Heat shock protein 2 promoter drives cre expression in spermatocytes of transgenic mice

Abstract We generated transgenic mouse line C57BL/6‐ Tg(Hspa2‐cre)1Eddy/J ( Hspa2 ‐cre), which expresses cre‐recombinase under the control of a 907‐bp fragment of the heat shock protein 2 ( Hspa2 ) gene promoter. Transgene expression was determined using Gt(ROSA)26Sor tm1Sor /J (ROSA26) and Tg(CAG‐Bgeo/GFP)21Lbe/J (Z/EG) reporter strains and RT‐PCR and immunohistochemistry assays. Hspa2 ‐cre expression mimicked the spermatogenic cell‐specific expression of endogenous HSPA2 within the testis, being first observed in leptotene/zygotene spermatocytes. Expression of the transgene also was detected at restricted sites in the brain, as occurs for endogenous HSPA2. Although the results of mating the Hspa2 ‐cre mice to mice with a floxed Cdc2a allele indicated that some expression of the transgene occurs during embryogenesis, the Hspa2 ‐cre mice provide a valuable new tool for assessing the roles of genes during and after meiotic prophase in pachytene spermatocytes. genesis 48:114–120, 2010. Published 2009 Wiley‐Liss, Inc.