Identification and Androgen Regulation of a 156-kDa Hemeprotein in the Harderian Gland of the Syrian Hamster

Vilchis, Felipe; Damsky, Rebeca; Heuze, Yvonne; Enríquez, Juana; Chávez, Bertha

doi:10.1006/gcen.1996.0032

Cited by 7 publications

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“…Notably, male sex steroids sustain repressive effects on ALA-S1 activity and porphyrin levels (Domínguez et al 1994) but do not change the abundance of type II cells (McMasters & Hoffman 1984) or the output of a haemcontaining protein, which was considered to be involved in regulation of porphyrin synthesis (Vilchis et al 1996). Here we found that the male HG contains less ferrochelatase mRNA than the liver, and the level of mRNA expression was not modified by castration or by the administration of testosterone to castrated males.…”

Section: Discussionmentioning

confidence: 51%

“…In this regard, the role of haem in HG physiology appears to be even less clear, particularly because the cellular content of haem is nearly undetectable and because HG ferrochelatase activity is minimal (Thompson et al 1984, Nagai et al 1997. Although the incorporation of ferrous iron into protoporphyrin IX to form haem has not been clearly demonstrated in Harderian tissue, the specific synthesis of considerable amounts of androgen-induced haemoproteins, whose production shows gender-associated differences (Vilchis et al 1996), along with the relative content of glandular cytochrome P450 scc (Vilchis et al 2002), is indirect evidence of local ferrochelatase activity.…”

Section: Discussionmentioning

confidence: 99%

“…However, the expression of this enzyme in HG is still a matter of controversy, especially because of its low or almost undetectable activity (Thompson et al 1984, Nagai et al 1997. Nevertheless, the relative abundance of cholesterol side-chain cleavage cytochrome P450scc (Vilchis et al 2002), together with the large amount of androgen-regulated haem proteins (Vilchis et al 1996) and the high concentrations of intraglandular iron (Hoffman & Jones 1981), strongly suggests a functional role for this mitochondrial enzyme. By isolating the specific cDNA, we provide experimental evidence of the transcriptional activity of ferrochelatase in HG.…”

Section: Introductionmentioning

confidence: 99%

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The influence of sex steroid hormones on ferrochelatase gene expression in Harderian gland of hamster (Mesocricetus auratus)

Vilchis¹,

Ramos²,

Timossi³

et al. 2006

Journal of Endocrinology

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Ferrochelatase (protohaem ferrolyase, EC 4·99·1·1), the terminal enzyme of the haem biosynthetic pathway, catalyses the insertion of ferrous iron into protoporphyrin IX to form protohaem. The Syrian hamster Harderian gland (HG) is known for its ability to produce and accumulate large amounts of protoporphyrins. In this species, the female gland contains up to 120 times more porphyrin than the male gland. Data from biochemical studies suggest that this gland possesses the enzymatic complex for haem biosynthesis but lacks ferrochelatase activity. The abundance of intraglandular haem proteins does not support this idea. To gain more insight into this process, we isolated cDNA for ferrochelatase from hamster liver, using the 5 -and 3 -rapid amplification of complementary DNA ends (RACE), and investigated its expression in HG from males and females. The full-length cDNA comprises an open reading frame of 1269 bp encoding a polypeptide of 422 amino-acid residues. Hamster DNA sequence exhibits 92% identity to mouse and 87% identity to human sequences. The predicted hamster enzyme was shown to have structural features of mammalian ferrochelatase, including a putative NH 2 -terminal presequence, a central core of about 330 amino-acid residues and an extra 30-50-amino-acid stretch at the carboxyl-terminus. RNA blotting experiments indicated that this cDNA hybridized to a liver mRNA of about 2·1 kb, while a weak hybridization signal was observed with mRNA from HG preparations. RT-PCR assays confirmed the expression of specific transcripts in both tissues. Male glands contained approximately twofold more enzyme mRNA than female glands. Likewise, the intraglandular content of mRNA varied during the oestrous cycle, with the highest levels found in the oestrous phase. These cyclic variations were less evident in liver. Ovariectomy plus treatment with progesterone or 17 -oestradiol plus progesterone increased ferrochelatase mRNA of the gland. In HG of short-or long-term castrated males, the administration of testosterone did not affect the ferrochelatase mRNA concentration. Based on mRNA expression levels, we conclude that Harderian ferrochelatase may play an active role in maintaining the physiological pool of haem required for processing cytochromes and other glandular haem proteins. Likewise, the sex-steroid hormones appear to have only a modest influence upon Harderian ferrochelatase.

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Section: Discussionmentioning

confidence: 51%