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Dynamically-expressed prion-like proteins form a cuticle in the pharynx of Caenorhabditis elegans.

George-Raizen JB, Shockley KR, Trojanowski NF, Lamb AL, Raizen DM - Biol Open (2014)

Bottom Line: We found strong transcriptional induction during the molt of 12 of 15 previously identified abu genes encoding Prion-like (P) glutamine (Q) and asparagine (N) rich PQN proteins, as well as 15 additional genes encoding closely related PQN proteins. abu/pqn genes, which we name the abu/pqn paralog group (APPG) genes, were expressed in pharyngeal cells and the proteins encoded by two APPG genes we tested localized to the pharyngeal cuticle.Deleting the APPG gene abu-14 caused abnormal pharyngeal cuticular structures and knocking down other APPG genes resulted in abnormal cuticular function.The strong developmental regulation of the APPG genes raises the possibility that such genes would be identified in transcriptional profiling experiments in which the animals' developmental stage is not precisely staged.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.

No MeSH data available.


Related in: MedlinePlus

Disruption of abu/pqn gene function results in cuticular abnormalities in the pharynx and poor digestion of bacteria.(A) Developmental delay of transgenic animals expressing myo-2>abu-6(RNAi) in comparison to control transgenic animals expressing abu-5>mCherry. White, vertical, diagonal, and black bars denote, L4, L3, L2 and L1 stages, respectively. (B) Cartoon depicting observations of feeding in wild-type animals and in abu-6(RNAi) animals. Normally, bacteria (green) are trapped in the corpus and anterior isthmus, and are disrupted by the grinder in the terminal bulb to release their contents into the anterior intestine (lighter color green). In abu-6(RNAi) transgenic animals, bacteria accumulate in the corpus and are poorly disrupted by the grinder, resulting in the presence of intact bacteria in the anterior intestine. (C) Example of a wild-type animal with bacteria trapped in the anterior isthmus and with disrupted green bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (D) abu-6(RNAi) animals fed fluorescent bacteria have a pharyngeal corpus stuffed with bacteria as well as intact bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (E) Aberrant pharyngeal development observed in an abu-14(ok1789) arrested first larval stage animal. Arrow indicates abnormal grinder. Anterior is to the left. Scale bar is 10 µm. (F) Aberrant pharyngeal cuticle in an adult animal over-expressing abu-14::gfp. Arrow indicates an abnormal grinder. Anterior is to the left. Scale bar is 5 µm. (G) In the absence of abu-14, most animals do not reach adulthood 3 days after hatching. This defect is fully rescued by a genomic DNA fragment containing the abu-14 gene and is partially rescued by a DNA fragment encoding an ABU-14::GFP protein fusion expressed under the control of an abu-14 promoter.
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f03: Disruption of abu/pqn gene function results in cuticular abnormalities in the pharynx and poor digestion of bacteria.(A) Developmental delay of transgenic animals expressing myo-2>abu-6(RNAi) in comparison to control transgenic animals expressing abu-5>mCherry. White, vertical, diagonal, and black bars denote, L4, L3, L2 and L1 stages, respectively. (B) Cartoon depicting observations of feeding in wild-type animals and in abu-6(RNAi) animals. Normally, bacteria (green) are trapped in the corpus and anterior isthmus, and are disrupted by the grinder in the terminal bulb to release their contents into the anterior intestine (lighter color green). In abu-6(RNAi) transgenic animals, bacteria accumulate in the corpus and are poorly disrupted by the grinder, resulting in the presence of intact bacteria in the anterior intestine. (C) Example of a wild-type animal with bacteria trapped in the anterior isthmus and with disrupted green bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (D) abu-6(RNAi) animals fed fluorescent bacteria have a pharyngeal corpus stuffed with bacteria as well as intact bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (E) Aberrant pharyngeal development observed in an abu-14(ok1789) arrested first larval stage animal. Arrow indicates abnormal grinder. Anterior is to the left. Scale bar is 10 µm. (F) Aberrant pharyngeal cuticle in an adult animal over-expressing abu-14::gfp. Arrow indicates an abnormal grinder. Anterior is to the left. Scale bar is 5 µm. (G) In the absence of abu-14, most animals do not reach adulthood 3 days after hatching. This defect is fully rescued by a genomic DNA fragment containing the abu-14 gene and is partially rescued by a DNA fragment encoding an ABU-14::GFP protein fusion expressed under the control of an abu-14 promoter.

Mentions: To determine the consequence of reduction of APPG gene function, we initially used an RNA interference knock-down approach. Given the high similarity between APPG proteins, we reasoned that there might be a high degree of degeneracy in their function and that, in order to detect a phenotype, knocking down more than one of the APPG genes would be required. We generated transgenic animals in which pharyngeal muscle cells expressed both the sense and anti-sense strands of abu-6. Because of the high nucleotide sequence identity among APPG genes, this RNAi treatment is predicted to affect several APPG genes (supplementary material Table S6). Transgenic animals grew poorly (Fig. 3A), likely because of inefficient pharyngeal transport and grinding of bacteria (Fig. 3B). This was evident by the high frequency of animals with their pharyngeal lumen stuffed with bacteria as well as occurrence of undigested bacteria in the anterior intestine (Fig. 3D). Whereas 0/50 wild-type animals had a stuffed pharynx phenotype or intact GFP-marked bacteria in the anterior intestine, 19/32 abu-6(RNAi) animals had a stuffed pharynx phenotype and 6/32 had intact bacteria in the anterior intestine. These results indicate that APPG protein function is required for the digestive action of the pharynx, consistent with the expression pattern.


Dynamically-expressed prion-like proteins form a cuticle in the pharynx of Caenorhabditis elegans.

George-Raizen JB, Shockley KR, Trojanowski NF, Lamb AL, Raizen DM - Biol Open (2014)

Disruption of abu/pqn gene function results in cuticular abnormalities in the pharynx and poor digestion of bacteria.(A) Developmental delay of transgenic animals expressing myo-2>abu-6(RNAi) in comparison to control transgenic animals expressing abu-5>mCherry. White, vertical, diagonal, and black bars denote, L4, L3, L2 and L1 stages, respectively. (B) Cartoon depicting observations of feeding in wild-type animals and in abu-6(RNAi) animals. Normally, bacteria (green) are trapped in the corpus and anterior isthmus, and are disrupted by the grinder in the terminal bulb to release their contents into the anterior intestine (lighter color green). In abu-6(RNAi) transgenic animals, bacteria accumulate in the corpus and are poorly disrupted by the grinder, resulting in the presence of intact bacteria in the anterior intestine. (C) Example of a wild-type animal with bacteria trapped in the anterior isthmus and with disrupted green bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (D) abu-6(RNAi) animals fed fluorescent bacteria have a pharyngeal corpus stuffed with bacteria as well as intact bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (E) Aberrant pharyngeal development observed in an abu-14(ok1789) arrested first larval stage animal. Arrow indicates abnormal grinder. Anterior is to the left. Scale bar is 10 µm. (F) Aberrant pharyngeal cuticle in an adult animal over-expressing abu-14::gfp. Arrow indicates an abnormal grinder. Anterior is to the left. Scale bar is 5 µm. (G) In the absence of abu-14, most animals do not reach adulthood 3 days after hatching. This defect is fully rescued by a genomic DNA fragment containing the abu-14 gene and is partially rescued by a DNA fragment encoding an ABU-14::GFP protein fusion expressed under the control of an abu-14 promoter.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4232772&req=5

f03: Disruption of abu/pqn gene function results in cuticular abnormalities in the pharynx and poor digestion of bacteria.(A) Developmental delay of transgenic animals expressing myo-2>abu-6(RNAi) in comparison to control transgenic animals expressing abu-5>mCherry. White, vertical, diagonal, and black bars denote, L4, L3, L2 and L1 stages, respectively. (B) Cartoon depicting observations of feeding in wild-type animals and in abu-6(RNAi) animals. Normally, bacteria (green) are trapped in the corpus and anterior isthmus, and are disrupted by the grinder in the terminal bulb to release their contents into the anterior intestine (lighter color green). In abu-6(RNAi) transgenic animals, bacteria accumulate in the corpus and are poorly disrupted by the grinder, resulting in the presence of intact bacteria in the anterior intestine. (C) Example of a wild-type animal with bacteria trapped in the anterior isthmus and with disrupted green bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (D) abu-6(RNAi) animals fed fluorescent bacteria have a pharyngeal corpus stuffed with bacteria as well as intact bacteria in the anterior intestine. Anterior is to the left. Scale bar is 10 µm. (E) Aberrant pharyngeal development observed in an abu-14(ok1789) arrested first larval stage animal. Arrow indicates abnormal grinder. Anterior is to the left. Scale bar is 10 µm. (F) Aberrant pharyngeal cuticle in an adult animal over-expressing abu-14::gfp. Arrow indicates an abnormal grinder. Anterior is to the left. Scale bar is 5 µm. (G) In the absence of abu-14, most animals do not reach adulthood 3 days after hatching. This defect is fully rescued by a genomic DNA fragment containing the abu-14 gene and is partially rescued by a DNA fragment encoding an ABU-14::GFP protein fusion expressed under the control of an abu-14 promoter.
Mentions: To determine the consequence of reduction of APPG gene function, we initially used an RNA interference knock-down approach. Given the high similarity between APPG proteins, we reasoned that there might be a high degree of degeneracy in their function and that, in order to detect a phenotype, knocking down more than one of the APPG genes would be required. We generated transgenic animals in which pharyngeal muscle cells expressed both the sense and anti-sense strands of abu-6. Because of the high nucleotide sequence identity among APPG genes, this RNAi treatment is predicted to affect several APPG genes (supplementary material Table S6). Transgenic animals grew poorly (Fig. 3A), likely because of inefficient pharyngeal transport and grinding of bacteria (Fig. 3B). This was evident by the high frequency of animals with their pharyngeal lumen stuffed with bacteria as well as occurrence of undigested bacteria in the anterior intestine (Fig. 3D). Whereas 0/50 wild-type animals had a stuffed pharynx phenotype or intact GFP-marked bacteria in the anterior intestine, 19/32 abu-6(RNAi) animals had a stuffed pharynx phenotype and 6/32 had intact bacteria in the anterior intestine. These results indicate that APPG protein function is required for the digestive action of the pharynx, consistent with the expression pattern.

Bottom Line: We found strong transcriptional induction during the molt of 12 of 15 previously identified abu genes encoding Prion-like (P) glutamine (Q) and asparagine (N) rich PQN proteins, as well as 15 additional genes encoding closely related PQN proteins. abu/pqn genes, which we name the abu/pqn paralog group (APPG) genes, were expressed in pharyngeal cells and the proteins encoded by two APPG genes we tested localized to the pharyngeal cuticle.Deleting the APPG gene abu-14 caused abnormal pharyngeal cuticular structures and knocking down other APPG genes resulted in abnormal cuticular function.The strong developmental regulation of the APPG genes raises the possibility that such genes would be identified in transcriptional profiling experiments in which the animals' developmental stage is not precisely staged.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.

No MeSH data available.


Related in: MedlinePlus