Differentiation of an apical extracellular matrix: the Drosophila larval cuticle

Group members: Alphabetical list

Secretary: Anna-Maria Entian
Phone: +49 (0)7071 - 601 336
Fax: +49 (0)7071 - 601 305

Epithelial apical extracellular matrices

To implement their physiological and barrier functions, many epithelia produce – along with extensive cell-cell contact sites, an apical extracellular matrix (aECM). The production of an aECM implies that basic cellular processes like transcription and secretion have to be coordinated in time and space. To study the molecular mechanisms of aECM production, we have chosen the exoskeleton of the Drosophila larva called the cuticle as a model tissue.   

The Arthropod Cuticle – an amenable aECM

Most organisms on Earth have an exoskeleton to protect themselves against enemies, pathogens and dehydration and to maintain their body shape. Probably due to their highly versatile exoskeleton, arthropods are a very successful taxon in evolution in terms of species number. The arthropod cuticle is a polysaccharide containing aECM that is produced by the epidermal cells at their apical side. It consists of three functional layers (Figure 1): the outermost waterproof lipids and wax-containing envelope, the middle epicuticle composed of cross-linked proteins, and the inner procuticle characterized by a highly ordered chitin-protein lattice; these to layers together are responsible for cuticle stiffness and elasticity.

Figure 1. The Drosophila larval cuticle.

Effectors of cuticle differentiation
In contrast to the well-described histology, the molecular mechanisms governing arthropod cuticle differentiation are largely unknown. We are focusing our analysis on genetically identified major effectors of cuticle differentiation like enzymes catalysing the last steps of chitin production (chitin synthase-1/Krotzkopf verkehrt, CS-1/Kkv and UDP-GlcNAc pyrophosphorylase/Mummy, Mmy) as well as on yet uncharacterised factors such as Knickkopf (Knk), Retroactive (Rtv) and Schlaff (Slf) that are needed for a correct organization of the chitin-protein lattice in the procuticle.

Control of cuticle differentiation
In order to learn about coordination of different molecular processes during aECM formation, we are studying the role of the evolutionary conserved transcription factor Granyhead (Grh) during and the impact of the steroid hormone ecdysone on cuticle differentiation.
 
Cuticle Evolution
To evaluate our findings we are comparing cuticle differentiation in Drosophila and in different higher and lower arthropods both at the molecular and at the histological level. Up to date, it seems that the Drosophila larval cuticle is simpler in its fine architecture than the ones in Tribolium and Parhyale for example, where especially the epicuticle texture is more elaborated.

Relevant publications:

• Moussian B, Schwarz H, Bartoszewski S, and Nüsslein-Volhard C. Involvement of chitin in exoskeleton morphogenesis in Drosophila melanogaster. J Morphol. 2005a Apr;264(1):117-30.
• Moussian B, Söding J, Schwarz H, and Nüsslein-Volhard C. Retroactive, a membrane-anchored extracellular protein related to vertebrate snake neurotoxin-like proteins, is required for cuticle organization in the larva of Drosophila melanogaster. Developmental Dynamics. 2005b Apr 20;233(3):1056-1063.
• Moussian B, and Uv AE. An ancient control of epithelial barrier formation and wound healing. Bioessays. 2005 Oct;27(10):987-90.
• Moussian B, Tang E, Helms S, Tonning A, Schwarz H, Nüsslein-Volhard C, and Uv AE. Drosophila Knickkopf and Retroactive are needed for epithelial tube growth and cuticle differentiation through their specific requirement for chitin filament assembly. Development. 2006 Jan;133(1):163-71.
• Tonning A, Helms S, Schwarz H, Uv AE, and Moussian B. Hormonal regulation of mummy is needed for apical extracellular matrix formation and epithelial morphogenesis in Drosophila. Development. 2006 Jan;133(2):331-41.
• Moussian B, Seifarth C, Müller U, Berger J, and Schwarz H. Cuticle differentiation during Drosophila embryogenesis. Arthropod Structure & Development. 2006 Sept;35(3):137-152.
• Moussian B, Veerkamp J, Müller U, and Schwarz H. Assembly of the Drosophila larval exoskeleton requires controlled secretion and shaping of the apical plasma membrane. Matrix Biology. 2007 Jun;27(5):337-347.
• Schwarz H and Moussian B. Electron-microscopic and genetic dissection of arthropod cuticle differentiation. Modern Research and Educational Topics in Microscopy. 2007 Méndez-Vilas A and Díaz J (Eds.) FORMATEX. 316-325.
• Moussian B. The role of GlcNAc in formation and function of extracellular matrices. Review. Comparative Biochemistry & Physiology Part B. 2008 Feb;149(2):215-26.
• Havemann J, Müller U, Berger J, Schwarz H, Gerberding M and Moussian B. Cuticle differentiation in the embryo of the amphipod crustacean Parhyale hawaiensis. Cell & Tissue Research. 2008 May;332(2):359-70.
• Gangishetti U, Breitenbach S, Zander M, Saheb SK, Müller U, Schwarz H. and Moussian B. Effects of benzoylphenylurea on chitin synthesis and orientation in the Cuticle of the Drosophila Larva. European Journal of Cell Biology. 2009 Mar;88(3):167-80
  

Scientists involved:

• Dr. Bernard Moussian, Group leader
• Umesh Gangishetti, PhD student
• Shaik Khaleelula Saheb, PhD student
• Michaela Norum, PhD student
• Anna Speidel, undergraduate student
  

Former lab members:

• Sigrun Helms, Technician
  
• Christoph Seifarth, Diploma student
• Hsin-Ning Ho, Master thesis
• Pascal Reisewitz, Diploma student
• Justus Veerkamp, Diploma student
• Koteswara Rao Thota, Master thesis
• Mareike Zander, undergraduate student
  
• Sophie Breitenbach, undergraduate student
• Roberta Haddad Tóvolli, undergraduate student