Peptide: N- glycanase (PNGase) enzyme cleaves oligosaccharides from the misfolded glycoproteins and prepares them for degradation. This enzyme plays a role in the endoplasmic reticulum associated degradation (ERAD) pathway in yeast and mice but its biological importance and role in multicellular development remain largely unknown.

The translationally controlled tumor protein (TCTP) is a highly conserved multifunctional protein, preferentially expressed in mitotically active tissues and is a potential biomarker and a therapeutic target for lung cancers. An understanding of the biology of this molecule and model systems for the screening of drugs is still awaited. In the absence of complete crystal structure, NMR structures as templates were used for homology modeling and MD optimization of both Dictyostelium discoideum and human TCTPs, which was followed by pocket-site prediction, ligand screening and docking. Rescoring of TCTP–ligand complexes was done using MD and MM-PBSA approaches. D. discoideum TCTP was expressed under a constitutive promoter and the endogenous RNA in multicellular structures formed was localized by in situ hybridization. Based on the interactions and binding energy scores, two novel compounds were identified as the best potential inhibitors that could be further used for the development of drug candidates. Inhibition of cell proliferation was observed in the strain overexpressing Dictyostelium TCTP and in situ hybridization results show them to be localized in the prestalk (dying cell population) cells. D. discoideum and human TCTPs share similar dynamic behaviors; overexpression of Dictyostelium TCTP inhibits cell proliferation. D. discoideum could be used as a model system for understanding the biology of this molecule and also for drug screening.

StarvedDictyosteliumcells aggregate into groups of nearly 10⁵cells. AMPK is a highly conserved serine/threonine protein kinase consisting of a catalytic and two regulatory subunits. As multi-cellular development inDictyosteliumis initiated upon starvation, we explored the role of the energy sensor, AMPK, which shows significant similarity to human AMPK and is expressed throughout development. Deletion of theampkαgene results in the formation of numerous small-sized aggregates that develop asynchronously to form few fruiting bodies with small sori and long stalks. On the other hand,ampkα^OEcells form fruiting bodies with small stalks and large sori when compared with wild-type, Ax2. A minimum of 5%ampkα⁻cells in a chimaera with Ax2 cells was sufficient to reduce the aggregate size. Also, the conditioned media collected fromampkα⁻cells triggered Ax2 cells to form smaller aggregates. The starvedampkα⁻cells showed low glucose levels and formed large aggregates when glucose was supplied exogenously. Interestingly,ampkα⁻cells exhibit abnormal cell-type patterning with increased prestalk region and a concomitant reduction of prespore region. In addition, there was a loss of distinct prestalk/prespore boundary in the slugs.

Sirtuins belong to class III histone deacetylases and require NAD+ for its activity. They relate to nutritional state of the cell and directly link cellular metabolic signalling to the state of protein post-translational modifications. Sirtuins play an important role in healthy aging, longevity, age-related diseases as well as the cell survival mechanism like autophagy. Here, we investigate the functions of Dictyostelium discoideum Sir2D that show similarity to human SIRT1. This gene is expressed throughout growth and development. Overexpression of sir2D promotes cell proliferation and the fusion protein show nuclear localization. To facilitate the study of the function of Sir2D, we created sir2D knockout by gene disruption, which show inhibition in cell proliferation and developmental defects like smaller aggregates and multi-tipped structures. When developed as chimeras with wild-type cells, the sir2D- cells show reduced ability to form spores. Results show prespore and prestalk differentiations to be impaired in the mutant strain. Sir2D regulates the expression of several autophagic genes (Atgs) and the sir2D deficient strain shows reduced autophagic flux. In conclusion, Sir2D plays a role in cell differentiation, modulates the expression of both prespore and prestalk genes and play a role in autophagy.