Expression of Drosophila lamin C is developmentally regulated: analogies with vertebrate A-type lamins.
Vertebrate nuclear lamins form a multigene family with developmentally controlled expression. In contrast, invertebrates have long been thought to contain only a single lamin, which in Drosophila is the well-characterized lamin Dm0. Recently, however, a Drosophila cDNA clone (pG-IF) has been identified that codes for an intermediate filament protein which harbors a nuclear localization signal but lacks a carboxy-terminal CAAX motif. Based on these data the putative protein encoded by pG-IF was tentatively called Drosophila lamin C. To address whether the pG-IF encoded protein is expressed and whether it encodes a cytoplasmic intermediate filament protein or a nuclear lamin we raised antibodies against the recombinant pG-IF protein. The antibodies decorate the nuclear envelope in Drosophila Kc tissue culture cells as well as in salivary and accessory glands demonstrating that pG-IF encodes a nuclear lamin (lamin C). Antibody decoration, in situ hybridization, western and northern blotting studies show that lamin C is acquired late in embryogenesis. In contrast, lamin Dm0 is constitutively expressed. Lamin C is first detected in late stage 12 embryos in oenocytes, hindgut and posterior spiracles and subsequently also in other differentiated tissues. In third instar larvae lamins C and Dm0 are coexpressed in all tissues tested. Thus, Drosophila has two lamins: lamin Dm0, containing a CaaX motif, is expressed throughout, while lamin C, lacking a CaaX motif, is expressed only later in development. Expression of Drosophila lamin C is similar to that of vertebrate lamin A (plus C), which loses its CaaX motif during incorporation into the lamina.
Riemer
D
D
Max-Planck-Institute for Biophysical Chemistry, Department of Biochemistry, Goettingen, FRG.
Stuurman
N
N
Berrios
M
M
Hunter
C
C
Fisher
P A
PA
Weber
K
K
D000818:Animals; D000906:Antibodies; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011994:Recombinant Proteins / Q000096:biosynthesis
D000906:Antibodies; D018076:DNA, Complementary; D029721:Drosophila Proteins; C440328:Lam protein, Drosophila; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; C440308:lamin C