Dysregulation of renal MMP-3 and MMP-7 in canine X-linked Alport syndrome.

Matrix metalloproteinases (MMPs) play an important regulatory role in many biological and pathological processes and their specific role in Alport syndrome (AS) is not yet clearly defined. In this study, the naturally occurring canine X-linked AS was used to demonstrate a potential role for MMP-3 and MMP-7 in Alport renal pathogenesis. Recently, we demonstrated that the expression of MMP-2, MMP-9 and MMP-14 was upregulated in the renal cortex of dogs with a spontaneous form of XLAS. In the present study, we examined necropsy samples of renal cortex from normal and XLAS dogs for MMP-3 and MMP-7 as they have the potential to activate MMP-2 and MMP-9. Immunohistochemical analysis showed strong immunostaining for both MMP-3 and MMP-7 in the interstitial space of XLAS kidneys, while virtually no immunostaining was observed in similar fields from normal dogs. RT-PCR and casein zymography confirmed that both mRNA transcripts and activities of MMP-3 and MMP-7 are elevated in XLAS kidneys. The induction of these MMPs likely contributes to tissue destruction associated with the fibrogenic process, while augmenting the activation of MMP-2 and MMP-9 by MMP-3 and MMP-7 in XLAS. Thus, these data further implicate a role for the MMPs in progressive renal pathogenesis associated with AS.

Cochlear whole mount in situ hybridization: identification of longitudinal and radial gradients.

The morphology of the organ of Corti has a radial asymmetry and also changes longitudinally from base to apex. Cellular localization of transcripts within the inner ear has relied primarily on the use of sectioned tissue with in situ hybridization. However, radial and longitudinal gradients of expression are not readily recognized using sectioned tissue owing to problems in visualization of signals with varying intensities. Herein, we describe the use of whole mount in situ hybridization for identification of cochlear longitudinal and radial expression gradients in the neurosensory epithelium, hair cells. Not only can these hair cell gradients be shown in adult tissues, but also the developmental up-regulation and down-regulation of genes and their associated spatio-temporal expression patterns can be demonstrated.