Introduction: A tribute to cell-to-cell channels

Hypothesis is the principle of growth in knowledge. In framing a hypothesis, one seems to contemplate the nonexistent and ponder over a number of alternatives, which do not necessarily exist. It is not put forward merely on a supposition, which is the work of imagination, but through integral knowing or intuition. Similarly, a creative work is not blind imitation or mechanical repetition. It is synthetic insight which advances by leaps. A new truth altogether unknown, startling in its strangeness, comes into being suddenly and spontaneously owing to the intense and concentrated interest in the problem (Radhakrishnan, 1937). Truth is not factitious; it is a thing which cannot be arbitrarily made but is (Radhakrishnan, 1937). One such truth was revealed four decades ago upon discovery of cell-to-cell channels that interconnected the cytoplasmic interiors of cells which were not electrically excitable (Kanno & Loewenstein, 1964a, 1966; Loewenstein & Kanno, 1964b, 1966). Startling in its strangeness was this truth, then as it is now - that the channels transmit somatic-genetic growth regulatory signals; Werner's intense and concentrated efforts aroused curiosity in the minds of many young investigators. This laid a solid foundation on which several glorious edifices that portray the many panoramic views of the functional role of cell-to-cell channels and the mysterious ways in which they conglomerate into gap junctions and then disassemble are continuing to be raised. The diversity of the connexin gene family and the many ways in which various connexins can oligomerize, form channels, assemble into gap junctions and transmit signals are constantly raising a vow among gap junction biologists: when the fire lights up, the smoke disappears. Werner Lowenstein both created the initial sparks and stoked them into the radiant flames that embody our current knowledge of gap junctions. Various articles authored by some of the foremost scientists in this special issue are living testament to Professor Werner Lowenstein's legacy in the field of gap junctions and cell-to-cell communication in health and disease. It is my sincere hope and ardent belief that these articles will inspire the future generation of biologists, as Werner's work inspired my generation of gap junction biologists.