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Fhl5/Act, a CREM-binding transcriptional activator required for normal sperm maturation and morphology, is not essential for testicular gene expression

Aurélie Lardenois1, Frédéric Chalmel1, Philippe Demougin2, Noora Kotaja3, Paolo Sassone-Corsi4 and Michael Primig1*

Author Affiliations

1 Inserm, U625, Université Rennes 1, IFR140, Rennes, F-35042, France

2 Biozentrum, Klingelbergstrasse 50-70, CH-4056 Basel, Switzerland

3 University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland

4 University of California, Irvine, CA 92697, USA

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Reproductive Biology and Endocrinology 2009, 7:133  doi:10.1186/1477-7827-7-133

Published: 24 November 2009



The LIM domain protein Fhl5 was previously found to interact with CREM, a DNA binding transcriptional regulator necessary for spermiogenesis in mammals. Co-transfection experiments using heterologous promoter constructs indicated a role for Fhl5 in transcriptional up-regulation of CREM-dependent testicular genes. Male mice lacking Fhl5 were reported to be fertile but displayed partially abnormal sperm maturation and morphology.


To identify Fhl5 testicular target genes we carried out two whole-genome expression profiling experiments using high-density oligonucleotide microarrays and total testis samples from Fhl5 wild-type versus homozygous mutant mice first in different and then in isogenic strain backgrounds.


Weak signal differences were detected in non-isogenic samples but no statistically significant expression changes were observed when isogenic Fhl5 mutant and wild-type samples were compared.


The outcome of these experiments suggests that testicular expression profiling is extremely sensitive to the genetic background and that Fhl5 is not essential for testicular gene expression to a level detected by microarray-based measurements. This might be due to redundant function of the related and similarly expressed protein Fhl4.