Mmp1a, the murine ortholog of human Matrix Metalloproteinase 1 (MMP1), is a key enzyme involved in extracellular matrix (ECM) degradation and remodeling. It is associated with various biological processes such as tumorigenesis, inflammation, and tissue repair, and is thought to signal through protease-activated receptor-1 (PAR1) [1,3,4]. The discovery of Mmp1a in 2001 provided a valuable tool for in vivo studies of MMP1-mediated processes in mice [1].

Mmp1a-deficient mice have been instrumental in understanding its functions. In lung cancer models, Mmp1a deficiency leads to significantly decreased tumor growth and angiogenesis [3]. Co-implantation of lung cancer cells with wild-type Mmp1a(+/+) fibroblasts can restore tumor growth in Mmp1a-deficient animals, highlighting the critical role of stromal-derived Mmp1a [3]. Also, in atherosclerosis models, deficiency of Mmp1a suppresses the development of atherosclerosis [2]. In contrast, in intervertebral disc degeneration, injection of recombinant MMP1a can induce mild to moderate degeneration of the intervertebral discs (IVDs) [5].

In conclusion, Mmp1a plays essential roles in tumorigenesis, angiogenesis, and atherosclerosis development as revealed by gene knockout mouse models. These models have provided insights into its functions in these disease areas, helping to understand the underlying mechanisms and potentially guiding the development of MMP-targeted therapeutics.