boundary cells together with cell cycle inhibitor p21. PB-cadherin, was downregulated in MHB in the FGFR1 mutants (Trokovic et al 2003). Later, PB-cadherin is expressed also in ventral midbrain; rostral population correlates with Pou4f1 expressing (glutamatergic) cells and posterior with Gad1 expressing (gabaergic) cells. At E18.5 PB-cadherin is expressed in specific regions in forebrain including indesium griseum, amygdala, hippocampus, midbrain and hindbrain. The function of PB-CAD in nervous system remains mainly unknown. To study this we generated a conditional mutant allele of PB-cad (Turakainen et al., 2009).The mice homozygous for a PB-cad null allele (PBCdel/del) are viable and fertile, although their number was less than expected at weaning. However, changes of compartmentalization in early embryos were lacking. Midbrainhindbrain neuronal populations were normal in E18 PBCdel mutants. As other type II cadherins such as OB-cadherin are co-expressed with PB-cad there might be functional redundancy among the type II cadherins.