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Transient receptor potential ion channel Trpm7 regulates exocrine pancreatic epithelial proliferation by Mg2+-sensitive Socs3a signaling in development and cancer.

Yee NS, Zhou W, Liang IC - Dis Model Mech (2010)

Bottom Line: The role of Socs3a in Trpm7-mediated signaling is supported by the findings that socs3a mRNA level is elevated in the trpm7 mutants, and antisense inhibition of socs3a expression improved their exocrine pancreatic growth.TRPM7 is generally overexpressed in human pancreatic adenocarcinoma.Results of this study indicate that Trpm7 regulates exocrine pancreatic development via the Mg(2+)-sensitive Socs3a pathway, and suggest that aberrant TRPM7-mediated signaling contributes to pancreatic carcinogenesis.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology, Oncology, and Blood & Marrow Transplantation, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA. nelson-yee@uiowa.edu

ABSTRACT
Genetic analysis of pancreatic development has provided new insights into the mechanisms underlying the formation of exocrine pancreatic neoplasia. Zebrafish sweetbread (swd) mutants develop hypoplastic acini and dysmorphic ducts in the exocrine pancreas, with impeded progression of cell division cycle and of epithelial growth. Positional cloning and allelic complementation have revealed that the swd mutations affect the transient receptor potential melastatin-subfamily member 7 (trpm7) gene, which encodes a divalent cation-permeable channel with kinase activity. Supplementary Mg(2+) partially rescued the exocrine pancreatic defects of the trpm7 mutants by improving cell-cycle progression and growth and repressing the suppressor of cytokine signaling 3a (socs3a) gene. The role of Socs3a in Trpm7-mediated signaling is supported by the findings that socs3a mRNA level is elevated in the trpm7 mutants, and antisense inhibition of socs3a expression improved their exocrine pancreatic growth. TRPM7 is generally overexpressed in human pancreatic adenocarcinoma. TRPM7-deficient cells are impaired in proliferation and arrested in the G0-G1 phases of the cell division cycle. Supplementary Mg(2+) rescued the proliferative defect of the TRPM7-deficient cells. Results of this study indicate that Trpm7 regulates exocrine pancreatic development via the Mg(2+)-sensitive Socs3a pathway, and suggest that aberrant TRPM7-mediated signaling contributes to pancreatic carcinogenesis.

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Supplementary Mg2+ partially rescues the growth defect of exocrine pancreas in swd mutants by improving cell-cycle progression and cell growth, with repression of p21cdkn1a and cyclin G1. Exocrine pancreas of the swdp75fm mutants and WT siblings incubated in medium with or without supplementary 20 mM or 40 mM MgCl2 was analyzed. The swdp75fm mutants were identified on the basis of their hypopigmented skin, which was minimally affected by the supplementary MgCl2. (A) Exocrine pancreas (red arrows) in the larvae of 5 dpf embryos by in situ hybridization using anti-trypsin riboprobes. The WT embryos were grown in medium supplemented with PTU, which inhibits skin pigmentation and facilitates visualization of the trypsin-expressing exocrine pancreas. Each larva shown is representative of 40 larvae in each experimental group, and this experiment was performed three times with similar results. (B) Proliferation assay to determine the proportion of BrdU+ nuclei (cells in S phase) in the exocrine pancreas at 72 hpf. (C) Morphometric analysis of exocrine pancreatic cell growth (area, in μm2, per cell) at 5 dpf. Each value represents the mean of five larvae + s.d. *P<0.05 is considered statistically significant. NS, not statistically significant. (D,E) Relative mRNA levels of p21cdkn1a and cyclin G1 by quantitative real-time PCR at 5 dpf. Each value represents the ratio of p21cdkn1a or cyclin G1 mRNA in the swd mutants to WT in the same experimental group. This experiment was repeated with reproducible results.
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f5-0040240: Supplementary Mg2+ partially rescues the growth defect of exocrine pancreas in swd mutants by improving cell-cycle progression and cell growth, with repression of p21cdkn1a and cyclin G1. Exocrine pancreas of the swdp75fm mutants and WT siblings incubated in medium with or without supplementary 20 mM or 40 mM MgCl2 was analyzed. The swdp75fm mutants were identified on the basis of their hypopigmented skin, which was minimally affected by the supplementary MgCl2. (A) Exocrine pancreas (red arrows) in the larvae of 5 dpf embryos by in situ hybridization using anti-trypsin riboprobes. The WT embryos were grown in medium supplemented with PTU, which inhibits skin pigmentation and facilitates visualization of the trypsin-expressing exocrine pancreas. Each larva shown is representative of 40 larvae in each experimental group, and this experiment was performed three times with similar results. (B) Proliferation assay to determine the proportion of BrdU+ nuclei (cells in S phase) in the exocrine pancreas at 72 hpf. (C) Morphometric analysis of exocrine pancreatic cell growth (area, in μm2, per cell) at 5 dpf. Each value represents the mean of five larvae + s.d. *P<0.05 is considered statistically significant. NS, not statistically significant. (D,E) Relative mRNA levels of p21cdkn1a and cyclin G1 by quantitative real-time PCR at 5 dpf. Each value represents the ratio of p21cdkn1a or cyclin G1 mRNA in the swd mutants to WT in the same experimental group. This experiment was repeated with reproducible results.

Mentions: The role of Trpm7 in cellular Mg2+ homeostasis suggests that Mg2+ transport is impaired in swd mutants. This raises the possibility that the swd mutation disrupts the function of Trpm7 in controlling cellular influx of Mg2+, resulting in reduced exocrine pancreatic epithelial proliferation. To determine whether supplementary Mg2+ complements the exocrine pancreatic defect of the trpm7 mutants, the swdp75fm and trpm7b508 mutant embryos, as well as their WT siblings, were incubated in medium with or without added MgCl2, and the exocrine pancreas was examined by in situ hybridization using anti-trypsin riboprobes. As shown in Fig. 5A and supplementary material Fig. S1C,D, respectively, there was partial improvement in the size of exocrine pancreas of the swdp75fm and trpm7b508 mutants when MgCl2 was present. There is no distinguishable difference in the size of exocrine pancreas of WT larvae grown in the presence or absence of supplementary Mg2+ (N.S.Y., unpublished). This suggests that the swdp75fm and trpm7b508 mutations impair the function of Trpm7 in controlling the cellular Mg2+ level, resulting in reduced size of exocrine pancreas.


Transient receptor potential ion channel Trpm7 regulates exocrine pancreatic epithelial proliferation by Mg2+-sensitive Socs3a signaling in development and cancer.

Yee NS, Zhou W, Liang IC - Dis Model Mech (2010)

Supplementary Mg2+ partially rescues the growth defect of exocrine pancreas in swd mutants by improving cell-cycle progression and cell growth, with repression of p21cdkn1a and cyclin G1. Exocrine pancreas of the swdp75fm mutants and WT siblings incubated in medium with or without supplementary 20 mM or 40 mM MgCl2 was analyzed. The swdp75fm mutants were identified on the basis of their hypopigmented skin, which was minimally affected by the supplementary MgCl2. (A) Exocrine pancreas (red arrows) in the larvae of 5 dpf embryos by in situ hybridization using anti-trypsin riboprobes. The WT embryos were grown in medium supplemented with PTU, which inhibits skin pigmentation and facilitates visualization of the trypsin-expressing exocrine pancreas. Each larva shown is representative of 40 larvae in each experimental group, and this experiment was performed three times with similar results. (B) Proliferation assay to determine the proportion of BrdU+ nuclei (cells in S phase) in the exocrine pancreas at 72 hpf. (C) Morphometric analysis of exocrine pancreatic cell growth (area, in μm2, per cell) at 5 dpf. Each value represents the mean of five larvae + s.d. *P<0.05 is considered statistically significant. NS, not statistically significant. (D,E) Relative mRNA levels of p21cdkn1a and cyclin G1 by quantitative real-time PCR at 5 dpf. Each value represents the ratio of p21cdkn1a or cyclin G1 mRNA in the swd mutants to WT in the same experimental group. This experiment was repeated with reproducible results.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3046099&req=5

f5-0040240: Supplementary Mg2+ partially rescues the growth defect of exocrine pancreas in swd mutants by improving cell-cycle progression and cell growth, with repression of p21cdkn1a and cyclin G1. Exocrine pancreas of the swdp75fm mutants and WT siblings incubated in medium with or without supplementary 20 mM or 40 mM MgCl2 was analyzed. The swdp75fm mutants were identified on the basis of their hypopigmented skin, which was minimally affected by the supplementary MgCl2. (A) Exocrine pancreas (red arrows) in the larvae of 5 dpf embryos by in situ hybridization using anti-trypsin riboprobes. The WT embryos were grown in medium supplemented with PTU, which inhibits skin pigmentation and facilitates visualization of the trypsin-expressing exocrine pancreas. Each larva shown is representative of 40 larvae in each experimental group, and this experiment was performed three times with similar results. (B) Proliferation assay to determine the proportion of BrdU+ nuclei (cells in S phase) in the exocrine pancreas at 72 hpf. (C) Morphometric analysis of exocrine pancreatic cell growth (area, in μm2, per cell) at 5 dpf. Each value represents the mean of five larvae + s.d. *P<0.05 is considered statistically significant. NS, not statistically significant. (D,E) Relative mRNA levels of p21cdkn1a and cyclin G1 by quantitative real-time PCR at 5 dpf. Each value represents the ratio of p21cdkn1a or cyclin G1 mRNA in the swd mutants to WT in the same experimental group. This experiment was repeated with reproducible results.
Mentions: The role of Trpm7 in cellular Mg2+ homeostasis suggests that Mg2+ transport is impaired in swd mutants. This raises the possibility that the swd mutation disrupts the function of Trpm7 in controlling cellular influx of Mg2+, resulting in reduced exocrine pancreatic epithelial proliferation. To determine whether supplementary Mg2+ complements the exocrine pancreatic defect of the trpm7 mutants, the swdp75fm and trpm7b508 mutant embryos, as well as their WT siblings, were incubated in medium with or without added MgCl2, and the exocrine pancreas was examined by in situ hybridization using anti-trypsin riboprobes. As shown in Fig. 5A and supplementary material Fig. S1C,D, respectively, there was partial improvement in the size of exocrine pancreas of the swdp75fm and trpm7b508 mutants when MgCl2 was present. There is no distinguishable difference in the size of exocrine pancreas of WT larvae grown in the presence or absence of supplementary Mg2+ (N.S.Y., unpublished). This suggests that the swdp75fm and trpm7b508 mutations impair the function of Trpm7 in controlling the cellular Mg2+ level, resulting in reduced size of exocrine pancreas.

Bottom Line: The role of Socs3a in Trpm7-mediated signaling is supported by the findings that socs3a mRNA level is elevated in the trpm7 mutants, and antisense inhibition of socs3a expression improved their exocrine pancreatic growth.TRPM7 is generally overexpressed in human pancreatic adenocarcinoma.Results of this study indicate that Trpm7 regulates exocrine pancreatic development via the Mg(2+)-sensitive Socs3a pathway, and suggest that aberrant TRPM7-mediated signaling contributes to pancreatic carcinogenesis.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology, Oncology, and Blood & Marrow Transplantation, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA. nelson-yee@uiowa.edu

ABSTRACT
Genetic analysis of pancreatic development has provided new insights into the mechanisms underlying the formation of exocrine pancreatic neoplasia. Zebrafish sweetbread (swd) mutants develop hypoplastic acini and dysmorphic ducts in the exocrine pancreas, with impeded progression of cell division cycle and of epithelial growth. Positional cloning and allelic complementation have revealed that the swd mutations affect the transient receptor potential melastatin-subfamily member 7 (trpm7) gene, which encodes a divalent cation-permeable channel with kinase activity. Supplementary Mg(2+) partially rescued the exocrine pancreatic defects of the trpm7 mutants by improving cell-cycle progression and growth and repressing the suppressor of cytokine signaling 3a (socs3a) gene. The role of Socs3a in Trpm7-mediated signaling is supported by the findings that socs3a mRNA level is elevated in the trpm7 mutants, and antisense inhibition of socs3a expression improved their exocrine pancreatic growth. TRPM7 is generally overexpressed in human pancreatic adenocarcinoma. TRPM7-deficient cells are impaired in proliferation and arrested in the G0-G1 phases of the cell division cycle. Supplementary Mg(2+) rescued the proliferative defect of the TRPM7-deficient cells. Results of this study indicate that Trpm7 regulates exocrine pancreatic development via the Mg(2+)-sensitive Socs3a pathway, and suggest that aberrant TRPM7-mediated signaling contributes to pancreatic carcinogenesis.

Show MeSH
Related in: MedlinePlus