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Post-translational processing and renal expression of mouse Indian hedgehog
R P Valentini1, W T Brookhiser, J Park
1Department of Pediatrics, University of Michigan Medical School, Ann Arbor, Michigan 48109-0676, USA.
The Journal of Biological Chemistry
|March 28, 1997
Summary
Indian hedgehog (Ihh) undergoes specific post-translational processing, similar to other hedgehog proteins. Ihh transcript expression is found in developing mouse tissues and adult kidney tubules.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- The Indian hedgehog (Ihh) protein is crucial for embryonic development.
- Understanding its processing and expression is key to deciphering its biological roles.
Purpose of the Study:
- To investigate the post-translational processing of mouse Indian hedgehog (Ihh).
- To determine the temporal and spatial expression patterns of Ihh during mouse development and in adult kidney.
Main Methods:
- Cloning of full-length mouse Ihh cDNA.
- In vitro transcription/translation assays.
- Site-directed mutagenesis to create Ihh mutants.
- In situ RNA hybridization.
- Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR).
Main Results:
- Two translation initiation sites were identified, with the internal site sufficient for producing mature Ihh forms.
- Ihh processing involves signal peptide cleavage and internal proteolytic cleavage, yielding 19-kDa and 26-kDa peptides, dependent on His313.
- Ihh transcript is detected early in developing gut (10 dpc), cartilage (14.5 dpc), and urogenital sinus.
- Transcript levels in the metanephros increase with gestational age, peaking in adulthood.
- In adult kidneys, Ihh expression is localized to proximal convoluted and straight tubules.
Conclusions:
- Mouse Ihh processing is analogous to Sonic and Drosophila hedgehog, requiring a conserved serine protease motif.
- Ihh exhibits dynamic temporal and spatial expression during embryogenesis and is specifically localized in adult kidney tubules, suggesting critical roles in kidney development and function.