Structure and implied functions of truncated B-cell receptor mRNAs in early embryo and adult mesenchymal stem cells: Cdelta replaces Cmu in mu heavy chain-deficient mice.
Stem cells exhibit a promiscuous gene expression pattern. We show herein that the early embryo and adult MSCs express B-cell receptor component mRNAs. To examine possible bearings of these genes on the expressing cells, we studied immunoglobulin mu chain-deficient mice. Pregnant mu chain-deficient females were found to produce a higher percentage of defective morulae compared with control females. Structure analysis indicated that the mu mRNA species found in embryos and in mesenchyme consist of the constant region of the mu heavy chain that encodes a recombinant 50-kDa protein. In situ hybridization localized the constant mu gene expression to loose mesenchymal tissues within the day-12.5 embryo proper and the yolk sac. In early embryo and in adult mesenchyme from mu-deficient mice, delta replaced mu chain, implying a possible requirement of these alternative molecules for embryo development and mesenchymal functions. Indeed, overexpression of the mesenchymal-truncated mu heavy chain in 293T cells resulted in specific subcellular localization and in G(1) growth arrest. The lack of such occurrence following overexpression of a complete, rearranged form of mu chain suggests that the mesenchymal version of this mRNA may possess unique functions.
Lapter
Smadar
S
Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Livnat
Idit
I
Faerman
Alexander
A
Zipori
Dov
D
D000818:Animals; D018014:Gene Transfer Techniques; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007075:Immunoglobulin M / Q000172:deficiency; D007148:Immunoglobulin mu-Chains / Q000235:genetics*; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000235:genetics*; D011947:Receptors, Antigen, B-Cell / Q000235:genetics*
D007143:Immunoglobulin Heavy Chains; D007075:Immunoglobulin M; D007148:Immunoglobulin mu-Chains; D012333:RNA, Messenger; D011947:Receptors, Antigen, B-Cell