ABSTRACT
Poly(ADP-ribose) polymerase (Parp)-1 catalyzes polyADP-ribosylation using NAD+ and is involved in the DNA damage response, genome stability, and transcription. In this study, we demonstrated that aged Parp-1-/- mouse incisors showed more frequent dental dysplasia in both ICR/129Sv mixed background and C57BL/6 strain compared to aged Parp-1+/+ incisors, suggesting that Parp-1 deficiency could be involved in development of dental dysplasia at an advanced age. Computed tomography images confirmed that dental dysplasia was observed at significantly higher incidences in Parp-1-/- mice. The relative calcification levels of Parp-1-/- incisors were higher in both enamel and dentin (p < 0.05). Immunohistochemical analysis revealed (1) Parp-1 positivity in ameloblasts and odontoblasts in Parp-1+/+ incisor, (2) weaker dentin sialoprotein positivity in dentin of Parp-1-/- incisor, and (3) bone sialoprotein positivity in dentin of Parp-1-/- incisor, suggesting ectopic osteogenic formation in dentin of Parp-1-/- incisor. These results indicate that Parp-1 deficiency promotes odontogenic failure in incisors at an advanced age. Parp-1 deficiency did not affect dentinogenesis during the development of mice, suggesting that Parp-1 is not essential in dentinogenesis during development but is possibly involved in the regulation of continuous dentinogenesis in the incisors at an advanced age.
Subject(s)
Dental Pulp/pathology , Dentin Dysplasia/etiology , Gene Expression Regulation, Developmental , Incisor/pathology , Odontoblasts/pathology , Odontogenesis , Poly (ADP-Ribose) Polymerase-1/physiology , Age Factors , Animals , Dental Pulp/metabolism , Dentin Dysplasia/pathology , Female , Incisor/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Inbred ICR , Mice, Knockout , Odontoblasts/metabolismABSTRACT
Poly(ADP-ribose) glycohydrolase (Parg) is a central enzyme for poly(ADP-ribose) degradation. We established a Parg+/- mice strain by deletion of a part of exon 1 and around 0.4-kb upstream of sequences of the Parg gene. Parg-/- embryos obtained by intercrossing the Parg+/- mice died in utero between 4.5 and 9.5â¯days postcoitum. We examined whether poly(ADP-ribose) polymerase-1 (Parp-1) deficiency could rescue embryonic lethality of Parg-/- mice. Parg-/-Parp-1-/- mice were born viable at a reduced frequency from the expected mendelian ratio in the intercross progeny of Parg+/-Parp-1-/- mice. The results suggest a possibility that the presence of Parp-1 is responsible for the lethality of Parg-/- embryos, and Parg molecules or Parg activity degrading poly(ADP-ribose) might be important for embryogenesis. In Parg-/-Parp-1-/- mice, Parg protein was not detected in various tissues, and the protein level of Timm23, a 5'-upstream gene of Parg, was reduced compared with that in Parg+/+Parp-1-/- mice. Parg-/-Parp-1-/- mice showed retarded growth compared with Parg+/+Parp-1-/- mice, and died within 3â¯months of age accompanied with severe renal failure. Glomerular sclerosis, tubular dilatation, and hyaline casts in the kidney were observed in Parg-/-Parp-1-/- mice. An increase in blood urea nitrogen (pâ¯<â¯0.05), a marked increase of albumin level in urine (pâ¯<â¯0.01) and its concomitant decrease in serum (pâ¯<â¯0.05) were also detected in Parg-/-Parp-1-/- mice compared with the Parg+/+Parp-1-/- counterpart. The results imply that the combined Parg and Parp-1 loss with a hypomorphic state of Timm23 leads to the development of severe renal failure.
Subject(s)
Glycoside Hydrolases/deficiency , Mitochondrial Membrane Transport Proteins/deficiency , Poly (ADP-Ribose) Polymerase-1/deficiency , Renal Insufficiency/metabolism , Renal Insufficiency/pathology , Animals , Coculture Techniques , Glycoside Hydrolases/genetics , Mice , Mice, 129 Strain , Mice, Inbred C57BL , Mice, Inbred ICR , Mice, Knockout , Mitochondrial Membrane Transport Proteins/genetics , Mitochondrial Precursor Protein Import Complex Proteins , Poly (ADP-Ribose) Polymerase-1/genetics , Renal Insufficiency/geneticsABSTRACT
Poly (ADP-ribose) polymerase family, member 1 (Parp1) has pleiotropic and disparate functions in multiple cellular signaling pathways through post-translational protein modification. It contributes to the regulation of various cellular processes, including DNA damage repair, cell death, and cell differentiation, genetically or epigenetically. Meanwhile, the functions of Parp1 in intercellular signaling remain to be established. To examine the functions of Parp1 in intercellular signaling, we examined microRNA (miRNA) regulation in exosomes derived from Parp1-deficient (Parp1-/-) embryonic stem (ES) cells. The percentages of miRNAs among total RNAs, including small RNAs such as miRNAs, snRNAs, snoRNAs, tRNAs, exonic RNAs, and intronic RNAs, in Parp1+/+ and Parp1-/- ES cell-derived exosomes were 8.2% and 3.5%, respectively. Overall, 329 distinct miRNAs exhibited ≥2-fold changes (118 upregulated; 211 downregulated). The upregulated miRNAs targeted 810 candidate genes, and the downregulated miRNAs targeted 716 candidate genes. Pathway analyses revealed that the upregulated miRNAs were significantly associated with five pathways including MAPK signaling cascades (pâ¯<â¯0.05), indicating that the target genes in these pathways were suppressed in Parp1-/- ES cells. In quantitative analyses of miRNA expression, miR365-3p, let-7a-5p, miR196b-5p, miR203-3p, miR98-5p, and miR146a-5p were increased byâ¯≥â¯2-fold in Parp1-/- ES cell-derived exosomes. Gene ontology enrichment analyses revealed that the upregulated miRNAs were significantly annotated for growth and stress-related cell signaling and cell communication (pâ¯<â¯0.05). Parp1 deficiency in ES cells led to inhibition of cell-cell communication, possibly by intercellular signal transduction, suggesting that Parp1 functions extracellularly by regulating exosomal miRNAs.