Two Human Homeobox Genes, Cl and C8
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Proc. Natl. Acad. Sci. USA Vol. 84, pp. 4914-4918, July 1987 Developmental Biology Two human homeobox genes, cl and c8: Structure analysis and expression in embryonic development ANTONIO SIMEONE*, FULVIO MAVILIOt, DARIO ACAMPORA*, ADELE GIAMPAOLOt, ANTONIO FAIELLA*, VINCENZO ZAPPAVIGNAt, MAURIZIo D'EsPosITO*, MARIA PANNESE*, GIOVANNI Russot, EDOARDO BONCINELLI*, AND CESARE PESCHLEt§ *International Institute of Genetics and Biophysics, Via Marconi 10, 80125 Naples, Italy; tDepartment of Hematology, Istituto Superiore di Saniti, Viale Regina Elena 299, 00161 Rome, Italy; and tDivision of Obstetrics and Gynecology, Ospedale di Avellino, 83100 Avellino, Italy Communicated by Frank H. Ruddle, April 14, 1987 (received for review February 18, 1987) ABSTRACT Two human cDNA clones (HHO.cl.95 and scripts, respectively, which are differentially expressed in a HHO.c8.5111) containing a homeobox region have been charac- variety of organs or body parts at 5 to 9 weeks of embryon- terized, and the respective genomic regions have been partially ic/fetal development. analyzed. Expression of the corresponding genes, termed cl and c8, was evaluated in different organs and body parts during METHODS human embryonic/fetal development. HHO.cl.95 apparently Human Embryos and Fetuses. Human embryos and early encodes a 217-amino acid protein containing a class I fetuses were obtained virtually intact from legal curettage homeodomain that shares 60 out of 61 amino acid residues with abortions and were maintained in sterile culture medium at the Antennapedia homeodomain of Drosophila melanogaster. +40C until processing (26). The age of embryos (5-8 weeks) HHO.c8.5111 encodes a 153-amino acid protein containing a was carefully established by morphologic staging according homeodomain identical to that of the frog ACI gene. Clones to multiple criteria (dating error was ± 2 days) (27, 28). Early HHO.cl and HHO.c8 detect by blot-hybridization one and two fetuses (9 weeks) were staged on the basis of standard specific polyadenylylated transcripts, respectively. These are age/crown-rump length plots. Different organs or body parts differentially expressed in spinal cord, backbone rudiments, limb were dissected under an inverted microscope and were stored buds (or limbs), heart, and skin of human embros and early in liquid nitrogen until analyzed. fetuses in the 5- to 9-week postfertilization period, thus suggesting cDNA Clones. Recombinant clones (8 x 105) of a cDNA that the cl and c8 genes play a key role in a variety of library prepared from poly(A)+ RNA of SV40-transformed developmental processes. Together, the results of the human fibroblasts (29) were originally screened with a 600-bp embryonic/fetal expression of cl and c8 and those of two BamHI-Pvu II fragment of clone 903 (4, 30) containing the previously analyzed genes (cdO and c13) indicate a coherent entire Antp homeobox region or a 1050-bp Pvu II fragment pattern of expression of these genes in early human ontogeny. containing the homeobox and the 3' region of theftz gene (4), both labeled to a high specific activity by nick-translation In the fruitfly Drosophila melanogaster, studies on develop- (31). Clones (2.5 x 105) of the same cDNA library were mental mutants have allowed the identification of a number subsequently screened with the insert of clone HHO.cl or of genes controlling morphogenesis, which are classified in HHO.c8 under stringent conditions. Recombinant positive three general groups: (i) maternal-effect genes, which specify clones were isolated, and the longest inserts (HHO.cl.95, the structure and spatial coordinates of the egg, (it) segmen- HHO.c8.5111) were characterized by restriction endonucle- tation genes, which determine the number and polarity of ase mapping and were sequenced (32). body segments, and (iii) homeotic genes, which specify the RNA and DNA Analysis. Total RNA was extracted from identity of each segment (reviewed in ref. 1). Most homeotic fresh or frozen samples by the guanidinium isothiocyanate genes identified so far are clustered in the Antennapedia technique and was selected for poly(A)+ RNA by one passage (Antp-C) and the bithorax (bx-C) complex (2, 3). Cloning of on an oligo(dT)-ceilulose column (33, 34). Ten micrograms of some of these genes has led to the identification of a total RNA or 2-3 pug of poly(A)+ RNA was electrophoresed 183-base-pair (bp) sequence, termed the homeobox, which is on a 1.0% agarose/formaldehyde gel, blotted on nitrocellu- contained in most segmentation and homeotic genes and lose or nylon membranes, and hybridized to 107 cpm ofDNA encodes a highly conserved protein domain (4, 5). Homeo- probe labeled by nick-translation to a specific activity of 3 X box-containing genes have also been cloned from sea urchin 108 to 8 x 108 dpm per Ag (31). The blots were washed under (6), frog (7-9), mouse (10-20), and human (21, 22); however, stringent conditions (cf. ref. 25). Probes were then removed direct evidence for their regulatory role in development is still by boiling in a 0.1% NaDodSO4 buffered solution, and the unavailable (cf. ref. 23). filters were rehybridized to a chicken .8-actin probe for We have reported the isolation of human cDNA clones, normalization (see refs. 24 and 25). Southern analysis was termed HHO.cl, HHO.c8, HHO.c1O, and HHO.c13, con- performed according to standard techniques (31). taining homeobox sequences that appear to represent tran- scripts from four different genes (22). HHO.c1O (24) and RESULTS AND DISCUSSION HHO.c13 (25) contain a conserved class I homeobox and The nucleotide sequence of HHO.cl.95 is shown in Fig. lA. detect by blot hybridization specific transcripts during human Conceptual translation of its longest open reading frame, embryogenesis. We report here the characterization ofclones starting from the ATG codon at position 100, produces a HHO.cl.95 and HHO.c8.5111 and part of the corresponding peptide sequence of 217-amino acid residues that contains a genomic regions. HHO.cl and HHO.c8 detect by blot hy- class I homeodomain. The carboxyl-terminus of this protein bridization one and two specific polyadenylylated tran- lies 20-amino acid residues downstream from the homeodo- main and ends in a row of six glutamic acid residues. A 609-bp The publication costs of this article were defrayed in part by page charge 3'-untranslated region contains a polyadenylylation signal payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. §To whom reprint requests should be addressed. 4914 Developmental Biology: Simeone et al. Proc. Natl. Acad. Sci. USA 84 (1987) 4915 (AATAAA) 20 nucleotides upstream from the poly(A) tail. A HHO.c1.95 contains a second open reading frame, which putative glycosylation site (Asn-Xaa-Thr) is present at the might ehcode a 156-amino acid protein, starting from the 60th amino acid residue of the homeodomain (Fig. LA), as is methionine codon at position 116 through a TGA codon at found in the Antp homeodomain (23). The original clone position 584 (halfway through the homeobox). Further anal- HHO.cl is identical to HHO.c1.95 at positions 450-1359. A TTAMCCCCCAGCACGATGCACGACCAGGGCTTGACCTTGCCAGCTGCACATGCCTCCGCCCGTCCTCTCTCCCA 75 A CGTTTTCGTCTAAATCTGC.ACTCTAATTCTGTAATATATCAAGCAATCTCCTAAA 55 GCCTCTTCCTCCTGCCCCCTTCTTCCAMCTCTCCTTAATTTTCTTTCCCTTTTCCATCATTATMTTATTTTTATTTTT 156 Met Ser Ser Leu Tyr Tyr Ala Aan Ala ACCGACACTMAACGTCCCTGCCTACAAATCATCCGCCCAAATTATG ACT TCA TTC TAT TAT (CG AAT GCT 126 A GMTTTATATAMACTATATCTGTCGTCGTCTCCASCTCAGACAGCTCCCCAGCCGCACAGMTCACSCAACGACCACM 233 10 20 Leu Phe Ser Lys Tyr Pro Ala Ser Ser Ser Val Phe Ala Thr Cly Ala Phe Pro Glu GIn -7- TTA TTT TCT MA TAT CCA CCC TCA ACT TCG CTT TTC GCT ACC CGA GCC TTC CCA GAA CAA 186 30 40 Thr Ser Cys Ala Phe Ala Ser Asn Pro Gln Arg Pro Gly Tyr Gly Ala Gly Ser Gly Ala TCMTTCCACCCCCTATCATCCACTCAGGCATTTCTCCACCTATGCACCGCCCGTCCCCCAaAACCC(CATCTACTCCAC 391 ACT TCT TGT GCC TTT GCT TCC MC CCC CAG CCC CCG GCC TAT CGA GCG CGT TCG GGC GCT 246 A 50 60 TCCCTTTTATTCCCCACACCACMTGTCCTGTTCAGTTCCACCCGCGCCCCCTATCACTATGCATCTAATTCCTTTTAC 470 Ser Phe Ala Ala Ser cet Gln Gly Leo Tyr Pro Gly Gly Gly Gly Met Ala Cly Gln Ser A TCC TTC GCC GCC TCG ATG CAG GGC TTC TAC CCC CGC GCC CGG GGC ATG GCG CAG ACC 10 GCC 306 Cys Arg Thr His Thr Thr A Met Leu Ser Asn Gln Acn Leu Cly Asn Gln Ser 70 80 CAGCACGAAGACATG CTC TCA MC TCC ACA CAA AAC ACC TTA SCA CAT MC ACA CAC ACC TCA 533 Ala Ala Gly Val Tyr Ala Ala Gly Tyr Gly Leu Glu Pro Ser Ser Phe Asn Met His Cys GCG GCC GGC GTC TAC GCC CCC CCC TAT GGG CTC GAG CCC ACT TCC TIC MC ATG CAC TCC 366 20 30 Ile Ala Gln Asp Phe Ser Ser Glu GSn Gly Arg Thr Ala Pro Gln Asp Gln Lys Ala Ser 90 100 ATC GCT CAG GAT TTT ACT TCT GAG CAG GGC AGG ACT GCG CCC CAG GAC CAG AM GCC AGT 593 Ala Pro Phe clu Gln Asn Leu Ser Sly Val Cys Pro Sly Ser Ala Lys Ala Ala Sly Acp 7 GCG CCC TmT GAG CAG MC CTC TCC GGG GTG TGT CCC GCC SAC TCC GCC MG GCG GCG GCC 426 40 S0 Ile Gln Ile Tyr Pro Trp Met Gln Arg Met Asn Ser His Ser Gly Val Gly Tyr Gly Ala 110 120 ATC CAG ATT TAC CCC TCC ATG CAC CGA ATG MT TCG CAC AGT GGG CTC GGC TAC GSA GCC 653 Ala Lys Glu Sln Arg Asp Ser Asp Leoi Ala Ala Clu Ser Acn Ile Tyr Pro Trp Phe Arg 60 70 GCC MS GAG CAG AGG GAC TCG SAC TTC GCG CCC GAG ACT MC TTC CGC ATC TAC CCC TCG 486 Asp Fr Arg Arg Gly Arg Cln Ile Tyr Ser Arg Tyr Gln Thr Leu Glu Leu Glu Lys Glu CAC CGC ASS CCC CGC CCC CAC ATC TAC TCC CCG TAC CAG ACC CTG GM CTG GAG MG GM 713 130 7 'A Met Arg Ser Ser Gly Thr Asp SrgLys Arg Gly Arg Gln Thr Tyr Thr Arg Tyr Gln Thr 80 90 ATG CGA ASC TCA GGA ACT GAC