Department of Biology New York University, New York, NY 10003, USA
* Author for correspondence (e-mail: jane.hubbard{at}nyu.edu)
Accepted 25 November 2003
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SUMMARY |
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Key words: Germline, Meiosis, Proliferation, Somatic gonad, C. elegans
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Introduction |
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Germline development in Caenorhabditis elegans hermaphrodites
shares phenomenological parallels with that of male mammals. Interactions with
the developing somatic gonad influence the time and position of early germline
proliferation and differentiation, and a spatially restricted population of
stem cells maintains the adult germ line
(Kimble and Hirsh, 1979;
Kimble and White, 1981
).
C. elegans gonadogenesis is relatively simple and is amenable to
genetic analysis, offering an attractive system to investigate soma/germline
interactions (Fig. 1). During
early germline development, all germ cells are proliferative. In the third
larval stage (L3), the proximal-most germ cells enter meiosis ('initial
meiosis'; Fig. 1). Initial
meiosis establishes a border: subsequent proliferation occurs distal to the
border and differentiation (meiotic development) proceeds proximally from it.
Transition (early prophase of meiosis I) and pachytene nuclei appear in the
L3, and gametogenesis occurs in the late L4 and adult. In the adult, sperm and
oocytes accumulate in the proximal germ line. The formation and maintenance of
this distal-to-proximal, proliferation/differentiation pattern requires
somatic gonad/germline interactions
(Kimble and White, 1981
).
|
Other non-DTC, non-AC soma/germline interactions influence robustness of
germline proliferation and meiotic progression
(McCarter et al., 1997).
Ablation of both spermatheca/sheath precursor cells (SS cells;
Fig.1) on one side of the gonad
at the L2/L3 molt reduces germline proliferation, meiotic progression, and
gametogenesis (McCarter et al.,
1997
). This ablation significantly reduces germline proliferation
even when GLP-1 is constitutively active, suggesting that it acts parallel to
DTC/germline signaling mediated by GLP-1
(McCarter et al., 1997
).
Ablation of the SS/dorsal uterus precursors (SS/DU, Z1.pa and Z4.ap;
Fig. 1) in the late L1 together
with ventral uterine precursor cells (VUs) causes a more dramatic defect:
proximal proliferation (Pro) (Seydoux et
al., 1990). The Pro phenotype is characterized by a mass of
proliferating germ cells (or `tumor') in the proximal part of the adult gonad.
Thus the normal distal-to-proximal developmental pattern is altered without
affecting germline cell fates per se. Mutants that display a Pro phenotype
include loss-of-function mutations in lin-12
(Seydoux et al., 1990
),
ego-3 (Qiao et al.,
1995
), gld-2 (Kadyk
and Kimble, 1998
) and puf-8
(Subramaniam and Seydoux,
2003
), and gain-of-function glp-1(Pro) mutants
(Pepper et al., 2003a
).
lin-12 acts in the somatic gonad
(Seydoux et al., 1990
),
whereas gld-2, puf-8 and glp-1 act in the germ line
(Austin and Kimble, 1987
;
Kadyk and Kimble, 1998
;
Subramaniam and Seydoux,
2003
).
Two distinct developmental errors can lead to a Pro phenotype: (1) a
reversion from meiotic development to mitosis and (2) a defect in initial
meiosis. An example of the first defect is the puf-8 Pro phenotype.
When puf-8 activity is reduced, germ cells proliferate, enter meiosis
at the correct time and position, and differentiation proceeds through meiotic
prophase. As germ cells begin spermatogenesis, however, some fail to complete
a reductional division and instead return to mitosis. Thus, the tumor in
puf-8 Pro animals derives from cells that entered meiosis but
reverted to mitosis (Subramaniam and
Seydoux, 2003). By contrast, in glp-1(Pro) mutants,
proximal-most mitotic cells derive from a population of early germ cells that
fail to enter meiosis and, instead, continue to proliferate. Meiosis
eventually occurs distal to the tumor, in the normal pattern from the distal
tip, resulting in a tumor proximal to gametes
(Pepper et al., 2003b
).
The glp-1(Pro) phenotype is partially dependent on proximal
LAG-2-producing cells, suggesting that these mutations render the GLP-1
receptor particularly sensitive to proximal sources of LAG-2
(Pepper et al., 2003b). The
establishment of lin-12(loss-of-function) Pro phenotype is also
AC-dependent, as is the Pro phenotype resulting from select SS/DU/VU ablations
mentioned above (Seydoux et al.,
1990
). Consistent with the possibility that the ablation-induced
Pro phenotype is due to inappropriate signaling to the germ line, the
phenotype is dependent on glp-1 activity and on the presence of at
least one cell capable of forming an AC
(Seydoux et al., 1990
).
We introduce pro-1, a gene identified by an hypomorphic (reduction-of-function) mutation, pro-1(na48), that causes a highly penetrant Pro phenotype. Our analysis indicates that the pro-1(na48) Pro phenotype emanates from faulty temporal and spatial patterning of initial meiosis. Unlike previously described Pro mutants with this etiology, the pro-1(na48) Pro phenotype is AC independent. We demonstrate that pro-1(+)activity is required in the sheath/spermatheca lineage of the somatic gonad to prevent proximal proliferation in pro-1(na48) mutants. A stronger depletion of pro-1 activity (by RNAi) severely disrupts somatic gonad development. pro-1 encodes the only C. elegans member of a subfamily of WD-repeat-containing proteins that are essential in both budding yeast and fission yeast, but have not been previously characterized in multicellular organisms. Our results point to a previously uncharacterized pro-1(+)-dependent role for the sheath/spermatheca lineage in the spatial patterning of early germline proliferation and differentiation.
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Materials and methods |
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LGI: mpk-1(ga111) (Lackner and
Kim, 1998), unc-79(e1068)
(Morgan et al., 1990
),
rrf-1(pk1417) (Sijen et al.,
2001
).
LGII: unc-4(e120), bli-1(e769), mIn1[dpy-10(e128) mIs14]
(Edgley and Riddle, 2001),
mIs14 is ccEx9747 (myo-2 and pes-10
promoters and a gut enhancer fused individually to GFP) integrated into
mIn1[dpy-10], mnDf58 (Sigurdson
et al., 1984
).
LGIII: dpy-17(e164), glp-1(e2141)
(Kodoyianni et al., 1992),
glp-1(ar202) (Pepper et al.,
2003a
), lin-12(n302)
(Greenwald et al., 1983
).
LGIV: fem-1(hc17) (Nelson et
al., 1978).
LGV: him-5(e1490).
Isolation, mapping and molecular identification of pro-1(na48)
pro-1(na48) was isolated in an ethyl methane sulfonate mutagenesis
(Pepper et al., 2003a).
Three-factor and single nucleotide polymorphism mapping (see Wormbase,
http://www.wormbase.org
for details) placed pro-1(na48) within a 120 kb interval on linkage
group II. PCR-amplified R166.4 from pro-1(na48) genomic DNA was
directly sequenced (DNA Analysis and Sequencing Facility, Columbia University,
NY), and a single base pair change G to A [(GAC) to (AAC)] was verified on
both strands. Three full-length cDNAs were sequenced (gifts of Y. Kohara;
yk1113c3, yk898h5, yk755f10). All splice junctions were identical to the
predicted cDNA sequence in Wormbase.
Phenotypic analysis of pro-1(na48) and pro-1(RNAi)
With the exception of pro-1(RNAi), all data in Tables
1 and
2 were collected after
synchronization by hatch-off as described
(Pepper et al., 2003a). For
Table 1, pro-1(+) and
pro-1(+)/pro-1(na48) live animals were scored at the adult molt for
Pro, Mig, vulval phenotypes and for the presence of gametes. Animals of all
other genotypes were similarly scored 18 hours (25°C), 22 hours (20°C)
and 24 hours (15°C) after the adult molt. pro-1(RNAi) animals
were scored as asynchronous adults. RNAi feeding was performed as described
previously (Timmons et al.,
2001
). L4 hermaphrodites were placed onto RNAi plates,
transferred, and progeny from the second day were scored as adults. For
Table 2, animals were scored
after fixation and DAPI staining at stages/times indicated.
|
|
Plasmid constructions for mutant rescue and RNAi
pGC16 (pro-1 rescuing construct)
A PCR product containing R166.4 genomic sequence plus 3318 bp upstream of
the start and 560 bp after the stop was inserted into pCR-XL-TOPO
(Invitrogen). The insert contains two changes (G to A and G to T at positions
-3230 and -342). unc-4 pro-1/mIn1 hermaphrodites were injected with
pGC16 and pRF4[rol-6(su1006)]
(Mello and Fire, 1995) or
pGC16, pRF4 and pTG96[sur-5::GFP]
(Yochem et al., 1998
) at 20
ng/µl, 100 ng/µl and 120 ng/µl respectively. Lines (naEx1
and naEx2, respectively) were generated from fertile F2 Rol Unc
animals. Unc non-Rol offspring were Pro. Neither pRF4 nor pTG96 rescues alone
(7 and 3 lines, respectively).
pGC15 (pro-1(RNAi) feeding construct)
AccI/PstI fragment (2.0 kb) of amplified R166.4 genomic
DNA was ligated into AccI/PstI sites in L4440
(Timmons and Fire, 1998). The
first intron of the R166.4 contains significant homology to other C.
elegans genomic sequences and was excluded.
Reporter constructs, expression constructs and immunohistochemistry
ajm-1::GFP (SU93) (Koppen et
al., 2001) marks adherens junctions and lim-7::GFP
(DG1575) marks gonadal sheath cell pairs 1-4
(Hall et al., 1999
).
Anti-CEH-18 (Greenstein et al.,
1994
) recognizes DTC and sheath nuclei. Anti-PGL-1
(Kawasaki et al., 1998
)
(1:5000) marks germ cells. Non-oocyte cells labeled by anti-phospho-histone H3
(Upstate Biotechnology; 1:3000) but not anti-MSP
(Miller et al., 2001
) (1:1000)
are in M phase of mitosis. Gonad dissections, fixation and
immunohistochemistry were carried out as described
(Pepper et al., 2003b
).
pGC29 (pro-1 promoter driving GFP): (1) 3318 bp upstream of pro-1 (including the ATG) was amplified from pGC16 (attB1, attB2 sites in the primers) and recombined into attP1, attP2 sites in pDONR221 (Invitrogen) to make pGC22. pGC22 was recombined with pPD117.01GtwyGFP (gift of B. Grant) that contains a Gateway donor cassette (attR1, attR2 in reading frame B ligated into a blunted Asp718 site) upstream of GFP and the let-858 3'UTR. pGC29 and pRF4 were injected at 100 µg/ml each to generate lines. The following were examined for GFP expression: the somatic gonad (DTC, sheath, spermatheca, and uterus), coelomocytes, hypodermis (tail tip, seam cells), vulva, intestine, unidentified neurons, excretory cell, body wall and pharyngeal muscles.
Mosaic analysis
Mosaic analysis was performed with unc-4 pro-1(na48); naEx2[pro-1(+),
sur-5::GFP, rol-6(su1006)]. Animals with the array were Unc Rol GFP
positive. Animals without the array were Pro non-Rol GFP negative (or non-Pro
pro-1(na48) phenotypes; Table
1). Adult mosaic non-Pro animals were identified as fertile GFP
mosaics. Adult mosaic Pro animals were identified as rare Pro, GFP-positive
worms. Cells were scored for GFP fluorescence as follows: AB, the ventral
nerve cord and anterior hypodermis nuclei; E, the intestine; MS, the somatic
gonad and coelomocytes; C, C-specific body wall muscles and hyp 11; D,
D-specific body wall muscles; P4, progeny. For mosaics within the MS lineage,
each arm was scored independently (DTC, sheath, spermatheca). The uterine
lineage could not be reliably scored in adults, hence losses within Z1.p and
Z4.a lineages were not further resolved. Losses within Z1.a or Z4.p-derived
spermatheca/sheath lineages versus Z1.p or Z4.a-derived spermatheca/sheath
lineages could be distinguished by GFP in the DTC (Z1.aa or Z4.pp).
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Results |
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We examined the effect of sex determination on the Pro phenotype. C.
elegans hermaphrodites first produce sperm and then switch to oogenesis,
thus cells destined to become sperm are the first to enter meiosis. It is
therefore possible that the proximal tumor in pro-1(na48) derives
from male germ cells. We found that the pro-1(na48) Pro phenotype was
still penetrant when the germ line was feminized by fem-1(hc17)
(Nelson et al., 1978)
(Table 3B), suggesting that the
sexual identity of germ cells is irrelevant to tumor formation.
pro-1(na48) males expressed the Pro phenotype at a significantly
lower penetrance than hermaphrodites (Table
3C). This result suggests that differences between male and
hermaphrodite gonadogenesis affect germline development.
The pro-1(na48) Pro phenotype depends on glp-1 but not on the anchor cell
GLP-1 activity in the germ line promotes the mitotic fate and/or inhibits
the meiotic fate (Austin and Kimble,
1987). In the absence of glp-1, all germ cells enter
meiosis early. To determine if glp-1 activity is required for the
pro-1(na48) Pro phenotype, we assessed the phenotype of
pro-1(na48); glp-1(e2141ts) double mutants. The double mutants
displayed the glp-1(loss-of-function) phenotype, indicating that
glp-1 activity is required for the pro-1(na48) Pro phenotype
(Table 3D). Because the GLP-1
receptor is activated by a somatic cell-produced ligand, this result is
consistent with pro-1(+) acting upstream of or in parallel with
glp-1 in a regulatory pathway (therefore, possibly in the soma) or
with a requirement for glp-1 activity to generate enough germ cells
for the pro-1 Pro phenotype to manifest.
Some previously described Pro phenotypes are dependent on the anchor cell
(AC) or its precursors, Z1.ppp and Z4.aaa. In these cases, this dependence is
probably due to inappropriate proximal LAG-2/GLP-1 signaling
(Seydoux et al., 1990;
Pepper et al., 2003b
). We used
both genetic and physical cell ablations to ask if the pro-1(na48)
Pro phenotype was dependent on the AC. No AC forms in lin-12(n302)
mutants and this no-AC phenotype correlates directly with the vulvaless (Vul)
phenotype (Greenwald et al.,
1983
). The Pro phenotype is penetrant in Vul animals
(Table 3E), suggesting that an
AC is not required for the pro-1(na48) tumor. LAG-2 produced by
Z1.ppp and Z4.aaa signals to germ cells in the L2
(Pepper et al., 2003b
).
Therefore it remained possible that mitosis-promoting levels of LAG-2 were
produced in the pro-1(na48); lin-12(n302) double mutant prior to the
AC/VU decision. To eliminate this possibility, we ablated the precursors to
these cells in pro-1(na48) (see Materials and methods). In 11
operated hermaphrodites 9/22 (41%), gonad arms displayed the Pro phenotype (in
one animal both arms were Pro) compared with 26 unoperated control animals
with 18/52 (35%) Pro. We conclude that LAG-2 produced by the AC or its
precursors is not contributing to the pro-1(na48) Pro phenotype.
pro-1 encodes a WD-repeat-containing protein
To better understand the role of pro-1, we cloned the gene. We
mapped pro-1(na48) to a physical interval containing 30 predicted
ORFs (see Materials and methods). Genome-wide RNAi studies indicated that RNAi
of R166.4 caused sterile, slow-growing and `patchy coloration' phenotypes
under low magnification (Kamath et al.,
2003), consistent with our observations for pro-1(na48).
R166.4 genomic DNA from pro-1(na48) animals contained a single base
change corresponding to a D211N substitution (see Materials and methods). D211
is highly conserved in phylogenetically diverse members of the WD-repeat
subfamily to which R166.4 belongs (Fig.
5) and is part of the consensus sequence for the WD-repeat motif
(van der Voorn and Ploegh,
1992
). Transgenic lines carrying R166.4-containing
extrachromosomal arrays (see Materials and methods; 2/2 lines) rescued
pro-1(na48) mutant phenotypes. We conclude from mapping, sequence and
rescue data that R166.4 is pro-1. The transgenic rescue also
suggested that pro-1(+) may function in the soma, given that simple
arrays are silenced in the C. elegans germ line
(Kelly et al., 1997
).
|
pro-1::GFP is widely expressed
To assess the pro-1 expression pattern, we fused pro-1
upstream sequences to GFP (Materials and methods). Three independent
transgenic lines expressed GFP in the embryo and in every major post-embryonic
lineage including the somatic gonad. Although we did not expect to observe
germline expression with this transgene, microarray experiments indicate that
R166.4 is expressed in the germ line
(Reinke et al., 2000).
pro-1(RNAi) causes severe lineage defects in somatic gonad development
Our temperature and dose analyses indicated that pro-1(na48) is an
hypomorphic allele with more severe and pleiotropic phenotypes at lower
temperatures. To assess a stronger loss-of-function phenotype, we depleted
PRO-1 by RNAi (see Materials and methods). The progeny of wild-type animals
fed bacteria expressing dsRNA complementary to pro-1 [hereafter
referred to as pro-1(RNAi) animals] exhibited phenotypes we observed
in pro-1(na48), including Mig and Pro phenotypes
(Table 1,
Fig. 6). An additional striking
phenotype was the absence of parts of the somatic gonad sheath, spermatheca
and uterine lineages (Gon phenotype, Gonad development abnormal). Both DTCs
and AC, however, were present (n=61 worms). The germ lines of
pro-1(RNAi) animals were also severely under-proliferated, consistent
with results of cell ablations that remove the spermatheca/sheath lineage
(McCarter et al., 1997).
|
To determine if the germline defects in pro-1(RNAi) animals were
solely the result of depletion of PRO-1 in the soma, we examined
pro-1(RNAi) animals in an rrf-1(pk1417) mutant background
that strongly reduces RNAi in the soma, but permits RNAi in the germ line
(Sijen et al., 2001). In
contrast to our results in an rrf-1(+) background,
pro-1(RNAi) treatment of rrf-1(pk1417) mutants produced
fertile, non-Gon progeny (Table
3F). These results suggest that both germline and somatic defects
in pro-1(RNAi) animals result from a depletion of PRO-1 in the
soma.
The pro-1(na48) Pro phenotype is associated with a reduction of pro-1 activity in the somatic gonad sheath/spermatheca lineage
Given our results suggesting that pro-1 acts in the soma, we asked
if anatomical somatic gonad defects would correlate with the Pro phenotype in
pro-1(na48). At 25°C, pro-1(na48) animals exhibited
normal vulval, uterine and spermathecal morphology (n=69, 23 and 12,
respectively; assayed by L4 vulva and uterus morphology under Nomarski optics
and spermathecal ajm-1::GFP pattern). By contrast, sheath cell
numbers were sometimes reduced, but this could not be directly correlated with
the Pro phenotype. That is, some Pro animals displayed a reduction in the
number of lim-7::GFP-positive or CEH-18-positive sheath cells
(Greenstein et al., 1994),
while others displayed the wild-type 8 lim-7::GFP-positive or 10
CEH-18-positive sheath cells (data not shown). Both gonadal sheath and gonad
arms in pro-1(na48) Pro animals were often mis-shapen (Figs
2,
3,
4). We examined the sheath cell
actin cytoskeleton by rhodamine-phalloidin staining
(Strome, 1986
;
McCarter et al., 1997
), and it
appeared variably abnormal in both Pro and non-Pro animals (data not shown).
We postulate that the pro-1(na48) Pro phenotype does not correlate
with a sheath cell generation defect, but may correlate with defects in sheath
cell growth, function and/or aspects of differentiation dispensable for
lim-7 or ceh-18 expression.
pro-1(+) is required in the sheath/spermatheca lineage to prevent the Pro phenotype
To determine the anatomical focus of pro-1(+) activity with
respect to the Pro phenotype, we performed a genetic mosaic analysis (see
Materials and methods); results are summarized in
Fig. 7. Mosaic Pro animals and
mosaic non-Pro animals were scored for lineages that had lost a transgenic
array carrying pro-1(+) in pro-1(na48) animals. The array
also contained sur-5::GFP, a cell-autonomous nuclear marker
(Yochem et al., 1998).
Independent mosaic Pro animals were identified that had lost the array in the
entire P1, EMS or MS lineages, all of which contribute to the somatic gonad.
Loss of the array in Z4 produced animals with a posterior Pro arm and an
anterior non-Pro arm. Analysis of losses within the Z1 or Z4 lineages
indicated that pro-1(+) must be present in the lineages descending
from both of the SS cells within a given arm to prevent a Pro mutant
phenotype in the neighboring germ line. Our data do not support a DTC role for
pro-1 vis-à-vis the Pro phenotype because we observed Pro
gonad arms adjacent to a pro-1(+) DTC. For example, two mosaic Pro
animals lost the array in Z1.p but retained it in Z1.a (similarly, for 4 Pro
Z4.a/Z4.p mosaics). The subsequent requirement for pro-1(+) in the
sheath versus spermatheca lineage is difficult to distinguish by mosaic
analysis (it would require one loss within each SS cell lineage in the same
gonad arm), but because the SS cells and their daughters normally contact the
L3 germ line during the time that germline pattern is established, it is
likely that pro-1(+) is required in these cells.
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Discussion |
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The sheath/spermatheca lineage and the spatial and temporal control of proliferation and differentiation
The SS cells and their daughters are in a position to influence the
neighboring germ line during the time that germline developmental pattern is
established (Kimble and Hirsh,
1979; McCarter et al.,
1997
) (Fig. 1).
Cell ablation of one or both SS cells per gonad arm
(McCarter et al., 1997
) is
comparable with pro-1 RNAi and mutant phenotypes. Ablation of both SS
cells at the L2/L3 molt (prior to initial meiosis) causes defects in germline
proliferation, pachytene exit and gametogenesis, similar to that observed in
pro-1(RNAi) animals. Ablation of one of the two SS cells allows more
robust proliferation but causes incompletely penetrant endomitotic oocytes
(Emo) and feminization of the germ line (Fog) phenotypes (the Fog animals
occasionally contain several proximal `undifferentiated' germ cells that do
not appear to proliferate and are likely defective in sexual fate
specification) (McCarter et al.,
1997
). We never observed feminization of pro-1(na48) germ
lines, but we did observe the Emo phenotype in non-Pro pro-1(na48)
animals (Table 1), suggesting a
defect in proximal sheath function
(Greenstein et al., 1994
;
Rose et al., 1997
;
McCarter et al., 1999
). Thus,
SS lineage defects can confer complex phenotypes, some of which may preclude
the identification of proliferation-dependent germline phenotypes. A clear
understanding of the SS lineage/germline interaction vis-à-vis germline
patterning may require further analysis of rare alleles.
Several models can accommodate results pertaining to an SS lineage function
in overall proliferation and proliferation/differentiation patterning. One
model is that the mitosis-promoting function
(McCarter et al., 1997) is
limited to the SS cells themselves, and the distal pair of SS cell progeny
take on a mitosis-inhibiting/meiosis-promoting function after they are born
(Fig. 1,
Fig. 8A). Another possibility
is that the proximal SS cell daughters take on a
mitosis-inhibiting/meiosis-promoting function while the distal progeny promote
mitosis (Fig. 8B). Together
with a critical distance from the DTC, either mechanism could ensure that the
mitosis/meiosis border is sharp and that meiotic entry is reproducibly
positioned in the proximal-most germ line, adjacent to the somatic gonad.
|
In its pro-1-dependent role in preventing proximal proliferation,
the SS lineage could indirectly facilitate or maintain the downregulation of
GLP-1-mediated signaling. Although our data do not rule out this mechanism,
pro-1(na48) enhanced both glp-1(loss-of-function) Glp and
glp-1(gainof-function) Pro phenotypes
(Table 3G,H), a result that is
inconsistent with this simple interpretation. Alternatively, the later SS cell
progeny could indirectly upregulate meiosis-promoting functions in the germ
line (such as gld-1 and gld-2 pathways)
(Kadyk and Kimble, 1998).
An alternate but not mutually exclusive model is that the SS lineage
provides a structural, physiological or nutritional role that is necessary for
normal germline patterning, and that the pro-1(na48) mutation
interferes with this role. EM studies on the distal sheath reveal prominent
Golgi apparatus, endoplasmic reticulum and vesicles, suggestive of a secretory
function for these cells (Hall et al.,
1999). Regardless of the exact mechanism by which PRO-1 acts, our
results provide a molecular in-road into a previously uncharacterized SS
lineage-to-germline interaction that influences the pattern of germline
proliferation and differentiation without perturbing germ cell fate
acquisition.
PRO-1 and putative orthologs likely play roles in many cellular processes
PRO-1 belongs to a subfamily of WD-repeat-containing proteins and has one
putative ortholog in representatives of every major eukaryotic phylogenetic
group. Apparent yeast orthologs of PRO-1 are Crb3 in Schizosaccharomyces
pombe and IPI3 in Saccharomyces cerevisiae. These proteins are
essential for viability (Saka et al.,
1997; Giaever et al.,
2002
), and a conditional allele of IPI3 suggests a role in
ribosome biogenesis (Peng et al.,
2003
). IPI3-interacting proteins have been identified
(Ito et al., 2001
;
Gavin et al., 2002
;
Ho et al., 2002
), and include
12 proteins involved in a variety of functions such as ribosome biogenesis,
cell-cycle, kinase regulation, nucleocytoplasmic transport, chromatin assembly
and ubiquitination. Because this information does not pinpoint a clear
molecular role for C. elegans PRO-1, it will be of considerable
interest to identify proteins that functionally and physically interact with
PRO-1.
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ACKNOWLEDGMENTS |
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REFERENCES |
---|
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---|
Austin, J. and Kimble, J. (1987). glp-1 is required in the germ line for regulation of the decision between mitosis and meiosis in C. elegans. Cell 51,589 -599.[Medline]
Brenner, S. (1974). The genetics of
Caenorhabditis elegans. Genetics
77, 71-94.
Brinster, R. L. (2002). Germline stem cell
transplantation and transgenesis. Science
296,2174
-2176.
Edgley, M. L. and Riddle, D. L. (2001). LG II balancer chromosomes in Caenorhabditis elegans: mT1(II;III) and the mIn1 set of dominantly and recessively marked inversions. Mol. Genet. Genomics 266,385 -395.[CrossRef][Medline]
Francis, R., Barton, M., Kimble, J. and Schedl, T.
(1995). gld-1, a tumor suppressor gene required for
oocyte development in Caenorhabditis elegans.
Genetics 139,579
-606.
Gavin, A. C., Bosche, M., Krause, R., Grandi, P., Marzioch, M., Bauer, A., Schultz, J., Rick, J. M., Michon, A. M., Cruciat, C. M. et al. (2002). Functional organization of the yeast proteome by systematic analysis of protein complexes. Nature 415,141 -147.[CrossRef][Medline]
Giaever, G., Chu, A. M., Ni, L., Connelly, C., Riles, L., Veronneau, S., Dow, S., Lucau-Danila, A., Anderson, K., Andre, B. et al. (2002). Functional profiling of the Saccharomyces cerevisiae genome. Nature 418,387 -391.[CrossRef][Medline]
Greenstein, D., Hird, S., Plasterk, R. H., Andachi, Y., Kohara, Y., Wang, B., Finney, M. and Ruvkun, G. (1994). Targeted mutations in the Caenorhabditis elegans POU homeo box gene ceh-18 cause defects in oocyte cell cycle arrest, gonad migration, and epidermal differentiation. Genes Dev. 8,1935 -1948.[Abstract]
Greenwald, I., Sternberg, P. and Horvitz, H. (1983). The lin-12 locus specifies cell fates in Caenorhabditis elegans. Cell 34,435 -444.[Medline]
Hall, D. H., Winfrey, V. P., Blaeuer, G., Hoffman, L. H., Furuta, T., Rose, K., Hobert, O. and Greenstein, D. (1999). Ultrastructural features of the adult hermaphrodite gonad of Caenorhabditis elegans: relations between the germ line and soma. Dev. Biol. 212,101 -123.[CrossRef][Medline]
Henderson, S., Gao, D., Lambie, E. and Kimble, J.
(1994). lag-2 may encode a signaling ligand for the
GLP-1 and LIN-12 receptors of C. elegans.
Development 120,2913
-2924.
Ho, Y., Gruhler, A., Heilbut, A., Bader, G. D., Moore, L., Adams, S. L., Millar, A., Taylor, P., Bennett, K., Boutilier, K. et al. (2002). Systematic identification of protein complexes in Saccharomyces cerevisiae by mass spectrometry. Nature 415,180 -183.[CrossRef][Medline]
Ito, T., Chiba, T., Ozawa, R., Yoshida, M., Hattori, M. and
Sakaki, Y. (2001). A comprehensive two-hybrid analysis to
explore the yeast protein interactome. Proc. Natl. Acad. Sci.
USA 98,4569
-4574.
Kadyk, L. and Kimble, J. (1998). Genetic
regulation of entry into meiosis in Caenorhabditis elegans.
Development 125,1803
-1813.
Kamath, R. S., Fraser, A. G., Dong, Y., Poulin, G., Durbin, R., Gotta, M., Kanapin, A., le Bot, N., Moreno, S., Sohrmann, M. et al. (2003) Systematic functional analysis of the Caenorhabditis elegans genome using RNAi. Nature 421,231 -237.[CrossRef][Medline]
Kawasaki, I., Shim, Y. H., Kirchner, J., Kaminker, J., Wood, W. B. and Strome, S. (1998). PGL-1, a predicted RNA-binding component of germ granules, is essential for fertility in C. elegans. Cell 94,635 -645.[Medline]
Kelly, W., Xu, S., Montgomery, M. and Fire, A.
(1997). Distinct requirements for somatic and germline expression
of a generally expressed Caenorhabditis elegans gene.
Genetics 146,227
-238.
Kiger, A. A. and Fuller, M. (2001). Male germ-line stem cells. In Stem Cell Biology (ed. D. R. Marshak, R. L. Gardner and D. Gottlieb), pp. 149-187. Cold Spring Harbor, New York: Cold Spring Harbor Laboratory Press.
Kimble, J. and Hirsh, D. (1979). The postembryonic cell lineages of the hermaphrodite and male gonads in Caenorhabditis elegans. Dev. Biol. 70,396 -417.[Medline]
Kimble, J. and White, J. (1981). On the control of germ cell development in Caenorhabditis elegans. Dev. Biol. 81,208 -219.[Medline]
Kodoyianni, V., Maine, E. and Kimble, J. (1992). Molecular basis of loss-of-function mutations in the glp-1 gene of Caenorhabditis elegans. Mol. Biol. Cell 3,1199 -1213.[Abstract]
Koppen, M., Simske, J. S., Sims, P. A., Firestein, B. L., Hall, D. H., Radice, A. D., Rongo, C. and Hardin, J. D. (2001). Cooperative regulation of AJM-1 controls junctional integrity in Caenorhabditis elegans epithelia. Nat. Cell Biol. 3,983 -991.[CrossRef][Medline]
Lackner, M. R. and Kim, S. K. (1998). Genetic
analysis of the Caenorhabditis elegans MAP kinase gene
mpk-1. Genetics
150,103
-117.
Lambie, E. J. and Kimble, J. (1991). Two homologous regulatory genes, lin-12 and glp-1, have overlapping functions. Development 112,231 -40.[Abstract]
McCarter, J., Bartlett, B., Dang, T. and Schedl, T. (1997). Soma-germ cell interactions in Caenorhabditis elegans: multiple events of hermaphrodite germline development require the somatic sheath and spermathecal lineages. Dev. Biol. 181,121 -143.[CrossRef][Medline]
McCarter, J., Bartlett, B., Dang, T. and Schedl, T. (1999). On the control of oocyte meiotic maturation and ovulation in Caenorhabditis elegans. Dev. Biol. 205,111 -128.[CrossRef][Medline]
McLaren, A. (2003). Primordial germ cells in the mouse. Dev. Biol. 262, 1-15.[CrossRef][Medline]
Mello, C. and Fire, A. (1995). DNA transformation. Methods Cell Biol. 48,451 -482.[Medline]
Miller, M. A., Nguyen, V. Q., Lee, M. H., Kosinski, M., Schedl,
T., Caprioli, R. M. and Greenstein, D. (2001). A sperm
cytoskeletal protein that signals oocyte meiotic maturation and ovulation.
Science 291,2144
-2147.
Morgan, P. G., Sedensky, M., Meneely, P. M. (1990). Multiple sites of action of volatile anesthetics in Caenorhabditis elegans. Proc. Natl. Acad. Sci. USA 87,2965 -2969.[Abstract]
Nelson, G. A., Lew, K. K. and Ward, S. (1978). Intersex, a temperature-sensitive mutant of the nematode Caenorhabditis elegans. Dev. Biol. 66,386 -409.[Medline]
Peng, W. T., Robinson, M. D., Mnaimneh, S., Krogan, N. J., Cagney, G., Morris, Q., Davierwala, A. P., Grigull, J., Yang, X., Zhang, W. et al. (2003). A panoramic view of yeast noncoding RNA processing. Cell 113,919 -933.[Medline]
Pepper, A. S., Killian, D. J. and Hubbard, E. J.
(2003a). Genetic analysis of Caenorhabditis elegans
glp-1 mutants suggests receptor interaction or competition.
Genetics 163,115
-132.
Pepper, A. S., Lo, T. W., Killian, D. J., Hall, D. H. and Hubbard, E. J. (2003b). The establishment of Caenorhabditis elegans germline pattern is controlled by overlapping proximal and distal somatic gonad signals. Dev. Biol. 259,336 -350.[CrossRef][Medline]
Qiao, L., Lissemore, J., Shu, P., Smardon, A., Gelber, M. and
Maine, E. (1995). Enhancers of glp-1, a gene
required for cell-signaling in Caenorhabditis elegans, define a set
of genes required for germline development. Genetics
141,551
-569.
Reinke, V., Smith, H. E., Nance, J., Wang, J., van Doren, C., Begley, R., Jones, S. J., Davis, E. B., Scherer, S., Ward, S. et al. (2000). A global profile of germline gene expression in C. elegans. Mol. Cell 6, 605-616.[Medline]
Rose, K. L., Winfrey, V. P., Hoffman, L. H., Hall, D. H., Furuta, T. and Greenstein, D. (1997). The POU gene ceh-18 promotes gonadal sheath cell differentiation and function required for meiotic maturation and ovulation in Caenorhabditis elegans. Dev. Biol. 192,59 -77.[CrossRef][Medline]
Saka, Y., Esashi, F., Matsusaka, T., Mochida, S. and Yanagida,
M. (1997). Damage and replication checkpoint control in
fission yeast is ensured by interactions of Crb2, a protein with BRCT motif,
with Cut5 and Chk1. Genes Dev.
11,3387
-3400.
Seydoux, G., Schedl, T. and Greenwald, I. (1990). Cell-cell interactions prevent a potential inductive interaction between soma and germline in C. elegans. Cell 61,939 -951.[Medline]
Sigurdson, D., Spanier, G. and Herman, R.
(1984). Caenorhabditis elegans deficiency mapping.
Genetics 108,331
-345.
Sijen, T., Fleenor, J., Simmer, F., Thijssen, K. L., Parrish, S., Timmons, L., Plasterk, R. H. and Fire, A. (2001). On the role of RNA amplification in dsRNA-triggered gene silencing. Cell 107,465 -476.[Medline]
Spradling, A., Drummond-Barbosa, D. and Kai, T. (2001). Stem cells find their niche. Nature 414,98 -104.[CrossRef][Medline]
Strome, S. (1986). Fluorescence visualization of the distribution of microfilaments in gonads and early embryos of the nematode Caenorhabditis elegans. J. Cell Biol. 103,2241 -2252.[Abstract]
Subramaniam, K. and Seydoux, G. (2003). Dedifferentiation of Primary Spermatocytes into Germ Cell Tumors in C. elegans Lacking the Pumilio-like Protein PUF-8. Curr. Biol. 13,134 -139.[Medline]
Tax, F., Yeargers, J. and Thomas, J. (1994). Sequence of C. elegans lag-2 reveals a cell-signalling domain shared with Delta and Serrate of Drosophila. Nature 368,150 -154.[CrossRef][Medline]
Timmons, L. and Fire, A. (1998). Specific interference by ingested dsRNA. Nature 395, 854.[CrossRef][Medline]
Timmons, L., Court, D. L. and Fire, A. (2001). Ingestion of bacterially expressed dsRNAs can produce specific and potent genetic interference in Caenorhabditis elegans. Gene 263,103 -112.[CrossRef][Medline]
van der Voorn, L., and Ploegh, H. L. (1992). The WD-40 repeat. FEBS Lett. 307,131 -134.[CrossRef][Medline]
Wicks, S. R., Yeh, R. T., Gish, W. R., Waterston, R. H. and Plasterk, R. H. (2001). Rapid gene mapping in Caenorhabditis elegans using a high density polymorphism map. Nat. Genet. 28,160 -164.[CrossRef][Medline]
Yochem, J., Gu, T. and Han, M. (1998). A new
marker for mosaic analysis in Caenorhabditis elegans indicates a
fusion between hyp6 and hyp7, two major components of the hypodermis.
Genetics 149,1323
-1334.
|