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1.
There are four species of Gymnetron in China recorded to date including Gymnetron
miyoshii Miyoshi, 1922, Gymnetron
villosipenne Roelofs, 1875, Gymnetron
auliense Reitter, 1907 and Gymnetron
vittipenne Marseul, 1876, of which the last two are new country records. The pre-imaginal stages including eggs, mature larvae and pupae of Gymnetron
miyoshii, Gymnetron
auliense and Gymnetron
vittipenne are described and illustrated. In addition, their diagnostic characters (larvae and pupae) are discussed and differentiated, and notes on some of their biological parameters are provided. Potential ecological impacts between Gymnetron weevils and their host Veronica spp. also are provided. 相似文献
2.
3.
Jiandong Zhao Yongyi Yuan Shasha Huang Bangqing Huang Jing Cheng Dongyang Kang Guojian Wang Dongyi Han Pu Dai 《PloS one》2014,9(11)
Background
Nonsyndromic enlargement of vestibular aqueduct (NSEVA) is an autosomal recessive hearing loss disorder that is associated with mutations in SLC26A4. However, not all patients with NSEVA carry biallelic mutations in SLC26A4. A recent study proposed that single mutations in both SLC26A4 and KCNJ10 lead to digenic NSEVA. We examined whether KCNJ10 excert a role in the pathogenesis of NSEVA in Chinese patients.Methods
SLC26A4 was sequenced in 1056 Chinese patients with NSEVA. KCNJ10 was screened in 131 patients who lacked mutations in either one or both alleles of SLC26A4. Additionally, KCNJ10 was screened in 840 controls, including 563 patients diagnosed with NSEVA who carried biallelic SLC26A4 mutations, 48 patients with nonsyndromic hearing loss due to inner ear malformations that did not involve enlargement of the vestibular aqueduct (EVA), 96 patients with conductive hearing loss due to various causes, and 133 normal-hearing individuals with no family history of hereditary hearing loss.Results
925 NSEVA patients were found carrying two-allele pathogenic SLC26A4 mutations. The most frequently detected KCNJ10 mutation was c.812G>A (p.R271H). Compared with the normal-hearing control subjects, the occurrence rate of c.812G>A in NSEVA patients with lacking mutations in one or both alleles of SLC26A4 had no significant difference(1.53% vs. 5.30%, χ2 = 2.798, p = 0.172), which suggested that it is probably a nonpathogenic benign variant. KCNJ10 c.1042C>T (p.R348C), the reported EVA-related mutation, was not found in patients with NSEVA who lacked mutations in either one or both alleles of SLC26A4. Furthermore, the normal-hearing parents of patients with NSEVA having two SLC26A4 mutations carried the KCNJ10 c.1042C>T or c.812G>A mutation and a SLC26A4 pathogenic mutation.Conclusion
SLC26A4 is the major genetic cause in Chinese NSEVA patients, accounting for 87.59%. KCNJ10 may not be a contributor to NSEVA in Chinese population. Other genetic or environmental factors are possibly play a role in the etiology of Chinese EVA patients with zero or monoallelic SLC26A4 mutation. 相似文献4.
Marcus Daniel C.; Wu Tao; Wangemann Philine; Kofuji Paulo 《American journal of physiology. Cell physiology》2002,282(2):C403
Striavascularis of the cochlea generates the endocochlear potential andsecretes K+. K+ is the main charge carrier andthe endocochlear potential the main driving force for the sensorytransduction that leads to hearing. Stria vascularis consists of twobarriers, marginal cells that secrete potassium and basal cells thatare coupled via gap junctions to intermediate cells. Mice lacking theKCNJ10 (Kir4.1) K+ channel in strial intermediate cells didnot generate an endocochlear potential. Endolymph volume andK+ concentration ([K+]) were reduced. Thesestudies establish that the KCNJ10 K+ channel provides themolecular mechanism for generation of the endocochlear potential inconcert with other transport pathways that establish the[K+] difference across the channel. KCNJ10 is also alimiting pathway for K+ secretion. 相似文献
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8.
Joseph T. Roland Lynne A. Lapierre James R. Goldenring 《The Journal of biological chemistry》2009,284(2):1213-1223
Rab proteins influence vesicle trafficking pathways through the assembly of
regulatory protein complexes. Previous investigations have documented that
Rab11a and Rab8a can interact with the tail region of myosin Vb and regulate
distinct trafficking pathways. We have now determined that a related Rab
protein, Rab10, can interact with myosin Va, myosin Vb, and myosin Vc. Rab10
localized to a system of tubules and vesicles that have partially overlapping
localization with Rab8a. Both Rab8a and Rab10 were mislocalized by the
expression of dominant-negative myosin V tails. Interaction with Rab10 was
dependent on the presence of the alternatively spliced exon D in myosin Va and
myosin Vb and the homologous region in myosin Vc. Yeast two-hybrid assays and
fluorescence resonance energy transfer studies confirmed that Rab10 binding to
myosin V tails in vivo required the alternatively spliced exon D. In
contrast to our previous work, we found that Rab11a can interact with both
myosin Va and myosin Vb tails independent of their splice isoform. These
results indicate that Rab GTPases regulate diverse endocytic trafficking
pathways through recruitment of multiple myosin V isoforms.Eukaryotic cells are comprised of networks of highly organized membranous
structures that require the efficient and timely movement of diverse
intracellular proteins for proper function. Molecular motors provide the
physical force needed to move these materials along microtubules and actin
microfilaments. Unconventional myosin motors, such as those belonging to
classes V, VI, and VII, have roles in the trafficking and recycling of
membrane-bound structures in eukaryotic cells
(1) and are recruited to
discrete vesicle populations. Myosin VI is involved in clathrin-mediated
endocytosis (2), whereas myosin
VIIa participates in the proper development of stereocilia of inner ear hair
cells and the transport of pigment granules in retinal pigmented epithelial
cells (3,
4). Similarly, the three
members of vertebrate class V myosins, myosin Va, myosin Vb, and myosin Vc,
are required for the proper transport of a wide array of membrane cargoes,
such as the melanosomes of pigment cells, synaptic vesicles in neurons, apical
recycling endosomes in polarized epithelial cells, and bulk recycling vesicles
in non-polarized cells (5).Members of the Rab family of small GTPases regulate many cellular systems,
including membrane trafficking
(6,
7). Certain Rab proteins
associate with and regulate the function of class V myosins. Rab27a, in a
complex with the adaptor protein melanophilin/Slac2-a, is required to localize
myosin Va to the surface of melanin-filled pigment granules in vertebrates
(8-10),
whereas Rab27a and Slac2-c/MyRIP associate with both Myosin Va and myosin VIIa
(3,
11). Rab11a, in a complex with
its adaptor protein Rab11-FIP2, associates with myosin Vb on recycling
endosomes
(12-14)
where the tripartite complex regulates the recycling of a variety of cargoes
(15-19).
In addition, Rab8a associates with both myosin Vb
(20) and myosin Vc
(21) as part of the
non-clathrin-mediated tubular recycling system
(20). Recently, Rab11a has
also been shown to associate with myosin Va in the transport of AMPA receptors
in dendritic spines (22),
contributing to the model of myosin V regulation by multiple Rab proteins.Previous investigations have documented alternative splicing of myosin Va
in a tissue-specific manner
(23-28).
Alternate splicing occurs in a region lying between the coiled-coil region of
the neck of the motor and the globular tail region. Three exons in particular
are subject to alternative splicing: exons B, D, and F
(23-25).
Exon F is critical for association with melanophilin/Slac2 and Rab27a
(8,
9,
29,
30). Additionally, exon B is
required for the interaction of myosin Va with dynein light chain 2 (DLC2)
(27,
28). Currently no function for
the alternatively spliced exon D has been reported. Similar to myosin Va,
myosin Vb contains exons A, B, C, D, and E, whereas no exon F has yet been
identified in myosin Vb (Fig.
1A). In addition, exon B in myosin Vb does not resemble
the dynein light chain 2 (DLC2) binding region in myosin Va
(27,
28), and therefore, it likely
does not interact with DLC2. On the other hand, exon D is highly conserved
among Myosin Va, myosin Vb, and myosin Vc, suggesting a common function in
these molecular motors.Open in a separate windowFIGURE 1.Tissue distribution of human myosin Va and myosin Vb splice
isoforms. A, schematic of the alternative exon organization in
the tails of myosin Va and myosin Vb. It is known that exons B, D, and F are
subject to alternative splicing in myosin Va, whereas there is only evidence
that exon D is alternatively spliced in myosin Vb, which does not contain exon
F. B, alignment of exon D sequences from mouse and human myosin V''s.
myosin Va and myosin Vb both contain exon D (amino acids 1320-1346 of myosin
Va and 1315-1340 of myosin Vb), whereas myosin Vc contains an exon D-like
region (amino acids 1124-1147 of human myosin Vc) that is not known to be
alternatively spliced. Alignment of the exon D regions from all three motors
reveals a high degree of homology, especially in the center of the exon.
Asterisks indicate amino acid identities. C, PCR-based
analysis of human tissue panels reveals the alternative splicing pattern of
exon D in myosin Va and myosin Vb. Primers flanking the region encoding exon D
for both motors were used to amplify cDNA from human MTC™ panels
(Clontech). cDNA amplified from HeLa cell RNA as well as myosin Va and myosin
Vb tail constructs were used as positive controls. Variants expressing exon D
(upper bands) and lacking exon D (lower bands) were visible.
Per., peripheral; Pos., positive.Here we report that Rab10, a protein related to Rab8a and thought to have
similar function
(31-35),
localizes to a system of tubules and vesicles overlapping in distribution with
Rab8a in HeLa cells. Utilizing dominant-negative myosin V tail constructs, we
show that Rab8a and Rab10 can interact with Myosin Va, myosin Vb, and myosin
Vc in vivo. In addition, we have determined that the alternatively
spliced exon D in both myosin Va and myosin Vb is required for interaction
with Rab10. In contrast to our previous findings, we demonstrate that Rab11a
is able to interact with both myosin Va and myosin Vb tails in an exon
independent-manner. These results reveal that multiple Rab proteins
potentially regulate all three class V myosin motors. 相似文献
9.
10.
Although agonist-dependent endocytosis of G protein-coupled receptors
(GPCRs) as a means to modulate receptor signaling has been widely studied, the
constitutive endocytosis of GPCRs has received little attention. Here we show
that two prototypical class I GPCRs, the β2 adrenergic and M3 muscarinic
receptors, enter cells constitutively by clathrin-independent endocytosis and
colocalize with markers of this endosomal pathway on recycling tubular
endosomes, indicating that these receptors can subsequently recycle back to
the plasma membrane (PM). This constitutive endocytosis of these receptors was
not blocked by antagonists, indicating that receptor signaling was not
required. Interestingly, the G proteins that these receptors couple to,
Gαs and Gαq, localized together with their
receptors at the plasma membrane and on tubular recycling endosomes. Upon
agonist stimulation, Gαs and Gαq remained
associated with the PM and these endosomal membranes, whereas β2 and M3
receptors now entered cells via clathrin-dependent endocytosis. Deletion of
the third intracellular loop (i3 loop), which is thought to play a role in
agonist-dependent endocytosis of the M3 receptor, had no effect on the
constitutive internalization of the receptor. Surprisingly, with agonist, the
mutated M3 receptor still internalized and accumulated in cells but through
clathrin-independent and not clathrin-dependent endocytosis. These findings
demonstrate that GPCRs are versatile PM proteins that can utilize different
mechanisms of internalization depending upon ligand activation.G protein-coupled receptors
(GPCRs)2 belong to a
superfamily of seven transmembrane-spanning proteins that respond to a diverse
array of sensory and chemical stimuli
(1–4).
Activation of GPCRs through the binding of specific agonists induces
conformational changes that allow activation of heterotrimeric guanine
nucleotide-binding proteins (G proteins)
(5,
6). To ensure that the signals
are controlled in magnitude and duration, activated GPCRs are rapidly
desensitized through phosphorylation carried out by G protein-coupled receptor
kinases (GRKs) (7). This
facilitates β-arrestin binding and promotes receptor uncoupling from the
G protein (8,
9). In addition to its role in
GPCRs desensitization, β-arrestins promote the translocation of the
receptor to the endocytic machinery involving clathrin and adaptor protein-2
(AP-2), thereby facilitating receptor removal from the plasma membrane
(10–15).
Once internalized, some GPCRs may even continue to signal from endosomes
(16).Although GPCR internalization is generally considered to be an
agonist-dependent phenomenon, some evidence suggests that GPCRs can be
endocytosed even in the absence of agonist, a process known as constitutive
internalization
(17–20).
The role of constitutive internalization of GPCRs is not clear. One
interesting study on cannabinoid CB1 receptors in neurons has shown that
constitutive internalization from the somatodendritic and not axonal membrane
is responsible for the overall redistribution of receptors from the
somatodentritic to the axonal membrane
(17). Another study on the
melanocortin MC4 receptor raised the possibility that constitutive endocytosis
could be a consequence of the basal activity of the receptor
(18).Even less is known about the potential trafficking of the transducer of
GPCR signaling, the G protein
(21). Generally, the binding
of the agonist to the GPCR promotes the exchange of GDP on the Gα
protein for GTP and allows the dissociation of the trimeric G protein into
Gα-GTP and Gβγ dimer subunits
(5,
22). Then, the activated G
proteins target different effectors
(23,
24). G proteins are localized
primarily to the PM where they interact with GPCRs; however, it is not known
whether G proteins always remain at the PM or whether they might move into
cells along endocytic pathways. Previous work showed that Gαs
does not colocalize with β2 receptor on internal compartments after
agonist stimulation, but the cellular distribution of Gαs was
not examined (25).In general, cargo proteins at the plasma membrane (PM) enter the cell
through a variety of endocytic mechanisms that can be divided into two main
groups: clathrin-dependent endocytosis (CDE) and clathrin-independent
endocytosis (CIE). CDE is used by PM proteins such as the transferrin receptor
(TfR) that contain specific cytoplasmic sequences recognized by adaptor
proteins allowing a rapid and efficient internalization through
clathrin-coated vesicles (26,
27). In contrast, CIE is used
by PM proteins that lack adaptor protein binding sequences including cargo
proteins such as the major histocompatibility complex class I protein (MHCI),
the glycosylphosphatidylinositol-anchored protein CD59, and integrins
(28–30).
In HeLa cells CIE is independent of, and CDE dependent on, clathrin and
dynamin and thus the two different endocytic pathways are distinct and well
defined (31). After
internalization in separate vesicles, MHCI-containing vesicles from CIE and
transferrin receptor-containing vesicles from CDE subsequently fuse with the
early endosomal compartment that is associated with Rab5 and the early
endosomal antigen 1 (EEA1)
(32). TfR is recycled back out
to the PM in Rab4- and Rab11-dependent processes. In contrast, some MHCI is
trafficked on to late endosomes and lysosomes for degradation, and some is
recycled back out to the PM along tubular endosomes that lack TfR and emanate
from the juxtanuclear area. Recycling of MHCI back to the PM requires the
activity of Arf6, Rab22, and Rab11
(33,
34).In this study, we analyzed the trafficking of GPCRs and their G proteins in
the presence and absence of agonist in HeLa cells. We examined the trafficking
of two prototypical class I GPCRs: the β2 adrenergic receptor (coupled to
Gαs) and the M3 acetylcholine muscarinic receptor (coupled to
Gαq). We find that β2 and M3 receptors traffic
constitutively via CIE, and then, in the presence of agonist, they switch to
the CDE pathway. We also examined the role of the third intracellular loop of
the M3 receptor in this process. To our knowledge, this study represents the
most comprehensive analysis of constitutive trafficking of class I GPCRs and
related Gα proteins. We demonstrate that GPCRs are versatile PM cargos
that utilize different mechanisms of internalization depending upon ligand
activation. Considering the high level of homology between class I GPCRs, this
evidence could be applicable to the other members of this family. 相似文献
11.
Jan Grijpstra Boris Tefsen Irma van Die & Hans de Cock 《FEMS immunology and medical microbiology》2009,57(2):142-150
The human pathogen Cryptococcus neoformans causes meningo-encephalitis. The polysaccharide capsule is one of the main virulence factors and consists of two distinct polysaccharides: glucuronoxylomannan and galactoxylomannan. The presence of this polysaccharide capsule was previously shown to interfere with maturation of human dendritic cells (DCs), possibly by shielding cell-wall components from interacting with these host immune cells. Here we show that two mutant strains of C. neoformans , both lacking a visible capsule due to a defect in glucuronoxylomannan synthesis, differentially activate human monocyte-derived DCs. Cells from a cap59 mutant, but not of a cap10 mutant strain, induce maturation of DCs as indicated by an increase in the expression of the costimulatory molecules CD80 and CD86, and production of the cytokines interleukin (IL)-10, IL-12p40 and tumor necrosis factor α. Interestingly, cap59 mutant cells reassociated with a concentrated culture medium of wild-type C. neoformans had lost their capacity to induce DC maturation. Summarizing, our data suggest that glucuronoxylomannan confers properties to the capsule that protect the fungus against activation of DCs; however, the presence of intact glucuronoxylomannan is not an absolute requirement to prevent activation of DCs. 相似文献
12.
Penicimutanin C, a new alkaloidal compound, was isolated from the neomycin‐resistant mutant strain 3‐f‐31 of the marine‐derived fungus, Penicillium purpurogenum G59, together with four known compounds. The structure of penicimutanin C, including the absolute configuration, was determined by spectroscopic and chemical methods. The absolute configuration of penicimutanin A was also re‐confirmed by Marfey's and chiral HPLC analyses of the hydrolyzed products. Penicimutanins C and A inhibited the proliferation of five human cancer cell lines to some extent. Penicimutanin C is the third dimer of diketopiperazine and penicimutanolone, which are only produced by mutants of P. purpurogenum G59 isolated to date, and it showed cytotoxic activity against human cancer cell lines. The neomycin‐resistant screening strategy has been previously successfully used to discover new compounds by activating silent metabolites in fungi, and the present results provide an additional example of the effectiveness of this method. 相似文献
13.
Yoon Namkung Concetta Dipace Jonathan A. Javitch David R. Sibley 《The Journal of biological chemistry》2009,284(22):15038-15051
We investigated the role of G protein-coupled receptor kinase
(GRK)-mediated phosphorylation in agonist-induced desensitization, arrestin
association, endocytosis, and intracellular trafficking of the D2
dopamine receptor (DAR). Agonist activation of D2 DARs results in
rapid and sustained receptor phosphorylation that is solely mediated by GRKs.
A survey of GRKs revealed that only GRK2 or GRK3 promotes D2 DAR
phosphorylation. Mutational analyses resulted in the identification of eight
serine/threonine residues within the third cytoplasmic loop of the receptor
that are phosphorylated by GRK2/3. Simultaneous mutation of these eight
residues results in a receptor construct, GRK(-), that is completely devoid of
agonist-promoted GRK-mediated receptor phosphorylation. We found that both
wild-type (WT) and GRK(-) receptors underwent a similar degree of
agonist-induced desensitization as assessed using [35S]GTPγS
binding assays. Similarly, both receptor constructs internalized to the same
extent in response to agonist treatment. Furthermore, using bioluminescence
resonance energy transfer assays to directly assess receptor association with
arrestin3, we found no differences between the WT and GRK(-) receptors. Thus,
phosphorylation is not required for arrestin-receptor association or
agonist-induced desensitization or internalization. In contrast, when we
examined recycling of the D2 DARs to the cell surface, subsequent
to agonist-induced endocytosis, the GRK(-) construct exhibited less recycling
in comparison with the WT receptor. This impairment appears to be due to a
greater propensity of the GRK(-) receptors to down-regulate once internalized.
In contrast, if the receptor is highly phosphorylated, then receptor recycling
is promoted. These results reveal a novel role for GRK-mediated
phosphorylation in regulating the post-endocytic trafficking of a G
protein-coupled receptor.Dopamine receptors
(DARs)3 are members of
the GPCR superfamily and consist of five structurally distinct subtypes
(1,
2). These can be divided into
two subfamilies on the basis of their structure and pharmacological and
transductional properties (3).
The “D1-like” subfamily includes the D1 and
D5 receptors, which couple to the heterotrimeric G proteins
GS or GOLF to stimulate adenylyl cyclase activity and
raise intracellular levels of cAMP. The D2-like subfamily includes
the D2, D3, and D4 receptors, which couple to
inhibitory Gi/o proteins to reduce adenylyl cyclase activity as
well as modulate voltage-gated K+ or Ca2+ channels.
Within the central nervous system, these receptors modulate movement, learning
and memory, reward and addiction, cognition, and certain neurendocrine
functions. As with other GPCRs, the DARs are subject to a wide variety of
regulatory mechanisms, which can either positively or negatively modulate
their expression and functional activity
(4).Upon agonist activation, most GPCRs undergo desensitization, a homeostatic
process that results in a waning of receptor response despite continued
agonist stimulation (5,
6). Desensitization is believed
to involve the phosphorylation of receptors by either G protein-coupled
receptor kinases (GRKs) and/or second messenger-activated kinases such as PKA
or PKC. Homologous forms of desensitization involve only agonist-activated
receptors and appear to be primarily mediated by GRKs. In many cases,
GRK-mediated phosphorylation has been shown to decrease receptor/G protein
interactions and also initiate arrestin binding, which further promotes
endocytosis of the receptor through clathrin-coated pits
(7–9).
Once internalized, GPCRs can engage additional signaling pathways
(10), be sorted for recycling
to the plasma membrane, or targeted for degradation
(7–9).
Among the DARs, the D2 receptor is arguably one of the most
validated drug targets in neurology and psychiatry. For instance, all
receptor-based anti-parkinsonian drugs work via stimulating the D2
DAR (11), whereas all Food and
Drug Administration-approved antipsychotic agents are antagonists of this
receptor subtype (12,
13). The D2 DAR is
also therapeutically targeted in other disorders such as restless legs
syndrome, tardive dyskinesia, Tourette syndrome, and hyperprolactinemia. As
such, more knowledge concerning the regulation of the D2 DAR could
be helpful in improving current therapies or devising new treatment
strategies.In comparison with other GPCRs, however, detailed mechanistic information
concerning regulation of the D2 DAR is mostly lacking, although
some progress has recently been made. For instance, we
(14) and others
(15) have found that
PKC-mediated phosphorylation can regulate both D2 receptor
desensitization and trafficking. In our PKC study, we mapped out all of the
PKC phosphorylation sites within the third intracellular loop (IC3) of the
receptor, and we determined the existence of two PKC phosphorylation domains.
Both of these domains were found to regulate receptor sequestration, whereas
only one domain regulated functional uncoupling in response to PKC activation
(14). In response to agonist
activation, the D2 DAR has also been shown to undergo functional
desensitization (4), although
this has not been intensively investigated. More thoroughly examined is the
observation that agonist stimulation of the D2 DAR promotes its
sequestration from the cell surface into vesicular compartments that appear
distinct from those harboring internalized D1 DARs or
β-adrenergic receptors
(16–21).
In addition to uncertainty over the endocytic pathway involved, controversy
also exists as to whether or not D2 DAR internalization is
dynamin-dependent and whether the internalized receptors can partially or
completely recycle to the cell surface or, alternatively, if they undergo
degradation (19,
21–24).
The D2 DAR does appear to undergo GRK-mediated phosphorylation upon
agonist activation, which has been suggested to promote arrestin association
and receptor sequestration
(16,
19,
25), although this process has
not been studied in detail and its relationship to functional
receptor desensitization is unknown.In this study, we have further characterized GRK-mediated phosphorylation
of the D2 DAR and determined its role in agonist-induced receptor
desensitization, internalization, and recycling. Using site-directed
mutagenesis, we have mapped out all of the GRK phosphorylation sites within
the D2 DAR and determined that these are distinct from the PKC
phosphorylation sites. Using a GRK phosphorylation-null mutant receptor, we
found, surprisingly, that GRK-mediated phosphorylation is not actually
required for agonist-induced receptor desensitization, arrestin association,
or internalization. In contrast, we found that the GRK phosphorylation-null
receptor was impaired in its ability to recycle to the cell surface subsequent
to internalization and was degraded to a greater extent in comparison with the
wild-type receptor. These results suggest that GRK-mediated phosphorylation of
the D2 DAR regulates its intracellular trafficking or sorting once
internalized, a novel mechanism for GRK-mediated regulation of GPCR
function. 相似文献
14.
Patrick Fischer Martina K. La Rosa Adriana Schulz Anette Preiss Anja C. Nagel 《PLoS genetics》2015,11(8)
In multicellular organisms, growth and proliferation is adjusted to nutritional conditions by a complex signaling network. The Insulin receptor/target of rapamycin (InR/TOR) signaling cascade plays a pivotal role in nutrient dependent growth regulation in Drosophila and mammals alike. Here we identify Cyclin G (CycG) as a regulator of growth and metabolism in Drosophila. CycG mutants have a reduced body size and weight and show signs of starvation accompanied by a disturbed fat metabolism. InR/TOR signaling activity is impaired in cycG mutants, combined with a reduced phosphorylation status of the kinase Akt1 and the downstream factors S6-kinase and eukaryotic translation initiation factor 4E binding protein (4E-BP). Moreover, the expression and accumulation of Drosophila insulin like peptides (dILPs) is disturbed in cycG mutant brains. Using a reporter assay, we show that the activity of one of the first effectors of InR signaling, Phosphoinositide 3-kinase (PI3K92E), is unaffected in cycG mutants. However, the metabolic defects and weight loss in cycG mutants were rescued by overexpression of Akt1 specifically in the fat body and by mutants in widerborst (wdb), the B''-subunit of the phosphatase PP2A, known to downregulate Akt1 by dephosphorylation. Together, our data suggest that CycG acts at the level of Akt1 to regulate growth and metabolism via PP2A in Drosophila. 相似文献
15.
16.
Tereza Cristina de Oliveira Corvelo Rosane do Socorro Pompeu de Loiola Délia Cristina Figueira Aguiar Gyselly de Cássia Bastos de Matos Danielle Calado de Brito 《PloS one》2013,8(7)
Background
The Lewis (FUT3) gene is responsible for the expression of the Lea and Leb blood group antigens. The individuals, who not synthesize these antigens have the phenotype Lewis negative, due to the presence of some single nucleotide polymorphisms (SNPs), such as 59T>G, 508G>A and 1067T>A, whose distribution is different in various ethnic groups. Our aim was to verify the frequencies of these SNPs in an admixed population of Belém-Pará-Brazil.Materials and Methods
Polymerase chain reaction/restriction enzyme method were used to detect these SNPs in the FUT3 gene, whereas Lewis phenotypes were defined by the direct hemagglutination and in saliva by Dot-Elisa assay in a random sample of 150 individuals from admixed population of Belém in the northeast Brazilian Amazon region.Results
The frequency of these SNPs was detected as 47.6% (59T>G), 17.3% (508G>A) and 5.3% (1067T>A).The discrepancies between blood and salivary Lewis phenotypes are related to the relatively high frequencies of 59T>G and the null allele 508G>A. Whereas 38.6% of the individuals were Lewis negative based on blood, only 17.24% also tested negative when their saliva were analyzed.Conclusion
We have found a marked consistency between the phenotypes and genotypes of the Lewis blood group system. Furthermore, our obtained FST values reveal distinct frequencies of the FUT3 SNPs between the present sample and its representative ancestral populations. These observations will help to evaluate the Lewis antigens impact as susceptibility markers, in genetic association studies to certain diseases. 相似文献17.
Leonardo P. Farias Greice Krautz-Peterson Cibele A. Tararam Bogar O. Araujo-Montoya Tatiana R. Fraga Henrique K. Rofatto Floriano P. Silva-Jr Lourdes Isaac Akram A. Da'dara R. Alan Wilson Charles B. Shoemaker Luciana C. C. Leite 《PLoS neglected tropical diseases》2013,7(10)
Background
It is believed that schistosomes evade complement-mediated killing by expressing regulatory proteins on their surface. Recently, six homologues of human CD59, an important inhibitor of the complement system membrane attack complex, were identified in the schistosome genome. Therefore, it is important to investigate whether these molecules could act as CD59-like complement inhibitors in schistosomes as part of an immune evasion strategy.Methodology/Principal Findings
Herein, we describe the molecular characterization of seven putative SmCD59-like genes and attempt to address the putative biological function of two isoforms. Superimposition analysis of the 3D structure of hCD59 and schistosome sequences revealed that they contain the three-fingered protein domain (TFPD). However, the conserved amino acid residues involved in complement recognition in mammals could not be identified. Real-time RT-PCR and Western blot analysis determined that most of these genes are up-regulated in the transition from free-living cercaria to adult worm stage. Immunolocalization experiments and tegument preparations confirm that at least some of the SmCD59-like proteins are surface-localized; however, significant expression was also detected in internal tissues of adult worms. Finally, the involvement of two SmCD59 proteins in complement inhibition was evaluated by three different approaches: (i) a hemolytic assay using recombinant soluble forms expressed in Pichia pastoris and E. coli; (ii) complement-resistance of CHO cells expressing the respective membrane-anchored proteins; and (iii) the complement killing of schistosomula after gene suppression by RNAi. Our data indicated that these proteins are not involved in the regulation of complement activation.Conclusions
Our results suggest that this group of proteins belongs to the TFPD superfamily. Their expression is associated to intra-host stages, present in the tegument surface, and also in intra-parasite tissues. Three distinct approaches using SmCD59 proteins to inhibit complement strongly suggested that these proteins are not complement inhibitors and their function in schistosomes remains to be determined. 相似文献18.
19.
Monica Sala-Rabanal Lilia Y. Kucheryavykh Serguei N. Skatchkov Misty J. Eaton Colin G. Nichols 《The Journal of biological chemistry》2010,285(46):36040-36048
Inwardly rectifying potassium channel Kir4.1 is critical for glial function, control of neuronal excitability, and systemic K+ homeostasis. Novel mutations in Kir4.1 have been associated with EAST/SeSAME syndrome, characterized by mental retardation, ataxia, seizures, hearing loss, and renal salt waste. Patients are homozygous for R65P, G77R, C140R or T164I; or compound heterozygous for A167V/R297C or R65P/R199Stop, a deletion of the C-terminal half of the protein. We investigated the functional significance of these mutations by radiotracer efflux and inside-out membrane patch clamping in COSm6 cells expressing homomeric Kir4.1 or heteromeric Kir4.1/Kir5.1 channels. All of the mutations compromised channel function, but the underlying mechanisms were different. R65P, T164I, and R297C caused an alkaline shift in pH sensitivity, indicating that these positions are crucial for pH sensing and pore gating. In R297C, this was due to disruption of intersubunit salt bridge Glu288–Arg297. C140R breaks the Cys108–Cys140 disulfide bond essential for protein folding and function. A167V did not affect channel properties but may contribute to decreased surface expression in A167V/R297C. In G77R, introduction of a positive charge within the bilayer may affect channel structure or gating. R199Stop led to a dramatic decrease in surface expression, but channel activity was restored by co-expression with intact subunits, suggesting remarkable tolerance for truncation of the cytoplasmic domain. These results provide an explanation for the molecular defects that underlie the EAST/SeSAME syndrome. 相似文献