The Multifaceted Roles of Lamins in Lung Cancer and DNA Damage Response.

Emerging evidence suggests that lamin functions are not limited to maintaining the structural integrity of the nucleus in eukaryotic cells but that these functions affect many facets of cancer biology. An increasing number of reports suggest that adaptive changes in the lamin subtype composition within the nuclear lamina could affect essential features of cancer development and aggressiveness. These include regulation of cellular stiffness and mobility as well as epithelial-to-mesenchymal transition (EMT), all of which directly impact the metastatic properties of cancer cells. Additionally, insights from studies on the physiological functions of lamins suggest that cancer cells could hijack the ability of lamins to modify chromatin accessibility, cell cycle regulation, and DNA damage response. Here, we present a comprehensive overview of the role of lamins in lung cancer and DNA damage response, which is commonly evoked by lung cancer therapies. Collectively, this information should help better understand the sometimes-conflicting reports on lamin functions in lung cancer as well as in other cancer types.

Mixotrophic growth of the extremophile Galdieria sulphuraria reveals the flexibility of its carbon assimilation metabolism.

Galdieria sulphuraria is a cosmopolitan microalga found in volcanic hot springs and calderas. It grows at low pH in photoautotrophic (use of light as a source of energy) or heterotrophic (respiration as a source of energy) conditions, using an unusually broad range of organic carbon sources. Previous data suggested that G. sulphuraria cannot grow mixotrophically (simultaneously exploiting light and organic carbon as energy sources), its photosynthetic machinery being repressed by organic carbon. Here, we show that G. sulphuraria SAG21.92 thrives in photoautotrophy, heterotrophy and mixotrophy. By comparing growth, biomass production, photosynthetic and respiratory performances in these three trophic modes, we show that addition of organic carbon to cultures (mixotrophy) relieves inorganic carbon limitation of photosynthesis thanks to increased CO2 supply through respiration. This synergistic effect is lost when inorganic carbon limitation is artificially overcome by saturating photosynthesis with added external CO2 . Proteomic and metabolic profiling corroborates this conclusion suggesting that mixotrophy is an opportunistic mechanism to increase intracellular CO2 concentration under physiological conditions, boosting photosynthesis by enhancing the carboxylation activity of Ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) and decreasing photorespiration. We discuss possible implications of these findings for the ecological success of Galdieria in extreme environments and for biotechnological applications.