Original Contributions |
From the Cardiovascular Biology Laboratory, Harvard School of Public Health (M.K.J., S.K., C.-M.H., M.D.L., S.-F.Y., N.E.S.S., M.T.C., M.W.F., E.H., M.-E.L.), the Department of Medicine, Harvard Medical School (M.K.J., N.E.S.S., M.T.C., R.L.M., E.H., M.-E.L.), and the Cardiovascular Division of the Department of Medicine (M.K.J., N.E.S.S., M.T.C., M.-E.L.) and the Department of Genetics (I.W., R.L.M.), Brigham and Women's Hospital, Boston, Mass.
Correspondence to Mu-En Lee, MD, PhD, Cardiovascular Biology Laboratory, Harvard School of Public Health, 677 Huntington Ave, Boston, MA 02115. E-mail lee{at}cvlab.harvard.edu
| Abstract |
|---|
|
|
|---|
Key Words: muscle, cardiac muscle, smooth development, mouse hybridization, in situ protein, zinc-finger
| Introduction |
|---|
|
|
|---|
All 4 classes of LIM proteins are important in the development and function of specific cell types. The LIM-HD protein Lhx3 is critical for pituitary organogenesis, as targeted disruption of the lhx3 gene eliminates all pituitary cell lineages except the corticotrophs.14 The LIM-only protein RBTN2 is essential for erythroid development, because a homozygous null mutation in RBTN2 leads to failure of yolk sac erythropoiesis and embryonic death.7 The LIM-K protein LIM-kinase1 has been implicated in impaired visuospatial constructive cognition.15
The cysteine-rich protein (CRP) family is a subclass of the LIM-only (class 2) proteins. Members include CRP1, CRP2/smooth muscle LIM protein (SmLIM), and CRP3/muscle LIM protein (MLP). CRP1 has been identified in avian tissues of the gut containing smooth muscle16 and implicated in muscle differentiation.17 CRP3/MLP was first described as a nuclear protein expressed principally in the heart and skeletal muscle of rodents. Overexpression of CRP3/MLP in cultured myoblasts augments differentiation, which suggests that this gene serves as a positive regulator of myogenesis.9 The importance of CRP3/MLP in striated muscle development was demonstrated recently in mice bearing a targeted disruption of the gene.18 CRP3/MLP-deficient animals exhibited profound defects in cardiac as well as skeletal muscle.
We cloned CRP2/SmLIM by homology screening. In adult animals, CRP2/SmLIM was expressed principally in the smooth muscle cells of blood vessels. Within the vasculature, it was expressed preferentially in arterial as opposed to venous tissue. CRP2/SmLIM can localize to both the nuclear and the cytoplasmic compartments.1 6 CRP2/SmLIM mRNA is downregulated markedly after smooth muscle cell dedifferentiation (in vitro and in vivo)6 and may play an important role in vascular smooth muscle development and differentiation.
To understand the role of CRP2/SmLIM in cardiovascular development, we conducted a detailed spatial and temporal analysis of its expression during mouse embryogenesis and compared the pattern with those of the other 2 members of the CRP family, CRP1 and CRP3/MLP. Our data suggest an important role for this gene family in the development of smooth and striated muscles.
| Materials and Methods |
|---|
|
|
|---|
To obtain tissue for in situ hybridization at embryonic day (E) 9, we purchased mouse embryo slides from Novagen. For all other time points, embryos were dissected from timed, pregnant CD-1 mice (Charles River Laboratories). Embryos were fixed in 4% paraformaldehyde in PBS. After dehydration and embedding in paraffin, embryos were sectioned at a thickness of 5 µm. Sense and antisense riboprobes labeled with 35S-labeled UTP were transcribed for each gene (CRP1, CRP2/SmLIM, and CRP3/MLP), and hybridization was carried out as described.6 Tissue sections were autoradiographed on Kodak NTB2 emulsion (Eastman Kodak) for 4 to 8 days at 4°C.
CRP1 and CRP3/MLP cDNAs were amplified from rat aortic smooth muscle cell RNA and mouse fetal heart RNA, respectively. The forward primer 5'-CCAAACTGGGGAGGAGGC-3' and the reverse primer 5'-CTCTGAATGGACCAAGGC-3' were used to amplify a 600-bp fragment of CRP1 by reverse transcription and polymerase chain reaction. The forward primer 5'-GAGTCTTCACCATGCCGAAC-3' and the reverse primer 5'-CTCTCCCACCCCAAAAATAG-3' were used to amplify a 799-bp fragment of CRP3/MLP. The identity of the PCR products was confirmed by nucleotide sequencing. The CRP2/SmLIM cDNA was obtained as described.6
Northern Analysis
Various tissues were obtained from CD-1 mice. Total RNA was
obtained by guanidinium isothiocyanate extraction and
centrifugation through cesium
chloride.20 All RNA was fractionated on a 1.3%
formaldehyde-agarose gel and transferred to a nitrocellulose filter,
after which it was hybridized with random-primed,
32P-labeled probes.20
Hybridized filters were washed in 30 mmol/L sodium chloride,
3 mmol/L sodium citrate, and 0.1% sodium dodecyl sulfate
at 55°C. Autoradiography was performed with Kodak XAR
film at -80°C. To correct for differences in loading, blots were
hybridized with an oligonucleotide probe complementary
to 28S rRNA. Filters were scanned and radioactivity was measured on a
PhosphorImager running the ImageQuant software (Molecular
Dynamics).
| Results |
|---|
|
|
|---|
|
At E10, CRP2/SmLIM expression was maintained in the atrium but
decreased slightly in the ventricle (Figure 2A
and 2B
) in comparison with expression
at E9. By E12 (Figure 2C
), this difference in CRP2/SmLIM expression in
the cardiac chambers became more apparent. Although at E12 CRP2/SmLIM
expression was maintained in the atrium (Figure 2C
), it decreased
markedly in the ventricle. This pattern of differential CRP2/SmLIM
expression was also maintained in the heart at E15 (Figure 3A
and 3B
) and in adults (Figure 6
).
|
|
|
Vascular Expression of CRP2 During Mouse Embryogenesis
At approximately E8, endothelial cells amalgamate
to form features of the embryonic vasculature such as the paired dorsal
aortae.21 Although the precise timing of smooth
muscle cell recruitment to the developing vasculature is unclear, it
probably occurs by E10.5, because at this point expression of highly
specific markers of differentiated smooth muscle cells is
visible.22 CRP2/SmLIM expression was first
visible within the vasculature at E10 (Figure 2A
and 2B
, dorsal aorta,
and umbilical vessel). By E15, expression occurred in several
additional vessel beds, such as the mesenteric vasculature (Figure 3C
)
and the pulmonary and cerebral vasculature (not shown).
Expression of CRP1 and CRP3/MLP During Mouse Embryogenesis
We performed a detailed analysis of CRP1 and CRP3/MLP
expression during mouse development to compare and contrast their
expression with that of CRP2/SmLIM. CRP1 expression was robust in both
the atrial and the ventricular chambers at E9 (Figure 4A
). Furthermore, CRP1 expression was
visible at this point in the paired dorsal aortae (Figure 4A
and 4B
)
and myotome (Figure 4A
). At E10, CRP1 expression was maintained in the
heart and vasculature (Figure 4C
), and at E15, a point at which the
primitive gut undergoes spatial development and differentiation, CRP1
expression was robust in the esophagus and the gut (Figure 4D
). CRP1
expression was also visible in both the parenchyma and blood vessels of
the lung (Figure 4D
and not shown).
|
Intense CRP3/MLP expression occurred at E9 in the developing atrial and
ventricular chambers of the heart (Figure 5A
and 5C
). Cardiac expression of
CRP3/MLP remained high throughout gestation (Figure 5B
and 5C
). Weak
expression of CRP3/MLP was also visible in the myotome at E10 (data not
shown). By E15, CRP3/MLP was visible in the skeletal musculature of the
back, chest wall, and diaphragm (Figure 5C
).
|
CRP Gene Expression in Adult Mice
To compare and contrast expression of the 3 CRP genes in
adult mice, we performed Northern analyses with a variety of
tissues (Figure 6
). The expression
pattern of each gene at E15 was similar in adults. CRP1 was expressed
in both arterial (aorta) and venous (vena cava) tissues,
whereas CRP2/SmLIM was expressed principally in arterial
tissue. Both genes were expressed at low levels in the atrial chambers
of the heart and at minimal levels in the ventricular
chambers (Figure 6
). In contrast, CRP3/MLP was expressed at high levels
in the 2 heart chambers. CRP1 was expressed highly in all tissues
containing nonvascular smooth muscle, such as uterus and colon (Figure 6
). CRP2/SmLIM was expressed in uterus and colon but at much lower
levels. In lung, CRP1 mRNA expression was high, whereas that of
CRP2/SmLIM was minimal (Figure 6
).
| Discussion |
|---|
|
|
|---|
Our results agree in general with the recent observations of Louis et
al23 on the pattern of CRP gene expression during
chick development. Using CRP isoformspecific antibodies, Louis et
al23 analyzed a number of tissues from
19-day chicken embryos by Western blotting. They found that CRP1 was
present predominantly in organs enriched in smooth muscle
(arteries, stomach, gizzard, intestine, and colon) and in lung and
fibroblasts. CRP2 expression was limited to arteries and fibroblasts,
whereas CRP3/MLP was expressed exclusively in heart, crop, and skeletal
muscle. An important difference between our observations and those of
Louis et al23 is that they found no expression of
CRP1 or CRP2 in embryonic chick hearts. This discrepancy is probably
due to the fact that Louis et al23 examined heart
samples at E19. We examined heart samples at earlier points during
mouse embryogenesis (Figures 1
and 4
).
Cardiac expression of CRP2/SmLIM begins early in gestation. CRP2/SmLIM
shares this feature with other smooth muscle markers, such as
-actin, calponin, and SM22
, the transient expression of which
occurs early during cardiac
morphogenesis.22 24 25 26 Given that the heart
begins as a tubular structure with rhythmic contractions, it has been
hypothesized that embryonic cardiomyocytes traverse a
smooth muscle cell-like phenotype during the development of the
heart.24 27 Our observations support this
hypothesis. The functional significance of an overlap in the genetic
programs of cardiac cells and smooth muscle cells early in development
is still not clear. However, even transient gene expression in
embryonic cardiomyocytes could be very important to the
normal development of the heart.
We have reported elsewhere that CRP2/SmLIM is expressed principally in
the vasculature of the adult rat.6 The data
presented here extend our earlier observations by showing that
CRP2/SmLIM is expressed in the mouse vasculature as early as E10
(Figure 2
). Thus, CRP2/SmLIM is among the earliest smooth muscle genes
expressed in the developing aorta. One sensitive indicator of
differentiated smooth muscle cells is smooth muscle myosin heavy
chain,22 which is expressed in the mouse aorta at
E10.5.22 CRP2/SmLIM is expressed in the
vasculature (at E10) shortly before smooth muscle cells are thought to
assume a differentiated phenotype.
The function of genes of the CRP family in the development of the heart and vasculature is still being elucidated. Our data support a primary role for CRP3/MLP in cardiogenesis and a role for CRP1 and CRP2/SmLIM in vasculogenesis. CRP3/MLP localizes to both the nucleus and the actin-based cytoskeleton.18 Its importance in cardiac development has been confirmed recently by the targeted disruption of CRP3/MLP in mice. Cardiomyocyte cytoarchitecture is profoundly disorganized in CRP3/MLP null mice, and although the animals are born alive they develop a dilated cardiomyopathy to which they succumb eventually.18
CRP1 localizes to the actin-based cytoskeleton by interacting
with 2 proteins associated with the cytoskeleton, zyxin (also a LIM
protein) and
-actinin, and CRP2/SmLIM has been identified both in
the nucleus and in the actin-based filaments in the
cytosol.1 6 We and others have shown that
expression of both CRP1 and CRP2/SmLIM is downregulated with cellular
dedifferentiation.6 8 These data suggest that
CRP1 and CRP2/SmLIM may coordinate cytoskeletal function and
subsequently regulate cellular proliferation and differentiation.
Targeted disruption of the CRP1 and CRP2/SmLIM genes should provide
insight into their functions in vascular and nonvascular smooth muscle
cells.
| Acknowledgments |
|---|
| Footnotes |
|---|
Received May 21, 1998; accepted July 29, 1998.
| References |
|---|
|
|
|---|
2. Schmeichel KL, Beckerle M. The LIM domain is a modular protein-binding interface. Cell. 1994;79:211219.[Medline] [Order article via Infotrieve]
3. Way JC, Chalfie M. mec-3, a homeobox-containing gene that specifies differentiation of the touch receptor neurons in C. elegans. Cell. 1988;54:516.[Medline] [Order article via Infotrieve]
4. Freyd G, Kim SK, Horvitz HR. Novel cysteine-rich motif and homeodomain in the product of Caenorhabditis elegans cell lineage lin-11. Nature. 1990;344:876879.[Medline] [Order article via Infotrieve]
5. Karlsson O, Thor S, Norberg T, Ohlsson H, Edlund T. Insulin gene enhancer binding protein Isl-1 is a member of a novel class of proteins containing both a homeo and a cys-his domain. Nature. 1990;344:879882.[Medline] [Order article via Infotrieve]
6.
Jain MK, Fujita KP, Hsieh C-M, Endege WO, Sibinga NES,
Yet S-F, Kashiki S, Lee W-S, Perrella MA, Haber E, Lee M-E. Molecular
cloning and characterization of SmLIM, a developmentally regulated LIM
protein preferentially expressed in aortic smooth muscle cells.
J Biol Chem. 1996;271:1019410199.
7. Warren AJ, Colledge WH, Carlton MB, Evans MJ, Smith AJH, Rabbits TH. The oncogenic cysteine-rich LIM domain protein Rbtn2 is essential for erythroid development. Cell. 1994;78:4557.[Medline] [Order article via Infotrieve]
8. Weiskirchen R, Bister K. Suppression in transformed avian fibroblasts of a gene (crp) encoding a cysteine-rich protein containing LIM domains. Oncogene. 1993;8:23172324.[Medline] [Order article via Infotrieve]
9. Arber S, Halder G, Caroni P. Muscle LIM protein, a novel essential regulator of myogenesis, promotes myogenic differentiation. Cell. 1994;79:221231.[Medline] [Order article via Infotrieve]
10. Gill GN. The enigma of LIM domains. Structure. 1995;3:12851289.[Medline] [Order article via Infotrieve]
11. Mizuno K, Okano I, Ohashi K, Nunoue K, Kuma K, Miyata T, Nakamura T. Identification of a human cDNA encoding a novel protein kinase with two repeats of the LIM/double zinc finger motif. Oncogene. 1994;9:16051612.[Medline] [Order article via Infotrieve]
12. Nunoue K, Ohashi K, Okano I, Mizuno K. LIMK-1 and LIMK-2, two members of a LIM motif-containing protein kinase family. Oncogene. 1995;11:701710.[Medline] [Order article via Infotrieve]
13. Bernard O, Ganiatsas S, Kannourakis G, Dringen R. Kiz-1, a protein with LIM zinc finger and kinase domains, is expressed mainly in neurons. Cell Growth Differ. 1994;5:11591171.[Abstract]
14. Sheng HZ, Zhadanov AB, Mosinger B Jr, Fujii T, Bertuzzi S, Grinberg A, Lee EJ, Huang S-P, Mahon KA, Westphal H. Specification of pituitary cell lineages by the LIM homeobox gene, Lhx3. Science. 1996;272:10041007.[Abstract]
15. Frangiskakis JM, Ewart AK, Morris CA, Mervis CB, Bertrand J, Robinson BF, Klein BP, Ensing GJ, Everett LA, Green ED, Pröschel C, Gutowski NJ, Noble M, Atkinson DL, Odelberg SJ, Keating MT. LIM-kinase1 hemizygosity implicated in impaired visuospatial constructive cognition. Cell. 1996;86:5969.[Medline] [Order article via Infotrieve]
16.
Crawford AW, Pino JD, Beckerle MC. Biochemical and
molecular characterization of the chicken cysteine-rich protein, a
developmentally regulated LIM-domain protein that is associated with
the actin cytoskeleton. J Cell Biol. 1994;124:117127.
17.
Pomiès P, Louis HA, Beckerle MC. CRP1, a LIM
domain protein implicated in muscle differentiation, interacts with
-actinin. J Cell Biol. 1997;139:157168.
18. Arber S, Hunter J, Ross J, Hongo M, Sansig G, Borg J, Perriard J, Chien K, Caroni P. MLP-deficient mice exhibit a disruption of cardiac cytoarchitectural organization, dilated cardiomyopathy, and heart failure. Cell. 1997;88:393403.[Medline] [Order article via Infotrieve]
19. Xu P, Woo I, Her H, Beier D, Maas R. Mouse Eya homologues of the Drosophila eyes absent gene require Pax6 for expression in lens and nasal placode. Development. 1997;124:219231.[Abstract]
20. Sambrook J, Fritsch EF, Maniatis T. Molecular Cloning: A Laboratory Manual. 2nd ed. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory Press; 1989.
21. Kaufman MH. The Atlas of Mouse Development. Cambridge: Academic Press; 1992.
22.
Miano J, Cserjesi P, Ligon KL, Periasamy M, Olson E.
Smooth muscle myosin heavy chain exclusively marks the smooth muscle
lineage during mouse embryogenesis. Circ Res. 1994;75:803812.
23.
Louis HA, Pino JD, Schmeichel KL, Pomiès P,
Beckerle MC. Comparison of three members of the cysteine-rich protein
family reveals functional conservation and divergent patterns of gene
expression. J Biol Chem. 1997;272:2748427491.
24.
Miano J, Olson E. Expression of the smooth muscle cell
calponin gene marks the early cardiac and smooth muscle lineages during
mouse embryogenesis. J Biol Chem. 1996;271:70957103.
25.
Li L, Miano J, Cseriji P, Olson E. SM22
, a
marker of adult smooth muscle, is expressed in multiple myogenic
lineages during embryogenesis. J Biol Chem. 1995;78:188195.
26.
Ruzicka D, Schwartz R. Sequential activation of
-actin genes during avian cardiogenesis: vascular smooth muscle
-actin gene transcripts mark the onset of cardiomyocyte
differentiation. J Cell Biol. 1988;107:25752586.
27. Olson EN, Srivastava D. Molecular pathways controlling heart development. Science. 1996;272:671675.[Abstract]
This article has been cited by other articles:
![]() |
L. C. G. Campos, A. A. Miyakawa, V. G. Barauna, L. Cardoso, T. F. Borin, L. A. d. O. Dallan, and J. E. Krieger Induction of CRP3/MLP expression during vein arterialization is dependent on stretch rather than shear stress Cardiovasc Res, July 1, 2009; 83(1): 140 - 147. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. van Tuyn, D. A. Pijnappels, A. A. F. de Vries, I. de Vries, I. van der Velde-van Dijke, S. Knaan-Shanzer, A. van der Laarse, M. J. Schalij, and D. E. Atsma Fibroblasts from human postmyocardial infarction scars acquire properties of cardiomyocytes after transduction with a recombinant myocardin gene FASEB J, October 1, 2007; 21(12): 3369 - 3379. [Abstract] [Full Text] [PDF] |
||||
![]() |
J.-r. Kim-Kaneyama, W. Suzuki, K. Ichikawa, T. Ohki, Y. Kohno, M. Sata, K. Nose, and M. Shibanuma Uni-axial stretching regulates intracellular localization of Hic-5 expressed in smooth-muscle cells in vivo J. Cell Sci., March 1, 2005; 118(5): 937 - 949. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. I. Dorrell, E. Aguilar, C. Weber, and M. Friedlander Global Gene Expression Analysis of the Developing Postnatal Mouse Retina Invest. Ophthalmol. Vis. Sci., March 1, 2004; 45(3): 1009 - 1019. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y.-F. Chang, J. Wei, X. Liu, Y.-H. Chen, M. D. Layne, and S.-F. Yet Identification of a CArG-independent region of the cysteine-rich protein 2 promoter that directs expression in the developing vasculature Am J Physiol Heart Circ Physiol, October 1, 2003; 285(4): H1675 - H1683. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. S. Kumar and G. K. Owens Combinatorial Control of Smooth Muscle-Specific Gene Expression Arterioscler. Thromb. Vasc. Biol., May 1, 2003; 23(5): 737 - 747. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. R. Henderson, D. Brown, J. A. Richardson, E. N. Olson, and M. C. Beckerle Expression of the Gene Encoding the LIM Protein CRP2: A Developmental Profile J. Histochem. Cytochem., January 1, 2002; 50(1): 107 - 112. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Kirchner, K. A. Forbush, and M. J. Bevan Identification and Characterization of Thymus LIM Protein: Targeted Disruption Reduces Thymus Cellularity Mol. Cell. Biol., December 15, 2001; 21(24): 8592 - 8604. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Oettgen Transcriptional Regulation of Vascular Development Circ. Res., August 31, 2001; 89(5): 380 - 388. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Kong, J. M. Shelton, B. Rothermel, X. Li, J. A. Richardson, R. Bassel-Duby, and R. S. Williams Cardiac-Specific LIM Protein FHL2 Modifies the Hypertrophic Response to {beta}-Adrenergic Stimulation Circulation, June 5, 2001; 103(22): 2731 - 2738. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. Zolk, P. Caroni, and M. Bohm Decreased Expression of the Cardiac LIM Domain Protein MLP in Chronic Human Heart Failure Circulation, June 13, 2000; 101(23): 2674 - 2677. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. T. Chin, K. Maemura, S. Fukumoto, M. K. Jain, M. D. Layne, M. Watanabe, C.-M. Hsieh, and M.-E. Lee Cardiovascular Basic Helix Loop Helix Factor 1, a Novel Transcriptional Repressor Expressed Preferentially in the Developing and Adult Cardiovascular System J. Biol. Chem., February 25, 2000; 275(9): 6381 - 6387. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Circulation Research Home | Subscriptions | Archives | Feedback | Authors | Help | AHA Journals Home | Search Copyright © 1998 American Heart Association, Inc. All rights reserved. Unauthorized use prohibited. |