Limits...
Identification and characterization of human Mex-3 proteins, a novel family of evolutionarily conserved RNA-binding proteins differentially localized to processing bodies.

Buchet-Poyau K, Courchet J, Le Hir H, Séraphin B, Scoazec JY, Duret L, Domon-Dell C, Freund JN, Billaud M - Nucleic Acids Res. (2007)

Bottom Line: The hMex-3 are phosphoproteins that bind RNA through their KH domains and shuttle between the nucleus and the cytoplasm via the CRM1-dependent export pathway.Our analysis further revealed that hMex-3A and hMex-3B, but not hMex-3C, colocalize with both the hDcp1a decapping factor and Argonaute (Ago) proteins in processing bodies (P bodies), recently characterized as centers of mRNA turnover.Taken together, these findings indicate that hMex-3 proteins constitute a novel family of evolutionarily conserved RNA-binding proteins, differentially recruited to P bodies and potentially involved in post-transcriptional regulatory mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Université de Lyon, Lyon, F-69003, France.

ABSTRACT
In Caenorhabditis elegans, the Mex-3 protein is a translational regulator that specifies the posterior blastomere identity in the early embryo and contributes to the maintenance of the germline totipotency. We have now identified a family of four homologous human Mex-3 genes, called hMex-3A to -3D that encode proteins containing two heterogeneous nuclear ribonucleoprotein K homology (KH) domains and one carboxy-terminal RING finger module. The hMex-3 are phosphoproteins that bind RNA through their KH domains and shuttle between the nucleus and the cytoplasm via the CRM1-dependent export pathway. Our analysis further revealed that hMex-3A and hMex-3B, but not hMex-3C, colocalize with both the hDcp1a decapping factor and Argonaute (Ago) proteins in processing bodies (P bodies), recently characterized as centers of mRNA turnover. Taken together, these findings indicate that hMex-3 proteins constitute a novel family of evolutionarily conserved RNA-binding proteins, differentially recruited to P bodies and potentially involved in post-transcriptional regulatory mechanisms.

Show MeSH

Related in: MedlinePlus

Expression profile of hMex-3 genes and hMex-3B protein. (A) Human Mex-3 gene expression levels (panels 1–4) were examined by RT-PCR with specific internal primers and were compared with expression level of ubiquitously expressed GAPDH gene (panel 5). RNA were extracted from 7 human cell lines (left) and from 20 human tissues (Multiple Tissue Total RNA panel, BD Biosciences) (right). (B) Human colon sections (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ antibody (panels 1 and 2), anti-hMex-3Bβ antibody + hMex-3B peptide, as control (panel 3). (C) Serial sections of human Meckel's diverticulum (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ (top left) and anti-MUC2 (bottom left), anti-hMex-3Bβ (top middle) and anti-Chromogranin-A (bottom middle), anti-hMex-3Bβ (top right) and anti-Lysozyme (bottom right).
© Copyright Policy - openaccess
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC1851655&req=5

Figure 2: Expression profile of hMex-3 genes and hMex-3B protein. (A) Human Mex-3 gene expression levels (panels 1–4) were examined by RT-PCR with specific internal primers and were compared with expression level of ubiquitously expressed GAPDH gene (panel 5). RNA were extracted from 7 human cell lines (left) and from 20 human tissues (Multiple Tissue Total RNA panel, BD Biosciences) (right). (B) Human colon sections (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ antibody (panels 1 and 2), anti-hMex-3Bβ antibody + hMex-3B peptide, as control (panel 3). (C) Serial sections of human Meckel's diverticulum (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ (top left) and anti-MUC2 (bottom left), anti-hMex-3Bβ (top middle) and anti-Chromogranin-A (bottom middle), anti-hMex-3Bβ (top right) and anti-Lysozyme (bottom right).

Mentions: To examine the expression pattern of the hMex-3 genes, RT-PCR analyses were performed on 8 human cell lines and 20 different human tissues with oligonucleotide specific to each hMex-3 transcript (Figure 2A). hMex-3D mRNA was found ubiquitously expressed in all the cell lines and tissues tested. The other three hMex-3 genes were expressed at varying levels in different tissues, with the highest expression being found in fetal brain and testis. hMex-3A, -3B and -3C genes were also expressed in thymus, salivary gland and uterus (Figure 2A). A weak expression of these three hMex-3 genes was also detected in the intestine.Figure 2.


Identification and characterization of human Mex-3 proteins, a novel family of evolutionarily conserved RNA-binding proteins differentially localized to processing bodies.

Buchet-Poyau K, Courchet J, Le Hir H, Séraphin B, Scoazec JY, Duret L, Domon-Dell C, Freund JN, Billaud M - Nucleic Acids Res. (2007)

Expression profile of hMex-3 genes and hMex-3B protein. (A) Human Mex-3 gene expression levels (panels 1–4) were examined by RT-PCR with specific internal primers and were compared with expression level of ubiquitously expressed GAPDH gene (panel 5). RNA were extracted from 7 human cell lines (left) and from 20 human tissues (Multiple Tissue Total RNA panel, BD Biosciences) (right). (B) Human colon sections (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ antibody (panels 1 and 2), anti-hMex-3Bβ antibody + hMex-3B peptide, as control (panel 3). (C) Serial sections of human Meckel's diverticulum (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ (top left) and anti-MUC2 (bottom left), anti-hMex-3Bβ (top middle) and anti-Chromogranin-A (bottom middle), anti-hMex-3Bβ (top right) and anti-Lysozyme (bottom right).
© Copyright Policy - openaccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1851655&req=5

Figure 2: Expression profile of hMex-3 genes and hMex-3B protein. (A) Human Mex-3 gene expression levels (panels 1–4) were examined by RT-PCR with specific internal primers and were compared with expression level of ubiquitously expressed GAPDH gene (panel 5). RNA were extracted from 7 human cell lines (left) and from 20 human tissues (Multiple Tissue Total RNA panel, BD Biosciences) (right). (B) Human colon sections (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ antibody (panels 1 and 2), anti-hMex-3Bβ antibody + hMex-3B peptide, as control (panel 3). (C) Serial sections of human Meckel's diverticulum (magnification: ×100 or ×400) were stained with anti-hMex-3Bβ (top left) and anti-MUC2 (bottom left), anti-hMex-3Bβ (top middle) and anti-Chromogranin-A (bottom middle), anti-hMex-3Bβ (top right) and anti-Lysozyme (bottom right).
Mentions: To examine the expression pattern of the hMex-3 genes, RT-PCR analyses were performed on 8 human cell lines and 20 different human tissues with oligonucleotide specific to each hMex-3 transcript (Figure 2A). hMex-3D mRNA was found ubiquitously expressed in all the cell lines and tissues tested. The other three hMex-3 genes were expressed at varying levels in different tissues, with the highest expression being found in fetal brain and testis. hMex-3A, -3B and -3C genes were also expressed in thymus, salivary gland and uterus (Figure 2A). A weak expression of these three hMex-3 genes was also detected in the intestine.Figure 2.

Bottom Line: The hMex-3 are phosphoproteins that bind RNA through their KH domains and shuttle between the nucleus and the cytoplasm via the CRM1-dependent export pathway.Our analysis further revealed that hMex-3A and hMex-3B, but not hMex-3C, colocalize with both the hDcp1a decapping factor and Argonaute (Ago) proteins in processing bodies (P bodies), recently characterized as centers of mRNA turnover.Taken together, these findings indicate that hMex-3 proteins constitute a novel family of evolutionarily conserved RNA-binding proteins, differentially recruited to P bodies and potentially involved in post-transcriptional regulatory mechanisms.

View Article: PubMed Central - PubMed

Affiliation: Université de Lyon, Lyon, F-69003, France.

ABSTRACT
In Caenorhabditis elegans, the Mex-3 protein is a translational regulator that specifies the posterior blastomere identity in the early embryo and contributes to the maintenance of the germline totipotency. We have now identified a family of four homologous human Mex-3 genes, called hMex-3A to -3D that encode proteins containing two heterogeneous nuclear ribonucleoprotein K homology (KH) domains and one carboxy-terminal RING finger module. The hMex-3 are phosphoproteins that bind RNA through their KH domains and shuttle between the nucleus and the cytoplasm via the CRM1-dependent export pathway. Our analysis further revealed that hMex-3A and hMex-3B, but not hMex-3C, colocalize with both the hDcp1a decapping factor and Argonaute (Ago) proteins in processing bodies (P bodies), recently characterized as centers of mRNA turnover. Taken together, these findings indicate that hMex-3 proteins constitute a novel family of evolutionarily conserved RNA-binding proteins, differentially recruited to P bodies and potentially involved in post-transcriptional regulatory mechanisms.

Show MeSH
Related in: MedlinePlus