Mrj is a chaperone of the Hsp40 family that regulates Orb2 oligomerization and long-term memory in Drosophila.

Orb2 the Drosophila homolog of cytoplasmic polyadenylation element binding (CPEB) protein forms prion-like oligomers. These oligomers consist of Orb2A and Orb2B isoforms and their formation is dependent on the oligomerization of the Orb2A isoform. Drosophila with a mutation diminishing Orb2A's prion-like oligomerization forms long-term memory but fails to maintain it over time. Since this prion-like oligomerization of Orb2A plays a crucial role in the maintenance of memory, here, we aim to find what regulates this oligomerization. In an immunoprecipitation-based screen, we identify interactors of Orb2A in the Hsp40 and Hsp70 families of proteins. Among these, we find an Hsp40 family protein Mrj as a regulator of the conversion of Orb2A to its prion-like form. Mrj interacts with Hsp70 proteins and acts as a chaperone by interfering with the aggregation of pathogenic Huntingtin. Unlike its mammalian homolog, we find Drosophila Mrj is neither an essential gene nor causes any gross neurodevelopmental defect. We observe a loss of Mrj results in a reduction in Orb2 oligomers. Further, Mrj knockout exhibits a deficit in long-term memory and our observations suggest Mrj is needed in mushroom body neurons for the regulation of long-term memory. Our work implicates a chaperone Mrj in mechanisms of memory regulation through controlling the oligomerization of Orb2A and its association with the translating ribosomes.

Evaluation of Morinda citrifolia (noni) fruit extract as a bone regenerative material in the treatment of periodontal intrabony osseous defects: Clinical and cone-beam computed tomography assessment.

BACKGROUND: Nature and its products can be utilized for regeneration in periodontal destruction and damage to supporting tissues. We come across the use of various graft materials to reestablish the lost bone and for the long-term survival of teeth. The objective of this study was to evaluate the bone fill efficacy of Morinda citrifolia fruit extract in the periodontal bone defect. MATERIALS AND METHODS: This randomized study included twenty patients indicated for periodontal regenerative therapy and were equally divided and assigned into the experimental and control group. Open flap debridement alone was performed in the control group, while placement of extract along with open flap debridement was done in the experimental group. Clinical parameters assessed were gingival index, probing pocket depth, and relative attachment level, and the amount of bone fill was assessed using cone-beam computed tomography (CBCT) at baseline and at 6-month interval. RESULTS: From the values of clinical parameters, there was a mean reduction in probing pocket and gain in attachment level and a 27.7% increase in bone fill in experimental group as compared to the control group from CBCT analysis. CONCLUSIONS: The use of M. citrifolia fruit extract in the intraosseous defect was found to be efficacious in terms of relative attachment level and the amount of bone fill, and it had shown some anti-inflammatory affect.

A role of cellular translation regulation associated with toxic Huntingtin protein.

Huntington's disease (HD) is a severe neurodegenerative disorder caused by poly Q repeat expansion in the Huntingtin (Htt) gene. While the Htt amyloid aggregates are known to affect many cellular processes, their role in translation has not been addressed. Here we report that pathogenic Htt expression causes a protein synthesis deficit in cells. We find a functional prion-like protein, the translation regulator Orb2, to be sequestered by Htt aggregates in cells. Co-expression of Orb2 can partially rescue the lethality associated with poly Q expanded Htt. These findings can be relevant for HD as human homologs of Orb2 are also sequestered by pathogenic Htt aggregates. Our work suggests that translation dysfunction is one of the contributors to the pathogenesis of HD and new therapies targeting protein synthesis pathways might help to alleviate disease symptoms.