Life history of animals is better characterized by a high variability of accessibility and composition of food as well as a variable, energy-consuming activity pattern. Despite all this variability, in or caused by the external environment, organisms have to ensure a relatively stable internal environment compatible with the needs of their metabolism.
In the case of energy metabolism the organism has to balance the needs of energy consumption by energy uptake or the mobilization of stored energy at any time. The regulatory process that guarantees this balance has been termed energy homeostasis.
Energy storage components, predominantly neutral lipids help to sustain the organismal energy homeostasis system in periods of negative energy balance. Much like in mammals, the fruit fly Drosophila stores lipids in intracellular lipid droplets of specialized cells, which are the building blocks of an extensive storage tissue called the fat body (shown in green in Fig.2).
The amount of lipids being stored in the fat body varies widely giving rise to “lean” or “obese” flies.

The groups research interest focuses on the identification and functional characterization of genes which control the amount of lipids being stored in flies and - if present - their mammalian orthologs.
To this aim we apply functional genomics, comparative transcriptome analysis involving GeneChips, subcellular proteomics and physiological assays.
Current projects involve the functional analysis of lipid storage droplet-associated proteins (to this issue see also the project of Dr. Mathias Beller) and lipases as well as members of the adipokinetic hormone signal transduction pathway to elucidate the mechanisms of lipometabolism in the fly and address their relevance for the understanding of human diseases such as obesity.

Selected publications:

Original articles:

Grönke, S., Bickmeyer, I., Wunderlich, R., Jäckle, H. and Kühnlein, R. P. (2009): curled Encodes the Drosophila Homolog of the Vertebrate Circadian Deadenylase Nocturnin. Genetics 183 (1), 219-232 ; issue highlight

Grönke, S., Müller, G., Hirsch, J., Fellert, S., Andreou, A., Haase, T., Jäckle, H., Kühnlein, R. P. (2007): Dual Lipolytic Control of Body Fat Storage and Mobilization in Drosophila. PLoS Biology 5 (6), e137, http://dx.doi.org/10.1371/journal.pbio.0050137

Beller, M., Riedel, D., Jänsch, L., Dieterich, G., Wehland, J., Jäckle, H. and Kühnlein, R.P. (2006): Characterization of the Drosophila lipid droplet subproteome. Mol. Cell. Proteomics 5 (6), 1082-1094

Grönke, S., Mildner, A., Fellert, S., Tennagels, N., Petry, S., Müller, G., Jäckle, H., Kühnlein, R. P. (2005): Brummer lipase is an evolutionary conserved fat storage regulator in Drosophila. Cell Metabolism 1 (5), 323-330

Grönke, S., Beller, M., Fellert, S., Ramakrishnan, H., Jäckle, H., Kühnlein, R. P. (2003): Control of Fat Storage by a Drosophila PAT Domain Protein, Current Biology 13 (7), 603-606

Review:

Kühnlein, R. P.: Drosophila as a lipotoxicity model organism - more than a promise?
Biochimica et Biophysica Acta – Molecular and Cell Biology of Lipids, published ahead of print September 23rd, 2009, http://dx.doi.org/10.1016/j.bbalip.2009.09.006

Fig.2